Segmental specificity and lateral asymmetry in the differentiation of developmentally homologous neurons during leech embryogenesis.
Segmental specificity and lateral asymmetry in the differentiation of developmentally homologous neurons during leech embryogenesis.
复制标题
水蛭胚胎发生过程中发育同源神经元分化的节段特异性和横向不对称性。
DOI：
10.1016/0012-1606(89)90192-9
复制
发表时间：
1989
影响因子：
2.7
通讯作者：
Martindale,MQ
中科院分区：
文献类型：
--
作者：
Shankland,M;Martindale,MQ
本文描述了三个水蛭神经元的胚胎发育经历空间调控的分化模式。在水蛭中，神经系统起源于胚胎细胞谱系的迭代阵列，并且每个神经元由一组双侧对称和分段重复的同源物表示。这里讨论的两个细胞，神经元nz 4和mz 3，染色的神经肽SCP和FMRFamide的抗体在其胚胎分化的过程中，但只有一个子集的最初的免疫反应性同源物继续表达这种免疫反应性到胚后的生活。保留免疫反应性的那些nz 4细胞被称为RAS神经元，并且持续免疫反应性的mz 3细胞被称为CAS神经元。显示持续表达的同源物的子集是节段特异性的，使得成熟的RAS和CAS神经元占据不同的节段结构域。此外，这两个神经元显示的最终模式的表达是横向不对称的，只有一个的两个同系物在每个节段保持RAS或CAS表型。对于任何给定的节段，不对称分化可以在任一方向上发生，尽管持续免疫反应性细胞存在非常强烈的倾向于位于连续节段的相对侧。暂时免疫反应同源物的命运尚不清楚，但细胞内谱系示踪剂的标记表明，有一些mz 3神经元存活到胚后生活的后期，从来没有表达可检测到的免疫反应水平。细胞内谱系示踪剂也使我们能够跟踪第三种神经元mz 4的发育，它不对任何一种肽进行染色。mz 4神经元最初是成对的，但经历了不对称的细胞死亡模式，这也显示出在连续的节段中交替两侧的强烈趋势。神经元存活和/或分化的这些空间协调模式表明，细胞相互作用在确定单个神经元的发育选择中发挥了作用，随后的论文将通过实验操作来表征这些相互作用。
This paper describes the embryonic development of three leech neurons which undergo spatially regulated patterns of differentiation. In leeches, the nervous system arises from an iterated array of embryonic cell lineages, and each neuron is represented by a set of bilaterally symmetric and segmentally repeated homologs. Two of the cells discussed here, the neurons nz4 and mz3, stain with antibodies to the neuropeptides SCP and FMRFamide during the course of their embryonic differentiation, but only a subset of the initially immunoreactive homologs continue to express this immunoreactivity into postembryonic life. Those nz4 cells which retain immunoreactivity are referred to as RAS neurons, and the persistently immunoreactive mz3 cells referred to as CAS neurons. The subset of homologs which show persistent expression is segment specific, such that the mature RAS and CAS neurons occupy different segmental domains. In addition, both neurons display a final pattern of expression which is laterally asymmetric, with only one of the two homologs in each segment maintaining the RAS or CAS phenotype. Asymmetric differentiation can occur in either orientation for any given segment, although there is a very strong tendency for the persistently immunoreactive cells to lie on opposite sides of successive segments. The fate of the transiently immunoreactive homologs is unclear, but labeling with intracellular lineage tracers suggests that there are some mz3 neurons which survive late into postembryonic life and never express detectable levels of immunoreactivity. Intracellular lineage tracers also allowed us to follow the development of a third neuron, mz4, which does not stain for either peptide. The mz4 neuron is initially paired, but undergoes an asymmetric pattern of cell death which also shows a strong tendency to alternate sides in successive segments. These spatially coordinated patterns of neuronal survival and/or differentiation suggest that cell interactions play a role in determining the developmental choices made by individual neurons, and a subsequent paper will characterize those interactions through experimental manipulation.