C. elegans - Caenorhabditis elegans genome

http://en.wikipedia.org/wiki/Caenorhabditis_elegans

The adult hermaphrodite has 959 somatic nuclei. Its gene density is about 1 gene/5kb. Introns are 26% of the genome. There are some large intergenic regions containing repetitive DNA sequences.

Many genes are arranged in operons: polycistronic series that are transcribed together. C. elegans and other nematodes are among the few eukaryotes currently known to have operons.

The C. elegans genome sequence is approximately 100 million base pairs long. The genome consists of 6 chromosomes (named I, II, II, IV, V and X) and a mitochondrion.

The genome contains approximately 20,470 protein-coding genes.The number of known RNA genes in the genome has increased greatly due to the 2006 discovery of a new class of 21U-RNA gene, and the genome is now believed to contain more than 16,000 RNA genes, up from as few as 1,300 in 2005.



RNA interference (RNAi) has been used extensively in C. elegans because it can be done by simply feeding the worms transgenic bacteria expressing RNA complementary to the gene of interest. This strategy for gene loss of function experiments is the easiest of all animal models, and thus, scientists were able to knock down 86% of the ~20,000 genes in the worm, establishing a functional role for 9% of the genome.