Expression and evolution of chemoreceptor genes in the model organism Daphnia

描述（由申请人提供）：化学感受，被认为对所有动物都至关重要，包括嗅觉，信息素检测，激素信号传导和各种其他基本过程。从系统发育的角度来看，许多动物对化学线索都有类似的反应，这意味着探测和区分气味的问题有一个古老的解决方案，在一个系统中学到的东西可以应用于其他系统。最近对水蚤基因组进行了测序，并确定了58个味觉受体基因（Grs）。其中49个Grs是水蚤特有分支的成员（与昆虫相比），其中2-3个Grs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水蚤大部分行为的基础。特别是，一些水蚤Grs似乎具有性别偏见的表达，在生物体中并不罕见，并且是调解交配行为的候选者。由于雌雄同体的克隆既可以表现为周期性孤雌生殖（即雌雄同体）。有性生殖)和强制性无性行为，我们可以在性选择的背景下研究Gr家族的进化。本研究的长期目标是利用生物信息学、基因进化理论、分子技术和新测序的水蚤基因组，为模型甲壳类动物化学接受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尚不清楚，但这对于对抗许多具有水生幼虫阶段的已知害虫（如蚊子幼虫）是必要的。这种了解可能有助于我们找到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，我们的水生生态系统的健康在很大程度上依赖于它的居民，包括浮游动物，探测和吃掉藻类和细菌的能力。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，我们实际上会导致有毒藻华，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.