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  1. Beenthere2Hippie
    The organs in our body may have a sexual identity of their own, new research suggests. The idea that our organs could be "male" or "female" raises the possibility that women and men may need different treatments as a result. The findings could also shed light on why it is that some cancers are more common in women, and others in men.

    The study, published today in Nature, was carried out in fruit files by a team at the MRC Clinical Sciences Centre (CSC), based at Imperial College London.

    "We wanted to ask a very basic question: whether it is just the cells of the sex organs of a fully developed organism that 'know' their sexual identity, or whether this is true of cells in other organs too -- and whether that matters," said Irene Miguel-Aliaga, who led the research and heads the Gut Signalling and Metabolism group at the CSC.

    To do this, the CSC team examined stem cells in flies' intestines. They used genetic tools that allow them to turn genes "on" and "off" specifically in these cells. This allowed them to tailor the cells to be more "female" or more "male." When the team feminised or masculinised the flies' gut stem cells this changed the extent to which the cells multiplied. Female, or feminised cells were better able to proliferate.

    This enhanced ability appears to allow the intestine in female flies to grow during reproduction. Miguel-Aliaga has previously shown that after mating, the female fly gut is re-sized and metabolically remodelled to sustain reproduction. She speculated at the time that if such enlargement also helps to ensure optimum nutrition for a developing fetus in humans, this may help to explain why women don't need to "eat for two" during pregnancy.

    In the current study, the team found that the effect of feminising adult gut stem cells was reversible. "If we take a female fly and then in the adult we masculinise the stem cells in the intestine and wait, within three weeks the gut shrinks to the smaller, male-like size," said CSC and EMBO*-postdoc, Bruno Hudry, who is first author on today's paper.

    The team also found that the female intestine was more prone to tumours. "We find it's a lot easier to create genetically-induced tumours in females than in males. So we suspect there is a trade-off going on. Females need this increased plasticity to cope with reproduction, but in certain circumstances that can be deleterious and make the female gut more prone to tumours."

    It was known that the gonads, or sex organs, of vertebrates retain considerable plasticity: adult ovary and adult testis cells in mice can trans-differentiate into their counterparts following just a single genetic change. So cells in the gonads must have their sexual identity continuously reinforced throughout their postnatal life.

    The teams believes this to be the first time, however, that such plasticity has been demonstrated in adult cells outside the gonads. "If we now take the fly in which we've masculinised the stem cells, and mate this fly, we see that its gut is not re-sized in response to reproduction. So we think that what the stem cell sexual identity is doing is to confer differential plasticity on the female gut," Hudry said.

    It may be obvious that males and females develop sex-specific organs as a fetus develops, but according to Miguel-Aliaga there has been an assumption that organs that are the same in both sexes function differently only because of different circulating hormones -- for example, the oestrogen in women and testosterone in men that kick-in at puberty.

    What's surprising is that in an adult organ found in both sexes, such as the intestine, differences remain, and that these are not due to either developmental history or circulating hormones. The benefit of using a fly model is that the team can masculinise or feminise individual adult stem cells and explore the outcome without changing the fly's developmental history or its circulating hormones.

    In the course of this research, the team identified a potentially important new mechanism behind this sex switching, which they suggest may be operating in more of the organs and tissues of our bodies than has previously been recognised. Miguel-Aliaga sees this as an important finding of today's paper.

    The formation of female or male characteristics involves a cascade of genetic events. "We saw that the sex determinants at the top of this cascade were active, but parts of the cascade that had previously been shown to be active, for example in the sex organs or during development, did not function in these stem cells. This told us a new branch of the sex determination pathway is at play."

    Until now, it has been assumed that the only cells with a sexual identity are those in which this recognised cascade is active. "We have found a new mechanism that is independent of this, which potentially means that every cell in the fly has a sexual identity."

    According to Miguel-Aliaga this raises the intriguing possibility that cells in many more fly organs than previously assumed may have their own sexual identity, and that this might be the case in people too. "We want to know what this new branch is all about. We have found three genes that are important in the gut stem cells, and are intrigued to know whether these three genes play a similar role in cells outside of the gut in other body tissues as well." The team is keen to examine these three genes further, not least because people carry genes that are analogous to the three they've now highlighted as important.

    Dr Des Walsh, head of the population and systems medicine board at the MRC, said: "This study is an interesting piece of biological research that extends our understanding of why male and female physiology is different, beyond the obvious. "Further research is now needed to see how this finding translates to humans. If this intrinsic knowledge held by stem cells is indeed driving the way our organs behave, it could also influence the way these same organs respond to treatment."

    The research was supported by the CSC Genomics and Bioinformatics facilities, and funded by the European Research Council and the Medical Research Council.

