C. elegans are a useful model organism
In the early 1970s Sydney Brenner established the free-living roundworm, Caenoerhabditis elegans as an elegant model system for examining development. Brenner selected C. elegans to use as a model for his genetic research because of its amenable genetics, which allow for the isolation of mutants and ease in breeding them to achieve mutants of interest. Since then C. elegans have become one of the most well-established models for fundamental genetic and neurobiology research (Brenner, 1974).
C. elegans offer many advantages as a model organism; the 1 mm adult C. elegans has a simple body system of 959 transparent cells whose origins and cell fates have all been mapped and many of the genes are conserved across metazoan. C. elegans are transparent, allowing for numerous visualization techniques to be implemented. Fluorescent markers, such as GFP, can be expressed in cells of interest to study cellular morphology, or attached to specific proteins to study their expression patterning and localization in the cell. Since the entire genome of C. elegans has been sequenced, the various mutations responsible for the induced mutant phenotype can be mapped to identify the causative mutation.
C. elegans exist as hermaphrodites producing spermatocytes during the larval stages and switching to produce eggs once adults. A single C. elegans hermaphrodite may lay somewhere between 200 and 300 eggs throughout its lifetime (Waggoner, Hardaker, Golik, & Schafer, 2000). Once laid, the eggs have a rapid life cycle in which they proceed through 4 larval stages, larval stage 1,2,3, and 4 (referred to as L1, L2, L3, and L4 respectively), before becoming mature adults. Male worms arise spontaneously at a low frequency (0.1%) due to improper chromosomal segregation during meiosis (Brenner, 1974).
Life Cycle of C. elegans
WormAtlas. Z.F. Altun and D. H. Hall (2012)
WormAtlas. Z.F. Altun and D. H. Hall (2012) Handbook of C. elegans Anatomy.http://www.wormatlas.org/hermaphrodite/hermaphroditehomepage.htm
The Genetics of CAENORHABDITIS ELEGANS, 1974 S. Brenner
Effect of a Neuropeptide Gene on Behavioral States in Caenorhabditis elegans Egg-Laying, Laura E. Waggoner, Laura Anne Hardaker, Steven Golik and William R. Schafer
GENETICS March 1, 2000