1. ‘Genetic switch’ determines whether germ cells become sperm or eggs

‘Genetic switch’ determines whether germ cells become sperm or eggs

'Genetic switch': Scientists have found a gene switch that controls whether germ cells eventually become sperm or eggs.

By: | Updated: June 14, 2015 9:15 AM

Scientists have found a ‘genetic switch’ that controls whether germ cells eventually become sperm or eggs. New experiments in the Japanese rice fish show that the fox13 gene appears to be the ‘genetic switch’ that determines whether a germ cell becomes an egg or sperm cell.

The finding could help researchers learn more about how the sexual fate of germ cells is determined during vertebrate development.

Toshiya Nishimura and colleagues demonstrated that fox13, which is expressed in germ cells but not in the surrounding cells of the fish’s reproductive organs, provides a molecular cue that prevents the start of sperm formation.

When the researchers disrupted fox13 in adult fish with two X chromosomes (the female state), sperm formed in the female ovary. These sperm were functional and could fertilize eggs normally.

The ‘genetic switch’ experiment results indicated that germ cells in these fish, and potentially other vertebrates, do not need to be in the environment of the male reproductive organ to begin their switch into sperm.

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Tags: Sperm
  1. P
    Jun 13, 2015 at 8:31 pm
    Very interesting, but why fish. Fishes are so far from us, mammals.
    1. A
      Albert Fisher
      Jun 13, 2015 at 1:14 pm
      If this can be demonstrated in people then women could finally do away with us men completely, as they could self fertilize and in effect create a clone of themselves, as there would be no other genetic input. Could the resulting child, though, be a male? It happens with bees. The queen fertilizes eggs she wishes to become female workers. Eggs left unfertilized produce haploid bees, genetically identical to the queen except they are males. Hmmm.
      1. J
        Jun 13, 2015 at 2:43 pm
        I suppose this explains immaculate conception.
        1. K
          Kevin Foster
          Jun 14, 2015 at 9:00 am
          I wonder if the converse is also true, could male testes produce eggs if the switch is flipped? Eggs are incredibly small single cells.

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