关键词: Archenteron Blastopore Blimp Mox Onychophora T-box transcription factor Twist mef2

来  源:   DOI:10.1186/s12983-024-00521-7   PDF(Pubmed)

Abstract:
BACKGROUND: Early during onychophoran development and prior to the formation of the germ band, a posterior tissue thickening forms the posterior pit. Anterior to this thickening forms a groove, the embryonic slit, that marks the anterior-posterior orientation of the developing embryo. This slit is by some authors considered the blastopore, and thus the origin of the endoderm, while others argue that the posterior pit represents the blastopore. This controversy is of evolutionary significance because if the slit represents the blastopore, then this would support the amphistomy hypothesis that suggests that a slit-like blastopore in the bilaterian ancestor evolved into protostomy and deuterostomy.
RESULTS: In this paper, we summarize our current knowledge about endoderm and mesoderm development in onychophorans and provide additional data on early endoderm- and mesoderm-determining marker genes such as Blimp, Mox, and the T-box genes.
CONCLUSIONS: We come to the conclusion that the endoderm of onychophorans forms prior to the development of the embryonic slit, and thus that the slit is not the primary origin of the endoderm. It is thus unlikely that the embryonic slit represents the blastopore. We suggest instead that the posterior pit indeed represents the lips of the blastopore, and that the embryonic slit (and surrounding tissue) represents a morphologically superficial archenteron-like structure. We conclude further that both endoderm and mesoderm development are under control of conserved gene regulatory networks, and that many of the features found in arthropods including the model Drosophila melanogaster are likely derived.
摘要:
背景:在牙列发育早期和胚带形成之前,后组织增厚形成后坑。在这种增厚的前面形成了一个凹槽,胚胎狭缝,这标志着发育中的胚胎的前后方向。这个狭缝被一些作者认为是胚孔,因此内胚层的起源,而其他人则认为后坑代表了胚孔。这场争论具有进化意义,因为如果狭缝代表胚孔,那么这将支持两栖式假说,该假说表明,双边祖先中的狭缝状胚孔进化为原造孔和氘代造口术。
结果:在本文中,我们总结了我们目前关于内胚层和中胚层发育的知识,并提供了早期内胚层和中胚层决定标记基因的额外数据,如飞艇,Mox,还有T-box基因.
结论:我们得出的结论是,在胚胎狭缝发育之前,牙列的内胚层形成,因此,狭缝不是内胚层的主要起源。因此,胚胎狭缝不太可能代表胚孔。相反,我们建议后坑确实代表了胚孔的嘴唇,胚胎狭缝(和周围组织)代表了一个形态上的浅表初肠样结构。我们进一步得出结论,内胚层和中胚层发育都受到保守基因调控网络的控制。在节肢动物中发现的许多特征,包括模型果蝇。
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