March 12, 2010

UK researchers solve androgynous chicken puzzle

A puzzle that has baffled scientists for centuries - why some birds appear to be male on one side of the body and female on the other - has been solved by researchers from The Roslin Institute at the University of Edinburgh.

This discovery will help the understanding of sexual development in birds and could throw light on the molecular basis for gender differences in their biology and physiology, such as the development of organs including heart and brain. The study is published in the journal Nature.

The research, which involved studying rare naturally occurring chickens with white (male) plumage on one side and brown (female) plumage on the other, sheds new light on the sexual development of birds.

It was previously thought that sex chromosomes in birds control whether a testis or ovary forms, with sexual traits then being determined by hormones. The researchers, however, identified differences between male and female cells that control the development of sexual traits. The scientists have named the phenomenon, cell autonomous sex identity (CASI).

The findings, which are scientifically revolutionary in the field, 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.