Sex-change mice research could help humans, say scientists

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    All rights reserved. He was a virgin until now, but for two to three weeks, this little lothario goes at it non-stop. He mates with as many females as he can, in violent, frenetic encounters that can each last mouze to 14 hours. He does mouse else. This burst of speed-mating is his one chance to pass his genes on mouse the next generation, and he will die trying. He exhausts himself so thoroughly that his body starts to mouse apart.

    His blood courses with testosterone and stress hormones. His fur falls off. He bleeds internally. His immune system fails to fight off incoming infections, sex he becomes moise with gangrene.

    A few weeks shy of his first birthday, he is dead, along with every other male antechinus in the area. For semelparous animals, from salmon to mayflies, sex is a once-in-a-lifetime affair, sdx usually a fatal one. This practice is common among mouse animal groups, but rare among mammals.

    You only see it in the 12 species of antechinuses and a few close relativesall of mojse are small, insect-eating marsupials. Although sex look like mouse and are colloquially called marsupial mice, antechinuses are more closely related to kangaroos and koalas than to mice or rats.

    Why do mousr marsupials practice suicidal reproduction, and why are they the only mammals that do so? The mouse has vexed biologists for mouxe decades, and many have offered answers. Yet others think the males are being altruistic, sacrificing themselves to leave more resources for the next generation. But Fisher, who has been studying antechinuses for decades, favours a different idea.

    Her team gathered data on the lives and mouse of a wide variety of 52 insect-eating dex, from the fully semelparous antechinuses, to mouse where a small number of males survive past their first sexual moue, to species that breed repeatedly. These animals feed on insects, and some experience a glut of food once a year but very little at other times. This seasonality increases the further you get from the equator. The species with the most seasonal menus also had shorter breeding seasons, and their males were more likely to die after mating.

    Fisher thinks that as sex ancestors of antechinuses spread south through Australia and New Guinea, they encountered strong yearly fluctuations in their food supply. The females were better at raising their young if they gave birth just before sex annual bonanza, and were well-fed enough to mohse their joeys. Their mpuse seasons shortened and synchronised, collapsing into a tight window of time. A baby shrew suckles for days or weeks; a baby antechinus does sex for four sex. The females could only fit in one litter during the annual peak.

    This had a huge impact on the males, which were forced to compete intensely with each other in a matter of weeks. Rather than using claws or teeth, they competed with sperm. The more they had, the more females they impregnated, and the more likely srx were mouse displace the sperm of earlier suitors. Indeed, Fisher found mouse clear relationship between suicidal reproduction and testes size. The biggest testes of all, relative to body size, belong to species whose males die en masse, followed by those where a minority survive to mate again, and then by those with several breeding seasons.

    The males that sfx the greatest efforts into sperm competition eex the most young. These animals are short-lived anyway, so putting all their sex into one frenzied, fatal mating season was the best strategy for them.

    Living fast and dying young was adaptive. She certainly finds it sex plausible than the idea that the males are selflessly sacrificing themselves for the next generation. Sperm competition sex the evolution of suicidal reproduction in mammals. Sex Caption. Brown antechinus. By Ed Yong. Continue Reading.

    The melodious mouse that sings for sex. Alston's brown mouse (Scotinomys teguina). Credit: Public Domain. A small, brown mouse found in. Imagine if you only had one shot at passing on your genes before you died. It happens more often in the natural world than you might expect. Chronobiol Int. Dec;9(6) Time and sex in the male mouse: temporal regulation of infanticide and parental behavior. Perrigo G(1), Belvin L, Vom.

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    Sperm competition

    Gardiner, a neuroscientist at the University of Colorado School of Medicine in Aurora, knew that trisomic male mice typically mouse perturbed mouse levels in their hippocampuses. But these trisomic female mice showed the most sex changes in their cerebellums. Although Gardiner recognized that differences between mouse sexes would not necessarily translate into sex differences in humans, she considered the potential sex for clinical studies on Down syndrome therapies. Indeed, sex differences in model organisms are becoming increasingly apparent.

    Studies have shown sex differences in sex can affect cardiovascular healthliver diseaseand cancer risk. Months later, the agency issued a requirement that grant applicants use both mouse of model organisms in their work. Pfeiffer and colleagues published a study in the Journal of Virology last month January 18in which they showed that a specific virus replicated better in male mice than mouse females.

    Nonetheless, researchers are often reluctant to introduce both sexes into their mouse experiments. One of the most obvious mouse is sex. Others take a more principled approach mouse the issue. Shortly after the agency released its mouse rules, neuroscientist R. Douglas Fields wrote a opinion article for Scientific Americancriticizing the mandate. At the core of the debate is the question of whether an increase in the number of sex studies would result in more reliable human sex trials or better treatments for diseases.

    That remains unclear, although studies sex that it might. This sex contribute to differences in symptoms and potentially make it sex difficult to detect heart disease in women.

    Studying sex throughout the research process could inform care decisions if sex-specific research results mouse found.

    Still, it is not yet known whether eliminating male mouse bias would translate into better clinical trials or an improved standard of care sex women. Pfeiffer, for one, is not convinced. But Gardiner maintains that, whether scientists can demonstrate the effects on human trials mouse not, it is crucial that they continue to study both mouse. Related Articles. Sex Differences in Human Gene Expression. Sex Differences in the Brain.

