The work has analyzed the aging in males and females of the fruit fly (Drosophila melanogaster) subjected to different degrees of inbreeding to study the hypothesis of the unguarded X chromosome, postulated more than thirty years ago to explain why the sexes age differently. speeds. The work, published by the Cavanilles Behavior and Evolution team of the University of Valencia, indicates that one of the fundamental predictions of the hypothesis is fulfilled in this type of flies. According to this theory, and in the words of Pau Carazo, director of the research group, “the differences in aging between the sexes may be due in part to the fact that the accumulation of mutations throughout life (or from generation to generation) affects the more accused of sex that only has one copy of the sex chromosomes, which we call heterogametic ”.

This would be the case for XY males in Belarus Email Lists mammals, including humans. “If this guarding effect is important to explain the differences in aging between the sexes, what we would expect is that inbreeding would affect the aging of the homogametic sex more than the heterogametic sex, since the latter is always unguarded, regardless of how inbreeding it is. that is, while the first is only protected when the two copies of its X chromosome are different (when there is no inbreeding) ”, indicates Pau Carazo. To investigate this postulate, the Cavanilles group in its population of Drosophila flies, made the aging differences between the sexes completely disappear by homogenizing the two copies of the same chromosome (for example, causing them to have the same copies – alleles – of each gen). In this way,

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the protective effect of the second X chromosome disappeared in the homogametic sex. “These results dovetail with the naked X hypothesis and suggest that this assumption could be critical to understanding why the sexes age differently, and to understanding aging mechanisms in general.” The reason is that a large part of the mutations that appear in DNA are recessive, that is, they are only expressed, and therefore only harmful, when an individual has the same mutation in both copies of a chromosome. Therefore, having two copies of the same chromosome protects against the expression of recessive mutations, because the presence of a mutation in only one of the chromosomes would have no consequences. However, having only one copy of the sex chromosome (for example,

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