Half and half – chickens that puzzled scientists
7 Apr 2010 by Evoluted New Media
Chickens that appear male on one side and female on the other have baffled scientists for years, but research from the Roslin Institute may have unscrambled the puzzle.
Chickens that appear male on one side and female on the other have baffled scientists for years, but research from the Roslin Institute may have unscrambled the puzzle.
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Male side (left/white) and female side (right/brown) of gynandromorph bird reflected in mirrors. Credit: The Roslin Institute, University of Edinburgh |
Scientists studied rare, naturally occurring chickens with both male and female plumage, expecting the birds to be half-male and half-female, with a mutation on one side of the body. They also expected hormones to control whether birds developed male or female characteristics.
Instead, researchers identified differences between male and female cells that control the development of sexual traits. The phenomenon has been named cell autonomous sex identity (CASI).
Dr Michael Clinton, who led the study said: “This research has completely overturned what was 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.”
The findings – published in Nature – are scientifically revolutionary in the field and may shed light on why males and females differ in behaviour and susceptibility to disease. Clinton and his group will now study the molecular mechanisms underlying the differences between male and female cells.
Clinton thinks the research will now cause scientists to reassess earlier work on developmental processes in other organisms. “There is already some evidence that organs such as the heart or brain are intrinsically different in males and females and bird may provide a model for understanding the molecular basis for these gender differences,” he said.
The work has implications for poultry production – the identification of the molecular differences between male and female cells could lead to better tests for sexing embryos before they hatch. It may also lead to ways of creating female birds with the growth characteristics of the male, which may have important implications for future food security.