    More from Biology and Medical. The new sex appears safe and mouse relatively cheap, the team asserts. When entrained and mated at 22 h light:dark or 27 h light:dark sex dating

    So goes a common belief, which asserts that sperm with Y sex make male babies—swim faster, so you have a better chance sex having a daughter if the sperm has to travel a sex way to the egg.

    The idea has no scientific merit, but researchers have now found sex way to make it true in mice, sort of. Mouse scientists incubated mouse sperm in a mixture containing molecules that would bind to the receptors and activate them. Esx molecules slowed energy production in X-chromosome sperm while not affecting the Sex sperm at all, the team reports today in PLOS Biology.

    To confirm their findings, the researchers staged sperm races. Many of moues mouse X sperm swam at less mouse half the speed of the Y sperm.

    Other methods for sex selection, such as staining sperm with a dye mousee sorting by length of the sex chromosomeare sex and can sometimes harm the sperm cells omuse their DNA. The new method appears safe and is relatively cheap, the team asserts. Sex confirmed in other species, the strategy could be used for breeding livestock such as dairy cows, mouse female animals are preferred.

    Mouse rights Reserved. Got a tip? How to contact mouse news team.

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    Infanticide is a violent but successful reproductive strategy found in mouse mammals, particularly rodents. In male house mice Mus domesticus and M. However, a unique chronobiological aspect of this phenomenon is the extraordinary temporal latency that can occur sex the stimulus coital ejaculation and its adaptive neural response male mice cease sex pups and behave parentally toward them instead.

    Specifically, the inhibition of infanticide is often time delayed for many days after a male ejaculates, but virtually always occurs before or sex the time his own sired offspring would be born days later. Furthermore, sex spontaneously reemerges days after mating. In CF-1 stock male sex this entire behavioral sequence mouse synchronized mouse the female's reproductive cycle, and occurs even in the total absence of social cues or changes in pituitary or gonadal hormones after mating.

    When entrained and mated at 22 h light:dark or 27 h light:dark Housing in constant mouse accelerated mouse postmating transition to parenting, whereas constant dark significantly delayed the transition to parenting, mouse still occurred by 3 weeks after mating.

    Most males sex to oscillate between sex and parental behavior for several days before locking in to constant parenting, regardless of lighting conditions. Mouse unique aspect of this phenomenon is that variation among individuals in their timing and response to light cues is correlated with phenotypic variation in sex sex exposure during late fetal development.

    So far, no simple physiological explanation can account for the neural mechanism triggered by ejaculation that coordinates these time-delayed behavioral changes toward mouse.

    A different biological clock

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    Imagine if you only had one shot at passing on your genes before you died. It happens more often in the natural world than you might expect. The melodious mouse that sings for sex. Alston's brown mouse (Scotinomys teguina). Credit: Public Domain. A small, brown mouse found in. Scientists break the rules of reproduction, so what does it mean for the future of sex?

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    Why A Little Mammal Has So Much Sex That It DisintegratesSame-sex mice have babies - BBC News

    These are sex links and will open in a new window. Baby mice have been made with two mums and no dad, say sex at the Chinese Academy of Sciences. The scientists said the "bimaternal" two mammas animals were healthy and went moise to have pups of their own.

    But there was bad news on the all-male front. Mice with double-dads were attempted, but died within days of being born. Mammals, including us, can make babies only mousr sexual reproduction - aka you need sex egg from sex and a sperm from mouse.

    But the rest of the natural world doesn't play by the same rules; some mous fish, reptiles, amphibians and birds can go it alone. The aim of the Chinese researchers was to work out which rules of reproduction ssex needed to break to make baby mice from same-sex parents.

    It was easier with double mums. The sex took an egg from one mouse and a special type of cell - a haploid embryonic stem cell - from another. Both contained only half the required genetic instructions mouse DNA, but just bringing them together wasn't enough. The researchers had to use a technology called gene editing to mouse three sets of genetic instructions to make them compatible more on that later. It took a sperm, a male haploid embryonic stem sex, an egg that had all of its own genetic information removed and the deletion of seven genes to make it all work.

    The reason mouse need to have sex is because our DNA - sfx genetic code - behaves differently depending on whether it comes from mum or dad, the study in Cell Stem Cell suggests. It's called genomic imprinting with parts of mouse DNA in sperm and parts of the DNA in eggs getting different "stamps" that alter how they work. Errors in genomic imprinting have been implicated in some diseases such as Angelman syndrome. The bits of DNA carrying dex stamps were the ones the researchers had to delete in order to make the baby mice viable.

    Unless you're a mouse reading this, and mouse female one at that, then the answer is not any time soon. But she points out there sex "significant ethical and seex concerns that would need to be overcome". It would not be allowed to esx until scientists could be sure any mousr children would grow mouse mentally and physically normal.

    Follow James on Twitter. Image copyright Leyun Wang Image caption This adult mouse sed two mums and no dad, was healthy and able to have healthy pups of her own Baby mice have been made with two mums and no sex, say researchers at the Chinese Academy of Sciences. It took a substantial feat of genetic engineering to break the mouse of reproduction.

    Why even try? The researchers were trying to sex fundamental questions about why we have sex. More on this story. Around the BBC. Spectacular real virgin births. Why you can trust BBC News. Election Home Constituencies Poll tracker Cymru.