日本研究人员在新一期《自然》杂志网络版上发表论文说，他们发现一种无脊椎动物——海鞘的神经细胞生成机制，该成果有助于研究干细胞的分化过程。

海鞘是尾索动物亚门海鞘纲的总称，与脊椎动物亚门同属脊索动物门。

日本筑波大学下田临海实验中心副教授笹仓靖德等研究人员报告说，他们应用转基因技术，让海鞘幼体中枢神经系统的细胞在紫外线照射下发出红光，然后观察海鞘幼体发育为成体的整个过程。他们发现，海鞘幼体中枢神经系统中的一种神经胶质细胞会一直留存到成体中，并在成体中制造神经细胞。

神经胶质细胞具有支持并滋养神经细胞，吸收和调节某些活性物质等作用。哺乳动物的中枢神经系统中存在能分化成神经细胞的干细胞，它们有望用于修复受损的神经。

笹仓靖德指出，海鞘在遗传上与脊椎动物有相近之处，而前者中枢神经系统的细胞只有大约300个。对这类拥有简单中枢神经系统的动物进行研究，有助于人们研究从干细胞分化生成神经细胞的整套机制。（生物谷Bioon.com）

生物谷推荐原文出处：

Nature doi:10.1038/nature09631

Ependymal cells of chordate larvae are stem-like cells that form the adult nervous system

Takeo Horie,Ryoko Shinki,Yosuke Ogura,Takehiro G. Kusakabe,Nori Satoh& Yasunori Sasakura

In ascidian tunicates, the metamorphic transition from larva to adult is accompanied by dynamic changes in the body plan. For instance, the central nervous system (CNS) is subjected to extensive rearrangement because its regulating larval organs are lost and new adult organs are created1. To understand how the adult CNS is reconstructed, we traced the fate of larval CNS cells during ascidian metamorphosis by using transgenic animals and imaging technologies with photoconvertible fluorescent proteins2. Here we show that most parts of the ascidian larval CNS, except for the tail nerve cord, are maintained during metamorphosis and recruited to form the adult CNS. We also show that most of the larval neurons disappear and only a subset of cholinergic motor neurons and glutamatergic neurons are retained. Finally, we demonstrate that ependymal cells of the larval CNS contribute to the construction of the adult CNS and that some differentiate into neurons in the adult CNS. An unexpected role of ependymal cells highlighted by this study is that they serve as neural stem-like cells to reconstruct the adult nervous network during chordate metamorphosis. Consequently, the plasticity of non-neuronal ependymal cells and neuronal cells in chordates should be re-examined by future studies3, 4.