snab invite an expert topic 4 - nuffield foundation · 12/10/1996 · 4 © 2008 gatsby technical...

© 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college.

1

Invite an expert

OutcomesStudents will be able to:

question a live presenter effectively•

evaluate live presentations•

provide polite, constructive feedback to a •speaker.

Time requiredAllow 30 minutes to 50 minutes for the speaker presentation plus 15 minutes for questions. Students shouldtakenotesonbriefingsheet1.

Outline of the activityYou will need to organise a speaker ahead of time, or help students arrange this. A group of students shouldberesponsibleforfindingoutaboutthespeaker. They should arrange who will introduce the speaker, and who will chair the question session and / or give the vote of thanks at the end. The speaker should be made aware that their presentation is part of an activity for pupils to develop their listening and observing skills.

Before the talk begins, give students a copy of briefingsheet1forthemtomakenotes,andmakesure they have had a chance to read the questions.

End with a discussion on what the students may have noticed in the presentation itself.

Did the speaker convey their passion for the •subject? How?

Was the speaker a natural communicator?•

Was it an enjoyable, engaging performance to •watch and listen to?

Did you feel the speaker was an expert in their •field?

Tips and strategiesThe talk could be given during an assembly, during a lunch break, or as part of a Post–16 event or a Science Club.

This activity can be run in conjunction with ‘Taking notes from a presentation’, so that students can constructively criticise the presentation, whilst being polite to the external speaker.

Ensure that the presenter is aware of the purpose of the session and that the students will be evaluating the presentation.

Emphasise to the students that their aim is to continue to improve their skills in listening and observing, so they should not get carried away with the evaluation side of the task. Point out that by evaluating the presentation like this, they are helping to consolidate their learning and identifying questions they could ask to extend their understanding.

Students should be made aware that asking questions is a polite way to let the speaker know you have been listening and you are interested in knowing more.

Thisactivitygivesstudentstheopportunitytochoose,organiseandbenefitfromoutsideexpertspeakers. There is an emphasis on treating the speaker courteously.

1 of 1

SNAB Topic 4



In this activity you will have the opportunity to practise the skills needed to make the most of presentations by experts.

Part A Before the presentation

1 Fill in the following before the presentation.

Name of speaker: __________________________________________________

Title of presentation: __________________________________________________ What is the presentation about?

Part B During the presentation

2 Make a note of all the questions you would like to ask the speaker at the end.

3 Make a note of the important points from the presentation.

Invite an expert

Briefing sheet 1

1 of 2

SNAB Topic 4


Invite an expert

Briefing sheet 1

Part C After the presentation 4 How would you rate the presenter on the scales below?

Quality of communication

OK Very good Brilliant

Quality of science content

OK Very good Brilliant How well structured and engaging was the talk?

OK Very good Brilliant Give reasons for your answer. This will be feedback for the speaker.

5 As a class, organise some polite and constructive feedback which can be forwarded to the speaker along with thanking them for their time and effort. Think about the balance of positive and less positive remarks. Is it possible to make constructive suggestions about how the talk could be made even better, rather than directly criticising?

2 of 2

SNAB Topic 4



Part D Self evaluation

Oncethepresentationhasfinished,evaluateyourself.Foreachitembelowgiveyourself a mark from 1 to 5.

Item Score 1-5

I concentrated throughout the whole presentation

I wrote appropriate notes which will help me remember points in the future

I was able to summarise what the speaker said

I understood everything that the speaker said

I was able to ask a question(s) at the end to help me understand a point better

I was thinking about other ideas in science that are related to the presentation

I made a note of good points and not so good points about the way the speaker presented, so I can improve my own style

TOTAL SCORE

After the presentation, discuss these questions in pairs or small groups.

1 Did the presenter answer the questions you formulated beforehand? If so, what were the answers?

2 What new information did you learn during the presentation?

3 Which questions were left unanswered?

4 Did the writing of questions before the presentation help you to learn from it? In what way?

5 In pairs, identify the key features which make a good presentation.

Invite an expert

Briefing sheet 2

1 of 1

SNAB Topic 4

© 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college. © 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college.

7

Listening to a podcast

The advent of the podcast, which can be downloaded onto a computer or portable audio player and listened to at anytime, is revolutionising the way programmes and information are being disseminated. This activity helps students to improve their learning from listening.


apply techniques for learning from podcasts•

take notes and summarise information given in •a podcast

identify the theme(s) covered in a podcast.•

Time requiredThe length of the podcast plus approximately 15 minutes.

Outline of the activityYou will not be surprised to see similarities between this activity and ‘Taking notes from a presentation’. It is worth covering this separately, as students are required to apply different skills in the absence of visual prompts.

1 As with ‘Taking notes from a presentation’, it is important to discuss the possible approaches to the task with students. The slides for ‘Taking notes from a presentation’ could be used to recap techniques.

2 Explain that students will be listening to an audio broadcast, and they will be required to produce a summary.Thebriefingsheetcanbeusedifyouthinkit appropriate – it is very similar to that used in ‘Taking notes from a presentation’. You may instead suggest to the students that they use what they’ve learned previously in tackling this activity.

As before, it is useful for the students to evaluate their summaries at the end of the activity. This could be done using self- or peer-assessment, or a combination of both. In this instance, no student evaluation form is provided – you could use the one in ‘Taking notes from a presentation’ if you feel one is needed.

Tips and strategiesAlthough this is a mode of learning that students are unlikely to encounter in the classroom, it is highly likely that they will use podcasts (or audio broadcasts) as sources at some point. Although students may become experts at digesting presentations, they may not recognise the skills required to fully access a podcast. As such, you should encourage the students to formalise their approach to listening in this way.

In this instance, you might want to listen to the podcast beforehand so you are ready for any questions that the students might have at the end.

A suggested podcast is provided in the links for Topic 4.

1 of 1

SNAB Topic 4



Listening to a podcast

Briefing sheet

You may have done some work already on learning effectively from presentations. In this activity you will learn from a podcast. This requires slightly different skills as there are no visual prompts for you.

These tips will be useful in helping you to produce a summary.

1 Before listening to the podcast, make sure you have the equipment you need (paper, pen etc). Focus your mind on the task.

2 Write the title of the podcast and the name of the presenter. It may also be useful to record the date and place where you are listening to the podcast, so you can reference any information you use later.

3 Draw a line down the page, about a third of the way in from the right. Put your summary of the podcast on the left and your own thoughts and any questions you think of on the right.

4 Don’t lose focus – write down any thoughts / questions quickly, so you don’t lose track of the podcast. Although you will not have the opportunity to ask questions directly at the end, you will be able to research them later.

5 As the podcast proceeds, try to break it down into sub-topics. These may be clearly indicated during the course of the podcast, but if they are not you need to pick them out yourself. As you write the summary, keep the sub–topics in separate paragraphs with headings.

6 Tryexperimentingwithvisualrepresentations(e.g.flowdiagram,spiderdiagram,concept map, mind map) for some sub-topics. Compare this with making notes in written text.

7 If time allows, write a sentence after each paragraph / sub–topic summarising the main message of that sub-topic in the podcast. You may prefer to do this at the end of the podcast.

8 If you are able to sketch some illustrations, this may be very helpful (the old adage says ‘apicturespeaksathousandwords’),butyoumaynotbeconfidentdoingsowhileyouarelistening.

9 At the end of your summary, record the main ideas covered in the podcast.

10 Write down anything that you feel you need to learn about, in addition to any questions younotedduringthepodcast.Itisgoodpracticetodosomeresearchtofindouttheanswers afterwards.

11Makebriefnotesreflectingonthedifferenttechniquesyouusedfortakingnotesfromthe podcast. Which ones worked well, and why?

1 of 1

SNAB Topic 4


11

Science whispers

This activity (based on a popular game) develops skills of listening and communicating. Students have to understand and relay information to their peers without losing the main content and meaning.


quicklyassimilatenewscientificinformation•

accurately disseminate the information they •have just learnt.

Time requiredAllow one hour class time (depends on how many pairings take place – see ‘Tips and strategies’).

Outline of the activityAsk students to get into groups of four. Each group picks a podcast to listen to and makes notes of all the essential information needed to tell someone else. The podcast should be no longer than ten minutes in length, so that students can listen to it again if wished. The group shares ideas of what to present and then splits up with their notes. Each personfindssomeonefromanothergroupandmakesa pair.

Intheirnewpairs,eachstudenthasfiveminutestorelay what they have found out from their podcast. They can make notes on each other’s presentations. Nowthispairingsplitsandeachmemberfindsanother student to partner up with and the process repeats. However, this time each student has to relay their original podcast information and the new information they got from the previous pairing. Once again students take notes and all students join their originalgroupstodiscusstheirfindings.

Do they all agree that they have the correct information, or do they feel they are missing some? Did they ask questions during / after the pair presentations? It is important to note the differences between listening to a podcast and listening to a person; in the latter type of presentation, if they

do not understand they have the opportunity to ask questionsandgainclarification.

The whole class reconvenes for a plenary session. Ask for a few volunteers to explain all four pieces of information they have gained to the rest of the class. The class (particularly those who gave the information to the volunteers) can agree or disagree about whether accurate information was shared. Or was someone, somewhere not concentrating?

1 of 1

Tips and strategiesThis activity can be run in conjunction with activities on making presentations, or with the activity ‘Listening to a podcast’.

There is no limit to how many times the students can pair up and swap information, but this will be determined by the length of your lesson.

A selection of podcasts (that you are familiar with) could be provided at the beginning of the lesson. As most podcasts last longer than ten minutes, choose appropriate ten minute segments from long podcasts for students to select.

An alternative would be for the student relaying the information to a new partner to be ‘watched’ by the student who gave them theinformationinthefirstplace.Afeedbacksession on whether the correct information was relayed (and understood) could follow.

This activity is an opportunity to cover a range of science sub-topics, or, for example, a range of views on a single topic.

SNAB Topic 4



Science whispers

Briefing sheet

In this activity you will share information from a podcast with other students. Here, the aim of the ‘game’ is to make sure information is not lost along the way!

1Inagroupoffour,findapodcastonthesciencetopicyouarestudyingthatyou would all like to listen to.

2 On your own, write down notes from the podcast that you think would be useful to tell someone else.

3 Compare your notes with the rest of your group. Decide which information is important and discuss whether you have all understood the content. Write down any extra notes you might need.

4 Find another person who was not in your group and take it in turns to give a fiveminutepresentationonwhatyoulearntfromyourpodcasts.Writenotesonwhat they have told you.

5 Find yet another person. This time take turns to give a presentation on the contents of the podcast and the new information from the previous pairing. Write down notes on what you learnt from their presentation.

6 Go back to your groups and look at all the information you have. Discuss the following questions.

•Doyouunderstandalltheinformation?

•Doesanythingnotmakesense?

•Howcanyouensurethatyoupickeduponaccurateinformationandthatyou understood everything?

•Didyouneedtoconsultyournoteswhenexplainingyourtopictoothers?

•Whatinformationwaslost(ifany)whengivingyourpresentations?

7Makeanoteofthespecificskillsandtechniqueswhichwouldallowyoutocarry out this activity successfully. Which of these are you good at, and which need developing further?

