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UNIT 1.2

Gravity and Biology

Presented by: Dr. Emily Morey-Holton


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UNIT 1.2Gravity and Biology

Dr. Emily R. Morey-Holton

Outline:

1. What is gravity?

2. What happens to life when gravity changes?a. Cells i. E. Coli ii. Renal Cells iii. Avian Muscle

b. Plants i. Above the Ground ii. Below the Ground

c. Vertebrate Development i. Amphibians ii. Quail

iii. Rodentsd. Adult Humans i. Fluid / Cardiovascular ii. Vestibular iii. Musculoskeletal

3. Is gravity necessary for life as we know it?4. Does gravity play a role in evolution?

NASAS VISION

To improve life here.To extend life there.To find life beyond.

NASAS MISSIONTo understand and protect our home planet.To explore the Universe and search for life.To inspire the next generation of explorers.

.as only NASA can!


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What is Gravity?

g = G u M 1m 2d 2

10G 5G10 -5 G

GRAVITY IS A CONTINUUM

MultiG Mentalityulti Mentality


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What Happens to Life When Gravity Changes?

http://www.csr.utexas.edu/grace/

Ichthyostega Moschops Bush Baby Gorilla Human350 MY 150 MY 70 MY 30 MY 1.6 MY

dg

Gravity is a far ranging force with intensity and direction and is the

most constant environmental factor through evolution.

Gravity on Earth = 1G throughout evolution

Weight = Mass x G level


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What Happens to Life When G Changes?

With reduced gravity:

o Rain does not fall

o Water does not drain

o Heat does not dissipate

o Air and water do not separate

o There is no falling "down"

o Altered fluid flow, structural support, g detection systems

o Shape changes rather than volume--requires generations, not acute studies

How much G is enough?

How much G is too much?

o Cells/Small Organisms--106G--easier transit through space

o Young Plants--10 minutes at 30-40G

o Rats--15G for 10 min (20G is lethal)

o Humans--4-5G for 10 minutes--take Earth along


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What Happens to Life When Gravity Changes: Cells

Klaus, D., S. Simski, P. Todd, and L. Stodieck. Investigation of space flight effects on E. Coli and aproposed model of underlying physical mechanisms. Microbiology 143:449-455, 1997.

Klaus, D.M. Microgravity and its Implication for Fermentation Technology. Trends in Biotechnology16:369 -373, 1998.

http://www.colorado.edu/ASEN/asen5016/Animation.gif

7 flights with E. Coli

Bottom line: ~ doubling of cellslikely due changes in environment

Microvilli

Static 1G

Static 1G

Static 1G

MIR

RWV 1 G

3 G

http://www.tmc.tulane.edu/astrobiology/microarray

Hammond, T.G., F.C. Lewis, T.J. Goodwin, et al. Geneexpression in space. Nature Medicine 5:359, 1999

RENAL CELLS


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Avian muscle fibersdecrease their rate of protein synthesis and lose fiber mass

Vandenburgh H, Chromiak J, Shansky J, Del Tatto M, Lemaire J. Space travel directly inducesskeletal muscle atrophy. FASEB J. 13:1031-1038, 1999.Ingber, D. How cells (might) sense microgravity. FASEB J. 13 (Suppl.), S3-S15, 1999.

AVIAN MUSCLE

Ingber, D. E. Tensegrity: The Architectural Basisof Cellular Mechanotransduction. Annu. Rev.Psiol. 59:575-59, 1997; The architecture of life.Sientific American, January 1998.

Ingber, D. E. Tensegrity I. Cell structure andhierarchical systems biology. J Cell Sci. 116:1157-1173, 2003.

Ingber, D. E. Tensegrity II. How structural networksinfluence cellular information processingnetworks. Cell Sci. 116:1397-1408, 2003.

Cell & molecular biology research in space. FASEBJ. 13 (Suppl.), S1-S177, 1999.

