Program of the 2001 International Worm Meeting - Sternberg Lab ...

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mediated endocytosis (Grant and Hirsh, 1999).
As autophagy is required for survival under
stress or nutrient starvation conditions, we
hypothesized that autophagy might be required
for dauer formation or survival of the dauer
larva. To investigate this hypothesis, we injected
daf-2 mutants with Ce beclin1 dsRNA. daf-2
mutants are dauer constitutive when raised at
the restricted temperature and have an increased
lifespan at the permissive temperature (Riddle,
1997). Ce beclin 1 (RNAi);daf-2 double mutants
arrested at different stages of dauer formation
when grown at the restrictive temperature.
Survival of the daf-2 dauers was also affected
after beclin1 RNAi. We are now using electron
microscopy to determine if autophagy is
increased upon dauer formation, and if
autophagy is affected in the Ce beclin 1 RNAi
mutants.
In summary, Ce beclin 1 RNAi-soaked N2
worms arrest at the L1 stage and display
intestinal defects, and the Ce beclin 1
RNAi-injected daf-2 worms arrest at different
stages of dauer formation. While the molecular
basis of these phenotypes is not yet known,
these observations suggest a possible role for
beclin 1-mediated autophagy in C. elegans
development and in the survival or formation of
the C. elegans dauer stage larvae.
B. Grant and D. Hirsh, 1999. Receptor-mediated
endocytosis in the Caenorhabditis elegans
oocyte. Mol Biol Cell 1999
Dec;10(12):4311-26.
X. H. Liang et al., 1999. Induction of autophagy
and inhibition of tumorigenesis by beclin 1.
Nature. 1999 Dec 9;402(6762):672-6.
D. L. Riddle, in Caenorhabditis elegans II, D.
Riddle, T. Blumenthal, B. Meyer, J. Priess, Ed.
(Cold Spring Harbor Laboratory Press, Cold
Spring Harbor, NY, 1997), pp. 739-768.
632. Oxygen Deprivation in
Caenorhabditis elegans
Pamela Padilla, Todd Nystul, Mark
Roth
Division of Basic Sciences, Fred Hutchinson
Cancer Research Center, Seattle, Washington
98109, USA
632
C. elegans respond to anoxia (0% oxygen) by
entering into a state of recoverable suspended
animation. Nematode exposure to anoxia causes
all microscopically observable movement to
cease, including cell division, developmental
progression, feeding, and motility. Upon
re-exposure to oxygen, animals resumed these
processes. All nematode life cycle stages are
capable of exhibiting this response to anoxia.
However, the survival rate to prolonged
exposure of anoxia depends on life cycle stage.
To determine if blastomeres from embryos
exposed to anoxia arrest during specific points
in the cell cycle we used various cell cycle
regulated antibodies for immunofluorescence
analysis. We found that blastomeres can arrest
during interphase, prophase, metaphase, and
telophase but not anaphase. To investigate the
mechanism by which so many diverse cellular
processes are coordinately regulated during
suspended animation we examined the
phosphorylation state of several proteins. We
found that phosphorylated forms of histone H3,
RNA Polymerase II, and cell cycle regulated
proteins recognized by the MPM-2 antibody
were not detectable in anoxia-arrested embryos.
In contrast, phosphorylated forms of SR
proteins were detectable in anoxic blastomeres.
This suggests that specific dephosphorylation of
key proteins may play a critical role in the
establishment and/or maintenance of a state of
suspended animation.