[
Nature,
1999]
Life is based on social contract, genes work for the good of the organism, and they are reproduced. But certain rogue genes, called transposons, wantonly reproduce at the expense of the organism, inserting new copies of themselves all over the genome. Reporting in Cell, Tabara et al., and Ketting et al. now show that organisms have systems to hold transposons in check. They suggest that one of the clues that organisms use to detect illicit activity is double-stranded RNA, and their results could explain the reason for the mysterious phenomenon of RNA interference.
[
Nature,
1998]
The human genome is predicted to contain between 50,000 and 100,000 genes. To work out what these genes do, an array of techniques is needed to evaluate the protein-protein interactions and biochemical pathways of any gene product. The nematode worm Caenorhabditis elegans is an excellent system for such studies because of its well-understood genetics and development, evolutionary conservation to human genes, small genome size and relatively short life cycle. The 100-megabase-pair genome will be completely sequenced this year, and a total of 17,000 genes have been predicted, many with human counterparts. Approaches used to manipulate gene expression in C. elegans include transposon-mediated deletion, antisense inhibition and direct isolation of deletions after mutagenesis. Although these methods have proved useful, limitations still exist.