1 of 1

SNAB Topic 4


15

Watching a film

This activity guides students through two viewings of a scientific film to help them to focus on specific areas of learning. The Millenium Seed Bank film available on the SNAB website can be used with this activity

2 While watching the film for the second time, students should look for the answers to the questions they formulated, writing the answers down on briefing sheet 2.

3 Ask different students if their questions were answered, and what the answers were. Answers to questions written on the board can be written up too. If there are any questions that have not been answered, ask the students where they might find the answers.

Tips and strategiesEnsure that the students are not assigned any specific instructions or tasks associated with the first viewing. Some of them may wish to take notes (perhaps this is their usual approach to watching a video in class), but encourage them simply to watch on this occasion.

It may be beneficial to give the students a little background information on the film / topic before the first viewing so they are not distracted from viewing because they are thinking ‘what is this about, then?’.

1 of 2


formulate questions after the first viewing • of a film that will help to enhance their understanding during a second viewing

extract key information and understanding from • a film through focussed observation.

Time requiredAllow 40-60 minutes, depending on the length of the film shown.

Outline of the activityOn first viewing a film we may experience a range of emotions which affect the message we take away from it. The first viewing will convey a general impression and raise questions in the viewers’ mind. It would be unfair to expect anyone to remember all the key facts in a film after the first viewing, but they are likely to remember the questions that the film raised. The second viewing allows these questions to be answered and the subtle details of the film to be absorbed.

1 Show the film (a 10-20 minute segment) without giving the students any specific instructions. After the viewing, issue briefing sheet 1 and get the students to fill them in. You may instead choose to use the board to go through this as a discussion. Discuss the outcomes with the whole class, putting a list of questions on the board. It is helpful to place the questions into categories, e.g. those addressing concepts, those addressing processes, those addressing science and those addressing people. It is important that students do not write answers to questions at this stage.

SNAB Topic 4


16

Watching a film

More teacher guidanceWe have all experienced the special feeling at the end of a movie: a minute or two of silence within yourself, when the emotional experience is still with you and the scenes from the movie are running rapidly through your mind. Immediately afterward, you experience a kind of renewed curiosity. Why did the film end that way? Who was really guilty? The response is primarily emotional.

If we watch the same movie twice then the second time is very different from the first: we discover new details about the plot; the characters take shape differently; the opening scene may have a more profound significance; we are more aware of the contribution made by the direction, the photography, the music and so on.

In the classroom, watching a scientific video is also a rich experience which stimulates the mind and the emotions, utilises the capacity for listening and observation and expresses the emotional involvement of the audience. At times, it also stimulates the watchers to express their opinions and take a position as if they were part of the film scenario. When using video in science teaching, these facts should be taken into account in order to make best use of this medium for learning.

In this activity, students practise watching a scientific video for the first and second time for learning purposes. The first viewing is intended to convey a general experience and impression and to raise questions. The second viewing enables students to observe more details and achieve an in-depth understanding of subjects related to the objectives of learning.

Students should be allowed to watch the video and enjoy it in their own way during the first viewing, with no accompanying briefing sheet. Directed questions in the first viewing may detract from the experience and the motivation to continue the activity.

In the discussion, direct the questions to areas of science related to the content being studied in the classroom at the time.

The second viewing may also be guided differently, by asking each group of students to direct their watching to a certain category of questions, according to the classification on the board.

Take into account the variance in learning styles; not all students learn well by listening and watching. A printed abstract of the film may be handed out, in order to see how this helps the students to learn more profoundly and understand better.

SNAB Topic 4

2 of 2



Watching a film SNAB Topic 4

Watching a film

Briefing sheet 1

In this activity you practise techniques which help to focus on gaining specific information from a film.

You have just watched a film. Complete this sheet without discussing it now. You will then watch the film again, the aim being to answer some of the questions you have come up with at this stage.

1 What questions about the science in the film can you think of? These can be on things that you did not understand, or things you want to know more about.

Question i ________________________________________________________

Question ii ________________________________________________________

Question iii ________________________________________________________

Question iv ________________________________________________________

Question v ________________________________________________________

2 Next to each question you have written in 1, write down ‘concept’ if it addresses a scientific concept, ‘person’ if it address a person or people, and ‘process’ if it addresses a process.

You will now watch the film for a second time. Use briefing sheet 2 to record answers to your questions.

3 Note down the key facts that you learned from the film.

For discussion

4 What were the learning benefits of this repetition?

5 Can the same benefit, or more or less, be gained by repeated contact with other kinds of resources, such as websites or textbooks?

6 How can you apply what you have learned about these benefits to your future work?

1 of 1



Watching a film

Briefing sheet 2While watching the film for the second time, you should aim to answer the questions you came up with after the first viewing. You are allowed to write things down during the film this time. There is no need to write out the questions again - just reference them from the first briefing sheet.

Question reference: __________________________________

Answer: _____________________________________________________________ _____________________________________________________________________


Answer: _____________________________________________________________ _____________________________________________________________________


Answer: _____________________________________________________________ _____________________________________________________________________


Answer: _____________________________________________________________ _____________________________________________________________________ Question reference: __________________________________

Answer: _____________________________________________________________ _____________________________________________________________________ Were any of your questions unanswered? If so, where could you find the answers?

1 of 1

SNAB Topic 4


20

© 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college. © 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college.21

Making sense of text: representing it in your own way

Students read a piece of text and then represent it in the way that best helps them to remember it.


locate the theme(s) and keywords within an •article

summarise the theme(s) of an article•

use these skills to make judgements about the •value of an article based on browsing.

Time requiredAllow 30 minutes.

Outline of the activityAny relevant piece of text can be used for this activity.

(The slides are written in the context of Chemistry, but the principles remain the same no matter which science subject you are teaching. You may wish to modify the slides for your own subject.)

1 Give students the text and a blank sheet of A4 paper(orthebriefingsheet).Tellthemthattheaimof the task is to develop their ability to summarise a piece of text in a way that they have not tried before.Theycoulddrawapicture,flowchart,orspider diagram for instance. This may help them to understand and learn the content more effectively than if they simply read through the text. If they are unsure of the different ways that this could be done, the slides may give them some useful ideas. Allocate 15 minutes or so to the activity, depending on the length of the text you have given the students.

2 Get the students into groups of four and get them to swap their work so everybody is looking at someone else’s. Ask students to identify what they like / do not like about the work and to point out

anything they think is incorrect. Get the groups to identify what they think is good practice. Discuss this with the whole class.

3 Make sure you tour the groups during stage 2 — you can then see the range of work being produced and you can identify students who can share their work with the class in a mini-plenary. If a scanner is available, the work of these students could be scanned in and projected onto the board, or they could transfer an outline onto an OHT.

1 of 1

Tips and strategiesMany students are familiar with their preferred learning style. Bring this into your discussion before starting the activity. Stress the importance of a clear visual representation, even for students who are not visuallearners;theyneedtobeabletofindthe key information easily. Students should be discouraged from copying sections wholesale from the text – abbreviations and shorthand should be encouraged.

Point out that visual representations are useful as they can be easier to remember than a large number of details. Students should be encouraged to practise representing information visually, even if this is not as natural to them as other techniques.

SNAB Topic 4

© 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college.221 of 5


Slides

SNAB Topic 4

© 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college. © 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college.232 of 5


Slides

SNAB Topic 4



Slides

SNAB Topic 4

© 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college. © 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college.254 of 5


Slides

SNAB Topic 4



Slides

SNAB Topic 4


27


Briefing sheet

1 Read the text you have been given. Read it through for a second time.

2 Use the space below to represent the text in a way that will help you to remember the key points and to understand how they link together.

3 Avoid copying sections of the text, but do try to capture all of the key points. Try to use abbreviations and shorthand where possible. You are trying to create something that will be easy for you to navigate through. Use a technique of note-makingthatyouhaven’ttriedbefore.Itcouldbeaflowchart,spiderdiagramortable for instance.

Your visual representation:

1 of 1

SNAB Topic 4


28


291 of 3


Biology resource

Humans have been using the warmth and lightfrom wood fires for hundreds of thousands ofyears. Even now up to half the people in the

world cook their food on open fires. Wood fuel isnews again now because it is a renewable source ofenergy. At present almost all our energy comes fromfossil fuels and in the long term these will run out.Burning fossil fuels also releases carbon dioxide andcontributes to global climate change. We need toreplace them with renewable and more sustainablesources of power.

The government has set a target for 10% of our elec-tricity to be generated from renewable sources by2010. At present, renewables supply only 1.5% of UKelectricity.

BiomassTrees are made of biomass. This term covers materialfrom both plants and animals. Wood, straw, animaldung and domestic refuse are all biomass fuels.

Biomass stores energy from the Sun. Chemicalreactions harness the energy in sunlight to synthesise

energy-rich compounds. This is the process of photo-synthesis. Carbon dioxide from the air and waterfrom the ground are combined in this process tomake the carbohydrates that are the main buildingblocks of biomass. When biomass is burnt the carbo-hydrates react with oxygen from the air to make

Photosynthesis

CO2

H2O

H2O

O2

Combustion

Useful�energy

16 Catalyst

Janet Taylor

Wood is a renewable source of energy. Could weuse wood to generate electricity in the UK, andwhat are the advantages and disadvantages?

GCSE key wordsBiomass

Energy resourcesPhotosynthesis

RenewablesSustainability Figure 1 When it burns, wood fuel gives off only the

carbon dioxide it took from the atmosphere when it grew

Box 1 Renewable and sustainableenergy sourcesWind, wave, tidal, solar voltaics (PV), hydro,geothermal and biomass are all renewable energysources. They are called renewable because they donot get used up. However they have another veryimportant advantage over fossil fuels. They do notincrease the amount of the greenhouse gas, carbondioxide, in the atmosphere.

Nowadays the word sustainable is often used inconnection with renewable energy sources. To besustainable, an energy source must not run out,damage the environment, create health hazardsor cause wars or social injustice. A sustainableenergy source is one whose use now will not makeit more difficult for future generations to meettheir needs.

� A tree weighs severaltonnes. About half thismass is carbon. Wherehave the carbon atomscome from?

� A useful website is:http://www.woodfuelresource.org.uk

Tree power

SNAB Topic 4


30

carbon dioxide and water again. The biomass gives offonly the carbon dioxide it took from the atmospherewhen it was growing (Figure 1). If the forests thatsupply the fuel wood are replanted at the same ratethey are cut down then the wood is a renewableenergy source.

Have we got wood to burn?About 9% of the total land area of Great Britain iswoodland. This could give a sustainable yield of nearly700 000 tonnes of air-dried wood per year. In thepast, wood was harvested as the raw material formaking paper but the paper industry has shiftedoverseas. We also import timber for the building

industry, so today we only harvest half the yearlygrowth of wood from our forests.

Table 1 shows that wood is a less concentratedstore of energy than any of the fossil fuels. Because itis bulky the use of wood increases lorry traff ic.However, a wood-fuel industry could help to createjobs in the countryside.

Converting wood energy into heat andelectricityDomestic and community heating projects are alreadyusing the thinnings and trimmings from existingwoods and forests. Landowners and farmers areincreasing the supply of wood fuel by growing ‘energycrops’ like willow or poplar. The wood-fired heatingsystem at Weobley School in Herefordshire uses150–300 tonnes of wood chips every year.

