WEDNESDAY, Dec. 2, 2009 (HealthDay News) -- Sperm genes may affect life span in humans and other mammals and could help explain why females tend to live longer than males, Japanese scientists say.
The researchers found that mice created using two female genomes -- bi-maternal mice -- lived an average of 186 days longer than mice created from the normal combination of a male and female genome. The normal life span of the mice used in the study is 600 to 700 days, which means the bi-maternal mice lived about one-third longer than normal.
The difference in life span may be caused by a gene on chromosome 9 associated with post-natal growth, the researchers explained in their report, which is published in the Dec. 2 online edition of the journal Human Reproduction.
"We believe that the most likely reason for the differences in longevity relates to the repression of a gene called Rasgrf1 in the bi-maternal mice. This gene normally expresses from the paternally inherited chromosome and is an imprinted gene on chromosome 9 associated with post-natal growth," study author Tomohiro Kono, of the department of bioscience at Tokyo University of Agriculture, explained in a news release from the journal's publisher.
"Thus far, it's not clear whether Rasgrf1 is definitively associated with mouse longevity, but it is one of the strong candidates for a responsible gene," Kono added.
"We have known for some time that women tend to live longer than men in almost all countries worldwide, and that these sex-related differences in longevity also occur in many other mammalian species. However, the reason for this difference was unclear and, in particular, it was not known whether longevity in mammals was controlled by the genome composition of only one or both parents," Kono stated in the news release.
"The study may give an answer to the fundamental questions: that is, whether longevity in mammals is controlled by the genome composition of only one or both parents, and just maybe, why women are at an advantage over men with regard to the life span," Kono concluded.
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