Animal Models

C. elegans – A Model Laboratory Citizen!

Caenorhabditis elegans is a free-living, non-parasitic soil nematode that feeds on bacteria, is easily cultivated in large numbers (10,000 worms/petri dish), and is safely used in the laboratory. It is the first multicellular organism to have its entire genome sequenced, revealing over 100 million base pairs organized into six chromosomes (five pairs of autosomes and one pair of sex chromosomes), in addition to the mitochondrial genome. The genome contains over 20,000 protein-coding genes at a density of one gene per 5000 base pairs. About one third of C. elegans genes have human homologs, and many human genes can substitute for worm genes when introduced into C. elegans. This similarity means that complex human processes can often be modeled and studied more comprehensively in nematodes.

The laboratory advantages of C. elegans start with its two sexes, hermaphrodites and males. Hermaphrodites can self-fertilize which makes worms easy to maintain and enables the propagation of genetic purity. However, hermaphrodites may also mate with males, producing 50% male and 50% hermaphrodite progeny. This enables researchers to mix and match genes in order to generate worms with desired genotypes and phenotypes. The advantages don’t stop there, worm genomes can be sequenced rapidly and genetically manipulated to introduce any new gene of interest, and the function of any gene can be quickly and easily blocked by genetic manipulation of its diet. Consequently, new genes can be studied much more rapidly in worms than in any other organism, and the high degree of conservation means these studies often help understand complex processes relevant to human health and medicine. Indeed, many physiological processes of considerable interest to the general public were first worked out in C. elegans and such studies have led to three Nobel Prizes, more than any other invertebrate model organism.

The Effect of Hypoxia on Mitochondria