12PULS-CEPublic understanding of life sciences - chemical ecology

NEwSLEttEr NovEmbEr 2008

imPrs Project: savanna ecology

Savannas are characterized by a co-dominance of grasses and woody plants (trees and/or shrubs). what are the mechanisms that allow both life forms to co-exist? ...

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career grant for max Planck Junior scientist

Silke Sachse, neurobiologist in the Department of Evolutionary Neu-roethology, has received 1.3 million euros from the German Federal min-istry of Education and research to establish her own research group...

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highlight: the right mixture is everything

Experiments with genetically modi-fied plants reveal new aspects of the biochemistry of flowers ...

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PULS-CE 12

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Editorial: Thinking outside the box ...

Dear Readers!Typically, human beings think linearly. Forward promises advance-ment, renewal, development, and in the end: success. Unfortunately, this way of thinking is often and too easily transferred one-to-one to processes in nature, so that active stimulus = increased reaction, more substance = larger effect, etc. However, as biology has repeatedly shown - cyberneticists won’t be surprised! - an allegedly negative impact may have positive ef-fects. In this issue of PULS we report on Silke Sachse, who - thanks to new

research funds - studies the brains of fruitflies and has discoverd a sensory stimulus that can temporarily switch off certains areas in the brain, although stimuli are better known to activate the brain. Danny Kessler, on the other hand, discovered in experiments with transgenic plants by means of video monitoring that tobacco flowers not only actively attract moths by emitting volatile compounds, but also fend off voracious hummingbirds with floral nectar that contains bitter nicotine (see page 3 of this issue). Why? Both

processes, attracting and deterring, indeed help the flowers to spread their pollen most effectively: Because of the nectar’s bitter taste, hummingsbirds take nectar from many flowers instead of drinking their fill from one, which helps to optimize plants’ outcrossing.

Merry Christmas!

Jan Kellmann

Career Grant for Max Planck Junior ScientistSilke Sachse has received 1.3 million euros from the German Federal Ministry of Education and Research to establish her own research group

Silke Sachse, neurobiologist in the Department of Evolutionary Neu-roethology of Bill Hansson, is one of five female scientists in Germany who was suggested for the funding of talented young neuroscientists by international experts.

The 1.3 million euros provided by the German Federal Ministry of Education and Research will cover the salaries of scientists, PhD students and technical assistants, as well as the purchase of special equipment and the running of newly equipped labs.

The project will run for five years. Research will focus on neurons in Drosophila brains. Using special fluorescent proteins and two-photon laser-scanning microscopy, Silke is able to observe and measure the activities in the insect brain. Focus-

ing on the sense of smell, she can visualize the processes of olfaction in the Drosophila brain. Results can be

transfered to the cerebral and neural functions of other animals, including humans.

Dr. Silke Sachse and Prof. Dr. Bill Hansson, Director at the MPI for Chemcial Ecology, in whose department the new research group will be located. Picture: MPI

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highlight: the right mixture is everythingExperiments with genetically modified plants reveal new aspects of the biochemistry of flowers

Plants are sessile organisms and require the help of a pollinator to transport pollen to receptive stigmas. The colors of flowers as well as their volatile signals attract different ani-mal visitors, which then transfer pol-len. on the other hand, bitter nectar ingredients deter nectar thieves. to understand the floral biochemistry and plants’ ecological interactions, researchers in the Department of molecular Ecology performed experi-ments with genetically modified wild tobacco. Apart from control plants, transgenic lines were created (by means of rNA interference) that were unable to produce either nicotine or the attractant benzyl acetone. A third line of transgenic plants could produce

neither nicotine nor benzyl acetone.Using video cameras, the researchers revealed that both attractant-deficient lines were rarely visited by humming-birds and moths. when visitors took nectar from flowers which contained a natural amount of deterring nicotine, they stayed for a short time only, while they enjoyed the nicotine-free nectar of the transgenic lines for longer times. To find out whether different visiting behaviors affect outcrossing and reproduction among plants, further analyses were performed, one focused on female fitness (production of seeds in the ovary), the other on male fitness (successful pollination of neighboring plants). To determine female fitness, the flowers of the transgenic plants were emasculated by removing the anthers. this enabled the researchers to measure only animal-mediated fer-tilization success rates, because self-pollination was prevented. only the control plants were normally crosspol-linated, and, moreover, the transgenic nicotine- and benzyl acetone-deficient plants produced less than half of the usual amount of seeds. the scientists measured the male fitness of the trans-genic plants by emasculating flowers

