A guardian gene for female sex
Researchers at INRA, France, have just uncovered one of the major genes responsible for female differentiation: FOXL2. During normal development, the formation of testes or ovaries in a foetus depends on the presence or absence of the SRYgene, carried by the Y chromosome. However, instances of sex reversal have been observed, where foetuses carrying two X chromosomes, which are programmed to develop an ovary, are actually born with all of the characteristics of a male. For more than a decade, researchers at INRA's Developmental Biology and Reproduction unit in Jouy-en-Josas have been studying and characterising the mutations responsible for XX males in domesticated animal species such as goats, exposing the importance of a gene (FOXL2) carried by an autosome (not a sex chromosome).