权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Reconstruction of Hexapod Basal Clades : Embryological Study on Protura

六足动物基底进化枝的重建: Protura 的胚胎学研究

基本信息

批准号：
17370030
负责人：
MACHIDA Ryuichiro
金额：
$ 7.14万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

“Entognatha - Ectognatha System", which is formulated as “Entognatha (=Ellipurata (=Protura + Collembola)+Diplurata (=Diplura))+Ectognatha (=Monocondylia (=Archaeognatha)+Dicondylia (=Zygentoma + Pterygota))", has been widely accepted with little challenge. However, the reality of the taxon Entognatha is suspect because it is supported principally only by entognathy. Recent comparative paleontological, morphological and comparative embryological researches have provided evidence discounting the validity of entognathy as a synapomorphy for the members of this group, and some molecular evolutionary evidence has emerged, suggesting a closer affinity between Protura and Diplura, and rejecting Ellipurata. Furthermore, the internal relationships among Arthropoda still remain furiously debated. This background makes Protura more significant in the reconstruction of relationships of hexapod basal clades than ever. The comparative embryological approach is one of the most promising methods for … More solving such phylogenetic problems, but we have no knowledge on proturan embryology. The aim of the present study is to first clarify the embryonic development of Protura, using Baculentulus densus (Imadate) as materials.Eggs of Baculentulus densus are spherical with a long axis of about 120 μm and with numerous, variously sized and shaped protuberances scattered over their surface. The proturan embryogenesis is characterized by 1) holoblastic cleavage, 2) embryogenesis of long germ band type, 3) simple blastokinesis, 4) neurogenesis accompanied by the formation ventral organs, and 5) formation of a primary dorsal organ, all of which represent the ancestral conditions in hexapod embryogenesis.A noticeable feature of proturan embryogenesis is that the serosa retains the ability to differentiate into the tergum or to participate in the definitive dorsal closure, which in light of the evolutionary transition of the functional specialization between the embryo proper and embryonic membranes among Hexapoda, suggests that Protura may represent a more basal clade in Hexapoda than ever elucidated. Less

“内颚-外颚系统”被表述为“内颚（=椭圆目（=原尾目+弹尾目）+双尾目（=双尾目））+外颚（=单髁目（=古颚目）+双髁目（=接合目+翼目））"，已被广泛接受，几乎没有挑战。然而，Entognatha分类群的真实性是可疑的，因为它主要只由内颌支持。最近的比较古生物学，形态学和比较胚胎学研究提供了证据折扣的有效性entognathy作为一个synapomorphy为这个组的成员，和一些分子进化证据已经出现，提出了更密切的亲和力之间的原尾和双尾类，并拒绝Ellipurata。此外，节肢动物门的内部关系仍然存在激烈的争论。这一背景使得原尾目在重建六足类基底分支关系方面比以往任何时候都更重要。比较胚胎学方法是最有前途的方法之一， ...更多信息解决了这样的系统发育问题，但我们没有关于原尾虫胚胎学的知识。本研究以致密拟杆菌（Baculentulus densus（Imadate））为材料，首次阐明了原尾类的胚胎发育过程。原尾虫胚胎发生的特点是：1）全胚卵裂，2）长胚带型胚胎发生，3）简单的卵裂分裂，4）神经发生伴随腹器官的形成，5）初级背器官的形成，原尾虫胚胎发生的一个显著特征是浆膜保留了分化成背片或背片的能力，参与了最终的背侧闭合，这与六足动物胚胎和胚胎膜之间的功能特化的进化过渡有关，表明原尾虫可能代表了六足动物中比以往阐明的更基础的分支。少