The difference between male and female life expectancy can occur at the level of the genome that Japanese researchers who believe that sperm genome has a negative effect on the lifespan of mammals. In their study, published in the journal Human Reproduction, found that female mice produced using genetic material from two mothers, but the father did not live much longer than mice with normal composition of maternal and paternal genes. Their results provide the first direct evidence that the genes of sperm may have negative consequences for life.
The average lifespan for this type of mice used in the study was 600-700 days. Mice were created by two female genomes (Bi-mom (BM) mice) lived an average of 186 days longer than control mice caused by a combination of normal male and female genomes.
"We have known for some time that women generally live longer than men in almost every country in the world and that these gender differences in longevity occurs in many other mammals. However, the reason for this difference were unclear, and in particular, there was not known whether the life expectancy in mammals is controlled by the genome of only one or two parents, "explained study co-author Prof. Tomohiro Kono, Department of Biological Sciences, Tokyo University of Agriculture.
In conducting the study, collected Dr. Kono and colleague Dr. Manabu Kawahara without cultivation of oocytes (eggs) with daytime rats with genetically engineered material in the egg, and thus behave down the genes of sperm, and then transplanted to manipulate the genetic material in a mature, unfertilized eggs adult mice that had their nuclei removed. These reconstructed oocytes become embryos transferred to surrogate mother mice. Mice were born as a result, Bi-mothers with the genetic material from two mothers, but not the father. Control mice were created by natural mating.
More to any of the control mice lived 996 days, with all but one of them dies at 800 days, and longevity of mouse BM was 1045 days, with all but three of those living in more than 800 days. The researchers tested the weight of mice at 49 days and 600 days and found that mouse BM was significantly smaller and lighter than the control mice. B. The mice seemed to be a better immune response, with a significant increase in the type of white blood cells (eosinophils).
"We believe that the most likely cause of differences in life expectancy due to the repression of the gene in mice Rasgrf1 BM. Gena is usually expressed from paternal chromosome and traditions characterized gene on chromosome 9 is associated with postnatal development. So far it is not clear whether Rasgrf1 definitively linked to longevity in mice, but a strong candidate, "said Dr. Kono.
These results are consistent with sex reproductive strategies, such as male maximum fitness by increasing investment in the reproduction of more bodies in order to obtain more reproductive opportunities, and thus a shorter lifetime. In contrast, women often do people who participate in such behavior, and instead of expensive, tend to maximize their reproductive output at the expense of saving for delivery, The Offspring, feeding, and avoid predators.
"This study may provide answers to fundamental questions: What if the life expectancy in mammals is controlled by the genome of only one or two parents, and perhaps this is because women are favored over men in their degree of life. Results Our research shows that gender differences in life expectancy for the origin of the genome, suggesting that the sperm genome has a negative effect on life span in mammals, "concluded Dr. Kono.
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