This is the first-known example of a dietary mineral affecting sex determination, says Vincent Harley, a molecular geneticist at the Hudson Institute of Medical Research in Melbourne, Australia. This 'presents an exciting new area of study', he adds. In mammals, biological sex is initially determined primarily by chromosomes ' females typically have XX chromosomes whereas males typically have XY ones ' and a primary gene then usually triggers formation of the corresponding sexual organs. Mice, for instance, with XY chromosomes usually develop testes if a gene called Sry is activated and ovaries if it is not. The researchers behind this latest study had previously shown that Sry is activated by an enzyme called histone demethylase2, which needs iron to function, says co-author Makoto Tachibana, an epigeneticist at Osaka University in Japan. The team speculated that altering how iron is metabolized by cells could affect histone demethylase activity, which would in turn alter Sry...
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