Force Coupling Between Extracellular Matrix and the Cytoskeleton


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Cells Summary:

Local microenvironment altered

Steady state gene expression may change

Cellular force coupling systems need further study

Mechanosensitive channels need further study

Cellular signaling mechanisms may be altered

Some cellular structures may have evolved to detect or oppose loading


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What Happens to Life When Gravity Changes: Plants

ABOVE THE GROUND:

Lessons Learned:

Stems branch at 90 in space vs 45 on Earth; main stem follows light similar to Earth Manual pollination is required With appropriate airflow and environmental control, plants ( Brassica ) can go through

all stages of development Decreased height and seed weight and quality in F2 and uneven ripening of

silique(starts at tip and moves to stem rather than uniform)(Musgrave, 2000)

Uneven ripening inBrassica (Musgrave, 2000)

Water droplet (with air bubble)sticks to leaf and doesnt bendstem


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Bingham, G.E., S.B. Jones, D. Or, Utah StateUniversity;

I. Podolsky, V. Sytchev, Institute of BiomedicalProblems, Moscow. Water ManagementLessons from Plant Full Life Cycle Experimentson Mir, Grav. Space Biol. Bull. 12: 56, 1998.

Jones, S.B. and D. Or. Microgravity effects on water flow and distribution in unsaturated porousmedia: analysis of flight experiments. Water Resources Research 35: 929-942, 1999.

What Happens to Life When Gravity Changes: Plants

BELOW THE GROUND:

Water Management for Wheat Production

Lessons Learned

Little distances have big effects on watermovement

Capillary forces become dominant as gravitationalforces decrease

Properly managed porous substrate root zones candeliver hydroponic class results in g.

Increasing light levels will increase the strain onthe root zone water delivery systems

Root growth media (wetting characteristics,particle size, and pore size) must optimizeavailability of water, dissolved nutrients, and gases

Plants Summary:

Plants must adapt to two environments- Above AND Below the ground. They have a shortlifespan, low light requirements, and small size complicating understanding of spaceflightadaptation.

The difference between the vertical rootzone water content distributions

observed in g and at 1g using 1-2 mmBalkanine porous media in the10 cm

tall Svet root modules


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What Happens When Gravity Changes: Vertebrate Development

SPECIES DOUBLING TIME

E. Coli (Bacteria): 0.01d (16 min)Yeast: 0.07d (100 min)Protozoa (Euglena in the dark): 0.5dParamecium: 0.75dEukaryotic cells in culture: 1dC. Elegans: 4d (on plates) or 8d (in suspension culture)Arabidopsis (Plant): 25d (light dependent)Drosophila: 13d (at 25C)Rodent: 21d gestation + 42d fertile age = 63d (2 mo)Zebrafish: 90d (3.2 mo)Quail/chicken: 20d egg + 70d fertile age = 90d (3 mo)Xenopus: 152d (diploid, 5 mo)

or 730d (pseudo tetraploid, 2 yr)Human: 270d gestation + 5110d = 5380d (15yr)

Species doubling times vary greatly between species. Invertebrates (bacteria throughinsects) can go through multiple generations during the 90-day crew rotation plannedfor ISS, while vertebrates have a minimal doubling time of 84 days. Humans haveonly spent ~1% of life span in space. Most data pre/post flight, not in flight.


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Major Findings:

A vertebrate can ovulate in the virtual absence of gravity Rotation of egg in space not essential for development Thicker blastocoel roof without obvious tadpole defects Eggs can develop to a free-living system in space Lungs of flight tadpoles did not inflate

Souza, K.A., S.D. Black, and R. J. Wassersug. Amphibian development in the virtual absence of gravity. PNAS92:1975-1978, 1995 .

0g

0g Inflight 1g

Picture data from Ken Souza, NASA Ames Research Center

AMPHIBIANS


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Preliminary Findings:

Adult quail adapted readily to thespaceflight environment.

Hatchlings did not develop motor skillsnecessary for prolonged survival in space.

