SYDNEY, Australia - Two sets of Australian researchers each have identified new human genes, one that is a direct link in the creation of male testes in embryos, and another thought to be the key to one type of obesity.

The second gene, discovered by researchers at the Department of Physiology at the University of Sydney, has more immediate commercial implications, with researchers patenting the gene and talking of a diagnostic kit.

Brian Morris, who headed the research team that discovered Ser363, said he believes that there would be a market for the kit, but he has not had much time to consider the issue.

He said that other genes previously identified as being connected with obesity are all just one of what may be a series of factors or different genes that act together to make an individual overweight.

However, Ser363, is strongly connected with one in five cases of obesity.

"There is no avoiding it [obesity] - or it is extremely difficult," Morris said.

The team, which has published its work in the British Medical Journal, believes the gene causes an amino acid change in the glucocorticoid receptor, making the receptor more sensitive to glucocorticoids. The most common of those molecules is cortisol, an important hormone in metabolism. People with Ser363 then have a defect in their metabolism that causes them to be overweight.

Morris and his team are now investigating the mechanism further to see whether it sheds light on other aspects of metabolism. But Morris also believes the discovery has immediate clinical implications, since it addresses 20 percent of the obese population.

The second gene discovery, that of a gene critical in the development of testes, was made by a team drawn from both the Royal Children's Hospital Research Unit in Melbourne and from Melbourne University, led by Andrew Sinclair.

Besides identifying the gene DMRT1 in humans, the team also found it in a range of animals, including mice, chickens and alligators.

Sinclair said DMRT1 was part of a pathway of genes in humans that led to the development of the testes, but was obviously important as it was found in those other animals as well. In other words it had appeared in animals at least 300 million years ago and had been conserved. The team is trying to work out more of the mechanism behind the development of the testes.