Hummingbird Selasphorus rufus taking nectar from Nicotiana attenuata flowers. Apart from different sug-ars the nectar of tobacco flowers also contains the toxin, nicotine. Picture: Danny Kessler

of surrounding wild grown tobacco plants and subsequently determining the origin of transgenic pollen which had fertilized their seeds using DNA probes. the control plants producing natural amounts of nicotine and ben-zyl acetone were the winners; the big losers (almost five times fewer cross-fertilized seeds) were pollinating plants that produced neither nicotine nor benzyl acetone. Interestingly, during the growing season, the male fertilization success switched from the attractant (benzyl acetone)-deficient to the nicotine-deficient plants. In other words: The influence of nicotine in the nectar on successful pollina-tor-mediated fertilization of tobacco plants decreased continuously, and the attractant became more and more important. these measurements were confirmed by video recordings which showed that early in the year, when hummingbirds visit tobacco, nicotine in the nectar causes them to drink less of the bitter nectar, and in turn visit other flowers, thus increasing pollen transfer. Later in the year, moths visit frequently, attracted by the odor of benzyl acetone. the bitter taste of the nectar doesn’t seem to bother them. (JwK)

original Publication: Kessler D; Gase K; Baldwin IT (2008): Field Experiments with Transformed Plants Reveal the Sense of Floral Scents. SCIENCE 321, 1200-1202

The experiments with flowering transgenic tobacco plants were conducted at the field station operated at Brigham Young University’s Lytle ranch Preserve in Utah, USA. Picture: Danny Kessler

Danny Keßler and Ian baldwin examine tobacco plants in the research greenhouse in Jena. Picture: MPI

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IMPRS Project: Savanna Ecology

Savannas are characterized by a co-dominance of grasses and woody plants (trees and/or shrubs). What are the mechanisms that allow both life forms to co-exist?

To find out, researchers investigated climate conditions, interaction be-tween grasses and trees, and the impact of fires and herbivores in savannas worldwide, but until now no general approach has been found to explain why grasses do not outcompete woody plants or vice versa. Generally, there seem to be four factors which play an important role: the amount of rainfall (available water), nutrient availability, fire regime, and herbivore activity.

However, the strength of each factor is unclear. Knowledge about the drivers of vegetation structure and dynam-ics in savannas is important for the management of shrub encroachment, namely, the increase of woody vegeta-tion that is associated with a reduction of the grass layer. This process has considerable consequences for the ecology (e.g. loss of habitat diversity) and the economy (e.g. decrease in productivity).

Although many studies have examined different aspects in savannas, only a few have investigated the interactions within a life-form, asking, in particu-lar, how woody plants influence each other.

In my PhD thesis I focus on this is-sue, because I believe the interaction between shrubs can contribute to our understanding of the vegetation struc-ture in savannas. Positive and nega-tive effects between shrubs determine the density of a shrub population and hence may influence other species: For example, a strong competitive effect between shrubs may decrease the density of the species and allows grasses to increase.

My work has two aspects: 1) field work for data collection and 2) modeling.

The field work was done in a semi-arid savanna in South Africa, where I focused on the two dominant shrub species in this savanna region: Tarchonanthus camphoratus (wild camphor tree) and Acacia mellifera(black thorn). Which processes influ-ence their density and growth? In particular, how strong is the impact of shrub-shrub interactions, such as competition and facilitation (positive plant-plant interaction), on the spatial distribution and growth rate? Now back in Jena, using my field data, I am simulating the population dynamics of T. camphoratus, A. mellifera, and grasses in a savanna patch model and analyzing their dynamics under differ-ent interaction and rainfall scenarios. With this simulation model, I hope to contribute to the understanding of grass-shrub dynamics and the origin of shrub encroachment in savannas.

