Fruitless mutant male mosquitoes gain attraction to human odor.
Fruitless mutant male mosquitoes gain attraction to human odor.
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DOI：
10.7554/elife.63982
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发表时间：
2020-12-07
期刊：
影响因子：
7.7
通讯作者：
Vosshall LB
中科院分区：
文献类型：
--
作者：
Basrur NS;De Obaldia ME;Morita T;Herre M;von Heynitz RK;Tsitohay YN;Vosshall LB
埃及伊蚊在取食过程中表现出极端的性别二型性。只有雌性才会被人类吸引，并从人类那里获得血液，它们用来刺激产卵。这个无果基因是性别特异性剪接的，编码一种BTB锌指转录因子，被认为是昆虫间雄性求偶和交配行为的主要调节因子。我们产生了无果的突变蚊子，并表明雄性蚊子无法交配，证实了该基因在雄性性行为中的祖先功能。值得注意的是，不结果子的雄性蚊子也会对活的人类宿主产生强烈的吸引力，这是野生型雄性蚊子从未表现出的行为，这表明雄性蚊子拥有寻找寄主所需的中枢或外周神经回路，而清除无果蚊子揭示了雄性蚊子的这种潜在行为。我们的结果突显了男性特有性行为的主要调控者出人意料地改变用途，以控制致命传染病媒介中女性特有的吸血行为的一个模块。性别二型性是动物、昆虫和植物之间的一种现象，即一个物种的两性在身体大小、身体特征或颜色上表现出差异。例如，雄狮浓密的鬃毛在雌狮身上是看不到的，只有雄性孔雀才有夸张的尾巴。大多数性二型性的例子，如精心设计的视觉展示或求爱行为，都与交配有关。然而，在少数物种中，两性之间的行为差异与交配无关。蚊子就是一个例子：雌性蚊子以人类为食，并被人体的热量和气味所吸引，而雄性蚊子对叮咬人类的血液几乎没有兴趣。因此，雌性蚊子是传播病毒的人，这些病毒会导致某些血液传播疾病，如登革热或寨卡病毒。确定哪些基因与蚊子的取食行为有关，可以让研究人员对雌性蚊子进行基因改造，使它们不再叮咬人，从而阻止这些疾病的传播。不幸的是，控制蚊子取食行为的基因还没有得到很好的研究。在其他昆虫中，一些控制有赖于性别的交配行为的基因已经被发现。例如，一种名为无果的基因控制着雄性苍蝇和家蚕的求偶行为，被认为是昆虫之间雄性性行为的“主要调节器”。然而，这种不结果实的基因是否对蚊子有任何影响还有待观察，蚊子的性别差异与摄食习惯有关。为了调查这一点，Basrur等人。从埃及伊蚊身上移除了不结果实的基因。经过基因改造的雄性蚊子无法成功交配，但与未经过基因改造的雄性蚊子类似，它们在进食时仍然更喜欢糖水而不是血液。然而，与未经修饰的雄性蚊子不同，没有结实的雄性蚊子会被人手臂的体味所吸引(就像雌性蚊子一样)。这些结果表明，控制其他昆虫性别特定交配行为的基因无果，控制着蚊子的性别特定取食行为。不结果实的基因，Basrur等人。推测，可能是在进化过程中获得了这种控制蚊子取食行为的作用。还需要更多的研究来充分了解这种不结果实的基因对雄性和雌性蚊子的影响。
The Aedes aegypti mosquito shows extreme sexual dimorphism in feeding. Only females are attracted to and obtain a blood-meal from humans, which they use to stimulate egg production. The fruitless gene is sex-specifically spliced and encodes a BTB zinc-finger transcription factor proposed to be a master regulator of male courtship and mating behavior across insects. We generated fruitless mutant mosquitoes and showed that males failed to mate, confirming the ancestral function of this gene in male sexual behavior. Remarkably, fruitless males also gain strong attraction to a live human host, a behavior that wild-type males never display, suggesting that male mosquitoes possess the central or peripheral neural circuits required to host-seek and that removing fruitless reveals this latent behavior in males. Our results highlight an unexpected repurposing of a master regulator of male-specific sexual behavior to control one module of female-specific blood-feeding behavior in a deadly vector of infectious diseases. Sexual dimorphism is a phenomenon among animals, insects and plants where the two sexes of a species show differences in body size, physical features or colors. The bushy mane of a male lion, for example, is nowhere to be seen on a female lioness, and only male peacocks have extravagant tails. Most examples of sexual dimorphism, such as elaborate visual displays or courtship behaviors, are linked to mating. However, there are a few species where behavioral differences between the sexes are not connected to mating. Mosquitoes are an example: while female mosquitoes feed on humans, and are attracted to a person’s body heat and odor, male mosquitoes have little interest in biting humans for their blood. Therefore, female mosquitoes are the ones responsible for transmitting the viruses that cause certain blood-borne diseases such as dengue fever or Zika. Determining which genes are linked to feeding behaviors in mosquitoes could allow researchers to genetically engineer females so they no longer bite people, thus stopping the spread of these diseases. Unfortunately, the genes that control mosquito feeding behaviors have not been well studied. In other insects, some of the genes that control mating behaviors that depend on sex have been identified. For example, a gene called fruitless controls courtship behaviors in male flies and silkworms, and is thought to be the ‘master regulator’ of male sexual behavior across insects. Yet it remains to be seen whether the fruitless gene has any effect in mosquitoes, where sex differences relate to feeding habits. To investigate this, Basrur et al. removed the fruitless gene from Aedes aegypti mosquitoes. The genetically altered male mosquitoes became unable to mate successfully, but – similar to unmodified males – still preferred sugar water over blood when feeding. Unlike unmodified males, however, the male mosquitoes lacking fruitless were attracted to the body odor of a person’s arm (like females). These results reveal that fruitless, a gene that controls sex-specific mating behaviors in other insects, controls a sex-specific feeding behavior in mosquitoes. The fruitless gene, Basrur et al. speculate, likely gained this role controlling mosquito feeding behavior in the course of evolution. More research is required to fully understand the effects of the fruitless gene in male and female mosquitoes.