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Integrative analysis of serotonin-mediated behavioural phase transition in the desert locust

沙漠蝗虫血清素介导的行为相变的综合分析

基本信息

批准号：
BB/H002537/1
负责人：
Swidbert Ott
金额：
$ 61.09万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FH002537%2F1
关键词：
Integrative analysis serotonin mediated behavioural

项目摘要

Animals may undergo profound changes in their behaviour, body shape and colour in response to varying environmental conditions. This poses a major problem in biology: how do the surroundings in which an animal lives, influence the expression of its genes and mould its brain function, its hormones, and hence its behaviour, so that it is appropriately adapted to changing circumstances. The Desert Locust shows an extreme example of this malleability; it can change reversibly from a shy and inconspicuous, solitary creature that flies at night to one that is highly conspicuous, day flying and occasionally aggregates in vast numbers which has devastating economic effects. These two forms - the solitarious and gregarious phases - are strikingly different in appearance, physiology and behaviour. They can be bred in the laboratory and made to switch from one phase to the other and back, by simply raising them in isolation or in a crowd. They have relatively few nerve cells in their brain so that it is possible to understand the changes that occur during these phase transitions and to illuminate the similar mechanisms that occur in more complex animals when they find themselves in new circumstances. The key decision a locust must make is to join with or avoid other locusts. Once this has been made subsequent changes in physiology, body shape and colour follow from the continuing presence or absence of other locusts. Tickling the hind legs of a solitarious locust to mimic the effects of jostling with others, or the sight and smell of other locusts, can, in 1-2 h, cause the behaviour to become gregarious. This transition is accompanied by substantial changes in the amounts of many chemicals in its nervous system. In particular serotonin (a substance that in human brains affects many moods such as aggression and depression, and the release of which is affected by drugs such as ecstasy) shows a large but short-lived increase and, critically, it is both necessary and sufficient to induce the change in behaviour. We have determined which nerve cells show changes in their serotonin levels. We now wish to understand how serotonin changes the workings of nerve cells to bring about the transformation of behaviour. To achieve this aim we have these key objectives: 1. Identify and characterise the nerve cells that change their production of serotonin during the initial change in behaviour. How far do they extend through the central nervous system? How do they respond in the presence of other locusts, and what effects do they have on other nerve cells to bring about changes in behaviour? 2. Identify the nerve cells that are influenced by the release of serotonin. What chemical changes does serotonin cause in the internal workings of these nerve cells? This will be examined at the level of specific molecules that engage in cascades of chemical reactions to pass information within one cell and to neighbours. 3. Serotonin can change the effectiveness and the time course of communication between nerve cells, providing an essential building block of learning. How do differing amounts of serotonin in the nervous system before, during and after the experience of crowding, affect communication between nerve cells? Does serotonin have different effects in solitarious and gregarious locusts? 4. Examine in detail how solitarious and gregarious locusts differ in their patterns of daily activity such as feeding, exploring their environment and sleeping, and begin to look at how genes that regulate their body clock differ in the two phases. 5. Gregarious locusts quickly revert to solitarious behaviour if they are removed from the crowd. What are the mechanisms that maintain their gregarious behaviour and what is the complimentary process that leads to solitarious behaviour?

动物可能会在行为、体型和颜色上经历深刻的变化，以应对不同的环境条件。这就提出了一个生物学上的主要问题：动物生活的环境如何影响其基因的表达，塑造其大脑功能、激素，进而塑造其行为，从而使其适当地适应不断变化的环境。沙漠蝗虫就是这种可塑性的一个极端例子；它可以从一种害羞、不显眼、独居、夜间飞行的生物，可逆地变成一种非常显眼、白天飞行、偶尔大量聚集的生物，这对经济产生了毁灭性的影响。这两种形态——独居期和群居期——在外表、生理和行为上都有显著不同。它们可以在实验室中繁殖，并通过简单地将它们隔离或在人群中饲养，从一个阶段切换到另一个阶段，然后再切换回来。它们大脑中的神经细胞相对较少，因此有可能理解在这些相变中发生的变化，并阐明在更复杂的动物发现自己处于新环境时发生的类似机制。蝗虫必须做出的关键决定是加入或避开其他蝗虫。一旦这种情况发生，其他蝗虫的出现或消失会导致生理、身体形状和颜色的变化。挠一只独居的蝗虫的后腿，以模仿与其他蝗虫挤在一起的效果，或者是其他蝗虫的视觉和气味，可以在1-2小时内使它们的行为变得群居。这种转变伴随着神经系统中许多化学物质数量的实质性变化。特别是血清素（一种在人脑中影响许多情绪的物质，如攻击性和抑郁，其释放受摇头丸等药物的影响）显示出大量但短暂的增加，关键的是，它是诱导行为变化的必要和充分条件。我们已经确定了哪些神经细胞的血清素水平发生了变化。我们现在希望了解血清素是如何改变神经细胞的工作方式，从而带来行为的转变。为实现这一目标，我们有以下几个主要目标：识别和描述在行为的初始变化中改变血清素产生的神经细胞。它们在中枢神经系统中延伸多远？它们在其他蝗虫面前是如何反应的？它们对其他神经细胞有什么影响，导致它们的行为发生变化？2. 识别受血清素释放影响的神经细胞。血清素在这些神经细胞的内部工作中引起了什么化学变化？这将在特定分子的水平上进行检查，这些分子参与化学反应的级联，在一个细胞内和相邻细胞内传递信息。3. 血清素可以改变神经细胞之间沟通的有效性和时间进程，为学习提供必要的基础。在拥挤之前、期间和之后，神经系统中不同数量的血清素是如何影响神经细胞之间的交流的？血清素对独居和群居蝗虫有不同的影响吗？4. 详细研究独居和群居蝗虫在日常活动模式（如进食、探索环境和睡眠）上的差异，并开始研究调节它们生物钟的基因在这两个阶段有何不同。5. 群居的蝗虫一旦被赶出人群，就会迅速恢复独居的行为。维持它们群居行为的机制是什么？导致它们孤僻行为的互补过程是什么？