American researchers say that the discovery of a new fruit fly gene suggests that new genes need not be formed from pre-existing ones.
The Cornell University researchers said that the new gene, called hydra, exists in only a small number of species of Drosophila fruit flies, signifying it was created about 13 million years ago, when the melanogaster subgroup species diverged from a common ancestor.
The finding is said to be consistent with work of other scientists who are discovering that many of the most recently formed functional genes in any species also are expressed in male testes and appear related to spermatogenesis.
"This is a de novo -- 'out of nowhere' - gene. People used to think that new genes were always formed from tinkering with other genes, but with this gene we can find no homologues [genes with a similar structure]. You cannot find any related genes in the fly genome or any species' genome, and that is what is unique," said Hsiao-Pei Yang, a senior research associate in Cornell's Department of Molecular Biology and Genetics and senior author of the paper.
Yang 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.
The researchers do not yet know how the hydra gene was created, but they contemplate that the gene may have developed from a piece of DNA junk called a transposable element (also known as a "jumping gene"), which may have been inserted into the genome by a virus. These transposons are known to copy and insert themselves into DNA sequences.