Similarities Found in Mouse Genes and Human's nytimes.com
[ Somewhat more verbosely . . . ]
This other 2 percent may include control regions — stretches of DNA upstream of a gene that serve as its on-off switch — as well as a novel class of genes called RNA genes.
RNA, a more ancient chemical version of DNA, performs many basic tasks in a cell, one of which is to form a copy or transcript of a gene and direct the synthesis of the gene's protein. Recently, some of these RNA transcripts have been found to have executive roles all their own, without making any protein. An RNA gene is responsible for the vital task of shutting all the genes on one of the two X chromosomes in each female cell, ensuring that women get the same dose of X-based genes as men, who have just one X chromosome.
The new analysis suggests that a large family of such RNA genes may exist, a point confirmed by a Japanese team under Dr. Yoshihide Hayashizaki of the Riken Genomic Sciences in Yokohama. Dr. Hayashizaki, whose report also appears in today's Nature, has collected almost all the RNA transcripts made by mouse cells taken from every tissue of the mouse's body.
Though most of the transcripts code for mouse proteins, he found as many as 4,280 he could not match to any known mouse protein, suggesting that a large part of the genome consists of nonprotein coding genes. The roles of almost all these RNA genes have yet to be understood.
[ Meanwhile, on the "Are you a man or a mouse front" . . . ]
The mouse genome is 2,510 million units of DNA in length, according to Celera, and 2,475 million units according to the consortium. The human genome, by comparison, is 2,900 million units. But since both species seem to possess around 30,000 protein-coding genes, the extra DNA in the human genome is probably of no direct importance. |
