These findings provide the first evidence that sperm genes may have a detrimental effect on the lifespan of mammals.
The research found that mice created from two female genomes (bi-maternal (BM) mice) lived an average of 186 days longer than control mice created from the normal combination of a male and female genome.
The average lifespan for the type of mice used in the study is between about 600-700 days, meaning that the BM mice lived approximately a third longer than normal.
Tomohiro Kono, professor in Bioscience, Tokyo University of Agriculture (TUA) and Manabu Kawahara (PhD), associate professor at the Lab of Animal Resource Development, Saga University (Japan), carried out the research.
They believe the reason for the difference in longevity could relate to a gene on chromosome 9 associated with post-natal growth.
"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," Kono said.
"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," added Kono.
Accordingly, Kono and Kawahara set out to study the life span of mice produced without sperm.
There were 13 BM mice and 13 control mice born between October 2005 and March 2006. Kono found that the average lifespan was 186 days longer in the BM mice than in the controls (841.5 days versus 655.5 days).
The longest time that any of the control mice lived was 996 days, with all but one of them dying by 800 days, while the longest time alive for the BM mice was 1045 days, with all but three of them living for more than 800 days.
The researchers checked the weight of the mice at 49 days and 600 days (around 20 months after birth) and found that the BM mice were significantly lighter and smaller than the control mice.
The BM mice also seemed to have better immune systems, with a significant increase in one type of white blood cell, eosinophil, said a TUA release.
Both sets of mice were kept in the same, infection-free environments, with free access to food, making it unlikely that some external environmental factor was the cause of the difference in life spans.
These findings were published online in the Wednesday edition of Human Reproduction.
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