L-R: Andrew Fire, Mechanism of RNAi- where siRNA (small interfering RNA) generated from the dsRNA by Dicer, recruits RNA interference silencing complex (RISC) to degrade the corresponding mRNA, Craig C Mello

Andrew Z Fire was born in 1959. He obtained his PhD in Biology at the Massachusetts Institute of Technology, USA. He began his research on the nematode C. elegans during his time as visiting scientist in MRC, UK, at the laboratory of Sydney Brenner. Currently, he is a Professor at Stanford University, USA

Craig C Mello was born in 1960. He obtained his PhD in Cellular and Developmental Biology from Harvard University. He did his postdoctoral work at Fred Hutchinson Cancer Centre in Seattle before joining as a Professor at University of Massachusetts, Worcester USA.

Fire and Mello worked on regulation of gene expression by double stranded RNA by a process called RNA interference using C elegans (worm) as a model organism.  They found that injecting together RNAs designed against both strands of a gene resulted in degradation of the protein encoded by that gene. However, injecting single stranded RNA against either of the one strand or against the non-coding part of the gene (intron) could not produce this effect. Thus, they concluded that this process takes after transcription and in the cytoplasm where then mRNA (containing only the coding part of a gene: exons) has already been produced.  Interestingly the effect of RNA interference can pass from cell to cell, tissue to tissue and even to offsprings. They also showed that RNA interference is highly specific (dsRNA silences only the corresponding gene from where it is generated) and thus have implications for a wide variety of research and therapeutics use. Regulation of gene expression in the cells take place by small RNAs called micro-RNAs that activate the RNA interference pathway. RNAi also protects us against viral RNAs. Jumping genes in our genomes that can hop to multiple locations and cause misregulation of genes are kept suppressed by RNAi that leads to heterochromatin formation.RNAi is routinely used in research laboratories to silence genes and study their functions. Scientists are actively trying to generate better treatment for diseases like cancer and HIV by harnessing the power of RNA interference.

Reference: Fire, A, Xu, S, Montgomery, MK, Kostas, SA, Driver, SE, and Mello, CC (1998). Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature 391, 806-811