Suspended animation of C' Elegans embryos using carbon monoxide

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Suspended animation of C. Elegans embryos using
carbon monoxide

• By Cyndi Edwards

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Hypoxia

• Normal air 21 kPa O2 (101 kPa 1 atm)
• Mild hypoxia 0.25-1.0 kPa O2
• Intermediate hypoxia 0.001-0.25 kPa O2
• During mild hypoxia
• HIF-1 (Hypoxia Inducible Factor-1)
• Anaerobic energy production genes up-regulated
• glycolytic enzymes, glucose transporters
• Antioxidant genes upregulated
• catalase, superoxide dismutase

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Anoxia

• lt0.001 kPa O2
• HIF-1 response alone is not sufficient to protect
  the cells from free radicals
• Oxidative phosphorylation ceases
• ATP demand must also decrease
• Cells of some organisms enter into a state called
  suspended animation

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Suspended Animation

• No observable movement is visible
• Developmental progression ceases
• Turtle hepatocytes in this state are capable of
  reducing their ATP demand by 94
• limit protein synthesis, ion channel activity,
  and anabolic pathways
• Zebrafish embryos and C. elegans embryos stop
  moving and developing

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C. Elegans Embryo Viability
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Carbon Monoxide A Competitive Inhibitor of
Oxygen Binding
CO

• CO binds and inhibits cytochrome c oxidase
  (complex IV), causing free radical production
• Thus CO effectively lowers the effective amount
  of oxygen electron carriers

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Can carbon monoxide induce suspended animation in
damaging low oxygen conditions?
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Experimental Setup
Embryos exposed to various levels of hypoxia or
to anoxia by changing gas inflow
Embryos put in 30 mL leak-proof glass syringes
with gas inlets
Two-cell embryos were harvested from adults of
the Bristol N2 strain
Embryos were then removed and immediately
photographed
Embryos were moved to culture plates to assay
their viability
Embryos were exposed to the same oxygen level for
24 hours
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Intermediate Hypoxic Exposure Resulted in
Abnormal Development
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Carbon monoxide was effective in inducing
suspended animation
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Take Home Message

• C. elegans embryos are capable of surviving in
  anoxia and mild hypoxia, but intermediate hypoxic
  conditions are lethal
• CO induced suspended animation in embryos
  experiencing intermediate hypoxia
• Embryos that had entered CO-induced suspended
  animation were highly viable

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References

• Article
• Nystul TG, Roth MB. Proc Natl Acad Sci USA. 2004
  Jun 15101(24)9133-6. Epub 2004 Jun 7. Carbon
  monoxide-induced suspended animation protects
  against hypoxic damage in Caenorhabditis elegans.
• Images
• http//biology.mcgill.ca/labs/roy/Researchinterest
  spage.html
• http//en.wikipedia.org/wiki/Carbon_monoxide
• http//www.castlefordschools.com/kent/07-0820less
  ons/Lessons/Chemistry20Lessons/chp201/Chemistry_
  files/image045.jpg