Effect of Juvenoids on Predator-Induced Polyphenism in the Water Flea, Daphnia pulex
Effect of Juvenoids on Predator-Induced Polyphenism in the Water Flea, Daphnia pulex
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DOI：
10.1002/jez.1807
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发表时间：
2013-10-01
影响因子：
2.8
通讯作者：
Miura, Toru
中科院分区：
文献类型：
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作者：
Miyakawa, Hitoshi;Gotoh, Hiroki;Miura, Toru
摘要蚤状蚤幼蚤头部会形成“颈齿”，这是一种防御性结构，以回应Chaoborus幼蚤释放的利它素。这一现象为研究捕食者诱导的多型性的发育机制和进化过程提供了一个模型实验系统。虽然人们认为利它素信号被感知并转化为生理信号，导致形态变化，但对这一过程的内分泌和生理机制知之甚少。保幼激素和相关化学物质，即保幼激素，是负责昆虫各种生理事件的关键激素，包括多型现象。在某些甲壳类动物中，已知法尼酸甲酯（MF）可作为保幼激素。为了研究保幼激素在防御形态形成中的功能，我们在发育阶段用MF以及JHIII（保幼激素III，昆虫保幼激素）和苯氧威（合成保幼激素类似物）处理水蚤。引人注目的是，在第一龄的青少年，所有检查juvenoids刺激的形成颈齿只有在利它素的存在下，而不是由自己。这种juvenoid效应对颈齿形成的影响可能是由于JH通路的干扰。Juvenoid治疗减少尾刺长度，而捕食性利它素是已知的拉长尾刺。这些结果表明，其他生理因素是负责尾刺的伸长。J. Exp. Zool.319A：440-450，2013. (c)2013 Wiley Periodicals，Inc.
ABSTRACTIn Daphnia pulex, juveniles form "neckteeth" a defensive structure on their heads, in response to predatory kairomones released by Chaoborus larvae. This phenomenon provides a model experimental system for the study of developmental mechanisms and evolutionary processes in predator-induced polyphenisms. Although it is thought that kairomone signals are sensed and converted into physiological signals resulting in morphological changes, little is known about the endocrine and physiological mechanisms of this process. Juvenile hormones and related chemicals, that is, juvenoids, are key hormones responsible for various physiological events in insects, including polyphenisms. In some crustaceans, methyl farnesoate (MF) is known to act as a juvenoid. In order to investigate the functions of juvenoids in defense morph formation, we treated daphnids with MF as well as JHIII (Juvenile Hormone III, an insect juvenoid) and fenoxycarb (a synthetic juvenile hormone analog) during their developmental stages. Strikingly, in the first-instar juveniles, all examined juvenoids stimulated the formation of neckteeth only in the presence of kairomones, not by themselves. This juvenoid effect on the neckteeth formation might be due to disturbance of the JH pathway. Juvenoid treatments reduced tail-spine length, whereas predatory kairomones are known to elongate tail spine. These results suggest that other physiological factors are responsible for the tail-spine elongation. J. Exp. Zool. 319A: 440-450, 2013. (c) 2013 Wiley Periodicals, Inc.