There is debate aboutwhether we haveenough land to growsufficient energy crops.

17September 2004

Fuel Energy content (kJ/g)Wood (air-dried) 15Paper (stacked newspapers) 17Dung (dried) 16Straw 14Domestic refuse 9Oil 42Coal 28Natural gas 55

Table 1 Energy content of fuels

Below: The 350 kWboiler at WeobleySchool inHerefordshire wasinstalled in 1998 toheat the primaryschool, the adjacentsecondary school andthe schools’swimming pool

Above: Coppiceplantations like thiscan provide newhabitats andencourage bio-diversity. They needsmaller amounts ofagricultural chemicalsthan arable crops

Wood is a source of energy for many people aroundthe world, including this family in Guatemala

Box 2 Growing energyThe best energy crop for northern Europeanconditions is coppiced willow. Saplings are plantedand, after 1 year, cut back close to the ground. Thisis called coppicing, and it stimulates several newwoody stems to grow. The crop is allowed to growfor 2–4 years and then the stems are cut. The plantwill grow more stems so the cycle is repeated. Onehectare of land can produce 10 tonnes of air-driedwood per year.

Chr

is K

napt

on/S

PL

Sean

Spr

ague

/Stil

l Pic

ture

s

Weo

bley

Sch

ool

2 of 3


Biology resource

SNAB Topic 4


313 of 3


Biology resource

Purpose-built biomass power stations that generateelectricity from wood burning are being planned andbuilt. Wood can also be burnt in combination withcoal (co-firing) in existing power stations.

Gasification and turbinesToday the furnaces that burn wood for space heatingare clean and eff icient. But when it comes togenerating electricity the favoured method is more hi-tech. Biomass is converted to power in an IGCC(integrated gasification combined cycle) power plant.

Gasification is a combustion process in which thereaction is ‘starved’ of oxygen so that it is notcompletely oxidised. Wood is mainly composed ofcarbon, hydrogen and oxygen. If it is oxidised

completely the carbon and the hydrogen atoms formcarbon dioxide and water:

C + O2� CO22H2 + O2� 2H2O

During gasification wood fuel is heated with a mixtureof gases and air in a sealed container. The mixturedoesn’t contain enough oxygen for all the carbon andhydrogen atoms to be completely oxidised. The overallreaction with the carbon atoms is:

2C + O2� 2CO

The gas produced is mainly carbon monoxide withsome hydrogen, hydrocarbon gases and nitrogen. Tarand ash, formed as by-products, are washed out ofthe mixture. The gas can still burn and is now the fuelfor a combined cycle gas turbine (CCGT) plant.

In these power plants the hot gases produced byburning the carbon monoxide turn the first turbine.They then also heat a boiler to make steam, whichdrives a second turbine. Both turbines turn generators,which produce electricity. Combining them makes thesystem very energy efficient.

Carbon monoxide is a deadly poison but good engi-neering and good practice at the plant make the risksnegligible. IGCC is a clean technology.

The ARBRE projectARBRE stands for ARable Biomass Renewable Energy.The project was set up in Yorkshire. It was a prototypefor a 10 MW IGCC plant, using forest residues andenergy crops. The hope was that it would be the firstof many for Britain.

The plan was to fuel the plant with forest residues atf irst and then switch to coppiced willow. By May2000 some 500 hectares had been planted, with afurther 625 hectares to be established within the year.There were many difficulties. Farmers were reluctantto grow willow, harvesting was difficult and expensive.At the end of May 2003, Yorkshire Water, the ownersand instigators of the ARBRE project, sold thecompany, and it was shut down. The plant hadproduced electricity for just 8 days.

The futureWind power provides the largest share of renewableelectricity. But there are days when there is hardly anywind across the whole of the UK (this happened for afew days during the cold spell in January 2003). It isessential to have other types of power station to backup windfarms on windless days.

Power stations fuelled by wood and other types ofbiomass have the great advantage of being able to gen-erate electricity on demand. The failure of the ARBREproject was a setback, but new projects must beencouraged. Energy crops are both green and flexible.

Janet Taylor is a science teacher and has contributed tomany websites and textbooks.

18 Catalyst

100 km

Below: During theSecond World Warthere was a shortageof petrol and 1 millionvehicles ran on gasfrom wood orcharcoal. Heremechanics are fitting a gas-producing unitto a car

Box 3How much electricitycould energy cropsproduce? Energy crops can be grown on farmland that is not neededfor food. The area could be 1 million hectares by 2010. This is 10 000 km2, about half the area of Wales (see map).

By 2010 energy crops couldgenerate 1000–2000 MW. This is less than 2% of our electricity.In the long term, if 10% of thefarmed area of the UK were tobe planted with willows forcoppicing, 9000 MW could beproduced, enough for two largecities.

Topf

oto

SNAB Topic 4


32


Reading and sharing

Biology

Students will work in pairs to extract information from an article which they will then share with their partner. Each student will then be tested on what they learned from their partner.


source information in an article needed to •complete a summary

present information in a way that can be •accessed by their partner.

Time requiredAllow 40 minutes.

Outline of the activityThis activity puts together a lot of the steps we have come across to support reading for detailed knowledge. It gets students to actively read an article, produce a summary and review their learning with a partner. This learning is then tested. This activity emphasises the effectiveness of teaching something to someone else as a learning tool.

1 Pair the students up and give them all a copy of thearticle.IssuestudentAwithbriefingsheet1,andstudentBwithbriefingsheet2.Tellthemtheyhave ten minutes to complete the task described ontheirbriefingsheet.They are not allowed to communicate with their partner during this part of the activity.

2 After ten minutes, collect all the copies of the article back in. Tell students they have ten minutes to share their summaries and to learn as much as they can from the other person’s work.

1of2

3 When the ten minutes are up, issue the test sheet. This is the same for all students, so they are tested on the aspects they summarised themselves, as well as those covered by their partner. Give them ten minutes to complete the test.

4 Go through the answers for the students to mark them. This could be done in a variety of ways, but is probably best done by peer marking (swapping with students in other pairs, of course) with whole class discussion.

5 Evaluate the activity - this could be done by issuing the student evaluation sheet, or in a discussion.

Tips and strategiesSee next page.

SNAB Topic 4

© 2008 Gatsby Technical Education Projects. This page may be copied solely for use in the purchaser’s school or college.34

Tips and strategiesThis activity follows on from ‘Making sense of text’, and also links to the material covered in ‘Writing a summary’ and ‘Preparing a short presentation’. It is quite a demanding activity, hence the suggestion of a topic covered later on in A2.

Dependingontheconfidenceofyourstudents,you may want to discuss the activities with them. But it will work better if the students do not know what their partner is looking for in the article, otherwise they will know what they are going to be tested on at the end!

You could give students longer than ten minutes to get the information and create their summary, butmorethan15minuteswillunderminethepoint of the activity.

In part 2, where students share their summaries, youcanchoosetoletthemfigureoutthebestway of using their time, or you may give them some guidance. One suggested format would be:

1minuteeach(2minutes)-tooutlinethecontents of their summary and what their brief was

5minutestoreadthroughthesummaryandmakenotes

1minuteeach(2minutes)forquestions

1minuteforfinalscrutinyofthesummary

Part 3 should be presented to the students as being somewhat informal, the aim being to get them thinking about what they did well and what could be improved. You could lighten the mood by offering a prize to the pair who score the highest combined mark.

Reading and sharing

Biology

2 of 2

SNAB Topic 4


35

In this activity you practise writing and sharing summaries.

Student A

Read through the article on ‘Animals in the testing of new therapies’. Then produce a visual summary that you can use to pass on what you have learned to your partner. Your partner will be completing a similar task to share with you. At the end, there will be a light-hearted test on what you have learned.

Your task is to produce some sort of time line of the history of the use of animals in drug safety testing, based on information only found in the article.

The main information to get across is when different drugs were discovered and whendifferentscientificpracticesemerged.Thesepracticesmaybetheresultofnew discoveries or the introduction of new regulations.

Anexamplewhichyoucouldincludeasthefirstpointonyourtimelinemightbe:

19thcenturychemistsinGermanytriedoutanaestheticslikechloroformonthemselves

You are not expected to include extensive details in your time line – you are focussing on the scientists and their practice.

Note that you will not be able to keep hold of your copy of the article after you finishwritingyoursummary.

1of1

Reading and sharing

Biology briefing sheet 1

SNAB Topic 4


36


37

In this activity you practise writing and sharing summaries.

Student B

Read through the article on ‘Animals in the safety testing of new therapies’. Then produce a visual summary that you can use to pass on what you have learned to your partner. Your partner will be completing a similar task to share with you. At the end, there will be a light-hearted test on what you have learned.

Your task is to expand on the points listed below.

1 What stages in the development of new drugs involve the use of animal testing?

2 How is the effect of the drug on an animal monitored?

3 What alternative tests are used to replace animal testing?

Note: You will not be able to keep hold of your copy of the article after you finish writing your summary.

1of1

Reading and sharing

Biology briefing sheet 2

SNAB Topic 4


38


39

1 Name two drugs that were developed in Germany before the First World War and which are still used today.

_____________________________________________________________________________________

2 Whodevelopedacureforsyphilisfromarsenicin1909?

_____________________________________________________________________________________

3Whichcountrywasfirsttointroducelegislationtoensuredrugsaretested before use in humans?

_____________________________________________________________________________________

4 Which animal is currently used to test the effect of hypertension drugs, due to the similarity of its circulatory system to that of humans?

_____________________________________________________________________________________

5 What organisms are used to assess the effects of potential new antibiotics at the ‘discovery’ phase?

_____________________________________________________________________________________

6 Why is the liver of test organisms checked following clinical studies?

_____________________________________________________________________________________

7 How are drugs tested to assess their effect on foetuses?

_____________________________________________________________________________________

8Howhavegeneticallymodifiedmicemadeitcheapertotestdrugsfortheir cancer-inducing effects?

_____________________________________________________________________________________

9 Are drugs used in veterinary medicine tested on animals?

_____________________________________________________________________________________

1of2

Reading and sharing

Biology test sheet

SNAB Topic 4


40

10 What proportion of animals used in the development of new drugs are used in safety testing?

_____________________________________________________________________________________

11 Which countries have collaborated in the last ten years to ensure that unnecessary animal testing is not required because of differences in their regulations?

