Thursday, 17 May 2012

Men's Y-chromosome is Not Going to Disappear


(42865188) Jin Joo Lee

www.scienceagogo.com/news/img/hormones.jpg
Have you heard about a horrific scientific rumour about men’s Y-chromosome extinction in 2009? This rumour was about the Y-chromosome which is the sex chromosome that only males carry, is being damaged and eventually it disappear in few million years (Melville 2009).

Before I get into the main discussion about this interesting article, I want to help you understand about sex chromosomes in humans. Humans have two sex-chromosomes called X and Y (Bailiy 2012). When X chromosome crosses with another X, it would form a girl fetus, and when X chromosome combines with Y chromosome, it would make a boy fetus.



It has been theorised that the sex chromosomes in mammals contain an additional DNA region for the recombination between X and Y DNA (Melville 2009). However, scientists found that there is no recombination between X and Y anymore, because Y specific DNA began to mutate rapidly while the X specific DNA was still in the same phase of the evolution (Melville 2009). So, it incurs the situation of the additional DNA region splitting into two completely different entities.


Evidence supporting this hypothesis was that there are less than 200 genes contained in human’s Y chromosome while the X chromosome contains approximately, 1100 genes, which means that few of the genes in Y chromosome would be essential for functioning, and some of the genes that has disappeared would not be important for functioning or had identical functional roles with X chromosome.

However, according to an article which contradicts this previous article, Y chromosome would not extinct from the world, which is a good news for men. Now I will introduce Jennifer Hughes, who is the researcher at the Whitehead Institute for Biomedical in Cambridge. She researched about the rumour and with her colleagues found that the rhesus macaque, a monkey that diverged from humans approximately 25 million years ago, contains 20 genes from Y chromosomes that matched with X chromosomes (Hamzelou 2012). More surprisingly, human Y chromosome contains 19 the same genes that the monkey contains. This research could be evidence to human Y chromosome losing only one gene since human and monkey diverged from the same ancestor (Hughes 2005).




Yet, it may be a rational to think at there would be no gene loss in Y-chromosomes in the future. According to the article, Jenny Graves from the University of Melbourne, Australia, said it is a nice piece of work and she also added that some genes from 19 genes crop with another genes, then the loss of Y-gene could possibly happened (Hamzelou 2012).

If the loss of gene in Y chromosomes happened somewhere in the future, it would not be the end of male, but Y chromosomes would be replaced by an empty space and it would be “X0" for male sex identification (Hamzelou 2012).

This is a very interesting new discovery of the genetic science. This is very relevant to us, humans because it is happening in our body, in our cells and nucleus.

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2 comments:

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