Localized maternal orthodenticle patterns anterior and posterior in the long germ wasp Nasonia
Localized maternal orthodenticle patterns anterior and posterior in the long germ wasp Nasonia
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DOI：
10.1038/nature04445
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发表时间：
2006-02-09
期刊：
影响因子：
64.8
通讯作者：
Desplan, C
中科院分区：
文献类型：
--
作者：
Lynch, JA;Brent, AE;Desplan, C
长期以来，果蝇的Bicoid （Bcd）梯度一直是形态因子在胚胎极性建立过程中作用的模型(1)。然而，现在很清楚，bcd是高等双翅目昆虫的独特特征（2,3）。一个进化上古老的基因，正畸（otd），在甲虫Tribolium中起着类似于生物的作用(4)。与Bcd梯度不同，Bcd梯度是由前定位信使RNA的蛋白质扩散引起的（1,5），Tribolium Otd梯度是由后定位因子对Otd mRNA的翻译抑制形成的。这些梯度形成的差异与胚胎模式的差异有关。果蝇采用长胚芽胚胎发生，胚胎来自整个前-后轴，所有节段在胚层阶段形成图案，在原肠胚形成之前。相比之下，Tribolium经历了短暂的胚胚发生：胚胎由卵后部的细胞产生，只有前段在胚层阶段形成图案，其余部分在原肠胚形成后从生长区产生。本文描述了otd在蜂长胚中所起的作用。我们发现，母源mRNA定位于胚胎的两极，并导致蛋白质梯度模式的两极。因此，局部的鼻虫有两个主要的作用，允许长胚芽发育。它以一种类似于Bcd梯度的方式激活卵前部的前靶，并且它是后间隙基因在原肠胚形成前表达所必需的。
The Bicoid (Bcd) gradient in Drosophila has long been a model for the action of a morphogen in establishing embryonic polarity(1). However, it is now clear that bcd is a unique feature of higher Diptera(2,3). An evolutionarily ancient gene, orthodenticle (otd), has a bcd-like role in the beetle Tribolium(4). Unlike the Bcd gradient, which arises by diffusion of protein from an anteriorly localized messenger RNA(1,5), the Tribolium Otd gradient forms by translational repression of otd mRNA by a posteriorly localized factor. These differences in gradient formation are correlated with differences in modes of embryonic patterning. Drosophila uses long germ embryogenesis, where the embryo derives from the entire anterior - posterior axis, and all segments are patterned at the blastoderm stage, before gastrulation. In contrast, Tribolium undergoes short germ embryogenesis: the embryo arises from cells in the posterior of the egg, and only anterior segments are patterned at the blastoderm stage, with the remaining segments arising after gastrulation from a growth zone. Here we describe the role of otd in the long germband embryo of the wasp Nasonia vitripennis. We show that Nasonia otd maternal mRNA is localized at both poles of the embryo, and resulting protein gradients pattern both poles. Thus, localized Nasonia otd has two major roles that allow long germ development. It activates anterior targets at the anterior of the egg in a manner reminiscent of the Bcd gradient, and it is required for pre-gastrulation expression of posterior gap genes.