Thursday, September 10, 2009

Sex Determination in Birds

Sex determination: Birds do it with a Z gene
The gene that determines sex in birds has eluded scientists for a decade. Now this all-important locus is revealed as a gene on the Z chromosome known for its proclivity for determining sex in all kinds of animals.

In mammals, males have XY chromosome pairs and females are XX, so the Y chromosome determines maleness and sex. In particular the SRY gene found on the Y chromosome determines testis.
In birds it's the other way around: males have ZZ chromosome pairs and females are ZW. However in birds the key gene is again for maleness and it resides on the Z chromosome.

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