Wednesday, September 02, 2009

In Search of Uniquely Human Genes:

... in 2006, geneticists showed for the first time that they could identify truly novel genes. In fruit flies, they came across five young genes that were derived from "noncoding" DNA between existing genes and not from preexisting genes. As a result, other researchers started looking for novel genes in other species.

Meanwhile, while looking for gene duplications in humans, geneticists Aoife McLysaght and David Knowles of Trinity College Dublin kept coming across genes that seemed to have no counterparts in other primates, suggesting that new genes arose in us as well. To determine which of these genes with no counterparts were de novo genes, McLysaght and Knowles first used a computer to compare the human, chimp, and other genomes. They eliminated all but three of the 644 candidates because their sequence in the database was not complete--or they had equivalents in other species.

Next, they searched the chimp genome for signs of each gene's birth. "We strove hard to identify the noncoding DNA that gave rise to the gene," McLysaght says. Only by finding that DNA could they be sure that the gene wasn't already present in the chimp genome but was somehow unrecognizable to gene-finding programs. At three locations where the chimp and human genomes were almost identical, telltale mutations indicated that it was impossible to get a viable protein from the chimp DNA sequence. In contrast, the human version of each sequence had mutations that made it a working gene, the researchers report online tomorrow in Genome Research.

The researchers were able to verify that the genes worked by checking messenger RNA databases and protein surveys done by other scientists. They are now using antibodies to find out where in the cells these proteins are active and are trying to disable the genes in cells to tease out their functions.

What these genes actually code for will be fascinating to find out. You also gotta love a researcher with a classic Irish name like Aiofe McLysaght (talk about right out of The Tain...)

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