Origin of Animal diversity considered from the early development of chaetognaths

从毛颌类的早期发育看动物多样性的起源

基本信息

批准号：
11640695
负责人：
GOTO Taichiro
金额：
$ 1.15万
依托单位：
Mie University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640695/
关键词：
chaetognath body axes developmental fate tetrahedral four-cell stage spiralians germ plasm カエデイソヤムシ 8細胞期胚らせん卵割

项目摘要

To elucidate developmental fates, single blastomeres of the four-celled and eight-celled embryos of Paraspadella gotoi were injected with a lineage-tracing dye. The distribution of the labels was observed in the hatchlings. The four-celled embryo consists of the animal and vegetal cross-furrow cells in a tetrahedral arrangement and one of the vegetal cross-furrow cells typically contains the germ plasm. When single cells were injected at the four-cell stage, four labeling patterns were observed (D, V, L and R). Injection at the eight-cell stage revealed eight labeling patterns which represent subsets of the four patterns observed in the hatchling injected at four-cell stage. The V pattern is probably generated from the blastomere containing the germ plasm. We found that the positions of the blastomeres at the four-cell stage correspond to the future body axes which is similar to classic spiralians and modified spiralians such as crustaceans. Furthermore, we confirmed that second cleavage occurs in a leiotropic fashion which is seen in the second cleavage of the classic spiralians. Labeled regions at the eight-cell stage were also examined at the gastrula and the hatchling of the same embryos. Most of body muscles were generated from the wall of the archenteron. This result supports the classical idea on the mesoderm formation of chaetognaths. The third cleavage divides the embryo into animal and vegetal halves. As gastrulation occurs from the vegetal region, the animal and vegetal cells produce the anterior and posterior regions of the body, respectively. The arrangement of the blastomeres corresponds to the body axis and the presumptive areas of the germ layers arrange along the animal-vegetal axis in chaetognaths. These are common characteristics among the triploblastica.

为了阐明发育命运，对 Paraspadella Gotoi 的四细胞和八细胞胚胎的单个卵裂球注射了谱系追踪染料。在孵化的幼体中观察到标签的分布。四细胞胚胎由呈四面体排列的动物和植物交叉沟细胞组成，其中一个植物交叉沟细胞通常含有种质。当在四细胞阶段注射单细胞时，观察到四种标记模式（D、V、L 和 R）。八细胞阶段的注射揭示了八种标记模式，它们代表了在四细胞阶段注射的孵化幼体中观察到的四种模式的子集。 V型可能是由含有种质的卵裂球产生的。我们发现四细胞阶段卵裂球的位置对应于未来的身体轴，这与经典螺旋动物和改良螺旋动物（例如甲壳类动物）相似。此外，我们证实第二次分裂以顺向性方式发生，这在经典螺旋虫的第二次分裂中可见。还在原肠胚和同一胚胎的孵化体中检查了八细胞阶段的标记区域。身体的大部分肌肉都是由弓肠壁产生的。这一结果支持了毛颌类中胚层形成的经典观点。第三次卵裂将胚胎分为动物和植物两半。当原肠胚形成从植物区域发生时，动物和植物细胞分别产生身体的前部和后部区域。卵裂球的排列对应于毛颌动物的身体轴，而胚层的假定区域沿着动植物轴排列。这些是三叶母细胞的共同特征。