Comparative study of serotonin-like immunoreactivity in the branchial basket, digestive tract, and nervous system in tunicates
Comparative study of serotonin-like immunoreactivity in the branchial basket, digestive tract, and nervous system in tunicates
复制标题
DOI：
10.1007/s00435-016-0317-8
复制
发表时间：
2016-09-01
期刊：
影响因子：
1
通讯作者：
Stach, Thomas
中科院分区：
文献类型：
--
作者：
Braun, Katrin;Stach, Thomas
被囊动物是脊索动物三大类群之一，具有高度的多样性，在脊椎动物进化起源的研究中一直扮演着重要的角色，特别是一些大规模的分子系统发育分析支持被囊动物是脊椎动物姐妹类群的假设。被囊动物内部关系的分子系统发育研究是高度矛盾的，被囊动物形态特征的分支分析仍然有限。为了更好地了解脊索动物的进化，我们比较研究了9种不同的被囊动物属于5个不同的高等被囊动物类群：Phlebobranchiata，Aplousobranchiata，Stolidobranchiata，海樽纲，和Aparthumularia使用免疫荧光标记与抗血清素抗体结合共聚焦激光扫描显微镜。我们发现，成年海鞘是可比的，在他们各自的模式的海鞘素样免疫反应细胞（海鞘素-LIR），而不同的海鞘在几个方面。在被囊类动物中，类胡萝卜素样免疫反应细胞的分布模式表明，类胡萝卜素样免疫反应在进化过程中可以作为一个独立的特征。虽然分布模式的callonin-lir细胞同意与经典的分类分组，系统发育的解释仍然是不确定的，因为特设的假设总是必要的解释矛盾的字符分布。基于光镜观察到的形态，我们可以区分三种不同类型的阿托宁-LIR细胞，最有可能的功能独特。这些细胞近似球形，可能参与纤毛跳动和粘液分泌的控制，细长的细胞可能参与摄食的激素调节，以及可能参与运动行为启动的神经元。
As one of the three major chordate taxa, the highly diverse taxon, Tunicata has always played a key role in considerations of evolutionary origins of vertebrates, especially since several larger-scaled molecular phylogenetic analyses support the hypothesis that tunicates are the sister group to vertebrates. Molecular phylogenetic studies of the relationships within Tunicata are highly contradictory, and cladistic analyses of morphological characters for Tunicata remained limited. In order to come to a better understanding of chordate evolution, we comparatively investigated nine different tunicate species belonging to five different higher tunicate taxa: Phlebobranchiata, Aplousobranchiata, Stolidobranchiata, Thaliacea, and Appendicularia using immunofluorescence labeling with antibodies against serotonin in conjunction with confocal laser scanning microscopy. We found that adult ascidians are comparable in regard to their respective patterns of serotonin-like immunoreactive (serotonin-lir) cells, whereas the planktonic tunicates differ in several aspects. The distribution patterns of serotonin-lir cells in tunicates suggest that serotonin-like immunoreactivity can behave as an independent character during evolution. While the distribution pattern of serotonin-lir cells agrees well with classical taxonomic groupings, phylogenetic interpretation remains inconclusive, as ad hoc hypotheses are always necessary to explain contradictory character distribution. Based on light-microscopically observed morphology, we could distinguish three different types of serotonin-lir cells, most probably functionally distinctive. These were approximately spherical serotonin-lir cells, possibly involved in the control of ciliary beating and mucus secretion, elongated serotonin-lir cells potentially involved in hormonal regulation of feeding, and serotonin-lir neurons that might be implicated in the initiation of locomotory behavior.