August 3, 2012
Mutations in Mitochondria Affect Lifespan Of Men, But Not Women
Connie K. Ho for redOrbit.com — Your Universe Online
Higher salaries and acceptance to elite colleges are a few of the benefits that men have over women. However, there is one title that women have long held over men—living longer. Researchers from Monash University in Australia recently discovered some of the facts that contribute to longer life expectancy for women, who, on average, live longer than men.
In the project, Dr. Damian Dowling of Monash worked with Florencia Camus, a doctoral student, and David Clancy, a researcher at Lancaster University in the United Kingdom, to determine the differences in biological aging and longevity.
They studied male and female fruit flies from 13 different groups that had mitochondria with varying origins.Researchers detailed how DNA mutations of the mitochondria could lead to different life expectancies for men and women. Through the project, they determined that the genetic variation found in mitochondria could help them estimate life expectancy in males but not in females.
"Intriguingly, these same mutations have no effects on patterns of ageing in females. They only affect males," commented Dowling, a professor of the Monash School of Biological Sciences, in a prepared statement.
The results of the study, published in a recent edition of Current Biology, described how mitochondria are necessary in life as they can change food into energy; this energy can then give the body the boost of power it needs.
"All animals possess mitochondria, and the tendency for females to outlive males is common to many different species. Our results therefore suggest that the mitochondrial mutations we have uncovered will generally cause faster male ageing across the animal kingdom," explained Dowling in the statement.
The scientists also believe that the mutations are due to the genes that are passed from parents to children.
"While children receive copies of most of their genes from both their mothers and fathers, they only receive mitochondrial genes from their mothers. This means that evolution's quality control process, known as natural selection, only screens the quality of mitochondrial genes in mothers," remarked Dowling in the statement. "If a mitochondrial mutation occurs that harms fathers, but has no effect on mothers, this mutation will slip through the gaze of natural selection, unnoticed. Over thousands of generations, many such mutations have accumulated that harm only males, while leaving females unscathed."
The researchers plan to look further into how the findings support previous studies that show a connection between male infertility and maternal inheritance of mitochondria. As well, the study helps to explain certain statistics about longevity.
According to BBC News, in regions like the United Kingdom, women outlive men; by 85 years of age, there are around six women for every four men and, by the age of 100, there are more than two females for every one male. The research allows scientists to better understand how biology plays a role in longevity issues. It also shows that male health differs from female health.
"Together, our research shows that the mitochondria are hotspots for mutations affecting male health. What we seek to do now is investigate the genetic mechanisms that males might arm themselves with to nullify the effects of these harmful mutations and remain healthy," concluded Dowling in the statement.
Other scientists are taking note of the results from the study.
"It may be it does tell us something rather important about mitochondria and the difference between male and female fruit flies. And we know that mitochondria are important for ageing in a number of species,” Tom Kirkwood, a professor at Newcastle University who studies aging, told BBC News. "But I certainly don't think this is a discovery that explains why women live five-to-six years longer than men. There are other things we know also count - lifestyle, social and behavioral factors. But the biggest difference in biology is that we have different hormones."