UNIT 1.2
Gravity and Biology
Presented by:
Dr. Emily Morey-Holton
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INTRODUCTION
UNIT 1.2
Gravity and Biology
Dr. Emily R. Morey-Holton
NASA’S VISION
To improve life here.
To extend life there.
To find life beyond.
NASA’S MISSION
To 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!
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. Rodents
d. 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?
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INTRODUCTION
What is Gravity?
M1m2
Fg = Gu
d2
GRAVITY IS A CONTINUUM
0G
10-5 G
1 5G
G
MultiG Mentality
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a
INTRODUCTION
What Happens to Life When Gravity Changes?
http://www.csr.utexas.edu/grace/
g
d
Ichthyostega
350 MY
Moschops
150 MY
Bush Baby
70 MY
Gorilla
30 MY
Human
1.6 MY
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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INTRODUCTION
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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INTRODUCTION
What Happens to Life When Gravity Changes: Cells
7 flights with E. Coli
Bottom line: ~ doubling of cells
likely due changes in environment
http://www.colorado.edu/ASEN/asen5016/Animation.gif
Klaus, D., S. Simski, P. Todd, and L. Stodieck. Investigation of space flight effects on E. Coli and a
proposed model of underlying physical mechanisms. Microbiology 143:449-455, 1997.
Klaus, D.M. Microgravity and its Implication for Fermentation Technology. Trends in Biotechnology
16:369-373, 1998.
Microvilli
RENAL CELLS
Static 1G
MIR
Static 1G
RWV 1 G
Static 1G
3G
Hammond, T.G., F.C. Lewis, T.J. Goodwin, et al. Gene
expression in space. Nature Medicine 5:359, 1999
http://www.tmc.tulane.edu/astrobiology/microarray
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INTRODUCTION
What Happens to Life When Gravity Changes: Cells
AVIAN MUSCLE
Avian muscle fibers
decrease their rate of protein synthesis and lose fiber mass
Vandenburgh H, Chromiak J, Shansky J, Del Tatto M, Lemaire J. Space travel directly induces
skeletal muscle atrophy. FASEB J. 13:1031-1038, 1999.
Ingber, D. How cells (might) sense microgravity. FASEB J. 13 (Suppl.), S3-S15, 1999.
Force Coupling Between Extracellular Matrix and the Cytoskeleton
Ingber, D. E. Tensegrity: The Architectural Basis
of Cellular Mechanotransduction. Annu. Rev.
Psiol. 59:575-59, 1997; The architecture of life.
Sientific American, January 1998.
Ingber, D. E. Tensegrity I. Cell structure and
hierarchical systems biology. J Cell Sci. 116:
1157-1173, 2003.
Ingber, D. E. Tensegrity II. How structural networks
influence cellular information processing
networks. Cell Sci. 116:1397-1408, 2003.
Cell & molecular biology research in space. FASEB
J. 13 (Suppl.), S1-S177, 1999.
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INTRODUCTION
What Happens to Life When Gravity Changes: Cells
Cells Summary:
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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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INTRODUCTION
What Happens to Life When Gravity Changes: Plants
ABOVE THE GROUND:
Uneven ripening in
Brassica (Musgrave, 2000)
Water droplet (with air bubble)
sticks to leaf and doesn’t bend
stem
on ISS (Budarin photo, 4/9/03)
Lessons Learned:
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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)
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INTRODUCTION
What Happens to Life When Gravity Changes: Plants
BELOW THE GROUND:
Water Management for Wheat Production
The difference between the vertical root
zone water content distributions
observed in µg and at 1g using 1-2 mm
Balkanine porous media in the10 cm
tall Svet root modules
Lessons Learned
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Little distances have big effects on water
movement
Capillary forces become dominant as gravitational
forces decrease
Properly managed porous substrate root zones can
deliver hydroponic class results in µg.
Increasing light levels will increase the strain on
the root zone water delivery systems
Root growth media (wetting characteristics,
particle size, and pore size) must optimize
availability of water, dissolved nutrients, and gases
Bingham, G.E., S.B. Jones, D. Or, Utah State
University;
I. Podolsky, V. Sytchev, Institute of Biomedical
Problems, Moscow. Water Management
Lessons from Plant Full Life Cycle Experiments
on Mir, Grav. Space Biol. Bull. 12: 56, 1998.
Jones, S.B. and D. Or. Microgravity effects on water
flow and distribution in unsaturated porous
media: analysis of flight experiments. Water
Resources Research 35: 929-942, 1999.
Plants Summary:
Plants must adapt to two environments- Above AND Below the ground. They have a short
lifespan, low light requirements, and small size complicating understanding of spaceflight
adaptation.
