Hobert Oliver
Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University Medical Center, New York, New York.
Genesis. 2014 Jun;52(6):528-43. doi: 10.1002/dvg.22747. Epub 2014 Feb 25.
Despite their gross morphological symmetry, animal nervous systems can perceive and process information in a left/right asymmetric manner. How left/right asymmetric functional features develop in the context of a bilaterally symmetric structure is a very poorly understood problem, in part because very few morphological or molecular correlates of functional asymmetries have been identified so far in vertebrate or invertebrate nervous systems. One of the very few systems in which a molecular correlate for functional lateralization has been uncovered is the taste sensory system of the nematode Caenorhabditis elegans, which is composed of a pair of bilaterally symmetric neurons, ASE left (ASEL) and ASE right (ASER). ASEL and ASER are similar in morphology, connectivity, and molecular composition, but they express distinct members of a putative chemoreceptor gene family and respond in a fundamentally distinct manner to taste cues. Extensive forward and reverse genetic analysis has uncovered a complex gene regulatory network, composed of transcription factors, miRNAs, chromatin regulators, and intercellular signals, that instruct the asymmetric features of these two neurons. In this review, this system is described in detail, drawing a relatively complete picture of asymmetry control in a nervous system.
尽管动物神经系统在总体形态上是对称的，但它们能够以左右不对称的方式感知和处理信息。在双侧对称结构的背景下，左右不对称的功能特征是如何形成的，这是一个目前还知之甚少的问题，部分原因是到目前为止，在脊椎动物或无脊椎动物的神经系统中，很少能确定与功能不对称相关的形态学或分子学特征。秀丽隐杆线虫的味觉感觉系统是极少数已发现功能偏侧化分子关联的系统之一，该系统由一对双侧对称的神经元组成，即左侧的ASE（ASEL）和右侧的ASE（ASER）。ASEL和ASER在形态、连接性和分子组成上相似，但它们表达假定化学感受器基因家族的不同成员，并且对味觉线索的反应方式也截然不同。广泛的正向和反向遗传学分析揭示了一个复杂的基因调控网络，该网络由转录因子、微小RNA、染色质调节因子和细胞间信号组成，它决定了这两个神经元的不对称特征。在这篇综述中，将详细描述这个系统，描绘出神经系统中不对称控制的相对完整图景。
