back to article Japanese female fish in sperm-producing strangeness

Japanese fish boffins have discovered – for the first time in vertebrates – a genetic switch which determines whether germ cells (essentially reproductive precursors) become either eggs or sperm. The gene has been named fox13 and has been identified using a small fish called medaka, also known as the Japanese rice fish due to …

  1. This post has been deleted by its author

    1. Phil O'Sophical Silver badge

      That Oxford comma makes all the difference...

      1. Old Handle

        Not in this case. Even under the mistaken interpretation that "Japanese fish" and "sex boffins" are separate, the Oxford comma wouldn't be used because there are less than three items in the list.

        1. Martin Budden

          @Old Handle

          there are less than three items in the list


    2. John Bailey

      "I never knew that fish were so clever! I mean, I've got a friend who is a sexologist, and I've never heard her mention fish working in the field..."

      Only in rice growing areas.. cos they need the water to breath in.

  2. Martin Gregorie Silver badge

    Confusion in paragraphs 4 and 5

    The article's author may like to revisit paragraphs 4 and 5 because, while both essentially describe the same condition, the apparent outcome is different. I may be a bear of very little brain, but I find this confusing.

    1. Anonymous Coward
      Anonymous Coward

      Re: Confusion in paragraphs 4 and 5

      My reading of the two paragraphs is that they both refer to the female fish with the genetic switch condition viz their ovaries produce predominantly sperm - but also a small number of eggs.

      I did have to reread it several times. The 5th paragraph has a construction that gives a sense of being about different fish with an alternative genetic condition - rather than two outcomes in the same female fish.

      1. Anonymous Coward
        Anonymous Coward

        Re: Confusion in paragraphs 4 and 5

        If a fish produces both the sperm and eggs then presumably it would become self-fertilising - if it can deposit both outside its body. A hermaphrodite rather than parthenogenesis. Many plants do this. Snails also produce both sperm and eggs - but only exchange with an S&M partner

        Is it so unusual to find that vertebrates share a DNA similarity with invertebrates eg a fruit fly?

        1. Def Silver badge

          Re: Confusion in paragraphs 4 and 5

          Presumably this is the trigger (or possibly there is more than one) that can cause fully female populations of certain species to produce offspring.

        2. Grikath

          Re: Confusion in paragraphs 4 and 5

          "Is it so unusual to find that vertebrates share a DNA similarity with invertebrates eg a fruit fly?"

          The proper scientific answer to that would be: "Funny you should ask that..." followed by a three-hour lecture.

          the TLDL version is: Vertebrates aren't supposed to be able to switch germ cell fate independent of gender. That particular switch is thought to be buried too deep within the gender instruction set to be messed with (at least not without Horrible Effects.. ). ymmv depending on exactly how gender is determined in a species, though. XY ( like with mammals ) is by far not the only method, and some mechanisms leave room for shenanigans.

          Gender-wise, fish are morphologically very similar between the sexes, with very little differentiation between the sexes' gonads, other than the type of germ cells they produce, so it's not impossibe per sé. Just very surprising, especially the viable de-coupling between gender-morphology and gamete production.

  3. Captain DaFt


    If a male Medaka tells a female Medaka to "Go fuck yourself!", is he liable for child support if she does?

  4. x 7

    its well known that certain types of fish e.g. wrasse, groupers can change sex - usually female > male, presumably with no genetic gender change during the process

    Is this not simply another example of this known process?

  5. Sarah Balfour

    No. What you're referring to is sequential hermaphroditism where an organism, in this case a fish, is born one sex, and may change sex as the need arises usually, as you say, from female to male. This usually occurs in species where the two sexes are vastly different in appearance, with the female being much smaller and duller-coloured than the male. If the male should die, then the female will take on the physical appearance of the male and court just like any other male of that species. It's also a survival tactic, as males remain reproductively active far longer than females.

    Oh fuck it, here's the wiki link! I'm too fucking splatted.

  6. Maryland, USA

    Hey: If Bruce can become Caitlyn...

    I'm just sayin'.

  7. User McUser

    So, gay couples can have thier own kids now?

    So two homosexual individuals could, theoretically, now have their own children (that is, genetically related to both parents)? Just have to flip the fox13 switch to the opposite for one of them, (and in the case of two males, find a surrogate womb) do some in vitro fertilization, and they're good to go.

    Probably won't be that easy in practice partly because the experiment was on fish and mammals are probably just different enough, but mostly because people don't like change. After all, look how insane everyone acts about gay *marriage*, and that's just a legal status. The religious wack-jobs are going to completely lose their shit when gay people want to start making their own children.

    1. Anonymous Coward
      Anonymous Coward

      Re: So, gay couples can have thier own kids now?

      Parthenogenesis is also another way that reproduction occurs in some species. Sharks in captivity are apparently known to have done this. The resulting offspring can be a full clone - or a half clone.

      Incidentally this would not validate the biblical virgin birth. Any such offspring would be female - as it can only inherit X chromosomes from its mother. A genetically male offspring requires an X and Y chromosome. In human reproduction the male provides the sex determining second chromosome of X or Y in the usual case of XX (girl) or XY (boy). What happens when more than two of these "sex" chromosomes are inherited gets very complicated for the gender identification of the person.

      As another poster has alluded - the X and Y chromosomes are not the only way that sex is determined. Some species have the Z and W chromosomes instead - which give interesting offspring combinations.

      Fascinating Wikipedia article:

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