Could iron deficiency (or excess of it) be the key to gender during embryonic development? According to some studies, it could, particularly in the fetuses of male mice, which develop female organs if their mother is iron deficient during pregnancy.
Indeed, chromosomes determine the biological sex in mammals – females have XX chromosomes and males XY ones, and a primary gene triggers the formation of the related sexual organs. Mice with XY chromosomes develop testes if a gene Sry activated, and ovaries if it’s not, Nature reported on June 4.
Testing the iron-deficient mothers theory
Specifically, in the latest study, Sry is activated by an enzyme called histone demethylase, which needs iron to function, and its authors have suggested that altering how cells metabolize iron could affect histone demethylase activity, which would then alter Sry expression.
According to the co-author Makoto Tachibana, an epigeneticist at Osaka University in Japan, a series of subsequent tests – in which mice were fed an iron-deficient diet for a month before pregnancy and for two weeks during and compared with mice fed a control diet – have proven this theory.
As Vincent Harley, a molecular geneticist at the Hudson Institute of Medical Research in Melbourne, Australia, pointed out, this was the first known example of a dietary mineral affecting gender determination, and added that it “presents an exciting new area of study.”
Elsewhere, scientists are making strides in other areas of genetics, including managing to observe how a human cell archives the process in which chromosomes form a compact X-shaped structure with two rod-like copies when preparing for transport to daughter cells during cell division.
Meanwhile, a study has found that flowerpot snakes – one of the world’s smallest snakes and the only known snake species with three sets of chromosomes instead of two (which can also reproduce without a mate) – could help in understanding conditions such as Down syndrome.
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