Cancer gene is also important for growth.

A tumor-suppressing gene known as PTEN appears to also control development in immature animals.

Like many organisms, the roundworm Caenorhabditis elegans pauses its development until conditions are fight for growth. After worms hatch, they remain small and immature until they find food. Only after a worm eats do its cells start growing.

To figure out what genes lie behind the natural state of stalled development, Joel Rothman of the University of California, Santa Barbara and his colleagues searched through a collection of mutant C. elegans for worms that started growing before they had their first meal.

The researchers discovered one set of mutants that fit the bill. The mutations occurred in a gene called DAF-18, which in mammals goes by the name PTEN. Rothman's team speculates in the April 18 Current Biology that the protein encoded by the gene keeps cell growth and division in check in young, unfed worms.

Previous studies had linked mutations in PTEN with the unchecked growth of cancer cells. Therefore, the researchers suggest that other genes that play similar controlling roles in animals' growth and development could lead scientists to new genes involved in tumor formation.--C.B.