■非模型生物幼体阶段的神经发育,专注于血清素和FMRFamide免疫反应性成分,近年来一直是研究的焦点。然而,一些分类群仍未得到充分研究。Nemertea(带状蠕虫)代表了这种未被研究的进化枝,关于神经系统发育的报道很少,主要来自系统发育或发育衍生的物种。探索其他物种的神经发育,以便能够记录多样性并推断共同模式以追踪神经系统发育的进化,这将是有见地的。
■用针对5-羟色胺和FMRF-酰胺的多克隆一级抗体和针对突触素的单克隆抗体进行的荧光免疫组织化学标记在两个nemertean物种Cephalothrixrufifrons的一系列固定幼虫阶段(Archinemertea,Palaeonemertea)和Emplectonemagracile(Monostilifera,Hoplonemertea)使用共聚焦激光扫描显微镜进行分析。
■从各自信号的首次出现开始,该贡献详细介绍了两种nemertean物种中神经系统5-羟色胺和FMRFamide免疫反应性亚群的发展。此外,有关突触素样免疫反应性的数据说明了神经纤维组件的一般结构。两种研究物种的共同事件是在FMRF样免疫反应性信号出现之前出现了5-羟色胺样免疫反应性信号,以及外侧神经索从前方位置的严格发展,朝向幼虫后极的环形脑。值得注意的差异是(1)长鼻神经系统在所研究的E.gracile幼虫阶段发育得更早;(2)明显的早期,但显然是短暂的,E.gracile幼虫额叶和尾极上的血清素能神经元,在C.rufifrons中似乎不存在。
■根据这项调查的结果,并与先前发表的关于神经系统发育的报道一致,Nemertea的最后一个共同祖先在长鼻开口周围有一个环形的大脑,一对腹外侧神经索从前向后发展。早期的额叶和尾部5-羟色胺能神经元后来退化或停止表达5-羟色胺是Nemertea的祖先特征,它们与其他几个螺旋体分支共享。
UNASSIGNED: Neurodevelopment in larval stages of non-model organisms, with a focus on the serotonin- and
FMRFamide-immunoreactive components, has been in the focus of research in the recent past. However, some taxonomic groups remain understudied. Nemertea (ribbon worms) represent such an understudied clade with only few reports on nervous system development mostly from phylogenetically or developmentally derived species. It would be insightful to explore neurodevelopment in additional species to be able to document the diversity and deduce common patterns to trace the evolution of nervous system development.
UNASSIGNED: Fluorescent immunohistochemical labeling with polyclonal primary antibodies against serotonin and FMRF-amide and a monoclonal antibody against synapsin performed on series of fixed larval stages of two nemertean species Cephalothrix rufifrons (Archinemertea, Palaeonemertea) and Emplectonema gracile (Monostilifera, Hoplonemertea) were analyzed with confocal laser scanning microscopy.
UNASSIGNED: This contribution gives detailed accounts on the development of the serotonin- and
FMRFamide-immunoreactive subsets of the nervous system in two nemertean species from the first appearance of the respective signals. Additionally, data on synapsin-like immunoreactivity illustrates the general structure of neuropil components. Events common to both investigated species are the appearance of serotonin-like immunoreactive signals before the appearance of FMRF-like immunoreactive signals and the strict progression of the development of the lateral nerve cords from the anteriorly located, ring-shaped brain toward the posterior pole of the larva. Notable differences are (1) the proboscis nervous system that is developing much earlier in investigated larval stages of E. gracile and (2) distinct early, but apparently transient, serotonergic neurons on the frontal and caudal pole of the larva in E. gracile that seem to be absent in C. rufifrons.
UNASSIGNED: According to the results from this investigation and in line with previously published accounts on nervous system development, the hypothetical last common ancestor of Nemertea had a ring-shaped brain arranged around the proboscis opening, from which a pair of ventro-lateral nerve cords develops in anterior to posterior progression. Early frontal and caudal serotonergic neurons that later degenerate or cease to express serotonin are an ancestral character of Nemertea that they share with several other spiralian clades.