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Men's genes 'may limit lifespan'

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    2 December 2009 Men s genes may limit lifespan  Some genes are only passed down by the sperm Men carry the seeds of their own destruction in the genes
    Message 1 of 1 , Dec 2 3:51 AM
      2 December 2009

      Men's genes 'may limit lifespan'

      Some genes are only passed down by the sperm

      Men carry the seeds of their own destruction in the genes present in their sperm, research suggests.

      Scientists working on mice have highlighted a specific gene which although carried by both sexes only appears to be active in males.

      They believe it allows males to grow bigger bodies - but at the expense of their longevity.

      The study, by Tokyo University of Agriculture, appears in the journal Human Reproduction.

       These are interesting findings but any sex differences in longevity may have more complex explanations than any single gene

      Professor Kay-Tee Khaw
      University of Cambridge

      Although the study was conducted on mice, the researchers believe it could apply to all mammals - including humans.

      They studied mice created with genetic material from two mothers, but no father.

      This was achieved by manipulating DNA in mouse eggs so the genes behaved like those in sperm.

      The altered genetic material was implanted into the eggs of adult female mice to create embryos.

      The resulting offspring, completely free of any genetic material inherited from a male, lived on average a third longer than mice with a normal genetic inheritance.

      Better immune function

      The mice with two mothers were significantly lighter and smaller at birth.

      But they appeared to have better functioning immune systems.

      The researchers believe the key is a gene passed on by fathers called Rasgrf1.

      Although it passes down to both sexes, it is silenced in females through a process known as imprinting.

      Lead researcher Professor Tomohiro Kono said: "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.

      "Our results suggested sex differences in longevity originating at the genome level, implying that the sperm genome has a detrimental effect on longevity in mammals.

      "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 lifespan."

      In the UK the average lifespan for men is 77.4 and for women 81.6.

      The researchers said in nature males tended to concentrate resources on building a large body, because strength and bulk help them fight for mating opportunities with females.

      In contrast, females tended to conserve energy for breeding and providing for their offspring.

      Professor Kay-Tee Khaw, an expert in ageing at the University of Cambridge, said the findings were not necessarily applicable to humans.

      She said: "These are interesting findings but I think any sex differences in longevity - which in humans have changed over time and differ in different environments - may have more complex explanations than any single gene."

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