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首页> 外文期刊>Journal of Cellular Physiology >The deuterostome ancestor.
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The deuterostome ancestor.

机译：后口动物的祖先。

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摘要

Hemichordates, the phylum of bilateral animals closest to chordates, can illuminate the evolutionary origins of various chordate traits to determine whether these were already present in a shared ancestor (the deuterostome ancestor) or were evolved within the chordate line. We find that an anteroposterior map of gene expression domains, representing 42 genes of neural patterning, is closely similar in hemichordates and chordates, though it is restricted to the neural ectoderm in chordates whereas in hemichordates, which have a diffuse nervous system, it encircles the whole body. This map allows an accurate alignment of the anterioposterior axes of members of the two groups. We propose that this map dates back at least to the deuterostome ancestor. The map of dorsoventral expression domains, organized along a Bmp-Chordin developmental axis, is also similar in the two groups in terms of many gene expression domains and for the placement of the gill slits, heart, and post-anal tail. The two groups, however, differ in two major respects along this axis. The nervous system and epidermis are not segregated into distinct territories in hemichordates, as they are in chordates, and furthermore, the mouth is on the Chordin side in hemichordates but the Bmp side in chordates. The dorsoventral dimension has undergone extensive modification in the chordate line, including centralization of the nervous system, segregation of epidermis, derivation of the notochord, perhaps from the gut midline, and relocation of the mouth. Based on the shared domain maps, speculations can be made for the remodeling of the body axis in the chordate line.
机译：Hemichordates,两国动物门接近脊索动物,可以照亮各种脊索动物的进化起源特征确定这些是否已经存在在一个共同的祖先(后口动物的祖先)在脊索动物行或进化。一个前后的基因表达的地图域,代表42基因的神经模式,在hemichordates密切相似和脊索动物,尽管它是限制的在脊索动物而在神经外胚层hemichordates,弥漫的紧张系统,它环绕整个身体。允许精确的校准anterioposterior轴的两个成员组。至少后口动物的祖先。背腹侧的表达领域,组织Bmp-Chordin发展轴,也是类似的两组的许多基因表达域的位置鳃缝、心脏和post-anal尾巴。然而,组织在两个主要方面有所不同这个轴。不隔离成不同的领土hemichordates,它们在脊索动物,此外,口腔Chordin一侧hemichordates但Bmp在脊索动物。背腹侧的维度经历了广泛的在脊索动物行修改,包括神经系统的集中化,隔离表皮,脊索的推导,也许从肠道中线,搬迁的的嘴。推测可以改造的脊索动物的身体轴。

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