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INTRODUCTION
What Happens When Gravity Changes: Vertebrate Development
SPECIES DOUBLING TIME
E. Coli (Bacteria):
Yeast:
Protozoa (Euglena in the dark):
Paramecium:
Eukaryotic cells in culture:
C. Elegans:
Arabidopsis (Plant):
Drosophila:
Rodent:
Zebrafish:
Quail/chicken:
Xenopus:
Human:
0.01d (16 min)
0.07d (100 min)
0.5d
0.75d
1d
4d (on plates) or 8d (in suspension culture)
25d (light dependent)
13d (at 25C)
21d gestation + 42d fertile age = 63d (2 mo)
90d (3.2 mo)
20d egg + 70d fertile age = 90d (3 mo)
152d (diploid, 5 mo)
or 730d (pseudo tetraploid, 2 yr)
270d gestation + 5110d = 5380d (15yr)
Species doubling times vary greatly between species. Invertebrates (bacteria through
insects) can go through multiple generations during the 90-day crew rotation planned
for ISS, while vertebrates have a minimal doubling time of 84 days. Humans have
only spent ~1% of life span in space. Most data pre/post flight, not in flight.
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INTRODUCTION
What Happens When Gravity Changes: Vertebrate Development
AMPHIBIANS
0g
Picture data from Ken Souza, NASA Ames Research Center
Major Findings:
•
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•
•
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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. PNAS
92:1975-1978, 1995.
0g
Inflight 1g
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INTRODUCTION
What Happens When Gravity Changes: Vertebrate Development
QUAIL
Preliminary Findings:
•
Adult quail adapted readily to the
spaceflight environment.
•
Hatchlings did not develop motor skills
necessary for prolonged survival in space.
MIR downlink video from Dr. T. Jones, U.Missouri-Columbia/Dr. K. Boda, Slovak Academy of Science
RATS
Preliminary Finding:
Neonates
Critical developmental periods may require gravity
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.
Vertebrate Development Summary:
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Development transitions may be lethal to tadpole.
•
Biomechanical loading may be required for Earth-like development of some
structures/innervation.
•
Habitats for multiple generations in space - may require different caging for different
stages of development.
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INTRODUCTION
What Happens to Life When Gravity Changes: Adult Humans
Percentage of lifespan spent in space
Humans ~1%
Rats ~2%
ABOUT LOAD
Dr. Rob Whalen
Spaceflight Changes
•
Fluid / Cardiovascular
•
Neurovestibular
• Musculoskeletal
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INTRODUCTION
What Happens to Life When Gravity Changes: Adult Humans
FLUID/CARDIOVASCULAR
Major Findings:
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•
•
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Fluid shifts toward the head
Reduced plasma volume
Decreased red blood cell number
Decreased central venous pressure challenges traditional concepts
Difficulty standing postflight
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INTRODUCTION
What Happens to Life When Gravity Changes: Adult Humans
NEUROVESTIBULAR
Major Findings:
•
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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
Major Findings :
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Increased calcium in urine with loss of bone
mineral 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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INTRODUCTION
What Happens to Life When Gravity Changes: Adult Humans
COUNTERMEASURE RECOMMENDATIONS
NASA TASK FORCE ON COUNTERMEASURES, May 1997
Exercise: heavy resistance for maximal force production to
maintain 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
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MEDICAL SYMPTOMS IN U.S SPACE PROGRAM
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Shuttle program (89 shuttle missions) 1981-1998
508 crew (439 men, 69 women)/ 4443 flight days
o 79% reported Space Motion Sickness
o 98% reported some medical symptom
ß 67% reported headache
ß 64% reported respiratory complaints
ß 59% reported facial fullness
ß 32% reported gastrointestinal complaints
ß 26% reported musculoskeletal complaints
Adapting to spaceflight is not an issue -- returning to Earth is!
FUNCTIONAL USE HYPOTHESIS
Use it or Lose it!
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INTRODUCTION
Conclusions - All Species
•
Is Gravity necessary for life as we know it?
o Life is plastic--adaptive (transient/chronic) changes in single generations
o Gravity may be essential for life as we know it
•
Does Gravity play a role in evolution?
Response to Hypergravity
Tree Snake>Land Snake>Aquatic Snake
Lillywhite, H.B. Snakes, blood circulation and gravity. Scientific
American. 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.
Tree Land
Sea
We can venture into space -- but could we come home after
multiple generations?
GRAVITY SHAPES LIFE!!!
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INTRODUCTION
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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INTRODUCTION
Notes:
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