Gene up-regulation in response to predator kairomones in the water flea, Daphnia pulex.
Gene up-regulation in response to predator kairomones in the water flea, Daphnia pulex.
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DOI：
10.1186/1471-213x-10-45
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发表时间：
2010-04-30
影响因子：
--
通讯作者：
Miura T
中科院分区：
文献类型：
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作者：
Miyakawa H;Imai M;Sugimoto N;Ishikawa Y;Ishikawa A;Ishigaki H;Okada Y;Miyazaki S;Koshikawa S;Cornette R;Miura T
许多情况下，捕食者诱导的多表型，其中交替表型是在响应外部刺激，已被报道在水生类群的日期。水蚤属（鳃足目，枝角类）提供了一个模式实验系统的发育机制和进化过程的研究与捕食诱导的多型性。In D.蚤状幼体对Chaoborus幼虫释放的利它素反应形成颈齿。以往的研究表明，D.蚤类一般可分为胚胎期和胚后发育期。因此，我们研究了哪些基因在胚胎和一龄幼虫阶段表现出不同的表达水平，在存在或不存在的捕食利它素。采用候选基因的方法，并确定差异表达的基因显示，形态发生因子，Hox 3，extradenticle和蜗牛，上调利它素在胚后阶段，可能是负责防御形态形成。此外，保幼激素途径基因JHAMT和Met以及胰岛素信号途径基因InR和IRS-1在一龄阶段上调。众所周知，这些激素途径参与许多昆虫物种形态发生后的生理调节。在胚胎阶段，当形态型确定，差异显示鉴定的新基因之一是上调，这表明该基因可能与形态型决定。在防御形态形成的背景下，上调基因的生物学功能进行了讨论。这表明，利它素信号的接收后，所确定的基因参与了一系列的防御表型的改变和防御表型的生产。
Numerous cases of predator-induced polyphenisms, in which alternate phenotypes are produced in response to extrinsic stimuli, have been reported in aquatic taxa to date. The genus Daphnia (Branchiopoda, Cladocera) provides a model experimental system for the study of the developmental mechanisms and evolutionary processes associated with predator-induced polyphenisms. In D. pulex, juveniles form neckteeth in response to predatory kairomones released by Chaoborus larvae (Insecta, Diptera). Previous studies suggest that the timing of the sensitivity to kairomones in D. pulex can generally be divided into the embryonic and postembryonic developmental periods. We therefore examined which of the genes in the embryonic and first-instar juvenile stages exhibit different expression levels in the presence or absence of predator kairomones. Employing a candidate gene approach and identifying differentially-expressed genes revealed that the morphogenetic factors, Hox3, extradenticle and escargot, were up-regulated by kairomones in the postembryonic stage and may potentially be responsible for defense morph formation. In addition, the juvenile hormone pathway genes, JHAMT and Met, and the insulin signaling pathway genes, InR and IRS-1, were up-regulated in the first-instar stage. It is well known that these hormonal pathways are involved in physiological regulation following morphogenesis in many insect species. During the embryonic stage when morphotypes were determined, one of the novel genes identified by differential display was up-regulated, suggesting that this gene may be related to morphotype determination. Biological functions of the up-regulated genes are discussed in the context of defense morph formation. It is suggested that, following the reception of kairomone signals, the identified genes are involved in a series of defensive phenotypic alterations and the production of a defensive phenotype.