Researchers at the University of California at San Francisco have discovered the patriarch of a family of genes closely tied to male infertility in many species. Humans share the new gene, named BOULE, with both mice and flies. And results published today in the Proceedings of the National Academy of Sciences suggest that BOULE is involved in the creation of sperm during meiosis¿the phase of division in which a cell duplicates its DNA and then splits twice, giving each cell half the necessary chromosomes.

Scientists had previously linked two descendants of BOULE¿genes known as DAZ and DAZL¿to male infertility. Mutations of DAZ are implicated in 13 percent of all cases of human male infertility, even though the gene doesn't seem to be essential to sperm development. Although DAZL¿s exact role in humans is not known, in frogs it appears to be fundamental to the development of both male and female reproductive cells, or germ cells, before meiosis occurs.

The new study¿s results suggest that BOULE, unlike DAZ, may be required for mature sperm development. If defects in BOULE are found to be a cause of human male infertility, lead author Eugene Yujun Xu notes, attempts at gene therapy¿in which a normal copy of the gene could be introduced into the testes and encouraged to replicate¿might be possible. And because the testes are located outside the body, the treatment would be less likely to damage other body tissues, he says.

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