Comparative analysis of the nervous systems in presumptive progenetic dinophilid and dorvilleid polychaetes (Annelida) by immunohistochemistry and cLSM
Comparative analysis of the nervous systems in presumptive progenetic dinophilid and dorvilleid polychaetes (Annelida) by immunohistochemistry and cLSM
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DOI：
10.1046/j.1463-6395.2002.00096.x
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发表时间：
2002-01-01
期刊：
影响因子：
1.2
通讯作者：
Westheide, W
中科院分区：
文献类型：
--
作者：
Müller, MCM;Westheide, W
用抗5-羟色胺、Phe-Met-Arg-Phe-NH 2（FMRFamide）和乙酰化α-微管蛋白的抗血清对嗜虫虫（两个物种）和三叶虫（三个物种）以及dorvilleids Parapodrilus psammophilus和Ophryotrocha gracilis（幼虫）的整个神经系统进行染色，并通过共聚焦激光扫描显微镜（cLSM）进行分析。成虫和dorvilleid幼虫表现出相同的腹神经索的结构，两个主要的神经间隔很远，一个正中神经和两个旁正中神经。神经元能神经丛位于旁正中神经对之间，在腹侧运动睫状带上方。成虫和幼虫之间的这些相似之处证实了推测的亲甲虫的原生起源。然而，由于其他多毛类的幼虫神经系统似乎也是以这种方式组织的，这一结果不能支持dinophilids起源于dorvilleids的观点。在沙蚕中，主要的神经索仅在最后一段广泛分离，这表明这种模式可能与没有副足有关。嗜沙棘齿虫（P.psammophilus）和许多其他多毛类动物的不成对正中神经被认为是环节动物基本身体计划的一部分。腹侧成对的dinophilid神经节的地面模式是由三个（前，主，后）连合，保存在大多数神经节的Dinophilus物种和主要减少到一个主连合的Trilobodrilus物种。与先前的观点相反，甲虫和P.psammophilus拥有六对神经节，表明有六个躯干节。两个环背后的prostomium在这两个dinophilid和dorvilleid物种只包含一对神经节，证实了假定的同源性，这口缘区在两个类群。Dinophilus神经系统具有12条纵向神经和每节三个垂直神经环，类似于扁形动物特有的正交神经结构。
Entire nervous systems of the dinophilids Dinophilus (two species) and Trilobodrilus (three species) and the dorvilleids Parapodrilus psammophilus and Ophryotrocha gracilis (larva) were stained with antisera directed against serotonin, Phe-Met-Arg-Phe-NH2 (FMRFamide) and acetylated alpha-tubulin and analysed by confocal laser scanning microscopy (cLSM). Adult dinophilids and the dorvilleid larva exhibit the same structure of the ventral nerve cord, with two main nerves spaced far apart, one median and two paramedian nerves. A serotonergic plexus is situated between the paramedian nerve pair, above the ventral locomotory ciliary band. These similarities between adults and larva corroborate the presumed progenetic origin of dinophilids. However, since larval nervous systems of other polychaete taxa also seem to be organized in this way, this result cannot support the view that dinophilids originate from dorvilleids. In P.psammophilus the main nerve cords are widely separated only in the last segment, indicating that this pattern may be correlated with the absence of parapodia. The unpaired median nerve of dinophilids, P.psammophilus and many other polychaetes, is considered to be part of the basic annelid body plan. The ground pattern of the ventral paired dinophilid ganglia is represented by three (anterior, main, posterior) commissures, conserved in most of the ganglia in the Dinophilus species and mostly reduced to a main commissure in the Trilobodrilus species. The dinophilid species and P.psammophilus possess six pairs of ganglia indicating six trunk segments - in contrast to former views. The two rings behind the prostomium in both the dinophilid and the dorvilleid species contain one pair of ganglia only, corroborating the presumed homology of this peristomial region in the two taxa. The Dinophilus nervous system with 12 longitudinal nerves and three perpendicular nerve rings per segment resembles orthogonal nervous structures characteristic of platyhelminths.