Women tend to live longer than men, which could be due to sperm genes, according to Japanese researchers.
Using genetic reprogramming technology, they produced female mice by using genetic material from two mothers but no father and found the mice lived much longer than mice with a mix of male and female genes. Mice normally live 600 to 700 days, but the mama-bred mice lived an average of 186 days longer. These mice were also much smaller and lighter than the normal mice. They seemed to have better immune systems and had higher rates of one type of white blood cell, the eosinophil.
"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," the lead author of the paper, Tomohiro Kono of Tokyo University of Agriculture, said in a news release. "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."
The scientists said they believe the longevity can be explained by a gene, called Rasgrf1, on chromosome 9. In the mama-bred mice, this gene, which is normally turned on from the paternally inherited chromosome, was repressed. This gene is associated with postnatal growth. It's not clear why it would influence longevity. "We cannot eliminate the possibility that other, unknown genes that rely on their paternal inheritance to function normally may be responsible for the extended longevity of the [mama-bred] mice," Kono said.
The study was published online this week in the journal Human Reproduction.
-- Shari Roan
Photo credit: Advanced Cell Technology Inc.