August 22, 2016

Caenorhabditis elegans

Caenorhabditis elegans is a free-living (non-parasitic) nematode (round worm). The members of this species inhabit almost all land masses of the world, except for the Antarctic and they live in nutrient- and microorganism-rich habitats such as composts.

It is a self-fertilizing hermaphroditic species. The hermaphrodites are about 1.3mm (0.05 inches) long and transparent and one hermaphrodite can give rise to about 300 offspring. They can easily be grown in the lab on agar plates with bacterial lawns and have a short generation time, going from the single-cell egg to an adult in 3.5 days at 20°C

Thanks to its transparency, invariant development and constant number of adult somatic cells (959 cells), it is possible to track cells and follow cell lineages. The complete sequence of all 100,269,912 bases across the 6 chromosomes of the Caenorhabditis elegans genome was finished in 1998, making it the first genome of a multi-cellular eukaryote in which every base is known. Its genome is about 20 times larger than E. coli’s genome and  about 30 times smaller than the human genome, yet it encodes close to 22,000 genes (slightly fewer than humans) with 40% homology to human genes.

It is a great model organism to study genetics, developmental biology, evolutionary biology, neurobiology, cell biology and behavior. Some of its significant contributions to biology are: Discovery of molecular regulators of Programmed Cell Death, Discovery of RNA interference pathways,  application of GFP (green fluorescent protein).

Early development in fluorescence

The germ line

More development

Cell division