Guidance of neuronal growth cones: selective fasciculation in the grasshopper embryo.
Guidance of neuronal growth cones: selective fasciculation in the grasshopper embryo.
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神经元生长锥的指导：蚱蜢胚胎中的选择性束动。
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
C. Goodman
中科院分区：
文献类型：
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作者：
J. Raper;M. Bastiani;C. Goodman
发育神经生物学的核心问题之一是个体神经元的多样性和特异性是如何在胚胎发育过程中产生的。神经元多样性的一个主要组成部分是单个神经元复杂的轴突形态，这在很大程度上是在发育早期产生的，并最终与神经元找到正确的突触目标的能力有关。通过精确的寻路过程，生长锥细胞找到合适的神经元或肌肉细胞，通常是沿着包括一系列细胞特异性选择和转弯的固定路线长途旅行。根据细胞培养实验，生长锥的运动包括三个阶段：伸展、附着和收缩（Bray 1982; Letourneau 1982）。生长球果延伸出许多指状丝状足，直径约0.1 / mm，长度可达50 / mm或更长。这些丝状足从生长锥向许多方向辐射，短暂地探索它们的环境。一些丝状足接触其他细胞表面或细胞外基底膜；它们强烈地附着在这些表面上，但它们对其他表面的附着力要弱得多。丝状足以收缩周期收缩。如果粘连较弱，则丝足缩回；然而，如果它的附着力很强，那么在收缩周期中，该方向的张力会增加，生长锥的尖端会向附着点移动（Bray 1982; Letourneau 1982）。因此，理解生长锥在胚胎发生过程中所做出的多样化和特异性选择的关键，在很大程度上涉及理解它们在做出细胞特异性决定时丝状足的行为、环境和选择性粘附。我们想了解不同神经元的生长锥在面对相同的环境时，是如何做出不同的、模式化的选择的。生长锥的这种分化选择意味着细胞环境的异质性和它们对环境的反应的异质性。我们想知道胚胎中什么细胞和分子信号影响了个体生长锥的选择，以及这些生长锥是如何通过它们的有丝分裂祖先和早期细胞相互作用来响应这些信号的。我们的策略是首先检查，然后操纵，胚胎发育过程中已确定的生长锥的细胞环境
One of the central questions of developmental neuro biology concerns how the diversity and specificity of individual neurons are generated during embryonic development. One major component of neuronal diver sity is the complex axonal morphology of individual neurons, largely generated early in development and in timately involved in the ability of neurons to find their correct synaptic targets. By a process of precise pathfinding, growth cones find the appropriate neurons or muscle cells, often by traveling long distances along stereotyped routes that involve a series of cell-specific choices and turns. Growth cone motility, as described from cell culture experiments, involves three phases: extension, adhe sion, and contraction (Bray 1982; Letourneau 1982). Growth cones extend numerous fingerlike filopodia, approximately 0.1 /im in diameter and up to 50 /tm or more in length. These filopodia radiate in many direc tions from the growth cone, transiently exploring their environment. Some of the filopodia contact other cell surfaces or extracellular basement membranes; they strongly adhere to some of these surfaces but their adhesion to others is much weaker. Filopodia are retracted in a contractile cycle. If adhesion is weak, the filopodium is retracted; if, however, its adhesion is strong, then tension in that direction is increased during the contractile cycle and the leading tip of the growth cone advances toward the point of attachment (Bray 1982; Letourneau 1982). Thus, the key to understand ing the diverse and specific choices made by growth cones during embryogenesis involves in large part un derstanding the behavior, environment, and selective adhesion of their filopodia as they make cell-specific decisions. We would like to understand how the growth cones of different neurons, confronted with the same environ ment, make different and stereotyped choices. Such di vergent choices by growth cones imply both hetero geneity in their cellular environment and heterogeneity in their responses to that environment. We would like to know what cellular and molecular cues in an embryo influence the choices made by individual growth cones, and how these growth cones are determined by their mitotic ancestry and earlier cell interactions to respond to those cues. Our strategy has been first to examine, and then to manipulate, the cellular environment of identified growth cones during embryonic develop