Neuron hemilineages provide the functional ground plan for the Drosophila ventral nervous system.
Neuron hemilineages provide the functional ground plan for the Drosophila ventral nervous system.
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DOI：
10.7554/elife.04493
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发表时间：
2015-07-20
期刊：
影响因子：
7.7
通讯作者：
Truman JW
中科院分区：
文献类型：
--
作者：
Harris RM;Pfeiffer BD;Rubin GM;Truman JW
果蝇的中枢神经元来自神经母细胞，这些神经母细胞以成对的方式产生神经元，两个子代为不同的A和B半系群提供了基础。33个胚胎后出生的半月体贡献了每个胸半段90%以上的神经元。我们设计了遗传学方法来定义这些半系中的大多数的解剖结构，并使用热敏通道dTRPA1来评估它们的功能作用。最简单的半线含有局部中间神经元，它们的激活导致缺乏肢体间协调的紧张性或相位性腿部运动。下一个层次是类似投射细胞的半线形，它们驱动节段间的协调行为，如行走。最高水平涉及半线条，其激活会引发复杂的行为，如起飞。这些激活表型表明，半线神经元的行为作用各不相同，其中一些参与了感觉运动处理的局部网络，另一些则具有将这些局部网络协调成复杂行为的更高阶功能。Http://dx.doi.org/10.7554/eLife.04493.001：昆虫的腿和翅膀长在构成胸部的身体中部。胸腔内的神经系统是昆虫相当于脊髓的一部分，包含一簇簇的中间神经元，在感觉神经、大脑和肌肉之间传递信号。这使昆虫能够执行复杂的动作，如行走和飞行。胸椎间神经元是由一组固定的干细胞产生的。每个干细胞通过产生一系列神经前体细胞来成对地制造神经元，然后每个神经前体细胞分裂产生两种不同类型的子神经元。所有同类型的子代神经元都被认为属于同一半线，在果蝇中，胸部的大多数中间神经元来自33个半线中的一个。昆虫胸腔中的每个中间神经元团由来自同一半系的细胞组成。Harris等人。开发了基因工具，可以标记果蝇胸部的不同半身线，并利用这一工具创造了一组果蝇，从而可以研究不同集群的作用。每种苍蝇类型都被修改，以便提高温度激活单一半线神经元中的热敏通道，Harris等人说。记录了由此产生的行为反应。当受到刺激时，每个半线都会导致苍蝇以一种独特的方式移动，其中许多运动是单一集群独一无二的。此外，半线型还可以根据其复杂程度分为不同的组。激活最简单的一组半线束会产生简单的动作，如腿部抽搐和伸展。然后，另一组半身人能够将这些动作组织成更复杂的行为，比如走路。第三个，也是最复杂的半直线可以协调几个复杂的动作，使苍蝇能够执行非常复杂的任务，比如起飞飞行。这些发现表明，在苍蝇胸腔中，半线条是神经系统的基本模块。此外，哈里斯等人开发的苍蝇和技术。将为未来研究神经系统的组织和功能提供宝贵的资源。DOI：http://dx.doi.org/10.7554/eLife.04493.002
Drosophila central neurons arise from neuroblasts that generate neurons in a pair-wise fashion, with the two daughters providing the basis for distinct A and B hemilineage groups. 33 postembryonically-born hemilineages contribute over 90% of the neurons in each thoracic hemisegment. We devised genetic approaches to define the anatomy of most of these hemilineages and to assessed their functional roles using the heat-sensitive channel dTRPA1. The simplest hemilineages contained local interneurons and their activation caused tonic or phasic leg movements lacking interlimb coordination. The next level was hemilineages of similar projection cells that drove intersegmentally coordinated behaviors such as walking. The highest level involved hemilineages whose activation elicited complex behaviors such as takeoff. These activation phenotypes indicate that the hemilineages vary in their behavioral roles with some contributing to local networks for sensorimotor processing and others having higher order functions of coordinating these local networks into complex behavior. DOI: http://dx.doi.org/10.7554/eLife.04493.001 The legs and wings of insects are borne on the middle body segments, which make up the thorax. The nervous system inside of the thorax is part of the insect equivalent of the spinal cord and contains clusters of interneurons that relay signals between the sensory nerves, the brain and the muscles. This enables the insect to perform complex actions such as walking and flying. The thoracic interneurons are produced by a fixed set of stem cells. Each stem cell makes neurons in a pair-wise fashion by producing a sequence of neural progenitor cells, each of which then divides to produce two different types of daughter neurons. All of the daughter neurons of the same type are said to belong to the same hemilineage, and in the fruit fly Drosophila, the majority of the interneurons in the thorax are from one of 33 hemilineages. Each interneuron cluster in the insect thorax is made up of cells from a single hemilineage. Harris et al. developed genetic tools that allow the different hemilineages in the Drosophila thorax to be labeled, and used this to create a set of flies that allows the role of the different clusters to be investigated. Each fly type was modified so that increasing the temperature activated a heat-sensitive channel in the neurons of a single hemilineage, and Harris et al. recorded the behavioral response this produced. Each hemilineage caused the fly to move in a distinctive way when stimulated, and many of these movements were unique to a single cluster. Furthermore, the hemilineages can be divided into different groups based on their complexity. Activating the simplest group of hemilineage clusters produces simple movements such as leg twitches and stretches. Another group of hemilineages are then able to organize these movements into more complicated behaviors, such as walking. The third, most complex, hemilineages can coordinate several complex actions to enable the flies to perform very complicated tasks, like take off for flight. These findings suggest that hemilineages act as the basic modules of the nervous system in the fly thorax. Furthermore, the flies and techniques developed by Harris et al. will provide valuable resources for future studies into the organization and function of the nervous system. DOI: http://dx.doi.org/10.7554/eLife.04493.002