Long Term Survival of Severed Distal Axonal Stumps in Vertebrates and Invertebrates
Long Term Survival of Severed Distal Axonal Stumps in Vertebrates and Invertebrates
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脊椎动物和无脊椎动物远端轴突断端的长期存活
DOI：
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发表时间：
1988
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影响因子：
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通讯作者：
G. Bittner
中科院分区：
文献类型：
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作者：
G. Bittner
概要。据报道，神经轴突的切断的远端残端在脊椎动物和无脊椎动物的神经系统中都能存活数月至数年。15至25°C之间的温度不是决定金鱼Mauthner轴突和许多无脊椎动物轴突存活时间的唯一重要因素。例如，当在相同的温度下研究小龙虾中的不同轴突时，不同轴突的长期存活率不同。在某些情况下，这些差异似乎是由于ghal反应的性质或突触接触的存在的差异。
长期存活的可能的细胞机制分为三大类：轴突蛋白质的缓慢降解从头轴浆蛋白质合成，以及蛋白质从相邻细胞转移到切断的轴突残端在小龙虾和鱿鱼的巨大轴突中，有证据表明蛋白质确实完整地从胶质细胞转移到轴突或从轴突转移到轴突，可能通过胞吐/胞吞过程然而长期存活的细胞机制在同一生物体的不同轴突中可能完全不同，更不用说来自不同门的生物体中的轴突之间，特别是显示出长期存活的myehnated脊椎动物轴突的ghal鞘，可能预期阻碍ghal/轴突或轴突/轴突蛋白质转移
切断的远端残端的长期存活的研究对于轴突再生的研究是重要的，因为在具有长存活时间的生物体中的轴突通常比在缺乏长存活时间的生物体中的轴突更快地显示出功能性重连，并且具有更高的特异性。长期存活的研究对于细胞生物学家理解允许细胞质从细胞中分离的分子机制也是重要的。直接细胞质接触任何细胞核，以保持形态完整和功能能力数月至数年。
SYNOPSIS. Severed distal stumps of nerve axons have now been reported to survive for months to years in both vertebrate and invertebrate nervous systems While low (>15°C) temperatures may increase survival times in some preparations such as unmyelinated garfish olfactory axons, temperature between 15 and 25°C is not the only significant factor determining the time course of survival in goldfish Mauthner axons and for many invertebrate axons For example when different axons in a crayfish are all studied at the same temperature, long term survival differs in different axons In some cases these differences appear to be due to differences in the nature of the ghal reaction or the presence of synaptic contacts.
The possible cellular mechanisms for long term survival fall into three general cate gories slow degradation of axonal proteins de novo axoplasmic protein synthesis, and transfer of proteins from adjacent cells to severed axonal stumps In crayfish and squid giant axons, there is evidence that proteins are indeed transferred intact from glia to axons or from axon to axon, possibly via exocytotic/endocytotic processes However cellular mechanisms for long term survival may well differ in different axons of the same organism, much less between axons in organisms from different phyla In particular the ghal sheaths of myehnated vertebrate axons which demonstrate long term survival might be expected to impede ghal/axonal or axonal/axonal protein transfer.
The study of long term survival of severed distal stumps is important for studies of axonal regeneration because axons in organisms having long survival times often show functional reconnection much more rapidly and with higher specificity than do axons in organisms lacking long survival times The study of long term survival is also important to cell biologists for an understanding of the molecular mechanisms which allow a piece of cytoplasm separated from direct cytoplasmic contact with any nucleus to remain morphologically intact and functionally competent for months to years.