_____________________________________________________________________________________

12 Why do governments not wish to see a reduction in the requirements to use animals in drug safety testing?

_____________________________________________________________________________________

Mark:____outof12

Total marks for the pair: ____ out of 24

2 of 2

Reading and sharing

Biology test sheet

SNAB Topic 4


41

1 What was good about your summary?

_____________________________________________________________________________________

_____________________________________________________________________________________

2 What would you do to improve your summary?

_____________________________________________________________________________________

_____________________________________________________________________________________

3 What was good about your partner’s summary?

_____________________________________________________________________________________

_____________________________________________________________________________________

4 What could your partner do to improve their summary?

_____________________________________________________________________________________

_____________________________________________________________________________________

5 Did you learn more from doing your own summary, or from your partner’s summary? Why do you think this was?

_____________________________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________

1of1

Reading and sharing

Biology evaluation sheet

SNAB Topic 4


42


43

Reading and sharing

Biology resource

School Science Review, December 2005, 87(319) 99

Greaves Safety testing of new therapies

Animals in the safetytesting of new therapies

Peter Greaves

Our society cannot have access to new therapies without someform of basic animal safety testing before they are first tried

in patients

There is no short cut from the chemicallaboratory to clinic, except one that passes tooclose to the morgue.(Leake, 1929)

Prior to the First World War the main source of newsynthetic drugs was Germany, as a product of itsrenowned chemical and dyestuffs industry. Althoughthe range of drugs was limited compared with modernmedicines, they included some that are recognisedtoday, such as aspirin, phenacetin and barbiturates,as well anaesthetics such as chloroform and novocain.In addition, a range of chemical modifications weremade to natural substances. One of these wasdiamorphine (heroin), a derivative of opium. Despiteits notoriety as a drug of addiction, it remains one ofthe most useful painkillers in patients with advancedcancer because it is more potent than morphine butcauses less nausea and low blood pressure.

In the latter part of the 19th century, scientistsoften studied the effects of these new chemicals onthem-selves. However, in these early days otheranimals were also used. For instance, arsenic wasknown to have some effects against infectious diseasesbut was also very toxic to humans. In 1909 PaulEhrlich, looking for a cure for infectious disease,screened a large number of arsenic-containingcompounds in mice, guinea pigs and rabbits (Drews,2004). He discovered that a compound #606 not onlykilled the syphilis microbe but also cured rabbits withsyphilis without causing death. This chemical wasmarketed as the first effective remedy for syphilisunder the name of Salvarsan. It became an immediatesuccess, selling all over the world and propellingGermany into world leadership in drug production.Moreover, as early as 1904, studies in mice alsopermitted Ehrlich to show that the dye trypan red wascapable of curing mice infected with parasitictrypanosomes. From this work, an effective analogue,suramin, was discovered in 1916 which remainsimportant in the treatment of trypanosomiasis, stillendemic over one-third of the African continent inthe tsetse fly belt.

The First World War interrupted the supplies ofthese new drugs from Germany. This raised questionsin the post-war era in the United States and UnitedKingdom about how such drugs should be producedand how they should be tested. Moreover, there wasthe moral imperative of applying ‘war chemistry’,which had been used for the production of explosivesand toxic gases, in the alleviation of human suffering.The approach of Paul Ehrlich was seen as an illustrat-ion of what could be achieved with proper systematictesting of new chemicals. Indeed, his approach leddirectly to the discovery in 1935 of another anti-

ABSTRACTSince the end of the 19th century animals havebeen used in the safety testing of new syntheticdrugs. Experience of the adverse effects ofdrugs and some disasters in patients havereinforced their use. Moreover, the NurembergCode, developed following horrific experimentsconducted by Nazi doctors on prisoners in thetesting of untried dangerous treatments, hashighlighted the ethical need for animal testing.Safety testing in laboratory animals is a legalrequirement in the European Union before newdrugs can be tested in patients.Animal safety testing remains important. Its mainobjective is to detect serious toxicity beforetesting of new remedies in both human andanimal patients. It is not a substitute for carefullyconducted clinical trials.

1of6

SNAB Topic 4


442 of 6

Reading and sharing

Biology resource Safety testing of new therapies Greaves

100 School Science Review, December 2005, 87(319)

infective drug, Prontosil, a sulphonamide.It was recognised that many potential medicines

were ‘poisons’, so some form of screening in animalmodels was required before new drugs could be triedin patients. It was widely agreed that these tests shouldtake the form of proper pharmacological andtoxicological testing in animals to avoid the risks topatients of being exposed to drugs that were toxicwithout evidence of efficacy. In 1929, ChaunceyLeake made the following recommendations in alecture to the American Medical Association:

Clinical trial of new chemical substancesshould be made only after critical disinterestedpharmacologic study has estimated:

the probable toxicity

the type and mode of action

the worthiness of application to humanbeings

the reasonableness of replacing existingdrugs.

(Leake, 1929)

These tenets concerning careful study of new medi-cines before testing and use in humans have beenreinforced over subsequent years. Basic legislationwas introduced in the United States in the inter-waryears, following one notable incident where the deathsof at least 76 people were caused by a poorly devel-oped elixir of sulphanilamide inadvertently containing72 per cent diethylene glycol.

After the Second World War, added impetus camefrom the Nuremberg Code that was formulated afterthe trials of the Nazi doctors convicted for conductinghorrific experiments on prisoners. Some of theseexperiments involved the testing of new, oftendangerously toxic, treatments on prisoners who hadpurposely been given infectious diseases such asmalaria, streptococcal infections, gas gangrene, andtetanus. Whilst the Nuremberg Code deals primarilywith the consent of volunteers and patients, article 3describes the vital importance of the justification forany experiments in humans being based on priorinformation derived from animal experiments:

The experiment should be so designed andbased on the results of animal experimentationand knowledge of the natural history of thedisease or other problem under study so that theanticipated result will justify the performance ofthe experiment. (Schuster, 1997)

Since the Second World War, the testing of any new

therapy in other animals has become mandatory inmost countries prior to study in humans. Althoughthe manner of testing has become embodied in a largenumber of guidelines and rules, many of which havebeen agreed internationally by government agencies,the basic concept for study of drug safety in animalsremains essentially the same: proper protection ofvolunteers or patients in the testing of new drugsthrough prior pharmacological and toxicologyinformation derived from animals (Greaves, Williamsand Eve, 2004).

Drug discovery anddevelopment

To understand the current place of animal studies inthe assessment of safety of modern drugs, a generalappreciation of the complex process of drug discoveryand development is needed. A summary of the basicscheme is given in Table 1. The process can be dividedinto four phases. The first is ‘Discovery’, which isthe selection of a chemical that shows promisingactivity in some model of human disease. This isfollowed by studies in humans, which by conventionare divided into three stages. Phase I clinical studiesrepresent the very first studies in humans to checkthe basic properties of a new drug and its dosageregimen, usually in healthy volunteers or, for somecancer drugs, volunteer cancer patients. Phase IIclinical studies are the first clinical trials in patientsin order to test whether the new drug has the intendedeffects in patients with disease. Phase III clinicalstudies represent much larger clinical trials designedto test critically effectiveness and safety in thousandsof patients prior to gaining government approval formarketing the drug for use by physicians.

Animal safety testing takes place as in the daysof Paul Ehrlich, before testing in humans but also inparallel with the evolving clinical programme (Figure1). However, the most crucial safety testing in animalsis in the early phases and they diminish in importanceas clinical studies progress and experience about anew drug is gained in patients. It is also of note thatcosts and the attrition rate of compounds failing tomeet the required standards are very high (Table 1)(Rawlins, 2004).

Discovery phaseAnimal studies still play an important part in theprocess of the selection of a potential new therapy,despite application of a vast array of novel approaches

SNAB Topic 4


45



using molecular biology, combinatorial chemistry andbioinformatics. Although activity of some drugs canbe identified with little or no use of animals, for othersit is essential. For example, the activity of antibioticsagainst bacteria can be examined directly in culturedstrains of bacteria. By contrast, the activity ofanticancer drugs is typically assessed using a batteryof mouse models for different cancer types. Mostdrugs that are important today in the treatment ofcardiac disease and hypertension have been selectedon the basis of their effects on the function of the dogheart and blood vessels, because these most closelyreflect effects in humans.

Phase I clinical studyFollowing identification of a potentially active newdrug, the next major step is testing for effects inhumans. However, the transition from the laboratorybench to the bedside represents a quantum leap forwhich animal studies are crucial. At this stage, a smallnumber of carefully planned and conducted animaltoxicity and safety pharmacology experiments areperformed (Figure 1). These allow the precisecharacterisation of the effects of the drug on bodyfunctions and toxicity. They provide the basis for thedesign and conduct of phase I clinical studies of thenew drug in volunteers.

At this stage, determining the safety profile of anew drug is not limited to animal toxicity experiments.There are also in vitro studies, such as the Ames test,

which uses bacteria, and other experiments using cellsto study whether the drug can damage DNA. Animalexperiments comprise single-dose studies (‘acutestudy’) in rodents and repeated dosing over a periodof up to one month (‘subacute study’) in two speciallybred animal species. The acute study investigates thetoxicity of a single high dose and provides importantinformation in the case of overdosage in patients. Nolonger performed is the so-called ‘LD50’ which wasdesigned specifically to define the lethal dose in alarge group of rodents. The subacute study is todemonstrate the safety of repeated dosing in a mannerthat mirrors the proposed way it is intended to dosepatients. One species used for this is a rodent, usuallylaboratory rats, and the other a non-rodent species,usually beagle dogs. Mice can be used instead of ratsalthough they are considered by some to be too small.Experiments in monkeys are avoided where possibleunless the compound being studied has particularcharacteristics that demand them. For example,primates would be used for some human proteins orfor drugs whose targets are not found in lower species.

The paradigm for an experiment is similar for mosttypes of animal toxicity studies. Animals are dosedwith the drug in a similar way and at the same doseand usually two higher doses on a body-weight basisas intended for use in patients. The minimum numberof animals of each sex in each dose group is mandatedin most government guidelines, notably those of theEuropean Union, United States and Japan. These

Table 1 The stages of drug discovery and development over time and overall costs (Boston ConsultingGroup, 2001), with approximate number of compounds studied and of patients treated at each stage. The redline represents the point at which work in humans starts and the blue line the point at which the product ismarketed. Both cost and risk of failure are high.

Discovery Product development

Time taken 3 years or more 5 years or more

Phase Research Preclinical PHASE I PHASE II PHASE III Submissiondevelopment and approval

Number of 5–10 000 10 5 3 2 1compoundsstudied

Number of 0 0 10s 100s 1000spatientsexposed

Cost 620 $M 260 $M

3 of 6

Reading and sharing

Biology resource

SNAB Topic 4


46

Safety testing of new therapies Greaves


studies are conducted to an agreed internationallaboratory standard known as Good LaboratoryPractice (GLP). This requires regular inspection oflaboratories by government agencies and also thatanimals are well housed and maintained.

The animals are monitored clinically withparticular attention being paid to changes in behaviourthat could signify adverse effects on critical functionssuch as the nervous system. Blood pressure, heart rateand electrocardiograms are usually monitored in thedog as they are more difficult to perform in rodents,which have a very fast heart rate. Eyes are an import-ant part of the examination, which uses sophisticatedoptical equipment similar to that used by anophthalmologist or optician. Blood is sampled andtested for any chemical or haematological alterationsin an identical manner to techniques used with humanpatients, often using identical laboratory analyticalapparatus. Levels of drug circulating in the body arealso usually monitored.

At the end of the dosing period, or if any ill healthintervenes, the animals are humanely killed with ananaesthetic or barbiturate and subject to a full autopsy

examination. Over 30 tissues from all the organs aretaken for microscopic examination by an experiencedveterinary pathologist to check for any organ damagethat could reflect danger to patients if they were to betreated with the new drug. For example, the liver isan important organ to check because it is frequentlyexposed to large amounts of drugs and theirmetabolites, as it is a major site of drug metabolism.Likewise the kidneys may be exposed to highconcentrations, as this is often the main pathway ofdrug excretion. Ovaries and testes are carefullyexamined to exclude any serious effects on repro-ductive organs, as are the lymph nodes, thymus andspleen for any deleterious effect on the immunesystem. Additional special studies are performed ifthere are findings of concern that need elucidation.This basic scheme is used for most drug typesalthough cancer drugs, which are often very toxic,are usually given for a limited period of five days.

