Wiring a periscope--ocelli, retinula axons, visual neuropils and the ancestrality of sea spiders.
Wiring a periscope--ocelli, retinula axons, visual neuropils and the ancestrality of sea spiders.
复制标题
DOI：
10.1371/journal.pone.0030474
复制
发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Melzer RR
中科院分区：
文献类型：
--
作者：
Lehmann T;Hess M;Melzer RR
Pycnogonida或海蜘蛛是神秘的，八条腿的节肢动物，在“潜望镜”或眼结节中有四个中单眼。在较早的重建真螯足类的尝试中，它们被称为节肢动物（Arthropoda incertae sedis），但最近的分子树将它们列为所有其他真螯足类甚至所有真节肢动物的姐妹群。因此，密子虫是现存最古老的节肢动物之一，并在了解节肢动物进化方面占有关键地位。这刺激了研究新的一套字符的分支分析，如chelifores和hox基因的表达模式。相比之下，对视觉系统结构的了解是粗略的。一些研究分析了单眼和不常见的“假倒置”小网膜细胞。此外，对视觉神经柱的分析仍处于汉斯特罗姆早期综合性著作的阶段。因此，我们已经使用各种技术来分析视觉纤维通路和它们在几个物种的相互关联的neuropil的结构。我们发现，pycnogonid ocelli的神经支配的第一和第二视觉neuropils在附近的一个不成对的中线neuropiles，即可能的弓状体，在某种程度上非常相似的祖先真节肢动物，如Euperipatoides rowelli（Onychophora）和Limulus polyphemus（剑水蚤）。这支持了密锥虫科的祖先，并揭示了密锥虫科的地面平面图中的眼睛可能“看起来”像什么。最近有人提出，节肢动物的眼睛起源于简单的单眼，类似于幼虫的眼睛。因此，在更复杂的节肢动物眼睛的财富中，Pycnogonid眼睛可能是早期的分支之一。
The Pycnogonida or sea spiders are cryptic, eight-legged arthropods with four median ocelli in a ‘periscope’ or eye tubercle. In older attempts at reconstructing phylogeny they were Arthropoda incertae sedis, but recent molecular trees placed them as the sister group either to all other euchelicerates or even to all euarthropods. Thus, pycnogonids are among the oldest extant arthropods and hold a key position for the understanding of arthropod evolution. This has stimulated studies of new sets of characters conductive to cladistic analyses, e.g. of the chelifores and of the hox gene expression pattern. In contrast knowledge of the architecture of the visual system is cursory. A few studies have analysed the ocelli and the uncommon “pseudoinverted” retinula cells. Moreover, analyses of visual neuropils are still at the stage of Hanström's early comprehensive works. We have therefore used various techniques to analyse the visual fibre pathways and the structure of their interrelated neuropils in several species. We found that pycnogonid ocelli are innervated to first and second visual neuropils in close vicinity to an unpaired midline neuropil, i.e. possibly the arcuate body, in a way very similar to ancestral euarthropods like Euperipatoides rowelli (Onychophora) and Limulus polyphemus (Xiphosura). This supports the ancestrality of pycnogonids and sheds light on what eyes in the pycnogonid ground plan might have ‘looked’ like. Recently it was suggested that arthropod eyes originated from simple ocelli similar to larval eyes. Hence, pycnogonid eyes would be one of the early offshoots among the wealth of more sophisticated arthropod eyes.
登录
查看更多内容
影响因子：
1.5
作者：
Melzer, Roland R.
通讯作者：
Melzer, Roland R.
影响因子：
--
作者：
Melzer, RR;Diersch, R;Smola, U
通讯作者：
Smola, U
影响因子：
--
作者：
RICHARDSON, KC;JARETT, L;FINKE, EH
通讯作者：
FINKE, EH
影响因子：
2.5
作者：
CHAMBERLAIN, SC;BARLOW, RB
通讯作者：
BARLOW, RB
影响因子：
2.9
作者：
Brenneis, Georg;Ungerer, Petra;Scholtz, Gerhard
通讯作者：
Scholtz, Gerhard