Fortunately for men, size doesn't matter (much)

January 10, 2012
The Tammar Wallaby; manlier than man?

(PhysOrg.com) -- Researchers from The Australian National University have discovered that the male-specific Y-chromosome is shrinking – and it’s happening at different rates across species.

The research team discovered that a marsupial’s is genetically denser than the human Y-chromosome, meaning that animals like the tammar wallaby are bounds ahead on the ‘manliness’ scale. However, even though the Y-chromosome is shrinking, in this case size doesn’t matter.

The international study, led by Dr Paul Waters from the ANU Research School of Biology, analysed DNA samples from tammar wallabies and found more genes on the male chromosome than expected.

“There were lots of genes that we weren’t expecting to find,” said Dr Waters. “These genes have been lost from the Y-chromosome in placental mammals like humans but, for some reason, they have been retained in marsupials.

“This means there are different rates of gene loss on the Y-chromosome across species.”

The Y-chromosome is one of two sex chromosomes carried in males from most mammal species. It contains male-specific genes including the testis determining gene, which triggers male sexual development. Dr Waters said that researchers have known for some time that the Y-chromosome is losing genetic material.

“It’s shrinking. It gets physically smaller as it loses genes,” said Dr Waters. “The Y-chromosome can theoretically lose chunks at a time – 50 genes, 100 genes – depending on how big the deletion is.

“When these genes are lost, the function they played is lost altogether. But genes will only be lost from the Y-chromosome if they no longer have a function of importance for males. If they do have some sort of male-specific role, such as in sperm production, they will be retained.”

Dr Waters added that despite the shrinking chromosome, there is no risk of men becoming extinct.

“Y-chromosomes have been completely lost in other species, such as in some rodents, and genes important for male development have moved somewhere else in the genome. The master switch that turns on male development can change and move around the genome, but the result will remain the same.

“Men will always be men, irrespective of the size of the Y-chromosome.”

Explore further: Researchers identify first sex chromosome gene involved in meiosis and male infertility

Related Stories

X chromosome exposed

May 29, 2008

Researchers from the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, and the EMBL-European Bioinformatics Institute (EMBL-EBI) in Hinxton, UK, have revealed new insights into how sex chromosomes are regulated. ...

Sex and the single chromosome

November 26, 2010

Is there value to sex? For higher organisms, absolutely. Animals, plants and fungi that reproduce only by cloning are scarce as hen's teeth, suggesting the gene shuffling of sex pays handsome dividends.

Chromosome number changes in yeast

July 21, 2011

Researchers from Trinity College Dublin have uncovered the evolutionary mechanisms that have caused increases or decreases in the numbers of chromosomes in a group of yeast species during the last 100-150 million years. The ...

Recommended for you

Discovery may benefit farmers worldwide

September 26, 2016

University of Guelph plant scientists have shown for the first time how an ancient crop teams up with a beneficial microbe to protect against a devastating fungal infection, a discovery that may benefit millions of subsistence ...

How the anthrax toxin forms a deadly 'conveyer belt'

September 26, 2016

Researchers have built a three-dimensional map of the anthrax toxin that may explain how it efficiently transfers its lethal components into the cytoplasm of infected cells. The study, "Structure of anthrax lethal toxin prepore ...

Yeast knockouts peel back secrets of cell protein function

September 26, 2016

Proteins are the hammers and tongs of life, with fundamental roles in most of what happens in biology. But biologists still don't know what thousands of proteins do, and how their presence or absence affects the cell.

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

tthb
1 / 5 (1) Jan 10, 2012
wolves, wimbeldon, down own end; false reporters behind them in a ring, & into it all; . . . . . it all falls down?
tthb
1 / 5 (1) Jan 10, 2012
rebound, the kill shot? Mordred by the trainload? work the crowd . . . . . . Mordred, a.k.a. cut'em in the water . . . ?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.