Mitosis or meiosis?
Infertility-related genes discovered
A group of Japanese researchers has discovered a gene that is associated with the activation of meiosis in cells. When it was turned off, mice of both sexes became infertile. The scientists reported their discovery in the journal Developmental Cell (Ishiguro et al., MEIOSIN Directs the Switch from Mitosis to Meiosis in Mammalian Germ Cells).
Most cells in the tissues of most organisms multiply through the division of somatic cells – mitosis. This is a continuous cycle in which a cell doubles its genetic information (chromosomes) and divides equally to create two copies. On the contrary, sex cells – eggs and spermatozoa – are formed through a special type of cell division called meiosis, which occurs in the gonads.
Drawings from the press release of Kumamoto University Discovery of genes involved in infertility – VM.
This process begins as a normal mitosis, but after a while switches to the creation of four genetically dissimilar germ cells that have half of the genetic material of the original cell. The mechanism that causes this transition has been of interest to researchers for a very long time, and controlling it is an important but difficult problem in the field of reproductive medicine.
Using mass spectrometry, a group of researchers from Kumamoto and Kyoto Universities in a new work was able to identify the gene "meiosin", which acts as a meiotic switch. This gene has an extremely rare property of being activated only at a certain time – just before the onset of meiosis in the gonads. In animal experiments, the researchers found that both male and female mice became infertile if meiosin was artificially turned off.
Further analysis of the male and female gonads of mice showed that this gene plays a significant role in the activation of meiosis. It acts as a control tower that simultaneously turns on hundreds of genes for the formation of germ cells, and is apparently involved in infertility. The authors expect that this discovery will be a big step forward for reproductive medicine.
"We were very surprised to find so many genes with unclear functions that are dormant and play a role in the reproduction process," says one of the authors of the study, an employee of the Institute of Molecular Embryology and Genetics at Kumamoto University Kei–Ichiro Ishiguro. – We have high hopes that the elucidation of the functions of these genes will significantly clarify the processes involved in the formation of embryos. If it eventually becomes possible to control meiosis, this will make it possible to achieve success not only in reproductive medicine, but also in agricultural production and even for the reproduction of rare species."
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