RUI: Using Direct Evidence to Determine the Energetic and Ecological Significance of Dissolved Organic Matter (DOM) for the Bryozoan Bugula Neritina

从最简单的细菌到最复杂的多细胞动物，所有的生物体都需要能量来维持新陈代谢、生长和繁殖。因此，为获得执行这些重要进程所需的能量而发展出各种各样的机制也就不足为奇了。在水生生物中发展起来的一种这样的系统涉及细胞运输和直接从周围介质中利用溶解的有机物(DOM)。该项目的工作将为DOM对海洋无脊椎动物的生态和能量作用提供亟需的直接证据。目前对海洋无脊椎动物利用DOM的研究大多局限于基于对DOM的代谢消耗和根据溶解化合物的吸收速率计算出的DOM的潜在贡献的比较的间接证据。虽然这种方法在确定DOM的理论贡献方面很有用，但它不能直接表征动物能量收支的已实现贡献。需要一种更直接的方法，基于在存在和不存在DOM的情况下动物代谢支出的比较。这项拟议的工作旨在通过一系列的实验室和野外实验，研究DOM在幼虫游泳和变态过程中的有效性如何影响与生态相关的参数，如幼虫游泳持续时间、变态能力、变态后的大小、成虫的生长速度以及繁殖的开始和数量，从而为苔藓虫建立这一关系。此外，将通过放射自显影技术建立DOM并入幼虫组织和变态后早期阶段的直接证据。这些数据将深入了解运输的化合物是如何以及何时被使用的(例如，用于游泳、变态、早期幼体生长)。综上所述，拟议的实验将提供直接证据，证明DOM对无脊椎动物营养生物学的实际贡献，大大加深了我们目前对DOM的生态和能量重要性的理解。

All organisms ranging from the simplest bacterium to the most sophisticated multicellular animal need energy for metabolic maintenance, growth, and reproduction. It is thus not surprising that a wide variety of mechanisms have evolved for acquiring the energy needed to carry out these vital processes. One such system that has developed among aquatic organisms involves cellular transport and utilization of dissolved organic matter (DOM) directly from the surrounding medium. The work from this project will add much needed direct evidence on the ecological and energetic role of DOM for marine invertebrate animals. Most of the current studies examining use of DOM by marine invertebrates are limited to indirect evidence based on comparisons of metabolic expenditure and potential contribution of DOM calculated from uptake rates of dissolved compounds. Although this approach is useful in determining the theoretical contribution of DOM, it does not directly characterize the realized contribution to an animal's energy budget. A more direct approach based on comparisons of metabolic expenditure of animals in the presence versus absence of DOM is needed. The proposed work seeks to establish this for the bryozoan Bugula neritina through a series of laboratory and field experiments examining how the availability of DOM during larval swimming and metamorphosis effects ecological relevant parameters such as, larval swimming duration, metamorphic competence, size after metamorphosis, adult growth rate, and onset and amount of reproduction. In addition, direct evidence for incorporation of DOM into larval tissues and those of early post-metamorphic stages will be established through autoradiographic techniques. These data will provide insight into how and when the transported compounds are being used (e.g., for swimming, metamorphosis, early juvenile growth). Taken together, the proposed experiments will provide direct evidence on the realized contribution of DOM to the nutritional biology of invertebrates, adding significantly to our current understanding of the ecological and energetic importance of DOM.