Female Moles Grow Testicles to Fight Through their Brutal Underground Existence
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Female Moles Grow Testicles to Fight Through Their Brutal Underground Existence:
If any animal understands the horrors of trench warfare, it has to be the mole. Faced with an enemy, there's no time for pleasantries. No place to hide. Aggression is all that matters.
To help them fight in this brutal world, evolution has granted the female mole a generous dose of 'roid rage' by tacking some testicles onto her ovaries - resulting in a unique bit of anatomy called an ovotestis.
[...] Lacking a Y chromosome makes it a lot harder for an embryo to kick off the chain of events that produce testes. So just how it happens in female moles, which have two X chromosomes instead of an X and Y, has long been a mystery.
[...] "We hypothesised that in moles, there are not only changes in the genes themselves, but particularly in the regulatory regions belonging to these genes," says geneticist Stefan Mundlos from the Max Planck Institute for Molecular Genetics.
[...] Specifically they found a region involved with testicular development is flipped, adding extra code to a region that activates the pro-testicular growth factor gene FGF9.
They also found two extra copies of a gene that controls for androgen synthesis
"The triplication appends additional regulatory sequences to the gene - which ultimately leads to an increased production of male sex hormones in the ovotestes of female moles, especially more testosterone," says lead author, Francisca Martinez Real from the Institute for Medical Genetics and Human Genetics in Germany.
Journal Reference:
Francisca M. Real, Stefan A. Haas, Paolo Franchini, et al. The mole genome reveals regulatory rearrangements associated with adaptive intersexuality [$], Science (DOI: 10.1126/science.aaz2582)
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