Tuesday, March 18, 2008

Fruit Fly Gene From 'Out Of Nowhere'

The new gene, called hydra, exists in only a small number of Drosophila fruit flies. It suggests that it was created about 13 million years ago. And early evidence indicates that the new gene is functional (as opposed to being nonfunctional "junk" DNA) and is likely to express a protein involved in late stages of sperm cell development (spermatogenesis).

The general idea was that new genes were always formed from tinkering with other genes, but there is no homologues [genes with a similar structure] in this gene. Any similar or related gene with the hydra has not been found yet. That is what hydra makes itself unique.

Hsiao-Pei Yang, a senior research associate in Cornell's Department of Molecular Biology and Genetics and senior author of a paper published in the July 6 issue of the online journal PLoS Genetics (Public Library of Science Genetics) conducted part of this research while at the National Yang-Ming University in Taiwan and part of the work in collaboration with Cornell's Daniel Barbash, assistant professor of molecular biology and genetics.

It has not yet been found out that how the hydra gene was created, but researchers assume that the gene may have developed from a piece of DNA junk called a transposable element (also known as a "jumping gene"), which might have been inserted into the genome by a virus. These transposons can copy and insert themselves into DNA sequences. For example, one theory is that when a transposon sits next to a gene and then jumps to a new location, it carries part of the gene sequence it was next to and inserts it in the new location. Often, transposable elements appear to have no function or may be harmful and are eliminated by natural selection, but researchers are beginning to think transposons may be a source for creating new functional genes as well. The hydra gene is named after the Greek mythological beast that had a hound's body and nine snake heads, because it has nine duplicated first exons (sections of the gene that contain protein-coding information). Each of these exons may serve as alternative starting positions for the gene to become activated. The researchers found that most of these exons had a sequence for a transposable element sitting right next to it. Duplicated sequences generated by transposons may be part of the mechanism for creating new genes, as the duplications provide more chances for a gene to evolve.

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posted by Taihei Sakaushi
Student number 41283244

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