RNAi

by Edward Hugh

The latest Nobel in medicine could not pass without some sort of comment on this blog. Now the work of Andrew Fire and Craig Mello concerns techniques which help us better understand the way that specific genes can be turned on and off, and thus accumulate evidence of gene function in the cellular metabolism. Specifically the two scientists are credited for their discovery of “RNA interference” (or RNAi). This is described by wikipedia as:

a mechanism in molecular biology where the presence of certain fragments of double-stranded ribonucleic acid (dsRNA) interferes with the expression of a particular gene which shares a homologous sequence with the dsRNA. RNAi is distinct from other gene-silencing phenomena in that silencing can spread from cell to cell and generate heritable phenotypes in first-generation progeny when used in the roundworm Caenorhabditis elegans.

As wikipedia notes this procedure has important implications for the study of model organisms through its role in gene 'knockdown':

RNAi has recently been applied as an experimental technique to study the function of genes in model organisms. Double-stranded RNA for a gene of interest is introduced into a cell or organism, where it through RNAi causes an often drastic decrease in production of the protein the gene codes for. Studying the effects of this decrease can yield insights into the protein's role and function. Since RNAi may not totally abolish expression of the gene, this technique is sometimes referred as a "knockdown", to distinguish it from "knockout" procedures in which expression of a gene is entirely eliminated by removing or destroying its DNA sequence.

And the relevance of all of this for our concerns on this blog? Well the 'knockdown' technique is obviously extremely useful in studying the molecular mechanisms which are associated with, among other things, ageing.