E-Book

E-Book 2nd Congress

  • The Relationship between Lack of Y Chromosome in Rats with Regard to Bio-Information Knowledge of Human Genetic Future
  • Ali Ahmadi,1,* Ali Neshaee Moghadam,2
    1. M.Sc. Student, Department of Genetics, Faculty of Advanced Technologies and Science in Medicine, Islamic Azad University Tehran Medical Science, Tehran, Iran
    2. M.Sc. Student, Department of Genetics, Faculty of Agriculture and Basic Science, Islamic Azad University Qaemshahr Branch, Qaemshahr, Iran


  • Introduction: For any mammal, the loss of the Y chromosome should mean the loss of males and the destruction of the species. Thus, the issue of how Amami prickly mice managed to live without the Y chromosome has puzzled biologists for decades. Now Asato Koroviva of Hokkaido University in Japan and colleagues have shown that one of the natural chromosomes of this rat has become practically a new male sex chromosome. Korovia says Y chromosomes have been shrinking in many mammals, including humans, over tens of millions of years and may eventually disappear. He says this prickly rat shows how this might happen. There are several sex determination systems in the animal series, but in almost all mammals the gender depends on the X and Y chromosomes. If the royani inherits two X chromosomes, it will become female, and if it inherits an X chromosome and a Y chromosome, it becomes male. This is because the Y chromosome contains a gene called SRY that activates male genes on other chromosomes. The most important of these genes is sox9 gene which causes testicular growth. Tokudaia osimensis, found on japan's Amami Oshima Island, is one of the few mammals that lacks the Y chromosome. In addition, females as well as males have only one X chromosome. As the presence of female mammal’s shows, the shrinking Y chromosome does not contain an important gene, so cells and individuals can live without it, the aim of this study was to determine the relationship between the absences of Y chromosome in rats, including receiving bio-information awareness of human genetic future.
  • Methods: This interventional research method was conducted with narrative review approach in 2022 by searching for keywords such Lack of Y Chromosome, Rats, Bio-Information and Human Genetic in valid databases such as Scopus, PubMed, Direct Science and Web of Science. Finally, 15 articles were studied, of which 10 were included in the study.
  • Results: In fact, recent studies have shown that the Y chromosome often disappears in cells when men grow old. But the loss of the Y chromosome from the entire population should lead to extinction, as there will no longer be males. Korovia and her colleagues first sequenced the genomes of several males and females to understand how prickly male mice still existed, but did not find a unique gene variant in males. They then examined more carefully and found that in male rats one of the two versions of chromosome 3 had a duplicate region right next to the SOX9 gene. The researchers conducted various experiments, including adding a repetitive area to laboratory mice, to show that this doubly increased SOX9 activity and thus practically replaced SRY. This means that chromosome 3 has become a Y pre-chromosome with this repetitive sequence, while this version is a pre-chromosome X without a duplicate sequence. To definitively illustrate this, researchers need to show that no males are created by removing repetitive sequences, says Robin Lovell-Bej of the Francis Crick Institute in London, one of the researchers who discovered the SRY gene. Of course, such experiments cannot be done, because the prickly mouse is a endangered species. However, their evidence is quite convincing, and it is difficult to discern iterations of this type, known as variations in copy numbers, explaining why past attempts to uncover how prickly mice become males have been fruitless. The identified iteration must have arisen at some point in time after two million years ago, because that's when prickly mice were separated from related species that still have the Y chromosome.
  • Conclusion: Since both sexes in Amami prickly mice now have only one X chromosome, this chromosome may also disappear over time. Koravieva says: Since this chromosome is unstable and mutations are accumulating, I think that the X chromosome will eventually disappear, however, if the descendants of the Prickly Amami mouse survive long enough, the pre-chromosome X and pre-chromosome Y may move along the same evolutionary lines of the X and Y chromosomes, and the small, pre-chromosome Y chromosome X is distinguished.
  • Keywords: Lack of Y Chromosome, Rats, Bio-Information and Human Genetic