UW researchers have identified a gene linked to the productivity of stem cells that produce sperm in mammals. The group, whose findings appear in the June issue of Nature Genetics, was led by Robert Braun, associate professor of genome sciences.

In adult organisms, germ stem cells, which produce sperm, can either produce more germ stem cells or produce daughter cells that eventually become sperm cells. Producing more germ stem cells helps keep sperm production going over the long term.

Braun and his colleagues identified a decades-old strain of mice they believed had a genetic mutation that caused their germ stem cells to be more likely to convert to sperm than to produce more germ stem cells and keep the cycle going. They obtained 30-year-old frozen embryos of the mouse strain from the Jackson Laboratory in Maine and conducted genetic tests to confirm the theory.

Researchers located the mutation on a gene called ZPF145, which produces the protein PLZF. They used a fluorescent antibody against the protein to show that PLZF is expressed in adult germ stem cells. Researchers also showed that another protein, OCT4, is also present in adult germ stem cells. That protein helps maintain the stem cells in the early embryo and in cultured embryonic stem cells.

The scientists hope their findings will have applications for further research in infertility, contraception, and stem cell transplantation therapy.