Jana Förster

Growth habits of Tarchonanthus camphoratus (Cam-phor bush) and Acacia mellifera (Blackthorn)

Picture: Jana Förster

PhD student Jana Förster doing field work in South Africa. Jana Förster, who holds a fellowship from the International Max Planck Research School, is working in the group of Prof. Kerstin Wiegand at the Institute of Ecology, University Jena. Picture: FSU

Semi-arid savanna in South Africa Picture: Jana Förster

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conference reports

lc-nmr Jena 2008

the coupling of separation techniques such as liquid chromatography (LC) and capillary electrophoresis with spectroscopic methods, especially nuclear magnetic resonance (Nmr) spectroscopy, is a highly efficient

way to identify and elucidate the structure of chemical substances, particularly metabolites occurring in nature. Such natural products me-diate the ecological interactions between organisms and are of special

Participants of the LC-Nmr Conference in August 2008 in front of the Abbe Centre beutenberg Picture: MPI

2nd Central and Eastern European Proteomics Conference: Group picture Picture: MPI

Proteomics conference in Jena

For the second time the “Central and Eastern European Proteomics Conference (CEEPC)” was held, this year from october 12 to 1�, 2008, in Jena. Among other topics discussed by the approximately 70 participants of the conference were protein-protein interactions, the application of new technologies in clinical diagnostics of diseases, and the fragmentation of peptides, the latter enabling the identification and discovery of new proteins. the conference, which was intended to provide an opportunity for young scientists from Central and Eastern Europe to meet the leading experts in this research field, was supported by the European Science Foundation.

interest in the development of new pharmaceuticals. the “International Conference on LC-Nmr and related techniques: Challenges in biological Systems”, with participating scientists from more that 20 countries, was or-ganized by the max Planck Institute for Chemcial Ecology and held at the Abbe Center on beutenberg Campus in Jena from August 27 to 29, 2008. At the conference pioneers in method development met with renowned scientists from academia and industry to discuss how to apply recently es-tablished coupling techniques to solve issues in biological, biochemical and ecological research. the participants appreciated the excellent scientific standard of the conference and agreed to meet regularly in the future. the conference was supported by the Ger-man research Foundation (DFG).

Bernd Schneider

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Impressum

PULS-CE can be downloaded free of charge on the homepage of the MPI for Chemical Ecologyand is distributed electronically as a PDF to subscribers. A print version can also be sent on request.Editor: MPI-CE, JenaManaging Director: Prof. Jonathan Gershenzon

Editorial Staff:Dr. Jan-W. Kellmann, Research CoordinationAngela Overmeyer, M.A., Information and Communication

www.ice.mpg.de

Junior Scientists Meet MPICE Alumni

For the first time the Max Planck In-stitute for Chemical Ecology invited former colleagues to this year’s insti-tute symposium. The evening session on the first day of the symposium provided two excellent lectures by two MPICE alumni: André Keßler, now assistant professor at Cornell University, Ithaca, NY, and Christian Hertweck, now full professor at Hans Knoell Institute and Friedrich Schiller University Jena. The alumni heeded the call to come back to the place where their scientific career began, among them Jürgen Kuhn, who is now

a member of the chemical ecology group at the University of Bielefeld, and Alfredo Ibáñez, currently a Hum-boldt fellow at the Institute of Medical Physics and Biophysics, University of Muenster.The highlight of the evening was when the alumni introduced themselves and talked about their lives and careers after they left the MPI. It was a very special moment, particularly for our junior scientists, who listened eagerly to their former colleagues’ descrip-tions and tried to imagine what their own career might look like!

In the evening, at a tasty dinner buffet, they had the opportunity to personally ask their former colleagues how they had managed.

The Max Planck Institute for Chemi-cal Ecology now wants to further develop contacts to its alumni and establish a format of regular alumni meetings, with a focus on interactions between former scientists and our cur-rent young research staff, interactions both sides may benefit from.

Angela Overmeyer

Christian Hertweck and André Keßler immersed in discussion Picture: MPI

The MPICE directors Bill Hansson, Jonathan Gershen-zon and David Heckel (from left) with Jürgen Kuhn

Picture: MPI

Alfredo Ibáñez (second from right) surrounded by his former colleagues Picture: MPI

maxNet is the communication platform of the MPG which is open to all former co-workers:

https://maxnet.mpg.de/