Thursday, November 24, 2011

Interesting Animals: C. elegans

One of the C. elegans roundworms.
Caenorhabditis elegans is one of the most commonly used research animals, especially when it comes to the world of genetics. In the wild, the species is very common and very harmless. The reason why it is so commonly used in research is due to one of its most unusual features: in the wild-type, hermaphroditic form, adults always have 959 cells. Unlike most animals, their is no variation in that number unless there is some underlying genetic issue or the individual is male. The small size and short generation time of these worms also makes them ideal, since at one millimeter they easily fit in a Petri dish and their life cycle is only three days. They also feed on the easy to cultivate Escherichia coli (among other things). Though there is no real common name for the species, in the research world it is simply called "the worm." The genome is rather small, so any changes in genes can be recognized and tracked fairly easily. In addition, gender in the species is controlled by X chromosomes, but not in the same way as in humans. XX individuals are hermaphrodites, and XO individuals are males. They also produce copious amounts of offspring, 300 when hermaphrodites mate, and even more when one mates with a male. So many aspects of C. elegans make it ideal for laboratory work.

The movement of C. elegans
Research that has been done on this animals varies greatly. Every cell has been tracked in detail from zygote (fertilized embryo) to adult. Mutants have been created so that researches can see how certain genes affect the number of cells in the adult and other characteristics. Their nerves have been studied so that a better understanding of neurological processes can be developed. Cell biology has been improved thanks to close examination of living worms. Breeding experiments have been done using the hermaphrodites and males of the species, which has led to the production of vast amounts of different genotypes and phenotypes. The genome has even been sequenced.  

C. elegans has become one of the model organism in the biology world, making its way into virtually every basic biology text. At this point, the vast knowledge base of these tiny worms is amazing. Also, for a humble worm, they are incredibly important to what is now understood about the living world. We owe a lot to them.

Sources are Animal Diversity Web and Worm Classroom. Images are from Wikimedia Commons under Creative Commons licenses: one, two.

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