caudal is required for gnathal and thoracic patterning and for posterior elongation in the intermediate-germband cricket Gryllus bimaculatus
caudal is required for gnathal and thoracic patterning and for posterior elongation in the intermediate-germband cricket Gryllus bimaculatus
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DOI：
10.1016/j.mod.2004.10.001
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发表时间：
2005-02-01
影响因子：
2.6
通讯作者：
Noji, S
中科院分区：
文献类型：
--
作者：
Shinmyo, Y;Mito, T;Noji, S
尽管指导果蝇胚胎的前后模式（长胚带模式）的分子机制已经很好地理解。这些机制是如何从昆虫胚胎发生的祖先模式进化而来的，在很大程度上仍然是未知的。为了深入了解昆虫胚胎发生的进化机制，我们研究了果蝇尾（CAD）在中间胚带蟋蟀双斑蟋蟀的直系同源基因的表达和功能。我们观察到，在早期胚胎中，双斑蟋蟀cad（Gb' cad）转录本水平形成了一个从后（高）到前（低）的梯度，然后Gb' cad在后部生长区表达，直到后部分割完成。通过RNA干扰降低Gb' cad表达水平导致胚胎中缺失颌部、胸部和腹部，仅保留前头部。我们发现，颌节和胸节可能是由Gb' cad通过Gb' hunchback和Gb' Kruppel等gap基因的转录调控而形成的。此外，发现Gb' cad参与后部伸长，作为Wingless/Armadillo信号通路的下游基因。这些发现表明Gb' cad不像果蝇那样发挥功能，表明cad的调节和功能变化发生在昆虫进化过程中。由于Wnt/Cdx途径参与脊椎动物的后部图案化，因此这种机制可能在经历从后部生长区连续分割的动物中保守。(C)2004爱思唯尔爱尔兰有限公司保留所有权利。
Although the molecular mechanisms directing anteroposterior patterning of the Drosophila embryo (long-germband mode) are well understood. how these mechanisms were evolved from an ancestral mode of insect embryogenesis remains largely unknown. In order to gain insight into mechanisms of evolution in insect embryogenesis, we have examined the expression and function of the orthologue of Drosophila caudal (cad) in the intermediate-germband cricket Gryllus bimaculatus. We observed that a posterior (high) to anterior (low) gradient in the levels of Gryllus bimaculatus cad (Gb' cad) transcript was formed in the early-stage embryo, and then Gb' cad was expressed in the posterior growth zone until the posterior segmentation was completed. Reduction of Gb' cad expression level by RNA interference resulted in deletion of the gnathum, thorax, and abdomen in embryos, remaining only anterior head. We found that the gnathal and thoracic segments are formed by Gb' cad probably through the transcriptional regulation of gap genes including Gb' hunchback and Gb' Kruppel. Furthermore, Gb' cad was found to be involved in the posterior elongation, acting as a downstream gene in the Wingless/Armadillo signalling pathways. These findings indicate that Gb' cad does not function as it does in Drosophila, suggesting that regulatory and functional changes of cad occurred during insect evolution. Since Wnt/Cdx pathways are involved in the posterior patterning of vertebrates, such mechanisms may be conserved in animals that undergo sequential segmentation from the posterior growth zone. (C) 2004 Elsevier Ireland Ltd. All rights reserved.