Duplications and inversions of DNA segments lead to the masculinization of female moles
Max Delbrück Center for Molecular Medicine in the Helmholtz Association
Female moles not only have ovarian, but also testicular tissue that produces male sex hormones – which lets them diverge from the categorization into two sexes. A team describes which genetic modifications contribute to this singular development.
Moles are special creatures that roam in an extreme habitat. As mammals that burrow deep into the earth, they have forepaws with an extra finger and exceptionally strong muscles. What’s more, female moles are intersexual while retaining their fertility. Typical for mammals, they are equipped with two X chromosomes, but they simultaneously develop functional ovarian and testicular tissues. In female moles, both tissue types are united in one organ, the ovotestis — something that is unique among mammals.
A lot of testosterone in the female mole’s blood
The testicular tissue of the female mole does not produce sperm, but large amounts of the sex hormone testosterone, meaning the females have similarly high levels as the males. Presumably this natural “doping” makes the female moles aggressive and muscular, an advantage for life underground, where they have to dig burrows and fight for resources.
In a study in the journal Science, Berlin scientists are now reporting on the genetic peculiarities that lead to this characteristic sexual development in moles. According to the study, it is primarily changes in the structure of the genome that lead to altered control of genetic activity. In addition to the genetic program for testicular development, this also stimulates enzymes for male hormone production in the females.
The study was conducted by an international team co-led by Professor Stefan Mundlos, Research Group leader at the Max Planck Institute for Molecular Genetics
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