Scientists and physicians review the assembleddata from all these experiments along withinformation from studies of drug metabolism prior todesign and conduct of first studies in humans. Any

Figure 1 This diagram shows the place of animal and in vitro toxicology studies (in red) within the contextof drug discovery and development. So called ‘screening toxicology’ might be conducted in rodents prior toentry into formal ‘acute’ and ‘subacute’ toxicology studies immediately before testing in man (red line). Inparallel with clinical phases I, II and III, further ‘chronic’ testing as well as studies on reproduction arecarried out prior to marketing (blue line). Italics show drug kinetics and metabolism studies, which areperformed in both humans and animals and enable effects in animals and man to be correlated.Development of animal medicines follows a similar scheme but with a programme in the target species to testefficacy and toxicity.

4 of 6

Reading and sharing

Biology resource

SNAB Topic 4


47



serious damage to an organ, tissue or DNA wouldnormally prevent studies in volunteers or patients andthe potential new drug would never be developed foruse. In all other cases a clear rationale based on atrade-off between any potential risks and likely long-term benefit would be generated prior to the conductof any human experiment. Moreover, there is amandatory ethical review of the study protocol by apanel not directly involved in the human studies. Thereview panel would be provided with a summary ofthe results of the animal safety information.Government agencies in the United States and morerecently in the European Union also have approvalprocesses for all such human studies.

Phase II and III clinical studyIn clinical studies in patients, dosing periods areusually longer and more subjects are involved. Thisis accompanied by animal toxicology studies of longerduration (Figure 1). The organisation of these toxicitystudies is similar to the earlier studies but the periodof dosing is extended from a period of up to one monthto a maximum period of dosing of usually 6 to 9months (‘chronic study’) for most drugs. Until phaseII clinical studies, women of childbearing age areusually excluded. As female patients are usually partof phase II studies, special experiments to examinethe effects of a new drug on reproductive functionand the developing foetus are conducted in twosensitive animal species, conventionally rat and rabbit.The same basic study design is used for these studiesbut they are complicated because of the need to givethe drug during precise parts of the reproductive cycleand to examine the foetus for any drug-induceddeformity or teratogenic effects.

The last experiments to be conducted are the so-called ‘carcinogenicity studies’. These are a require-ment for most drugs that are going to be used forextended periods in patients. As these studies are bothlarge and expensive they are not usually run until anew drug has shown such promise in phase II clinicalstudies that there is a commitment to commence thelarger and more expensive phase III clinical studies.The studies have typically been mandated in tworodent species, mouse and rat. More recently, shorterstudies using genetically modified, cancer-prone micehave been accepted by government drug agencies inplace of one of these two large studies. Again, theorganisation of the studies is similar to thoseconducted previously except that the dosing period isfor two years – most of the lifetime of a rodent. Group

sizes are larger (50 per sex per group) so that anyeffect on tumour development can be detected. Oldrodents develop tumours naturally so it requires asufficient number of animals for an effect of the drugto be seen against this background. These animals aresimply housed and treated without any other inter-vention for the period of the experiment, and killedhumanely either when sick or at two years; 30 tissuesfrom each are examined and all tumours diagnosedby a pathologist.

Therapies for animals

Some 90 per cent of the medicines used in veterinarymedicine are drugs developed for human patients, soidentical safety testing is used for the development ofanimal treatments. Indeed, as the dog is commonlyused for development of drugs for humans, no furthersafety testing is usually performed for treatments fordogs. However, for remedies in other companionspecies, such as cats, or in farm animals, someadditional safety testing is conducted along the samelines as for human medicines. Usually a form oftoxicity experiment to test tolerance in the intendedspecies – for example cat, cow or horse – is performedusing doses up to several times the intendedtherapeutic dose.

Discussion

Outlined above is the basis for animal safety testingof new medicines and how this is currently performedfor most drugs. It has been estimated that this form oftesting represents about 10 per cent of the overallexpenditure on the discovery and development of anew drug, estimated to total in excess of $800 million.Perhaps more surprisingly it also uses a smallpercentage (10 per cent) of the animals used in thediscovery of new medicines.

Considerable efforts have been made over the lastdecade to rationalise safety testing. For example, inthe past, companies were frequently required to repeatsimilar studies because different government agenciesrequired experiments to be performed in slightlydifferent ways to suit local custom and practice. Nowagreements between the agencies of the United States,European Union and Japan have reduced thisredundant testing. Undoubtedly, though, the numbersof animals used for safety testing could be reduced.There is resistance by government agencies to reduce

5of6

Reading and sharing

Biology resource

SNAB Topic 4


48

Safety testing of new therapies Greaves


the requirements for testing, even though industrytoxicologists have proposed ways in which this canbe done. The role of these agencies is to protect thepatient population from adverse effects of drugs, sonot surprisingly there is an unwillingness to acceptreduction of testing that might be perceived to poseadded risk to patients.

Although the numbers of animals could bereduced, it is probable that this reduction would be atbest limited. Cell systems are already widelyemployed and computers are used to predict toxicityfrom chemical structures. However, slight changes tothe structure or formulation of a chemical can havemajor unforeseen consequences and can producedamage to critical and complex systems such as thebrain, heart and eye.

It is important to underline that the use of animalsafety testing is limited to screening for serioustoxicity of drugs to permit their safe testing in humans.

It is no substitute for careful study of new drugs inpatients to test their ability to treat disease and formonitoring of any adverse effects. Adverse effectsoccurring in one in 10 000 or 100 000 patients can bedevastating, but would never be detected in the smallnumber of healthy animals used in safety testing. Forexample, aspirin remains a very important medicinethat has been widely used for over 100 years and mostof its common side effects can be detected in animals.However, the association of aspirin treatment withReye’s syndrome, a very rare but devastating form ofliver failure in children with viral infection, was onlyclearly understood after careful clinical work inpatients over the last two decades.

Although clearly some individuals have greatdifficulty accepting any animal experiments, it is quitemisleading to suggest that our society can have accessto new therapies without some form of basic animalsafety testing before they are first tried in patients.

ReferencesBoston Consulting Group (2001) A revolution in R&D: how

genomics and genetics are transforming thebiopharmaceutical industry. Boston, MA: BostonConsulting Group. (Also covered in Rawlins, 2004.)

Drews, J. (2004) Paul Ehrlich: Magister Mundi. NatureReviews Drug Discovery, 3, 797–801.

Greaves, P., Williams, A. and Eve, M. (2004) First dose ofpotential medicines to humans: how animals help. NatureReviews Drug Discovery, 3, 226–236.

Leake, C. D. (1929) The pharmacological evaluation of newdrugs. JAMA, 93, 1632–1634.

Rawlins, M. D. (2004) Cutting the cost of drug development.Nature Reviews Drug Discovery, 3, 360–364.

Schuster, E. (1997) Fifty years later: the significance of theNuremberg Code. New England Journal of Medicine, 337,1436–1440.

WebsitesDetailed notes for guidance on toxicity testing in theEuropean Union can be found at the EuropeanMedicines Agency website: http://www.emea.eu.int/In the United States, guidelines for safety testing canbe found at the website of the Food and DrugAdministration: http://www.fda.gov/cder/regulatory/default.htm

Peter Greaves is a medical graduate and pathologist by training who is senior lecturer in the Department ofCancer Studies and Molecular Medicine at the University of Leicester. He has extensive experience in the studyof the adverse effects of medicines and is a member of the UK government’s Veterinary Products Committee.Email: [email protected]

6 of 6

Reading and sharing

Biology resource

SNAB Topic 4


Preparing a longer presentation

This activity develops the skills needed to prepare and deliver a formal presentation. The presentations will be delivered and evaluated as part of the activity ‘Evaluating presentations’.


select an appropriate topic for a presentation to •the class

carry out necessary research to collect the •information needed

deliver the presentation to the class (as part of •‘Evaluating presentations’).

Time required20minutesbriefing,onelessonforpresentationsandhomework.

Outline of the activity1 Recap the ‘Good practice for presentations’ as discussed in the SNAB ‘Using powerpoint’ skills support activity.

2 Issuestudentbriefingsheetandrunthroughthepoints listed. This is aimed at getting the students to think about the structure and content of a presentation before engaging in a planning process. Ten biology resource sheets are provided as a stimulusforpresentations.Alternatively,thiscanbeused as a revision activity.

3 Explain to the students that they will be preparing and delivering a 10 minute presentation on a topic oftheirchoiceselectedfromaspecifiedareaofthistopic,suchas‘Thedesignofcriticaltrials’.

4 Ifusedasasummativeactivity,askstudentsto present on different topics. For homework get students to plan their talk. During the next lesson peer-review their plans in pairs or groups. Allow students to modify their plan.

5 Iftimeallows,usethePowerpointpresentationto help advise the students on how to go about delivering a good presentation.

Tips and strategiesDependingonthegroup’sexperience,you may choose to get the students to do part of the planning in class so you can keep tabs on how they are going about the task and provide assistance where required.

If you have a couple of lessons between setting the task and the students delivering their presentations,youmightspend5minutesineach lesson discussing progress to identify problems and to encourage the students to give their best.

Ensure that students have access to any computing facilities that they require – some maynothaveaPCathome,butmaystillwishtousePowerpoint.Inthiscase,itwouldbegood if the students were able to use school facilities to do the work.

1 of 1

SNAB Topic 4


50


Inthisactivity,youwillpreparealongerpresentationonasciencetopic.Givingpresentationsisoneoftheskillsthatmanyemployerswillexpectyoutohave,soyoushould make the most of any experience you can get at school and college. Read this guidance sheet before planning your presentation.

Things to think about when preparing a presentation

Who will you be talking to?

How much do they know about the subject already?

What effect do you want your presentation to have?

How long have you got?

Do you have to follow a certain format?

Where will you be giving your presentation?

Decide on your main points: no more than three points in a 10-minute talk.

Is there a logical connection between these points?

What evidence can you produce to support your points and make your case clear?

Things to think about when delivering a presentation

Brieflyintroduceyourself.

Check that your audience can all see and hear you.

Let them know if you are going to take questions as you proceed or if you prefer to invite discussion at the end.

Youmaywanttogiveanoutlineofthestructureofthetalk,sotheaudienceknowwhereit is going.

You’llneedtogaintheaudience’sattention,sothinkcarefullyhowyouwillintroduceyourtopic–forexample,youcouldstartwithananecdote,aquestionorsomecontradictory statements.

Prepare your talk so you lead the audience through your main points in a logical and interesting fashion. It helps if you plan for variety in the ways you present your case. Wheretheyareappropriate,youcouldplantouse:

•examples,anecdotesandcasehistories

•chartsandgraphs

•handouts(willyouissuethematthestart?inthemiddle?attheend?)

•slides

•videoclips

•artefactswhichpeoplecanpassround.


