Edinburgh, Scotland, UK. Scientists have identified a fundamental difference between female and male cells that control the development of sexual traits. The scientists have named the phenomenon cell autonomous sex identity (CASI).

Findings from the study, performed by the Roslin Institute at the University of Edinburgh, appear in the journal Nature.

It was previously thought that sex chromosomes in birds control whether a testis or ovary forms, with sexual traits then being determined by hormones.

Biologists must now reassess how this developmental process occurs in other organisms. There is already some evidence that organs such as the heart and brain are intrinsically different in males and females. Birds may provide a model for understanding the molecular basis for these sex differences.

TS-Si Science & Medicine

Key Genetic Catalyst For Human Diversity Discovered

Leicester, England. Sir Alec Jeffreys, whose work led to the development of genetic fingerprinting, is the senior author of an important new paper on the genetic basis of human diversity. The Jeffreys team has now defined th...

read more...

---

Guideline: Diagnosis and Treatment of Congenital Adrenal Hyperplasia (CAH)

Chevy Chase, MD, USA. The Endocrine Society has released a new clinical practice guideline on the diagnosis and treatment of congenital adrenal hyperplasia (CAH). The guideline features a series of evidence-based clinical rec...

read more...

Dr. Michael Clinton, who led the study, specializes in the developmental biology of sexual differentiation: understanding the molecular regulation of gonadal development and the acquisition of sexual phenotype.

Clinton said: "This research has completely overturned what we previously thought about how sexual characteristics were determined in birds. We now believe that the major factors determining sexual development are built into male and female cells and derive from basic differences in how sex chromosome genes are expressed. Our study opens a new avenue for our understanding of sexual development in birds.

The findings may also be relevant to why males and females differ in behaviour and in susceptibility to disease.

"They could also lead to improvements in poultry production — identification of some of the molecular differences between male and female cells should lead to better tests for sexing embryos prior to hatch. It might even be possible to devise ways of obtaining the growth characteristics of male birds in females, with improvements in feed efficiency and productivity that could contribute to future food security.

The group will now study the molecular mechanisms underlying the differences between male and female cells.

FundingThe Roslin Institute at the University of Edinburghhttp://www.ed.ac.uk/home receives key funding from the Biotechnology and Biological Sciences Research Council (BBSRC).

CitationSomatic sex identity is cell autonomous in the chicken. D. Zhao, D. McBride, S. Nandi, H. A. McQueen, M. J. McGrew, P. M. Hocking, P. D. Lewis, H. M. Sang amd M. Clinton. Nature 2010; 464: 237-242. doi:10.1038/nature08852.

Abstract

In the mammalian model of sex determination, embryos are considered to be sexually indifferent until the transient action of a sex-determining gene initiates gonadal differentiation. Although this model is thought to apply to all vertebrates, this has yet to be established. Here we have examined three lateral gynandromorph chickens (a rare, naturally occurring phenomenon in which one side of the animal appears male and the other female) to investigate the sex-determining mechanism in birds. These studies demonstrated that gynandromorph birds are genuine male:female chimaeras, and indicated that male and female avian somatic cells may have an inherent sex identity. To test this hypothesis, we transplanted presumptive mesoderm between embryos of reciprocal sexes to generate embryos containing male:female chimaeric gonads. In contrast to the outcome for mammalian mixed-sex chimaeras, in chicken mixed-sex chimaeras the donor cells were excluded from the functional structures of the host gonad. In an example where female tissue was transplanted into a male host, donor cells contributing to the developing testis retained a female identity and expressed a marker of female function. Our study demonstrates that avian somatic cells possess an inherent sex identity and that, in birds, sexual differentiation is substantively cell autonomous.

To create link towards this article on your website,
copy and paste the text below in your page.

<style type="text/css"><!--.quote {width:400px; padding: 6px; border: solid 1px #456B8F; font: 11px helvetica, verdana, sans-serif; color: #222222; background-color: #ffffff}.quote a {font: 13px arial, serif; color: #003399; text-decoration: underline}.quote a:hover {color: #FF9900; }//--></style><div style="float:left;padding:5px;"><img src="http://ts-si.org/images/stories/HalfMFchicken.jpg" width="125" alt="" /></div><div class="quote"><a href="http://ts-si.org/genetics-&-genome/23744-solving-the-half-female-and-half-male-chickens" target="_blank">Solving the Half Female and Half Male Chickens</a><br />Friday, 12 March 2010<div align="right" style="width:400px"><p style="text-align:right;"><a href="http://ts-si.org/" target="_blank">TS-Si.org</a></p></div></div>

Preview :

Solving the Half Female and Half Male Chickens
Friday, 12 March 2010

TS-Si.org

Comments (0)

Subscribe to this comment's feed

Show/Hide comments

Show/Hide comment form

Name

Email

Website

Title

Comment

smaller | larger

I have read and agree to the Terms of Usage.

Add Comment