A paper in the July 20, 2006 issue of Nature (Vol. 442, No. 7100, pp. 295-298) adds weight to the emerging idea that RNA partly determines the inherited characteristics of plants and animals.
Vicki Chandler and her colleagues studied a phenomenon called paramutation: a form of non-mendelian inheritance in which one allele of a gene can heritably dampen the expression of another. They hunted down a gene called mop1 (mediator of paramutation1), which is required for paramutation at the b1 locus in maize, and found that it produces an enzyme that manufactures RNA.
The team proposes that this enzyme produces RNA from unique tandem repeats of DNA, which are also essential for paramutation at this locus. Although the details are not yet known, the repeat RNA may accumulate to a threshold level at which it establishes and maintains the heritable state of chromatin (DNA attached to proteins) required for silencing the maize b1 locus.
Vicki Chandler (University of Arizona, Tucson, AZ, USA)
(C) Nature press release.
Message posted by: Trevor M. D'Souza