Expression and evolution of chemoreceptor genes in the model organism Daphnia

描述(申请人提供)：化学感受，被认为是至关重要的所有动物，包括嗅觉，信息素检测，荷尔蒙信号和各种其他必要的过程。Siimilar对化学线索的反应在广泛的动物系统发育中是相同的，这意味着对于检测和识别气味的问题有一个古老的解决方案，并且在一个系统中学到的东西可以应用到其他系统中。最近对水蚤的基因组进行了测序，并鉴定了一组58个味觉受体基因(GR)。这些GR中有49个是水蚤专属分支的成员(与昆虫相比)，有2-3个GR类似于已知的节肢动物糖受体。这组相对较小的受体基因可能是大型水蚤大部分行为的基础。特别是，几个水蚤GR似乎具有性别偏见的表达，这在有机体中并不少见，并且是调节交配行为的候选。正如D.Pulex无性系可以表现出两种周期性孤雌生殖(即。有性繁殖)和强制无性繁殖，我们可以在性选择的背景下研究GR家族的进化。这项研究的长期目标是利用生物信息学、基因进化理论、分子技术和最新测序的水蚤基因组，为模型甲壳动物中化学接收的分子和进化理解奠定基础。如何在水生系统中检测到化学线索还不是很清楚，但对对抗许多已知的具有水生幼虫阶段的害虫来说是必要的，例如蚊子幼虫。这样的认识可能有助于我们开发干扰它们生存和发展的方法，从而减少登革热和黄热病等疾病的传播。此外，我们水生生态系统的健康在很大程度上依赖于其居民，包括浮游动物，检测和食用藻类和细菌的能力。当我们通过毒素或其他人为化学物质干扰它们检测关键化学线索的能力时，我们实际上可能导致有毒的藻类水华，增加携带疾病的细菌(如霍乱弧菌)的发生，并破坏平衡的生态系统。

DESCRIPTION (provided by applicant): Chemoreception, regarded as vitally important for all animals, encompasses olfaction, pheromone detection, hormonal signaling and various other essential processes. Siimilar responses to chemical cues are shared in a phylogenetically broad array of animals, implying that there is an ancient solution to the problem of detecting and discriminating odorants, and what is learned in one system can be applied to others. The Daphnia genome has recently been sequenced and a set of 58 gustatory receptor genes (Grs) has been identified. 49 of these Grs are members of a Daphnia-specific clade (when compared to insects), with 2-3 Grs resembling known arthropod sugar receptors. This relatively small set of receptor genes is presumably the basis for much of Daphnia's behavioral repertoire. In particular, several Daphnia Grs appear to have sex-biased expression, not uncommon among organisms, and are candidates to mediate mating behavior. As D. pulex clones can exhibit both cyclical parthenogenesis (ie. sexual reproduction) and obligate asexuality, we can investigate the evolution of the Gr family in the context of sexual selection. The long term aim of this research is to establish a foundation for the molecular and evolutionary understanding of Chemoreception in a model crustacean, using bioinformatics, gene evolution theory, molecular techniques, and the newly sequenced genome of Daphnia. How chemical cues are detected in an aquatic system is not well understood, yet necessary to combat many known pests with aquatic larval stages, such as mosquito larvae. Such understanding may help us develop ways of interfering with their survival and development, thus decreasing the spread of diseases such as dengue and yellow fever. In addition, the health of our aquatic ecosystems relies heavily on the ability of its inhabitants, including zooplankton, to detect and eat algae and bacteria. When we interfere with their ability to detect critical chemical cues, through toxins or other anthropogenic chemicals, we in fact can cause toxic algal blooms, increase the occurrence of disease-carrying bacteria (such as Vibrio cholera), and destroy balanced ecosystems.