Skip to main content

Disappearing Y chromosome

Disappearing Y chromosome: Could the future of humanity be at risk?


The sex of human and other mammal babies is determined by a male-determining gene on the Y chromosome. However, this crucial chromosome is gradually degenerating and may disappear in a few million years, potentially leading to our extinction unless a new sex-determining gene evolves.
The good news is that two branches of rodents have already lost their Y chromosome and survived. A 2022 study published in peer review journal ‘Proceedings of the National Academy of Science’ reveals that the spiny rat has successfully evolved a new male-determining gene, offering hope for humanity’s future.

Role of the Y chromosome

In humans, females have two X chromosomes, while males possess one X and one Y chromosome. The Y chromosome, though much smaller with only about 55 genes compared to the X chromosome’s 900, plays a vital role in determining male sex by triggering the development of the testis in an embryo.
At around 12 weeks after conception, the master gene on the Y chromosome, known as SRY (sex-determining region Y), activates a genetic pathway that leads to the formation of male reproductive organs. This gene works by stimulating another key gene, SOX9, which is crucial for male development across vertebrates.

Decline of the Y chromosome

Most mammals share a similar X and Y chromosome structure, but this system presents challenges due to the unequal gene dosage between males and females. Interestingly, Australia’s platypus possesses entirely different sex chromosomes, resembling those of birds, suggesting that the mammal X and Y chromosomes were once ordinary chromosomes.
Over the 166 million years since humans and platypuses diverged, the Y chromosome has lost a significant number of active genes, shrinking from 900 to just 55. If this trend continues, the Y chromosome could vanish entirely within the next 11 million years.

Rodents without a Y chromosome

Fortunately, two rodent lineages—the mole voles of eastern Europe and the spiny rats of Japan—have already lost their Y chromosome and continue to thrive. In these species, the X chromosome remains in both males and females, but the Y chromosome and SRY gene have disappeared.

A research team led by Asato Kuroiwa from Hokkaido University discovered that in spiny rats, most genes from the Y chromosome had been relocated to other chromosomes. However, the SRY gene was missing, and they found a small duplication near the SOX9 gene on chromosome 3 in males, which could substitute for SRY.

When introduced into mice, this duplication increased SOX9 activity, suggesting that spiny rats have evolved a new mechanism for male sex determination without the Y chromosome.

Implications for the future of humanity

The possible disappearance of the human Y chromosome raises concerns about the future of our species. Unlike some reptiles that can reproduce asexually, mammals, including humans, require sperm to reproduce, making men indispensable for the continuation of our species.

However, the evolution of a new sex-determining gene, as seen in spiny rats, offers a glimmer of hope. Yet, this process comes with risks — if multiple new sex-determination systems evolve in different regions, it could lead to the emergence of new human species, each with distinct sex chromosomes.

X chromosome, Y chromosome, genetic inheritance, sex-linked traits, autosomes, chromosomal abnormalities, Turner syndrome, Klinefelter syndrome, dosage compensation, X-inactivation, non-disjunction, SRY gene, pseudoautosomal regions, genomic imprinting, sex determination, XY system, XX system, homologous recombination, meiotic division, and chromatin structure.

#SexChromosomes, #XChromosome, #YChromosome, #GeneticInheritance, #SexLinkedTraits, #ChromosomalAbnormalities, #TurnerSyndrome, #KlinefelterSyndrome, #DosageCompensation, #XInactivation, #NonDisjunction, #SRYGene, #PseudoautosomalRegions, #GenomicImprinting, #SexDetermination, #XYSystem, #XXSystem, #HomologousRecombination, #MeioticDivision, #ChromatinStructure

Comments

Post a Comment

Popular posts from this blog

Fruitful innovation

Fruitful innovation: Transforming watermelon genetics with advanced base editors The development of new adenine base editors (ABE) and adenine-to-thymine/ guanine base editors (AKBE) is transforming watermelon genetic engineering. These innovative tools enable precise A:T-to-G and A:T-to-T base substitutions, allowing for targeted genetic modifications. The research highlights the efficiency of these editors in generating specific mutations, such as a flowerless phenotype in ClFT (Y84H) mutant plants. This advancement not only enhances the understanding of gene function but also significantly improves molecular breeding, paving the way for more efficient watermelon crop improvement. Traditional breeding methods for watermelon often face challenges in achieving desired genetic traits efficiently and accurately. While CRISPR/Cas9 has provided a powerful tool for genome editing, its precision and scope are sometimes limited. These limitations highlight the need for more advanced gene-e...
Post a Comment
Read more

Genetic factors with clinical trial stoppage

Genetic factors associated with reasons for clinical trial stoppage Many drug discovery projects are started but few progress fully through clinical trials to approval. Previous work has shown that human genetics support for the therapeutic hypothesis increases the chance of trial progression. Here, we applied natural language processing to classify the free-text reasons for 28,561 clinical trials that stopped before their endpoints were met. We then evaluated these classes in light of the underlying evidence for the therapeutic hypothesis and target properties. We found that trials are more likely to stop because of a lack of efficacy in the absence of strong genetic evidence from human populations or genetically modified animal models. Furthermore, certain trials are more likely to stop for safety reasons if the drug target gene is highly constrained in human populations and if the gene is broadly expressed across tissues. These results support the growing use of human genetics to ...
Post a Comment
Read more

Genetics study on COVID-19

Large genetic study on severe COVID-19 Bonn researchers confirm three other genes for increased risk in addition to the known TLR7 gene Whether or not a person becomes seriously ill with COVID-19 depends, among other things, on genetic factors. With this in mind, researchers from the University Hospital Bonn (UKB) and the University of Bonn, in cooperation with other research teams from Germany, the Netherlands, Spain and Italy, investigated a particularly large group of affected individuals. They confirmed the central and already known role of the TLR7 gene in severe courses of the disease in men, but were also able to find evidence for a contribution of the gene in women. In addition, they were able to show that genetic changes in three other genes of the innate immune system contribute to severe COVID-19. The results have now been published in the journal " Human Genetics and Genomics Advances ". Even though the number of severe cases following infection with the SARS-CoV-...
Post a Comment
Read more