Canonical terminal patterning is an evolutionary novelty
Canonical terminal patterning is an evolutionary novelty
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DOI：
10.1016/j.ydbio.2013.02.010
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发表时间：
2013-05-01
影响因子：
2.7
通讯作者：
Dearden, Peter K.
中科院分区：
文献类型：
--
作者：
Duncan, Elizabeth J.;Benton, Matthew A.;Dearden, Peter K.
果蝇胚胎末端区域的模式化是通过一种精细调控的信号实现的，这种信号在卵巢的卵泡细胞和发育中的胚胎之间传递。然而，这种途径在其他昆虫中缺失或被修饰。在这里，我们通过检查其组成部分的起源和表达来追踪这一途径的演变。该通路的三个核心组成部分：躯干、躯干和类躯干具有不同的进化历史，并逐步组装形成果蝇和拟谷盗的典型末端图案化通路。躯干，躯干和一个与终端模式无关的基因，促胸激素（PITH），显示了一个密切相关的进化历史，每一个全变态昆虫，除了蜜蜂，拥有PITH和躯干基因。躯干在其系统发育分布上更受限制，仅存在于双翅目和赤拟谷盗属中，令人惊讶的是，在螯形的肩胛硬蜱中，提高了躯干和躯干比以前认为的更早进化的可能性。在果蝇中，躯干样限制了胚胎两极的终端图案通路的激活。躯干一样的泛甲壳类动物的血统，但基于典型的终端图案化系统的半变态昆虫豌豆蚜和全变态昆虫蜜蜂的组件的表达，我们发现，典型的终端图案化系统是不活跃的，在这些昆虫。因此，我们提出，躯干类的祖先功能是无关的终端模式，躯干类已成为增选到终端模式的谱系导致鞘翅目和双翅目。我们还表明，这种选择并没有导致这种蛋白质的分子功能的变化。来自豌豆蚜虫、蜜蜂和果蝇的躯干样蛋白，尽管以不同的模式表达，但在功能上是等同的。我们认为，共同选择的躯干样限制活动的躯干和躯干促进了这一途径的进化的最后一步，捕获的转录控制的靶基因，如无尾和huckebein的这一复杂和新颖的图案化途径。(C)2013 Elsevier Inc. All rights reserved.
Patterning of the terminal regions of the Drosophila embryo is achieved by an exquisitely regulated signal that passes between the follicle cells of the ovary, and the developing embryo. This pathway, however, is missing or modified in other insects. Here we trace the evolution of this pathway by examining the origins and expression of its components. The three core components of this pathway: trunk, torso and torso-like have different evolutionary histories and have been assembled step-wise to form the canonical terminal patterning pathway of Drosophila and Tribolium. Trunk, torso and a gene unrelated to terminal patterning, prothoraciotrophic hormone (PITH), show an intimately linked evolutionary history, with every holometabolous insect, except the honeybee, possessing both PITH and torso genes. Trunk is more restricted in its phylogenetic distribution, present only in the Diptera and Tribolium and, surprisingly, in the chelicerate Ixodes scapularis, raising the possibility that trunk and torso evolved earlier than previously thought. In Drosophila torso-like restricts the activation of the terminal patterning pathway to the poles of the embryo. Torso-like evolved in the pan-crustacean lineage, but based on expression of components of the canonical terminal patterning system in the hemimetabolous insect Acyrthosiphon pisum and the holometabolous insect Apis mellifera, we find that the canonical terminal-patterning system is not active in these insects. We therefore propose that the ancestral function of torso-like is unrelated to terminal patterning and that torso-like has become co-opted into terminal patterning in the lineage leading to Coleoptera and Diptera. We also show that this co-option has not resulted in changes to the molecular function of this protein. Torso-like from the pea aphid, honeybee and Drosophila, despite being expressed in different patterns, are functionally equivalent. We propose that co-option of torso-like into restricting the activity of trunk and torso facilitated the final step in the evolution of this pathway; the capture of transcriptional control of target genes such as tailless and huckebein by this complex and novel patterning pathway. (C) 2013 Elsevier Inc. All rights reserved.