A C. elegans adult hermaphrodite imaged using Nomarski
microscopy [Abbi Cox].
C. elegans is a powerful model system for
exploring the cellular mechanisms of early development, for
several reasons:
(1) They're simple: The adult
hermaphrodite has just a little over 1000 somatic nuclei (a
few cells fuse together into multinucleate cells called
syncytia). At the time most morophogenesis takes place,
there are only several hundred cells in the embryo.
(2) They're transparent: Living C.
elegans embryos can be imaged using Nomarski
microscopy, or by imaging transgenic embryos expressing
fluorescent proteins such as GFP.
(3) They're reproducible: Embryonic
development is incredibly reproducible from embryo to
embryo. Largely through the work of Nobel laureate John
Sulston and colleagues, this allowed the determination of
the complete lineage of every cell in C. elegans,
i.e., the "history" of each cell in the embryo can be
traced back to the one-celled zygote.
For more, see the WormAtlas and WormClassroom web site. For some cool
movies, see Bob Goldstein's movie repository
(some of our stuff is there, too!).
C. elegans is a powerful model system for
exploring the molecular mechanisms of early development as
well, for several reasons:
(1) Genetics: Mutants can be isolated that
have specific defects in development, and the mutated gene
can be identified through positional cloning.
(2) Genomics: C. elegans was the
first higher eukaryote whose genome was sequenced. As a
result, there are a huge number of molecular reagents and
bioinformatics tools available.
(3) Reverse genetics: RNA-mediated
interference, or RNAi, was initially discovered in C.
elegans. Worms can be injected with double-stranded
RNA corresponding to a gene or fed bacteria that produce
such RNA. The result is a knockdown of the function of that
gene. RNAi clones spanning most of the genome are available
for use in genome-wide screens.
For more, see WormBase.