Briefing sheet

1 of 2

SNAB Topic 4



Briefing sheet

2 of 2

SNAB Topic 4

At the endSummarise what you have said: ‘In this talk we have discussed...’

Make your conclusions: ‘It is clear that...’

Plan to leave the audience a parting shot to stimulate their thoughts.

Your task is to prepare a 10 minute presentation on a topic agreed with your teacher.

Your talk should include the following:

•Anexplanationofwhyyouchoseyourtopic.

•Backgroundinformationaboutthetopic.

•Anexplanationofthetopic.

•Anexplanationofanyimplicationsofthescienceanditsapplications.

Ifpossible,youshoulddiscusssomedata(intableorgraphform)obtainedfromtheuseof your analytical method in the context you are presenting.

An explanation of the impact of your analytical method in the context you are presenting (e.g.howhasitaffectedefficiency,arethereanynotablesuccessstoriesetc).

YoumaychoosetouseICT(e.g.slidepresentation),oryoumaywriteontheboard.Youshould use whichever method you are comfortable with. Make sure that you are able to display data and graphs so they can easily be inspected by the audience. This may be most effective as a handout.

The intention is that you will deliver your presentation to a group of your peers who will assess your performance as part of a subsequent activity.

Structure

Yourpresentationshouldhaveaclearintroductionatthestart,andshouldfinishwithaconclusion in which you summarise your key points.

Youshouldtelltheaudiencewhetheryouwantthemtoaskquestionsduringthetalk,orif you would prefer them to wait until the end.

Reflection

Whenyouhavereceivedfeedbackonyourpresentation,writedownthreepointsforimprovement next time you do a presentation:


‘Horror frog’ breaks own bones to produce clawsCatherine Brahic, 28 May 2008

“Amphibian horror” isn’t a movie genre, but on this evidence perhaps it should be. Harvard biologists have described a bizarre, hairy frog with cat-like extendable claws.

Trichobatrachus robustus actively breaks its own bones to produce claws that puncture their way out of the frog’s toe pads, probably when it is threatened. David Blackburn and colleagues at Harvard University’s Museum of Comparitive Zoology, think the gruesome behaviour is a defence mechanism.

The researchers say there are salamanders that force their ribs through their skin to produce protective barbs on demand, but nothing quite like this mechanism has been seen before.

The feature is also found in nine of the 11 frogs belonging to the Astylosternus genus, most of which live in Cameroon.

Instant weapon “Some other frogs have bony spines that project from their wrist, but in those species it appears that the bones grow through the skin rather than pierce it when needed for defence,” says Blackburn.

At rest, the claws of T. robustus, found on the hind feet only, are nestled inside a mass of connective tissue. A chunk of collagen forms a bond between the claw’s sharp point and a small piece of bone at the tip of the frog’s toe.

The other end of the claw is connected to a muscle. Blackburn and his colleagues believe that when the animal is attacked, it contracts this muscle, which pulls the claw downwards. The sharp point then breaks away from the bony tip and cuts through the toe pad, emerging on the underside.

1 of 1


Resource 1

Hirsute horror The end result may look like a cat’s claw, but the breaking and cutting mechanism is very different and unique among vertebrates. Also unique is the fact that the claw is just bone and does not have an outer coating of keratin like other claws do.

Because Blackburn has only studied dead specimens, he says he does not know what happens when the claw retracts – or even how it retracts. It does not appear to have a muscle to pull it back inside so the team think it may passively slide back into the toe pad when its muscle relaxes. “Being amphibians, it would not be surprising if some parts of the wound heal and the tissue is regenerated,” says Blackburn.

Males of the species, which grows to about 11 centimetres, also produce long hair-like strands of skin and arteries when they breed (see image). It is thought that the “hairs” allow them to take in more oxygen through their skin while they take care of their brood.

Spiky snack In Cameroon, they are roasted and eaten. Hunters use long spears and machetes to kill the frogs, apparently to avoid being hurt by their claws.

“This is an incredible story,” says Ian Stephen, curator of herpetology at the Zoological Society of London, UK. “Some frogs grow spines on their thumbs during breeding season, but this is entirely different. For me, it highlights the need for a lot more research on amphibians especially in light of the threat of mass extinctions” he adds.

The existence of frogs with erectile claws like cats was first described by Belgian zoologist George Boulenger in 1900 in frogs found in the French Congo, now the Republic of Congo. http://www.newscientist.com

SNAB Topic 4


54


Incredible shrinking frogs: The price of deforestation? Matt Kaplan, 27 May 2008

Human disruption to habitats not only causes populations to get smaller, it also seems to cause the individuals of some species to literally shrink.

Johanna Delgado-Acevedo and Carla Restrepo at the University of Puerto Rico collected specimens of two common species of Puerto Rican frogs from nine sites in the northern regions of the island.

The sites were all subtropical, moist environments, but differed dramatically from one another in the amount of foliage present. Some were heavily forested, while others had barely any forest left at all. Collected frogs were X-rayed and had their bones measured.

Remarkably, the team found that frogs collected in habitats with foliage coverage of 20% or less were physically 5 to 10% smaller than those collected in habitats with 70% or more foliage cover. They also found that the frogs collected in more disturbed habitats had bodies that were less symmetrical than those in pristine areas.

Size matters

“It has been reported before that amphibian body size decreases when the animals are exposed to large numbers of predators,” says Delgado-Acevedo, “but discovering this in response to human environmental disruption is really surprising.”

The reduction could be the result of natural selection. With few resources available in deforested areas, smaller frogs that make more

1 of 1

modest demands on the habitat may be the most successful. However, the disturbed habitats might also be affecting the frogs during their early development, by exposing them to stresses that they would normally not encounter.

It is difficult to say if the size reduction is for better or for worse. Small size usually goes hand in hand with slower movement, greater heat loss, and faster dehydration, but it also makes hiding easier.

Environmental tool

“Being smaller has some advantages, but these species are not small because of natural causes, they are small in response to habitat disturbance, [which] we think is a bad thing,” says Delgado-Acevedo.

“They have uncovered some interesting trends that need further investigation,” says Rachel Santymire, an endocrinologist who measures stress in endangered species at the Lincoln Park Zoo in Chicago, Illinois.

“We think that body size combined with measurements of symmetrical traits could be used as a tool to evaluate the health of natural populations,” says Delgado-Acevedo.

“What I really wonder is whether pollutants, pathogens, or competition are causing the morphological changes in the fragmented forest dwelling frogs,” says Santymire.

http://www.newscientist.com


Resource 2

SNAB Topic 4


56



Resource 3

How a thriving social life can boost lifespanLinda Geddes, 6 May 2008

They say you are only as old as the woman (or man) you feel – now we might be closer to understanding why.

It has been suggested that humans and other vertebrates live longer if they have more social interactions, and now this has been verified – in fruit flies.

Chun-Fang Wu and Hongyu Ruan at the University of Iowa in Iowa City studied fruit flies with a genetic mutation that reduces their lifespan by interfering with an enzyme that mops up dangerous free radicals.

The same enzyme is implicated in age-related diseases like Alzheimer’s and Parkinson’s in humans.

Mutant flies that shared a home with younger flies, or non-mutants, lived longer and were more mobile than those sharing a home with similar-aged flies. They were also more resistant to the effects of extreme physical exertion, heat and oxidative stress.

Courtship and aggression

Impairing the movement or activity of younger flies reduced this effect, suggesting that social interaction with the younger flies through

1 of 1

courtship, aggression, or grooming, plays a key role in increasing the lifespan of the older flies. “Social activity is the key,” says Wu.

Keeping the flies in the dark, so they could not see each other, also reduced the effect.

The next step is to unravel how these social interactions override the mutant gene at the molecular level. In doing so, Wu hopes to understand how similar interactions could benefit ageing humans.

“This study shows that the lifespan of these flies is plastic and can be conditioned by social interactions, corroborating the notion that human patients of certain age-dependant neurological diseases may be benefited by an appropriate social environment,” he says.

However, Wu has studied several genes that influence lifespan in fruit flies, and not all of them can be overridden by social interaction, he says.


SNAB Topic 4


58


Orchid lures bees with promise of sex with strangersNora Schultz, 26 May 2008

Male bees with an urge to add to the gene pool are exploited by orchids that pose as irresistibly scented exotic females, new research suggests.

Sexually deceptive orchids rely for their own reproduction on male insects’ drive to copulate. If a male mistakes the flowers for a female insects, his fruitless mating attempts will pollinate the orchid.

Some orchid flowers are so exciting to males that they even ejaculate on the flower, but although the visual deception is often superb, what really drives the males wild is the female sex pheromone cocktail that the orchid imitates.

Now Nicolas Vereecken and Florian Schiestl at the University of Zürich in Switzerland have discovered a new trick in the orchids’ repertoire of sexual lures.

Inbreeding bees

When they studied geographic variation in pheromone mixes between 15 different populations of the bee Colletes cunicularius and the orchid that mimics it, Ophrys exaltata, they were surprised to find that the flowers consistently smelled slightly different than the female bees in any given population.

“This was not at all what we expected. If the orchids thrive on imitating female bees, the match should be as perfect as possible”, says Schiestl.

1 of 1


Resource 4

Unless, of course, the males like their girls just a little bit different.

Since the bees enjoy a quiet life and do not travel much, Vereecken and Schiestl speculated that inbreeding may be a common problem. Mating with a stranger may be a welcome opportunity to stir up the gene pool for a bit more variety.

Exotic dancers

And indeed, male bees have the hots for exotic perfume. Given the choice between a dummy infused with the pheromone cocktail produced by the girl bee next door and another one with the bouquet of a female from another population, the males visited the scent that was new to them 50% more often.

But orchid scent, with yet greater differences in the pheromone mix, was even more popular. In choice tests it attracted males up to five times as often as that of a local female.

Manipulating the natural perfume blend of the bees to mimic that of the orchids also nearly doubled the bees’ attractiveness to males.

In other species, such as mice, rare females are popular when inbreeding is common. “When outbreeding is desirable, it makes sense for males to look for females with exotic scent,” says chemical ecologist Manfred Ayasse at the University of Ulm in Germany. “But in this case, what they find instead is the orchid.” http://www.newscientist.com

SNAB Topic 4


60


Lab rats turn cannibal in cleaner cages23 May 2008

As the old adage has it, cleanliness is next to godliness, but it also has sinister consequences for lab rats: they are much more likely to cannibalise their young if their cages are frequently cleaned.

Charlotte Burn at the University of Oxford and Georgia Mason at the University of Guelph in Ontario, Canada, found that nearly twice as many pups were eaten in cages cleaned twice a week as in those cleaned fortnightly. Cannibalism was most likely if the cages were cleaned soon after the pups were born.

Burn notes that cannibalism in rodents is not unusual; mothers sometimes eat unhealthy young to conserve energy for raising healthy ones. But while this might be normal behaviour, it could be disruptive in a research context.

1 of 1


Resource 5

The findings suggest that cleaning their cages disrupts the rats’ ability to recognise their kin, according to Volker Rudolf at Rice University in Houston, Texas. Burn says that scent is the key to rats being able to recognise their pups. She suggests minimising the handling of very young pups to avoid interfering with the scents that bond their parents to them.

