Featured Research

from universities, journals, and other organizations

The Masculinization Of The X Chromosome: Many Genes For Early Male Sperm Production Reside On The X Chromosome

Date:
March 30, 2001
Source:
Whitehead Institute For Biomedical Research
Summary:
In an entirely counterintuitive result, scientists have found that nearly half of all genes related to the earliest stages of sperm production reside not on the male sex (Y) chromosome as expected, but on the X chromosome, a chromosome universally thought of as the female sex chromosome.

In an entirely counterintuitive result, scientists have found that nearly half of all genes related to the earliest stages of sperm production reside not on the male sex (Y) chromosome as expected, but on the X chromosome, a chromosome universally thought of as the female sex chromosome.

Related Articles


The finding, published in the April issue of Nature Genetics, comes as a big surprise and is causing scientists to rethink the "gender identity" of the X chromosome.

"Scientists and non-scientists alike are comfortable thinking about the Y chromosome as a specialist in male characteristics. By default, we’ve traditionally thought of the X chromosome as sexually neutral or as a specialist in female characteristics. Our findings indicate that the X chromosome has a specialty in sperm production, much like the Y chromosome does," says David Page, lead author on the paper and a researcher at the Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute.

The finding also raises the speculation that infertility due to low sperm production may be an X-linked disorder, passed on to male children through their mothers, much like color-blindness or hemophilia.

In this study, the Page lab researchers and their colleague John McCarrey at Southwest Foundation for Biomedical Research, in San Antonio, Texas, sought to study the genetic underpinnings of spermatogonia—-stem cells in the testes that give rise to sperm. Spermatogonia are "the mother of all sperm cells," but unlike other stem cells, such as blood stem cells, which have been the subject of intense study, sperm stem cells have remained largely unexplored. So Jeremy Wang, a postdoctoral fellow in the Page lab, and his colleagues conducted a systematic search for genes that are active exclusively in sperm stem cells in mice.

The researchers found 25 genes, including 19 new ones, that were expressed exclusively in mouse sperm stem cells. They found that of these, only 3 were linked to the Y chromosome and 10 were linked to the X chromosome.

"This was a big surprise because if the genes had been distributed randomly in the genome, we would have expected none, or at the most a couple, of these sperm-specific genes to be X-linked," says Page.

This finding is yet another chapter in the 300 million year story of the X and the Y chromosomes, adds Page whose research is unfolding, chapter by chapter, the odyssey of the sex chromosomes that began their lives as autosomes (or non-sex chromosomes) but have since become specialized.

Aside from the intellectual surprise, this finding has enormous implications for future scientific investigation, and it opens up a whole new territory scientifically, says Page.

"The X chromosome is one of the most intensely studied chromosomes, and the X-linked mode of inheritance is a textbook classic—it is one of the three modes of inheritance that we study in medical genetics," says Page.

In this mode of inheritance, a genetic defect on the X chromosome may cause a disease (for example color blindness or hemophilia). The mother, who has a defective gene on one of her two X chromosomes, is protected against the disease because women have two copies of the X, and her normal X makes up for the defective one. Her sons have a 50 percent chance of inheriting the defective X and succumbing to the disease. Her daughters have a 50 percent chance of inheriting the defective X and becoming carriers.

The finding that sperm-specific genes are found on the X chromosome suggests a new avenue for study, says Page. One obvious possibility is that the X chromosome plays a role in some forms of male infertility that results from low sperm counts. Thus far, researchers have combed the Y chromosome looking for the genetic underpinnings of low sperm counts. But in these cases, the defects on the Y may tell only part of the story. The researchers will have to do further studies to see if they can find the other part of the story in the X chromosome.

Finally, this study spurs researchers to ask if infertility can be inherited, just like color blindness and hemophilia. Previous research from the Page lab had suggested that the genetic defect underlying low sperm count can be inherited by sons from their fathers when infertile fathers use intracytoplasmic sperm injection (ICSI) to have children.

"Now it appears that we may face the possibility that genetic defects underlying low sperm count can be inherited through mothers," says Page.


Story Source:

The above story is based on materials provided by Whitehead Institute For Biomedical Research. Note: Materials may be edited for content and length.


Cite This Page:

Whitehead Institute For Biomedical Research. "The Masculinization Of The X Chromosome: Many Genes For Early Male Sperm Production Reside On The X Chromosome." ScienceDaily. ScienceDaily, 30 March 2001. <www.sciencedaily.com/releases/2001/03/010330071542.htm>.
Whitehead Institute For Biomedical Research. (2001, March 30). The Masculinization Of The X Chromosome: Many Genes For Early Male Sperm Production Reside On The X Chromosome. ScienceDaily. Retrieved November 27, 2014 from www.sciencedaily.com/releases/2001/03/010330071542.htm
Whitehead Institute For Biomedical Research. "The Masculinization Of The X Chromosome: Many Genes For Early Male Sperm Production Reside On The X Chromosome." ScienceDaily. www.sciencedaily.com/releases/2001/03/010330071542.htm (accessed November 27, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Thursday, November 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola Leaves Orphans Alone in Sierra Leone

Ebola Leaves Orphans Alone in Sierra Leone

AFP (Nov. 27, 2014) — The Ebola epidemic sweeping Sierra Leone is having a profound effect on the country's children, many of whom have been left without any family members to support them. Duration: 01:02 Video provided by AFP
Powered by NewsLook.com
Experimental Ebola Vaccine Shows Promise In Human Trial

Experimental Ebola Vaccine Shows Promise In Human Trial

Newsy (Nov. 27, 2014) — A recent test of a prototype Ebola vaccine generated an immune response to the disease in subjects. Video provided by Newsy
Powered by NewsLook.com
Pet Dogs to Be Used in Anti-Ageing Trial

Pet Dogs to Be Used in Anti-Ageing Trial

Reuters - Innovations Video Online (Nov. 26, 2014) — Researchers in the United States are preparing to discover whether a drug commonly used in human organ transplants can extend the lifespan and health quality of pet dogs. Video provided by Reuters
Powered by NewsLook.com
Today's Prostheses Are More Capable Than Ever

Today's Prostheses Are More Capable Than Ever

Newsy (Nov. 26, 2014) — Advances in prosthetics are making replacement body parts stronger and more lifelike than they’ve ever been. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins