fruitless tunes functional flexibility of courtship circuitry during development.
fruitless tunes functional flexibility of courtship circuitry during development.
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开发过程中求爱巡回赛的毫无结果的曲调灵活性。
作者：
Chen J;Jin S;Chen D;Cao J;Ji X;Peng Q;Pan Y
果蝇雄性求偶是由雄性特有的无果(Frum)基因产物及其表达的神经回路控制的。Frum被认为是控制男性求爱方方面面的主宰基因。通过在时间和空间上操纵Frum的表达，我们发现Frum是先天向雌性求爱的关键发育时期所必需的，而它在成年期的功能涉及到抑制男性与男性的求爱。通过改变或消除Frum的表达，我们产生了天生的异性恋、同性恋、双性恋或没有天生的求爱行为，但可以通过依赖经验的方式获得这样的行为。这些发现表明，Frum对于求爱并不是绝对必要的，但在发育过程中至关重要，可以构建灵活性降低而效率提高的性回路，并为Frum如何调谐性回路的功能灵活性而不是传统认为的开启其功能提供了新的观点。与生俱来的行为是不需要学习的行为。这些活动包括在鸟类中筑巢和在蜘蛛中织网。另一种被广泛研究的行为通常被认为是天生的，那就是果蝇的求偶行为。雄性果蝇通过振动它们的翅膀来创造复杂的旋律来为潜在的配偶唱小夜曲。这种行为是由一种名为“无果”的基因控制的，这种基因会产生几种不同的蛋白质，其中包括一种男性特有的蛋白质。多年来，这种名为Frum的蛋白质被认为是激活求爱行为的主开关。但最近的发现对这一想法提出了挑战。研究表明，虽然缺乏Frum的雄性果蝇在单独饲养的情况下无法表现出求偶行为，但如果在群体中饲养，它们仍然可以学习这些行为。这表明，Frum的角色比之前认为的更复杂。为了确定Frum是如何控制求爱行为的，Chen等人。使用遗传工具来操纵雄性果蝇在生命周期的不同阶段和神经系统不同细胞的Frum活动。结果显示，在雄性果蝇向雌性果蝇求爱的关键发育时期--但不是成年期--Frum必须在场。然而，Frum强烈地影响着雄蝇表现出的求偶行为类型。FRUM的数量和位置决定了雄性是否表现出异性恋、同性恋或双性恋的求爱行为。果糖水平较低的成年果蝇表现出同性恋求爱增加，异性求爱减少。这些发现为掌握基因如何产生复杂而灵活的行为提供了一个新的视角。他们表明，无果果蝇及其编码的Frum蛋白在不同的生命周期中发挥着不同的作用，改变雄性果蝇表现出的求偶行为类型，而不是简单地开关求爱行为。Frum到底是如何在果蝇的大脑中发挥作用来实现这些复杂的效果的，还需要进一步的研究。
Drosophila male courtship is controlled by the male-specific products of the fruitless (fruM) gene and its expressing neuronal circuitry. fruM is considered a master gene that controls all aspects of male courtship. By temporally and spatially manipulating fruM expression, we found that fruM is required during a critical developmental period for innate courtship toward females, while its function during adulthood is involved in inhibiting male–male courtship. By altering or eliminating fruM expression, we generated males that are innately heterosexual, homosexual, bisexual, or without innate courtship but could acquire such behavior in an experience-dependent manner. These findings show that fruM is not absolutely necessary for courtship but is critical during development to build a sex circuitry with reduced flexibility and enhanced efficiency, and provide a new view about how fruM tunes functional flexibility of a sex circuitry instead of switching on its function as conventionally viewed. Innate behaviors are behaviors that do not need to be learned. They include activities such as nest building in birds and web spinning in spiders. Another behavior that has been extensively studied, and which is generally considered to be innate, is courtship in fruit flies. Male fruit flies serenade potential mates by vibrating their wings to create a complex melody. This behavior is under the control of a gene called ‘fruitless’, which gives rise to several distinct proteins, including one that is unique to males. For many years, this protein – called FruM – was thought to be the master switch that activates courtship behavior. But recent findings have challenged this idea. They show that although male flies that lack FruM fail to show courtship behaviors if raised in isolation, they can still learn them if raised in groups. This suggests that the role of FruM is more complex than previously thought. To determine how FruM controls courtship behavior, Chen et al. have used genetic tools to manipulate FruM activity in male flies at different stages of the life cycle and distinct cells of the nervous system. The results revealed that FruM must be present during a critical period of development – but not adulthood – for male flies to court females. However, FruM strongly influences the type of courtship behavior the male flies display. The amount and location of FruM determines whether males show heterosexual, homosexual or bisexual courtship behaviors. Adult flies with lower levels of FruM show an increase in homosexual courtship and a decrease in heterosexual courtship. These findings provide a fresh view on how a master gene can generate complex and flexible behaviors. They show that fruitless, and the FruM protein it encodes, work distinctly at different life cycles to modify the type of courtship behavior shown by male flies, rather than simply switching courtship behavior on and off. Exactly how FruM acts within the fruit fly brain to achieve these complex effects requires further investigation.