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Adulthood triggered by 'maturity gene'

作者:山泅奔    发布时间:2019-03-02 02:17:04    

By Anna Gosline A single gene which hastens a fruit fly larva’s change into a buzzing sexual adult has been unveiled by researchers. This “maturity gene” could help scientists understand the stormy process of growing up in all animals and maybe even generate ways to manipulate the length of childhood in higher vertebrates, including humans. “It’s metamorphosis in insects and puberty in humans. Either way, it’s just the onset of adult form. Anyone who has watched a child mature knows that they change in very dramatic ways,” says Carl Thummel at the University of Utah in Salt Lake City, US, one of the study authors. The timing of maturity is a complex process, influenced by factors like the availability food and genetics. But the molecular pathways remain similar throughout the animal kingdom. For example, the steroid hormones oestrogen and testosterone play an important role human adolescence, while the steroid ecdysone drives maturation in flies. To better understand the network of signals that control metamorphosis in flies, Thummel and his colleagues reduced the function of a receptor called DHR4 in the fruit fly Drosophila melanogaster. To their surprise, they found that mutant flies with reduced DHR4 activity had a shorter juvenile phase and proceeded to adulthood at a smaller size. The immature larvae had cut short their youthful feeding frenzy by a day. This feeding session – crucial during the maturation process from hatching to pupae – usually lasts about four days. Instead the larvae prematurely entered their “wandering” phase, where they stop feeding and search for a safe place to become a pupa and metamorphose into an adult. But flies in which the gene had been knocked out completely died soon afterwards, failing to emerge from their pupal cases as adults, many without limbs, wings or heads. Researchers have previously quickened maturation times by reducing the availability of food, for example. Once larvae reach their “critical weight,” which is likely to be a minimal amount of stored fats and proteins, they can withstand the necessary starvation during the change into pre-adult pupae. But this is the first gene found that seems to regulate the timing of maturity in Drosophila. The authors suggest that DHR4 controls the timing of metamorphosis by coordinating the fly’s response to their critical weight. The gene would, in essence, make sure they ate enough as youngsters before risking the flip into adulthood. If that is true, it would be very exciting, says Drosophila behavioural geneticist, Marla Sokolowski at the University of Toronto, Canada. “If there is some kind of sensor in how animals respond to their own weight, it would be a direct link to processes that are highly relevant to other mammals like us,” she adds. Humans have an analogous gene to DHR4, though it only exists in germline cells – such as sperm or eggs – and is unlikely to have a similar activity. Nevertheless, the basic physiology of the entire maturation and growth system is similar. And while the complexities of working with higher vertebrates make playing with their development unthinkable today, the future could see pet owners keeping their kittens as kittens forever. It might even tempt parents who want to enjoy their children for longer. “Desperate parents might think about that,” says Thummel. “Worrying that their kids are all going to grow up and leave.” Journal Reference:

 

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