Gene limits male lifespan9th December 2009
Genes people inherit from their fathers shorten their lifespan considerably, according to recent Japanese research.
researchers arrived at their conclusions after observing the lifespan
of mice engineered with paternal genes omitted from their DNA.
The scientists concluded that male sperm contains genes that limit the lifespan of mammalian offspring.
Tomohiro Kono of the the Department of Bioscience at Tokyo University of Agriculture said that his team already knew that women live longer than men in almost all countries.
He said that sex-related differences in longevity also occur in many other mammalian species.
For the purposes of the study, the scientists used the genomes of two female mice to develop what they called a bi-maternal mouse, by making females' eggs behave like sperm.
When the modified eggs were implanted in surrogate mothers, the bi-maternal mice lived 186 days longer than control mice, on average.
The researchers said they believe that the gene which limits mammalian lifespan may reside on chromosome 9, and that it allows males to grow bigger bodies.
Bi-maternal mice had very low birth weights, but better immune systems than control mice.
The mice with two mothers had higher levels of eosinophil, a type of white blood cell that provides general immunity.
The Japanese team nursed 13 bi-maternal mice and 13 control mice between October 2005 and March 2006.
The average lifespan for bi-maternal mice was 842 days, whereas the average lifespan for the control mice was 656 days.
The longest-living bi-maternal mouse died 1045 days after birth, and 10 of the 13 mice lived longer than 800 days.
Kono said that his team believes the difference lies in the repression of Rasgrf1.
He said that although it is still not certain that Rasgrf1 is definitively associated with mouse longevity, but it is one of the strongest candidates for a responsible gene.
Rasgrf1 is always present in the female mammalian genome, though it is turned off by another process.
Kono said that his team's study may answer fundamental questions such as whether longevity in mammals is controlled by the genome composition of only one or both parents, and why women have longer lifespans.
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Title: Gene limits male lifespan
Author: Luisetta Mudie
Article Id: 13440
Date Added: 9th Dec 2009