Aging  

Human supercentenarians share at least one thing in common--over 95 percent are women. Scientists have long observed differences between the sexes when it comes to aging, but there is no clear explanation for why females live longer.

Human supercentenarians share at least one trait in common—over 95 percent are women. Scientists have long noticed the differences between the sexes in aging, but there is still no clear explanation for why females live longer.

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Now, in a discussion paper of what we know about stem cell behavior and sex, Stanford University researchers Ben Dulken and Anne Brunet argue that it's time to look at differences in regenerative decline between men and women. This line of research could open up new explanations for how the sex hormones estrogen and testosterone, or other factors, affect lifespan.

It's known that estrogen has direct effects on stem cell populations in female mice, from increasing the number of blood stem cells (which is very helpful during pregnancy) to enhancing the regenerative capacity of brain stem cells at the height of estrus. Whether these changes have a direct impact on lifespan is what's yet to be explored. Recent studies have already found that estrogen supplements increase the lifespan of male mice, and that human eunuchs live about 14 years longer than non-castrated males.

"As the search continues for ways to ameliorate the aging process and maintain the regenerative capacity of stem cells, let us not forget one of the most effective aging modifiers: sex."

Though interactions between stem cells, aging, and sex have been topics of great interest, the intersection of all three—the effect of sex on the aging of stem cells—has not been well studied. However, several mechanisms could be involved in establishing and perpetuating sexual dimorphism during the aging of stem cells.

More work is also needed to understand how genetics impacts stem cell aging between the sexes. Scientists have seen that knocking out different genes in mice can add longevity benefits to one sex but not the other, and that males in twin studies have shorter telomeres—a sign of shorter cellular lifespan—compared to females.

"It is likely that sex plays a role in defining both lifespan and healthspan, and the effects of sex may not be identical for these two variables," the authors write. "As the search continues for ways to ameliorate the aging process and maintain the regenerative capacity of stem cells, let us not forget one of the most effective aging modifiers: sex."

SOURCE  EurekAlert

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 Longevity  

Sequencing fewer than twenty genomes of the world's oldest peopleUsing fewer than 20 genomes, we were unable to find rare protein-altering variants significantly associated with extreme longevity, researchers were unable to find rare protein-altering variants significantly associated with extreme longevity, according to a new study.

B y sequencing 17 genomes of the world's oldest people, researchers were so far unable to find any markers that would potentially be associated with extreme longevity, according to a study published in the open-access journal PLOS ONE.

Supercentenarians are the world’s oldest people, living beyond 110 years of age. Seventy-four are currently alive worldwide. The study authors, led by Hinco Gierman from Stanford University, performed whole-genome sequencing on the individuals to determine if there were any genetic reasons for their extreme longevity.

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"Using fewer than 20 genomes, we were unable to find rare protein-altering variants significantly associated with extreme longevity."

Due to the small sample size, the researchers conclude they were unable to find rare protein-altering variants significantly associated with extreme longevity compared to control genomes. "It is not surprising that a highly complex trait such as longevity is not explained by a single Mendelian gene," the authors conclude.

"Using fewer than 20 genomes, we were unable to find rare protein-altering variants significantly associated with extreme longevity," said Gierman.

They did find that one supercentenarian carries a variant associated with a heart condition, which had little or no effect on his/her health, as this person lived over 110 years.

The authors have publicly published the genomes, making them available as a resource for future studies on the genetic basis of extreme longevity.

SOURCE  PLOS ONE, Top Image - Mike Ip

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