EAGER: Identification of Diagnostic Markers of Diapause Preparation in the Copepod Calanus Finmarchicus

Calanidae科的海洋桡足类动物，如Calanus finmarchicus，是地球上数量最多的动物之一，它们通过将浮游植物的能量转移到更高营养层，在海洋食物网中起着关键作用。这些桡足类动物的生活史已经得到了很好的研究，但是关于一个叫做滞育的重要休眠时期的调节仍然存在一些基本问题。在幼体发育的最后一个阶段，C. finmarchicus要么进行终端蜕皮（即蜕皮为成虫），要么垂直迁移到深处并开始滞育。这种发育途径的差异对金marchicus种群动态具有重要意义，但很难进行实验研究，因为金marchicus像所有其他Calanidae家族的桡足类动物一样，在实验室中不可靠地进入滞育。此外，大多数温带类鱿鱼桡足类种群在一年内有多代繁殖，其繁殖和发育时间的变化导致年龄结构的显著异质性。因此，对这些异质种群进行实地取样，得出的结果是混合的桡足类动物，有的正在准备滞育，有的正在准备终末蜕皮，或者还没有为这两种命运做好准备。研究这些种群的滞育准备是非常困难的。为了能够直接研究影响滞育起始的因素，我们需要在异质种群中可靠地预测个体桡足类命运（进入滞育或继续成熟到成年）的标记。幸运的是，在挪威海岸附近的峡湾，晚春期间的C. finmarchicus种群是非常同步的，由幼桡足类组成，它们都注定要经历滞育。该项目将使用高通量454焦磷酸测序技术来鉴定在这些桡足类动物进入滞育过程中表达变化的基因。在与挪威研究人员的合作下，研究人员还将在一个独特的连续培养环境中饲养桡足类动物，并进行额外的转录分析，以确定桡足类动物准备换毛时表达变化的基因。比较野生种群和养殖种群的基因表达模式将使主要研究人员能够开发出强大的滞育准备标记，可用于研究更多异质性温带种群的滞育起始。智力优势：尽管经过了几十年的研究，我们仍然对引发滞育的过程一无所知，因此甚至不能为一个世代的鱿鱼类桡足类动物建立种群动态模型。在我们对海洋生态系统的理解中，这是一个长期存在的、众所周知的差距，在这个研究问题上的进展可能是变革性的。通过开发分子标记来识别滞育的准备，研究人员寻求实现新的生理和生态研究，最终确定控制进入滞育的内在和外在因素。他们的方法是基于一个假设，即野生种群的基因表达模式足够一致，可以作为滞育准备的可靠指标。这一基本假设还有待检验；因此，这项工作是有风险的，但有潜在的高回报，适合于EAGER项目。更广泛的影响：该项目将使美国和挪威研究人员之间的高度互补的新合作以及本科生和研究生的培训成为可能。调查结果将通过社交媒体传播给广大受众。滞育准备生物标志物的开发和应用最终将使建模者能够参数化滞育，并提高生态系统模型预测人类对海洋和气候变化影响的能力

Oceanic copepods in the family Calanidae, such as Calanus finmarchicus, are among the most abundant animals on the planet, and they serve a key role in marine food webs by transferring energy from phytoplankton to higher trophic levels. The life history of these copepods has been well-studied, but fundamental questions remain about the regulation of an important period of dormancy called diapause. In the last juvenile stage of development, C. finmarchicus either proceed to the terminal molt (i.e., molt into adults) or vertically migrate to depth and initiate diapause. This divergence in developmental pathways has critical implications for C. finmarchicus population dynamics, but is difficult to study experimentally because C. finmarchicus, like all other copepods in the family Calanidae, do not reliably enter diapause in the laboratory. In addition, most temperate populations of calanoid copepods have multiple generations in a single year with variability in the timing of reproduction and development that causes significant heterogeneity in age structure. Thus, field sampling of these heterogeneous populations yields a mixture of copepods that are preparing for diapause, are preparing for the terminal molt, or are not yet preparing for either fate. Studies of diapause preparation in such populations are extremely difficult.To enable direct investigation of the factors that influence diapause initiation, we require markers that reliably predict the fate of individual copepods (entry into diapause or continued maturation to adulthood) within heterogeneous populations. Fortunately, the fjord population of C. finmarchicus off the coast of Norway during the late spring is remarkably synchronous and is comprised of juvenile copepods that are all destined to undergo diapause. This project will use high-throughput 454 pyrosequencing to identify genes that change in expression as these copepods progress toward diapause. In collaboration with Norwegian researchers, the investigators will also rear copepods in a unique continuous culture and conduct additional transcriptional profiling to identify genes that change in expression as copepods prepare for the terminal molt. Comparison of gene expression patterns in the wild and cultured populations will enable the principal investigators to develop robust markers of diapauses preparation that can be used to study diapause initiation in more heterogeneous temperate populations.Intellectual Merit: Despite decades of research, we are still ignorant of the processes that trigger diapause and are therefore unable to model the population dynamics of calanoid copepods for even a single generation. This is a long-standing and well-known gap in our understanding of marine ecosystems, and progress on this research problem could be transformative. By developing molecular markers to identify preparation for diapause, the investigators seek to enable novel physiological and ecological research that will ultimately identify both intrinsic and extrinsic factors that control entry into diapause. Their approach is based on an assumption that gene expression patterns in wild populations are sufficiently consistent to be used as a reliable indicator of diapause preparation. This fundamental assumption has yet to be tested; thus, this work is risky but with potentially high reward and suitable for an EAGER project. Broader Impacts: This project will enable a highly complementary new collaboration between US and Norwegian researchers and the training of undergraduate and graduate students. The results will be communicated to broad audiences through social media. Development and application of biomarkers of diapause preparation will ultimately allow modelers to parameterize diapause and improve the ability of ecosystem models to forecast changes associated with human impacts to oceans and climate change