Hydra, the mythical gene

Stephen Huang
http://www.biotechnews.com.au/index.php/id;703620077;fp;4;fpid;1012

Recent discoveries have drawn to light a gene in some fruit flies that has no relation to any known genome. The gene now known as hydra exists only in a small number of species (the melanogaster subgroup) indicating that the gene originated from about 13 millions years ago.

Senior research associate Hsiao-pei yang has stated that this was a ‘de novo “out of nowhere” gene’ because it was thought that ‘new genes were always formed from tinkering with other genes’. However in this case there were no homologues (genes with similar structure) in the fly genome or any species’ genome, making this discovery unique. Evidence found indicated that hydra is a functional gene and is likely to express a protein in the late stages of sperm cell development (spermatogenesis).

The researchers do not know yet how the hydra gene was created, but it has been speculated that the gene may have been created by junk DNA called a transposable element (transposons) or jumping genes that have the ability to move around to different positions within the same genome of a single cell. Transposons have no function and are eliminated by natural selection, but now researchers are beginning to think that they may be a source of creating new functional genes.

The gene was named hydra because of the mythical nine headed monster slain by Hercules. This is in conjunction with the 9 identical exons (any region of DNA that will be represented in mRNA) the gene contains. This is due to the fact that one of the exons had undergone recurrent duplication leading to the formation of these exons. The researchers have also demonstrated that 4 of the duplicate exons can function as an alternative transcription sites. It was also found that 7 of the duplicate exons had a specific transposable element close by. Thus the idea that transposons may have a role in creating new genes was generated.