Women’s Chromosomes are Responsible for Sperm Production

Mammalian cells contain sex chromosomes. They are the 23rd pair of a common chromosome set of a human and determine the sex of the unborn child. One chromosome is passed from each parent, which subsequently pair up.

In women, the 23rd pair is a XX combination, in men this pair is expressed by a XY combination. For a long time, scientists were convinced that the Y chromosome was a carrier of genes regulating male-specific properties. However, this is not entirely true.

As part of his study David Page, the geneticist from the Whitehead Institute for Biomedical Research, compared X chromosomes in humans and in mice, separated by 80 million years of evolution. When the genome was decoded, Page compared mouse and human genes containing in the active X chromosome. Most of the 800 genes appeared to be identical. All of these genes are quite stable and active in the organisms of both males and females. Mutations in them cause various diseases, such as hemophilia or Duchenne muscular dystrophy.

Scientists have also found another feature of the active X chromosome - a human has 144 unique genes that have no analogues in the mouse chromosome, while the rodents have 197 genes. Out of the 144 specific genes in humans, 107 exist in a few copies that modify with great speed. Page concluded that these genes appeared in human cells after we separated from a common ancestor with mice during evolution.

Changes in genes are the essence and the result of the evolution. Page believes that these specific genes have important functions in the organism. In order to understand what the specific genes of a human are responsible for, Page and his colleagues took eight samples of tissues from men and women. In contrast to the standard set of X genes, some of them are not even expressed in the woman's body. Instead, they are active in men and involved, for example, in sperm production.

Duplications of genomic regions are of great importance for research in medicine and biology. They may suggest different methods of treatment of serious diseases such as cancer and infertility. But first, one needs to understand exactly how these genes function, what they are responsible for, and when appeared. Page hopes his work will inspire other biologists for a more thorough study of these genes, which ultimately may lead to the development of a cure for testicular cancer and male infertility.

For this article material from was used

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