MIR downlink video from Dr. T. Jones, U.Missouri-Columbia/Dr. K. Boda, Slovak Academy of Science

Preliminary Finding:

Vertebrate Development Summary:

Development transitions may be lethal to tadpole.

Biomechanical loading may be required for Earth-like development of somestructures/innervation.

Habitats for multiple generations in space - may require different caging for differentstages of development.

Movie clips from Dr. Kerry Walton/Dr. Rodolfo Llinas, NYU Medical Center Walton, K. Postnatal development under conditions of simulated weightlessness and space flight.Brain Res. Reviews 28:25-34, 1998 .

QUAIL

RATS

Neonates

Critical developmental periods may require gravity


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What Happens to Life When Gravity Changes: Adult Humans

Spaceflight Changes

Fluid / Cardiovascular

Neurovestibular

Musculoskeletal

Percentage of lifespan spent in space

Humans ~1%Rats ~2%

ABOUT LOAD

Dr. Rob Whalen


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Major Findings:

Fluid shifts toward the head Reduced plasma volume Decreased red blood cell number Decreased central venous pressure challenges traditional concepts Difficulty standing postflight

FLUID/CARDIOVASCULAR


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Major Findings:

Space adaptation syndrome Increased reliance on touch and sight for vertical alignment of the body early in flight Later in flight, down is where the feet are (internal alignment) Postflight: postural instability--reinterpret cues Postflight: slowed reflexes associated with posture and gait

MUSCULOSKELETAL

NEUROVESTIBULAR

Major Findings :

Increased calcium in urine with loss of bonemineral in the weight-bearing bones

Minimal loss in total body mineral Loss of bone may be associated with muscle loss,

both are site-specific Loss of lean body mass in lower extremities and

trunk>bone loss Functional/phenotype change in postural

(antigravity) muscles Postflight: reduced muscle strength and power


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Adapting to spaceflight is not an issue -- returning to Earth is!

FUNCTIONAL USE HYPOTHESISUse it or Lose it!

COUNTERMEASURE RECOMMENDATIONSNASA TASK FORCE ON COUNTERMEASURES, May 1997

Exercise: heavy resistance for maximal force production tomaintain Earth loading levels

Diet sufficient for energy expenditure and hydration needs UV light Artificial g: g direction and g gradient are very important Drugs to be used only if physical countermeasures are ineffective

MEDICAL SYMPTOMS IN U.S SPACE PROGRAM

Shuttle program (89 shuttle missions) 1981-1998 508 crew (439 men, 69 women)/ 4443 flight days

o 79% reported Space Motion Sicknesso 98% reported some medical symptom

67% reported headache 64% reported respiratory complaints 59% reported facial fullness 32% reported gastrointestinal complaints 26% reported musculoskeletal complaints


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Conclusions - All Species

Is Gravity necessary for life as we know it?o Life is plastic--adaptive (transient/chronic) changes in single generationso Gravity may be essential for life as we know it

Does Gravity play a role in evolution?

We can venture into space -- but could we come home aftermultiple generations?

GRAVITY SHAPES LIFE!!!

Response to HypergravityTree Snake>Land Snake>Aquatic Snake

Tree Land Sea

Lillywhite, H.B. Snakes, blood circulation and gravity. ScientificAmerican. 256:92-98, 1988.Lillywhite, H.B., R.E. Ballard, A.R. Hargens, and H.I. Rosenberg.

Cardiovascular responses of snakes to hypergravity.Gravitational Space Bio. Bull. 10 (2):145-152, 1997.


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Reference Materials and Web Links

http://www.csr.utexas.edu/grace/

http://www.colorado.edu/ASEN/asen5016/Animation.gif

http://www.tmc.tulane.edu/astrobiology/microarray

http://astrobiology.arc.nasa.gov/home.html

http://space.arc.nasa.gov

http://lifesci.arc.nasa.gov


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Notes:

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