It is also important, she says, to avoid introducing foreign scents into the rats’ cages. For example, lab technicians should avoid handling several rats one after another.

Finally, Burn advises, cleaning the rats’ cages should not “stress the parents with loud noises or physical disturbance”.

From New Scientist issue 2657, 23 May 2008, page 18 http://www.newscientist.com

SNAB Topic 4


62


Six ‘uniquely’ human traits now found in animals Kate Douglas, 22 May 2008

1 Culture

Art, theatre, literature, music, religion, architecture and cuisine – these are the things we generally associate with culture. Clearly no other animal has anything approaching this level of cultural sophistication. But culture at its core is simply the sum of a particular group’s characteristic ways of living, learned from one another and passed down the generations, and other primate species undoubtedly have practices that are unique to groups, such as a certain way of greeting each other or obtaining food.

Even more convincing examples of animal cultures are found in cetaceans. Killer whales, for example, fall into two distinct groups, residents and transients. Although both live in the same waters and interbreed, they have very different social structures and lifestyles, distinct ways of communicating, different tastes in food and characteristic hunting techniques – all of which parents teach to offspring.

Hal Whitehead, Dalhousie University writes:

“Since our 2001 review, people have often considered culture as a potential explanation of the behavioural patterns that have turned up in their studies of whales and dolphins.

“Our own work has concentrated on the non-vocal forms of sperm-whale culture. The different cultural clans of sperm whales, although in basically the same areas, use these waters very differently, and are affected very differently by El Niño events. They also have different reproductive rates. “In sperm whales, and likely other whales and

1of3


Resource 6

dolphins, culture has the potential to affect population biology, and so issues as diverse as genetic evolution and the impacts of global warming on the species.” 2 Mind reading

Perhaps the surest sign that an individual has insight into the mind of another is the ability to deceive. To outwit someone you must understand their desires, intentions and motives – exactly the same ability that underpins the “theory of mind”. This ability to attribute mental states to others was once thought unique to humans, emerging suddenly around the fifth year of life. But the discovery that babies are capable of deception led experts to conclude that “mind-reading” skills develop gradually, and fuelled debate about whether they might be present in other primates

Experiments in the 1990s indicated that great apes and some monkeys do understand deception, but that their understanding of the minds of others is probably implicit rather than explicit as it is in adult humans.

Marc Hauser, Harvard University, writes:

“The tamarin work didn’t pan out, but there are now several studies that show evidence of theory of mind in primates, including work by Brian Hare, Josep Call, Mike Tomasello, Felix Warneken, Laurie Santos, Justin Wood, and myself on chimps, rhesus monkeys and tamarins. There is nothing quite like a successful Sally-Anne test, but studies point to abilities such as seeing as a form of knowing, reading intentions and goals.”

SNAB Topic 4


3 Tool use

Some chimps use rocks to crack nuts, others fish for termites with blades of grass and a gorilla has been seen gauging the depth of water with the equivalent of a dipstick, but no animal wields tools with quite the alacrity of the New Caledonian crow. To extract tasty insects from crevices, they craft a selection of hooks and long, barbed tapers called stepped-cut tools, made by intricately cutting a pandanus leaf with their beaks. What’s more, experiments in the lab suggest that they understand the function of tools and deploy creativity and planning to construct them.

Nobody is suggesting that toolmaking has common origins in humans and crows, but there is a remarkable similarity in the ways in which their respective brains work. Both are highly lateralised, revealed in the observation that most crows are right-beaked – cutting pandanus leaves using the right side of their beaks. New Caledonian crows may force us to reassess the mental abilities of our first toolmaking ancestors.

Gavin Hunt at the University of Aukland, writes:

“The general aim of our research on New Caledonian crows is to determine how a ‘bird brain’ can produce such complex tools and tool behaviour. Since the New Scientist article appeared in 2002, our team has focused on continuing to document tool manufacture and use in the wild (New Zealand Journal of Zoology, vol 35 p 115), the development of tool skills in free-living juveniles, the social behaviour and ecology of NC crows on the island of Maré, experimental work investigating NC crows’ physical cognition and general intelligence, and neurological work.

“Some of this work is being undertaken collaboratively with laboratories in Germany (neurology) and New Zealand (genotyping). A very similar study is also being carried out independently at the University of Oxford. This parallel research has produced findings that are both confirmatory and conflicting.”

Alex Kacelnik, University of Oxford, adds:

“We now know for sure that genetics is involved in the tool-making abilities of new Caledonian crows. We raised nestlings by hand and found that chicks that had never seen anybody handle objects of any kind started to use tools to extract food from crevices at a similar age to those who were exposed to human tutors using tools (Animal Behaviour, vol 72, p 1329). Clearly, observing others is not necessary for the tool use. However chicks exposed to tutoring exhibit a greater intensity of tool-related activity. Not surprisingly, genes and experience show a complex interaction.

“We have also developed a new technique, consisting of loading tiny video cameras on free-ranging birds, so as to see what they see and document the precise use of tools in nature. We have discovered that they use tools in loose soil, that they use a kind of tool not previously described (grass stems), and that they hunt for vertebrates (lizards). All of this, together with laboratory analysis of their cognitive abilities is forming a richer picture of what the species can do.”

4 Morality

A classic study in 1964 found that hungry rhesus monkeys would not take food they had been offered if doing so meant that another monkey received an electric shock. The same is true of

2of3


Resource 6

SNAB Topic 4


rats. Does this indicate nascent morality? For decades, we have preferred to find alternative explanations, but recently ethologist Marc Bekoff from the University of Colorado at Boulder has championed the view that humans are not the only moral species. He argues that morality is common in social mammals, and that during play they learn the rights and wrongs of social interaction, the “moral norms that can then be extended to other situations such as sharing food, defending resources, grooming and giving care”.

Marc Bekoff, University of Colorado, writes:

“Work published this year showed that animals are able to make social evaluations and these assessments are foundational for moral behaviour in animals other than humans. Francys Subiaul of the George Washington University and his colleagues showed that captive chimpanzees are able to make judgments about the reputation of unfamiliar humans by observing their behaviour - whether they were generous or stingy in giving food to other humans. The ability to make character judgments is just what we would expect to find in a species in which fairness and cooperation are important in interactions among group members

5 Emotions

Emotions allow us to bond with others, regulate our social interactions and make it possible to behave flexibly in different situations. We are not the only animals that need to do these things, so why should we be the only ones with emotions? There are many examples of apparent emotional behaviour in other animals.

Elephants caring for a crippled herd member seem to show empathy. A funeral ritual

performed by magpies suggests grief. Was it spite that led a male baboon called Nick to take revenge on a rival by urinating on her? Divers who freed a humpback whale caught in a crab line describe its reaction as one of gratitude. Then there’s the excited dance chimps perform when faced with a waterfall – it looks distinctly awe-inspired. These days, few doubt that animals have emotions, but whether they feel these consciously, as we do, is open to debate.

6 Personality

It’s no surprise that animals that live under constant threat from predators are extra-cautious, while those that face fewer risks appear to be more reckless. After all, such successful survival strategies would evolve by natural selection. But the discovery that individuals of the same species, living under the same conditions, vary in their degree of boldness or caution is more remarkable. In humans we would refer to such differences as personality traits.

From cowardly spiders and reckless salamanders to aggressive songbirds and fearless fish, we are finding that many animals are not as characterless as we might expect. What’s more, work with animals has led to the idea that personality traits evolve to help individuals survive in a wider variety of ecological niches, and this is influencing the way psychologists think about human personality.


3of3


Resource 6

SNAB Topic 4


66


Cell ‘organs’ get plastic upgradesTamsin Osborne, 23 May 2008

Human cells could have their metabolisms upgraded without altering their genes by inserting tiny plastic packages of enzymes, Swiss researchers have shown. They hope the technique could allow advanced cancer therapies, or even upgrade a person’s metabolism.

The cells of multi-cellular organisms and some advanced single-celled organisms have internal compartments called organelles to carry out specialised metabolic functions. Researchers at University of Basel, Switzerland, used artificial polymer organelles to upgrade live human cells in a lab dish.

Meier and colleagues coated their polymer vesicles in a chemical that encouraged human white blood cells called macrophages to engulf them. The small capsules contained enzymes, just like natural organelles. The enzymes chosen produced fluorescent chemicals, signalling they were working without problems inside their new host.

The artificial organelle’s membrane can be chemically tuned to control which chemicals can pass through it and regulate the reactions inside, according to Wolfgang Meier, one of the researchers. “We call it a ‘nanoreactor’,” he says

At 200 nanometres across, the organelles are 400 times smaller in width than a human hair.

Targeting cancer

Meier says the artificial organelles would also work in other human cells, opening up the

1 of 2


Resource 7

possibility of a new cancer therapy that tricks diseased cells into poisoning themselves from the inside out.

An advanced chemotherapy technique involves giving patients a harmless “prodrug” that only becomes toxic in the presence of a particular enzyme. This enzyme bonds to an antibody that seeks out cancer but ignores healthy cells – this means the drug will only become active around cancerous cells.

Meier says that the artificial organelles might provide a way to introduce prodrug-converting enzymes actually inside cancer cells, where the drug can be more effective. They could targeted to cancer cells using a similar method to that used for enzymes alone.

“You can create, inside these cells, a little compartment that is able to convert the non-toxic prodrug into a toxic drug that kills [them],” he says. “There would be no other enzyme in the human body available that can catalyse this reaction.”

Human ‘photosynthesis’

Artificial organelles might also be able to treat conditions caused by a deficit of a particular enzyme. For example, someone with lactose intolerance could have their digestive cells given artificial organelles containing lactose-digesting enzymes. In the far future, it might be possible to introduce non-human metabolic functions into human cells. “We could, in principle, bring in a

SNAB Topic 4


nanoreactor that [lets] your skin do something like photosynthesis. So if you are hungry, you just lie in the Sun,” says Meier.

Human tests are still a distant prospect, but Patrick Couvreur at the Université de Paris-Sud, France, says he eagerly anticipates the results of more imminent explorations into what artificial organelles might do.

“The concept of artificial organelles based on functionalised polymer vesicles is certainly an exciting approach,” he says. “We are now waiting for practical medical applications in animal models.”


2 of 2


Resource 7

SNAB Topic 4


Can flu viruses survive winter in frozen lakes?Catherine Brahic, 29 November 2006

Evidence of flu viruses frozen in Siberian lakes has prompted researchers to examine the possibility that global warming may release microbes locked in glaciers for decades or even centuries.

“Our hypothesis is that influenza can survive in ice over the winter and re-infect birds as they come back in spring,” says Scott Rogers of Bowling Green State University, Ohio, US. He believes the frozen lakes act as “melting pots” for flu viruses, allowing viruses from one year to mix with those from previous years.

Rogers has spent decades searching ice for micro-organisms. He teamed up with Dany Shoham at Bar-Ilan University, Israel, and David Gilichinsky, at the Russian Academy of Sciences, to obtain samples of ice from Siberian lakes where migratory birds stop.

The group looked for pieces of genetic material from flu viruses in ice taken from three lakes that freeze and thaw each year. In the lake that is most visited by migratory birds, Lake Park, they found fragments of RNA coding for haemagglutinin, the surface protein that allows flu viruses to bind to the cells they infect.

