Abnormally small female knockout mice are incompetent mothers.

2004 NOV 4 - (NewsRx.com & NewsRx.net) -- Female mice that are abnormally small due to gene knockout technology are also bad mothers whose poor parenting skills cause their young to die within a day or two of birth, scientists reported.

Since Chawnshang Chang, PhD, cloned the gene for testicular orphan receptor 4 (TR4) 10 years ago, he and other scientists have tried to learn its function. (Scientists call it an "orphan" receptor because they don't know what protein links up with it). So a team led by Chang, director of George Whipple Laboratory for Cancer Research at the University of Rochester Medical Center, knocked out the gene in mice, then watched what happened.

According to their paper published the week of October 15, 2004, in the online edition of the Proceedings of the National Academy of Sciences, they found that many of the mice died before birth. Those that lived are markedly smaller than their normal counterparts: They're born far smaller and then make up some of the difference as they grow, but generally they are about 20% to 30% smaller by the time they reach adulthood.

The miniature mice are not as fertile as normal mice, having only about half the offspring as other mice.

Most visibly, the females have very bad parenting skills: They don't build nests, nurse their young, or tend to their offspring, which die within a day or two as a result.

"Basically, we ...