Lnenicka G A, Blundon J A, Govind C K
Neurobiology Research Center, Department of Biological Sciences, State University of New York, Albany 12222.
Dev Biol. 1988 Sep;129(1):84-90. doi: 10.1016/0012-1606(88)90163-7.
The development of functional asymmetry between a pair of homologous motoneurons of the claw closer muscles in lobsters, Homarus americanus, was studied. In juvenile lobsters, 3-5 years old, where the paired claws are highly specialized into a major (crusher) and minor (cutter) type, the fast closer excitor (FCE) motoneuron fired longer bursts of spikes in the crusher claw compared to those in its cutter counterpart. The intraburst impulse frequency was greater for the cutter FCE and its neuromuscular synapses showed greater facilitation at these high impulse frequencies compared to that of the crusher claw. However, such asymmetry in firing patterns and synaptic facilitation was absent in lobsters raised without a substrate and having paired cutter claws. In the earliest juvenile stage, synaptic facilitation was similar between the paired claws and then developed in either an asymmetric or symmetric manner depending on whether the lobsters experienced a substrate or not. In a substrate-free environment asymmetry could be produced by exercising one of the claws during development, implicating bilateral differences in the reflexive activity of the claws as a control mechanism.
对美洲螯龙虾（Homarus americanus）爪闭合肌一对同源运动神经元之间功能不对称性的发育进行了研究。在3至5岁的幼年龙虾中，其成对的爪子高度特化为主要（碾碎爪）和次要（切割爪）类型，与切割爪中的快速闭合肌兴奋运动神经元（FCE）相比，碾碎爪中的该运动神经元发放的尖峰串更长。切割爪FCE的爆发内冲动频率更高，并且与碾碎爪相比，其神经肌肉突触在这些高冲动频率下表现出更大的易化作用。然而，在没有基质且具有成对切割爪的饲养龙虾中不存在这种放电模式和突触易化的不对称性。在最早的幼年期，成对爪子之间的突触易化作用相似，然后根据龙虾是否接触基质以不对称或对称方式发展。在无基质环境中，发育过程中锻炼其中一只爪子可产生不对称性，这表明爪子反射活动的双侧差异是一种控制机制。