Genetic analysis revealed the haemagglutinin was most closely related to an H1-strain flu virus that was around in the 1930s and later resurfaced in the 1960s.

Frozen droppings

Rogers’ team is now looking at ice cores from glaciers in Alaska and Wyoming in the US, and

1 of 2

from Canada. They intend to study cores from Siberia and the Himalayas as well.

Many of these glaciers are on the flight paths of migratory birds, which will deposit virus onto the ice in their droppings, where it freezes. Rogers believes there is a possibility that, as global warming melts glaciers, they will release the viruses, and perhaps other microbes such as bacteria and fungi that have otherwise disappeared from our environment.

The idea is plausible, says Jonathan Stoye, head of virology at the UK National Institute for Medical Research in London. But he adds: “The important issue is whether or not there’s infectious virus” in the ice, rather than just fragments of RNA. Rogers is collaborating with researchers at sufficiently biosecure labs to try and answer this question.

Freeze-thaw process

Stoye says that whether or not the viruses are infectious depends largely on how the virus was frozen. Viruses frozen in water are likely to be inactivated by the water’s relatively low pH. “But if the virus was in droppings, which presumably is how it was deposited, there seems to be no reason why it should not freeze and survive at low temperatures.”

He adds that viruses are more likely to survive in a frozen state if they freeze and thaw only once, as the freeze-thaw process kills at least 90% of virus each time.

Karen Lacourciere, programme officer for influenza at the US National Institute of Allergy and Infectious Diseases, which funded Rogers’


Resource 8

SNAB Topic 4


research, thinks the ice cores are unlikely to contain viruses shed by humans.

“The kind of consistently freezing conditions you would expect to need to preserve a virus are unlikely to be found in places that are heavily populated with people,” she says. She also notes the samples Rogers has looked at so far are taken from the middle of lakes that are almost exclusively visited by birds.

The first ancient virus discovered frozen in ice was found in 1999 in the Arctic by Rogers and colleagues at Syracuse University in New York, US. Other researchers have revived a bacterium that sat dormant in a frozen pond in Alaska for 32,000 years. And a 250-million-year-old bacterium stored in salt has also been brought back to life.

Journal reference: Journal of Virology (vol 80, p 12229)


2 of 2


Resource 8

SNAB Topic 4


Single virus gene may cause obesity

1 of 1


Resource 9

04 April 2008

If obesity seems to be spreading like a virus, that could be because it is. We’re now closer to understanding how adenovirus-36 (Ad-36), thought to be responsible for some cases of obesity, causes fat cells to grow.

Last year Nikhil Dhurandhar at Louisiana State University at Baton Rouge showed that Ad-36 causes precursor cells to differentiate into fat cells, and could promote obesity in humans and animals. Now he has shown that a single viral gene is responsible for triggering this process, meaning that one day it may be possible to treat “viral obesity” by altering the action of that gene.

Dhurandhar’s team engineered stem cells from human fat to express a single gene from Ad-36, called E4 ORF-1. The cells were much more likely to differentiate into fat cells than those

that did not express the gene. When they blocked expression of E4 ORF-1 in cells infected by Ad-36, the cells failed to differentiate into fat cells - proof that this gene is both necessary and sufficient for fat cell differentiation. Researchers may someday be able to block E4 ORF-1 in humans to prevent Ad-36-induced obesity, he says.

The gene also makes cells more responsive to insulin, so drugs that mimic this part of the gene’s action may also be useful in treating type 2 diabetes. Hopefully they’ll find a way to tease out this part of the gene’s action from the fat-promoting part.

From New Scientist issue 2650, 04 April 2008, page 15


SNAB Topic 4


72


Science : Gut bacteria recycle rivals’ wasteBob Holmes, 12 October 1996 One person’s waste is another’s livelihood. And the same rule, it seems, applies in the microbial world: slow-growing strains of a bacterium found in our guts hold their own against faster-growing strains by feeding off their competitors’ excreta.

As part of a series of experiments on bacterial evolution, researchers led by Paul Turner of Michigan State University in East Lansing grew hybrids of laboratory strains of Escherichia coli.

According to classical ecological theory, such an environment should soon become dominated by a single strain. “What we expect is that the most fit competitor should take over,” says Turner.

Instead, two strains settled into an apparently stable coexistence. When Turner looked more closely, he found that the two used very different strategies for survival. Every 24 hours, he took a small sample of the culture and transferred it into a fresh flask of broth rich in glucose. In this new growth medium, one strain initially multiplied quickly, but stopped growing once it had consumed all the glucose. But the other strain continued to grow, albeit slowly.

1 of 1


Resource 10

Through further experiments, Turner showed that the slow-growing strain could only keep growing if the more competitive strain was also present - which indicated that the sluggish strain was feeding off the by-products of its companion’s metabolism (Ecology, vol 77, p 2119).

These studies show how easily natural systems can transform simple environments into more complex ones, says Turner. He believes that biologists may have overlooked other examples of “cross-feeding”, because most bacterial strains are difficult to tell apart.

From New Scientist issue 2051, 12 October 1996, page 15


SNAB Topic 4


74


Evaluating presentations

Having done the preparation, students deliver their presentations to a group of their peers as part of a guided evaluation exercise. Encourage students to think about the process of giving feedback when they are evaluating other students’ presentations.

Tips and strategies

Each presentation will require ten minutes for the presentation, plus five minutes for discussion of the evaluation. As many students as possible should do this. You might be able to split the class in two, with half going to another room to deliver their presentations. You should divide your time between the groups. Or, you could ask the students to attend an after school presentation session (however unpopular this may appear at the first suggestion!)

You may not want each student to fill in an evaluation sheet for each presentation. You could get the whole of the audience to agree on a consensus, filling the form in at the end of the presentation.

If you did not go through the slide presentation ‘Delivering your presentation’ associated with Activity 6.1, you could use this before students give their presentations. The slides from this presentation are also available as a PDF which can be downloaded from the LSS website http://www.sep.org.uk/lss.


deliver a presentation and evaluate their own • performance

evaluate presentations delivered by other • students, and give verbal and written feedback.

Time requiredDepends on the number of presentations – see ‘Tips and strategies’ for suggestions.

Outline of the activityGive students one or more evaluation sheets, and talk them through the contents. Selected students give their presentations. Each student fills in an evaluation form for each presentation.

At the end of a presentation, the presenter should comment on what they thought was good and bad about their own presentation and its delivery. A selection of students from the audience should be asked to give some constructive feedback based on the evaluation form they have filled in.

The evaluation sheet should be adapted depending on the criteria for the presentation agreed in Activity 6.1.

1 of 1

SNAB Topic 4


76


This sheet can be used to evaluate presentations. Listen to the presentation and award a mark at the end. You may want to make notes or tick off the criteria as the presentation proceeds. Each category has a weighting. For instance, content is 35 %, so you award a mark out of 35 in that category.

Criteria for assessment Weighting Mark

Content

The reason for choosing the topic was explained.

Background information was given in appropriate detail.

The application of the science was explained.

Suitable data was presented in table or graph form, and was discussed.

The impact of the science in the context presented was explained.

There was evidence that the topic had been thoroughly researched.

35 %

Structure

The presentation was clearly structured with an introduction at the start and a conclusion at the end.

The talk flowed smoothly throughout.

The introduction set the scene and made you want to listen.

The conclusion summarised the key points of the talk.

20 %

Oral delivery

The presenter(s) presented their ideas clearly and maintained eye contact with the audience.

The presentation didn’t simply recite the material from the board, but showed some versatility and imagination.

20 %

Voice

The presenter spoke clearly, projecting their voice so that they could be heard clearly at all times.

The presenter had an engaging style and maintained their audience’s interest throughout.

15 %

Questions

The presenter(s) answered questions clearly, without waffling. If they didn’t know an answer, they suggested where it might be found.

10 %

Evaluating presentations

Briefing sheet

1 of 1

Total mark: _______ %

SNAB Topic 4




organise large amounts of data effectively and •clearly into a table

interpret the data to produce a visual •representation, such as a graph.

Time requiredAlllow one hour, to include peer evaluation and feedback. The individual activity of transforming the data into a table and subsequent visual representation could probably be completed in 30–40 minutes.

Outline of the activityStudents are provided with a piece of data from the conventional on Biological Diversity about biomes loss due to human impact. They work independently to produce a table from the data, then share their work with a partner. Having chosen one of the tables, or a combination of the two, they then work together to transform the data table into a different kind of visual representation.

Thefinalpartoftheactivityinvolvesstudentsevaluating each other’s visual representations and tables, to see the variety of approaches used. They consider the merits and disadvantages of the variety of representations and audiences.

Processing and representing data

Tips and strategies This activity assumes that students already have some experience of handling data and interpreting tables. It may be useful to start the session by discussing the key attributes that are required from a data table, and / or to provide some examples of information in tables.

A discussion on the most appropriate type of graph to use and whether average values, and trend line mask important features of the data is useful before starting this activity.

The evaluation section could involve students presenting their work to each other. Alternatively this could be done less formally by giving students a period of time to view each others’ work, then coming back together as a group to discuss the merits of what they have seen.

SNAB Topic 4

Scientists often have to interpret large amounts of complex data. In order to do so, they need to be able to process the raw data into a form that is easy to understand. In this activity, students are given a set of raw data and are asked to convert it into a data table, then to select an appropriate visual presentation.

1 of 1



Processing and representing data

In this activity you will process data presented in continuous text.

A local Green group reported some global data about the loss of biomes due to human impact in their newsletter. The intention was to alert people to the seriousness of the situation. The data were not presented very clearly. this is what was written.

It is possible to extrapolate data from current soil and climate conditions to estimate the condition of biomes before human impact. The loss of original biomes is thought to have taken place significantly before 1950. 67% of Mediterranean forests, woodlands and scrub was lost by 1950, with a further 2% loss after 1990. The total loss projected by 2050 is 70%. This compares with Tropical and sub-tropical coniferous forests, where only 45% of the boime is expected to be lost by 2050. Deserts are thought to have suffered less, with 24% of biome loss by 1950, and 28% by 1990. A further 2% loss is expected by 2050.

Your task is to re-organise the data into table form, to make it as clear as possible. Process the data to produce an average set of results. Now compare your table with one produced by someone else in the group. Are they the same? Similar? Which is clearer and easier to understand? Why? Choose the one that you both agree presents the information in the clearest form, or combine aspects of both to make a detailed, clear data table.

Now,usingthefinaldatatable,turnthedataintoavisualrepresentationthatshows the trends and patterns in the data. Are there any discrepancies between the two sets of data? If so, how can you highlight them? What annotations can you add to your piece of work to highlight the key pieces of information that it contains? Consider whether you should plot both data sets or average values. Should you use a scatter graph, bar chart or line graphs, and is a trend line useful?

Whenyouhavefinished,compareyourvisualrepresentationwiththoseofothersin the class. Justify why you have presented the data in the way you chose. Are there similarities in the way the data has been presented? What differences are there?

1 of 1

SNAB Topic 4

snab invite an expert topic 4 - nuffield foundation · 12/10/1996 · 4 © 2008 gatsby technical...

Documents