Pereanu Wayne, Spindler Shana, Im Elisabeth, Buu Natalie, Hartenstein Volker
Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, California 90095, USA.
Dev Neurobiol. 2007 Oct;67(12):1669-85. doi: 10.1002/dneu.20538.
Larval behavioral patterns arise in a gradual fashion during late embryogenesis as the innervation of the somatic musculature and connectivity within the central nervous system develops. In this paper, we describe in a quantitative manner the maturation of behavioral patterns. Early movements are locally restricted "twitches" of the body wall, involving single segments or parts of segments. These twitches occur at a low frequency and have low amplitude, reflecting weak muscle contractions. Towards later stages twitches increase in frequency and amplitude and become integrated into coordinated movements of multiple segments. Most noticeable among these is the peristaltic wave of longitudinal segmental contractions by which the larva moves forward or backward. Besides becoming more complex as development proceeds, embryonic movements also acquire a pronounced rhythm. Thus, late embryonic movements occur in bursts, with phases of frequent movement separated by phases of no movement at all; early movements show no such periodicity. These data will serve as a baseline for future studies that address the function of embryonic lethal genes controlling neuronal connectivity and larval behavior. We have analyzed behavioral abnormalities in two embryonic lethal mutations with severe neural defects, tailless (tll), which lacks the protocerebrum, and glial cells missing (gcm), in which glial cells are absent. Our results reveal prominent alterations in embryonic motility for both of these mutations, indicating that the protocerebrum and glial cells play a crucial role in the neural mechanism controlling larval movement in Drosophila.
幼虫的行为模式在胚胎发育后期以渐进的方式出现，这是随着体壁肌肉组织的神经支配以及中枢神经系统内的连接性发展而产生的。在本文中，我们以定量的方式描述了行为模式的成熟过程。早期的运动是体壁局部受限的“抽搐”，涉及单个节段或节段的部分区域。这些抽搐发生频率低且幅度小，反映出肌肉收缩较弱。在发育后期，抽搐的频率和幅度增加，并整合为多个节段的协调运动。其中最明显的是纵向节段收缩的蠕动波，幼虫通过这种蠕动波向前或向后移动。除了随着发育进程变得更加复杂外，胚胎运动还呈现出明显的节律性。因此，胚胎后期的运动以爆发形式出现，频繁运动的阶段与完全没有运动的阶段交替出现；早期运动则没有这种周期性。这些数据将作为未来研究的基线，这些研究旨在探讨控制神经元连接性和幼虫行为的胚胎致死基因的功能。我们分析了两种具有严重神经缺陷的胚胎致死突变体的行为异常，即无尾（tll）突变体，其缺乏前脑；以及神经胶质细胞缺失（gcm）突变体，其中没有神经胶质细胞。我们的结果显示，这两种突变体的胚胎运动性都有显著改变，表明前脑和神经胶质细胞在控制果蝇幼虫运动的神经机制中起着关键作用。
