Linking Bioturbation and Sensory Biology: Chemoreception Mechanisms in Deposit-Feeding Polychaetes

软沉积物底栖生境在海洋环境中普遍存在，其典型特征是大型底栖动物群落，包括大量以沉积物为食的无脊椎动物，如多毛类、双壳类、腹足类、甲壳类、海参类和半索动物。通过它们的进食，部分受化学感受的调节，这些生物对其栖息地的生态学，生物学，地质学和化学有着深远的影响。然而，关于存款馈线化学感受的生理学和分子生物学知之甚少。 本研究对存款摄食的多毛类海鞘化学感受的感觉协调机制进行了全面的研究。它直接解决了这种信息的缺乏，因此将对目前了解多毛类动物和其他海洋无脊椎动物的化学感受产生重大影响。在三个目标的第一个，超微结构和神经支配的spionid多毛类动物触须推定的感觉结构将使用电子和共聚焦显微镜。第二，将通过行为学分析和活性依赖细胞标记研究来测试触须感觉细胞和项器官的化学感受能力。行为测定将识别引起显著摄食反应的化学线索，并建立它们的阈值敏感性。补充的免疫细胞化学实验将确定（1）引起行为反应的化学物质是否激活目标1中描述的感觉细胞;（2）感觉细胞的敏感性（即，刺激阈值）;以及（3）响应特定化学线索的细胞的分布。 第三，功能性生化方法将被用来表征和分离与外周感觉细胞和颈部器官相关的候选化学感受器蛋白。这项研究的几项成果具有特别重要的意义。首先，细胞标记的方法将进一步完善用于小型无脊椎动物，并将提供一个强大的工具，为未来的研究协调栖息地选择的许多物种的海洋无脊椎动物幼虫的神经机制。其次，序列信息和纯化的受体将为mRNA和抗体探针的开发奠定基础，这些探针可用于检查基因表达并详细说明多毛类动物和其他海洋无脊椎动物中的化学感觉转导途径。这些信息对研究无脊椎动物门之间的进化关系和感觉结构的进化感兴趣的研究人员将是有用的。除了其科学相关性，该项目为研究生和本科生培训提供了重要的机会。三名K-12教育工作者或高中生也将通过缅因州教师和学生研究实习计划参加。他们的参与不仅增加了这个超额订阅计划的能力，而且加强了当地K-12社区和缅因州大学之间的联系。将建立因特网活动和资源，重点是海洋环境的感官知觉和生态。这些材料将把研究工作扩大到更多的因特网用户，并有助于将海洋科学实例纳入通常只从陆地和人类角度探讨的专题。

Soft-sediment benthic habitats are ubiquitous in the marine environment and typicallyfeature macrofaunal assemblages that include large numbers of deposit-feeding invertebratessuch as polychaetes, bivalves, gastropods, crustaceans, holothurians, and hemichordates. Viatheir feeding, modulated in part by chemoreception, these organisms have profound effects onthe ecology, biology, geology, and chemistry of their habitats. Very little is known, however,concerning the physiology and molecular biology of chemoreception in deposit feeders. This research is a comprehensive investigation of the sensory mechanisms coordinatingchemoreception in deposit feeding spionid polychaetes. It directly addresses this lack ofinformation and will therefore have a significant impact on the current understanding ofchemoreception in polychaetes and other marine invertebrates. In the first of three objectives, the ultrastructure and innervation of putative sensory structures on spionid polychaete palps will be described using electron and confocal microscopy. Second, the chemoreceptive capacity of palp sensory cells and nuchal organs will be tested withbehavioral assays and activity-dependent cell labeling studies. The behavioral assays will identify chemical cues that elicit significant feeding responses and establish their threshold sensitivities. Complementary immunocytochemistry experiments will determine (1) if the chemicals that elicit behavioral responses activate the sensory cells described in objective 1; (2) the sensitivity of the sensory cells (i.e., stimulation thresholds); and (3) the distribution of cells responding to a particular chemical cue. Third, a functional biochemical approach will be used to characterize and isolate candidate chemoreceptor proteins associated with the peripheral sensory cells and nuchal organs. Several outcomes of the research are of particular significance. First, the cell-labeling method will be further refined for use with small invertebrates, and will provide a powerful tool for future studies of the neural mechanisms coordinating habitat selection by many species of marine invertebrate larvae. Second, the sequence information and purified receptor will set the stage for development of mRNA and antibody probes that can be used to examine gene expression and detail the chemosensory transduction pathways in polychaetes and other marine invertebrates. Such information will be useful to researchers interested in the evolutionary relationships among invertebrate phyla and the in evolution of sensory structures. In addition to its scientific relevance, the project provides significant opportunities for graduate and undergraduate student training. Three K-12 educators or high school students will also participate through the Maine Research Internships for Teachers and Students program. Their participation not only increases the capacity of this over subscribed program, but also strengthens the links between the local K-12 community and the University of Maine. Internet activities and resources will be created that focus on sensory perception and ecology in the marine environment. These materials will extend the research to an even larger Internet audience and facilitate the incorporation of ocean science examples into topics typically approached only from a terrestrial and human perspective.