    *European Molecular Biology Organisation.

    Story Source: The above post is reprinted from materials provided by MRC Clinical Sciences Centre/Institute of Clinical Sciences (ICS) Faculty of Medicine, Imperial Coll. The original item was written by Susan Watts. Note: Materials may be edited for content and length.

    Journal Reference: Bruno Hudry, Sanjay Khadayate, Irene Miguel-Aliaga. The sexual identity of adult intestinal stem cells controls organ size and plasticity. Nature, 2016; 530 (7590): 344 DOI: 10.1038/nature16953

    Science Daily/Feb. 7, 2016
    Newshawk Crew


    A non-drug story offered because the subject of sex often goes hand in hand with drugs (and rock n' roll...)

    Author Bio

    BT2H is a retired news editor and writer from the NYC area who, for health reasons, retired to a southern US state early, and where BT2H continues to write and to post drug-related news to DF.


  1. cren
    This is fascinating. I know so many people that identify outside of the gender norm, and this is only beginning to become understood. There is so much more to be done and so many implications for this research
  2. rawbeer
    For a long time I thought people who identified with as a gender that didn't correlate to their sex organs were just a little bit goofy in the head. I mean, I wish I was taller and had a bigger cock, but it ain't so. But then I read about how some people basically have genitals showing one sex, but most of their genetics actually reflect the opposite sex. It wasn't a matter of being "confused" or deluded; some people are actually mainly female but just happen to have male genitals, and vice versa.

    Now I still think many transgender people are not actually genetically transgender. They just identify more easily with the cultural features identified with the opposite sex and so they transition in some way. What seems strange to me is that someone would be so staunchly opposed to culturally-determined gender roles, but then change their own gender based on those very roles. If a man wants to act in ways that are traditionally thought of as female, that's just fine. But I don't think that makes them female, unless we want to completely divorce gender from sex. Which is what a lot of trans people want to do. There's just not very much cultural, historical precedence for that and so it makes it very hard for most people to accept. For most, gender is just how you show your sex when your junk is covered.

    This is really fascinating research because it indicates that maybe there's a whole level we're just not seeing here. Maybe the act of transitioning could actually have some impact at the cellular level, or maybe there's some previously unforeseen genetic activity that drives the desire to transition. I'm still inclined to think most of it is just cultural and personal preference; I mean, would having "female" intestines really make a man want to identify as a woman? Could identifying as a woman trigger genetic changes? Maybe so, maybe not. If we could prove that it would make it a lot harder to deny trans people their preferred identities (not that conservative people would have a hard time simply ignoring the science). If not we'd be right where we are now.

    It's a fascinating topic to me not only because it's come to the forefront of cultural debate but also because I've known quite a few trans people, and some of them seemed like wonderful people who redefine themselves to find happiness in their own skin. Some of them honestly seem mentally deluded and bitter that the world won't play along with their fantasy. I think if there wasn't such a heavy focus on the labels of male and female, it wouldn't be nearly the issue it is. If people were just content to act as they wish, and others were accepting enough to let them, it would be much easier than someone with a penis insisting they're a female. I don't see why that label is so important to someone who wants to shatter gender roles; I do see why it's so important to someone who sees sex and gender as identical and both of them as basic biological facts.

    The trans faction of the LGBT community is spearheading what has to be the most revolutionary attempt at cultural change ever attempted. The division between male and female is extremely basic and hard wired into pretty much every human culture that has ever existed, and is particularly important in civilized (in the anthropological meaning of the word) societies. Science was always used by racists to justify their beliefs. It used to seem "obvious" that some races were inferior. It now seems "obvious" that male = penis, female = vagina. But if that turns out to not be true, I think humans will have a much harder times wrapping their heads around the truth than with racial differences.
  3. Joe-(5-HTP)
    Even if a male has a 'female' liver, does that really cause them to actually feel like a female? That's the connection I'm not seeing from this article.
  4. rawbeer
    I think the question I see is, at what point does the scale tip, if ever? Because obviously having a male penis does not cause some males to feel like males! While there are those very rare people who feel like the opposite sex because they are in many ways genetically of the opposite sex, why do people who do not have this rare condition feel that way?

    My guess is that in most cases it has nothing to do with genetics, this just adds an interesting twist and a possibility that maybe it is. However I believe the more likely answer is just that most trans people are not comfortable with their biological sexuality for environmental reasons.

    I don't think being trans, or homosexual is necessarily a "choice" but I have my doubts that most cases are strictly genetic. It doesn't seem like anything is strictly genetic because the environment triggers genes to express themselves in certain ways. Our personalities are products of environmental factors beyond our control.
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