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

哲水蚤科的海洋桡足类，如Calanus finmarchicus，是地球上最丰富的动物之一，它们通过将能量从浮游植物转移到更高的营养级，在海洋食物网中发挥关键作用。这些桡足类的生活史已经被很好地研究过了，但是关于一个叫做滞育的重要休眠期的调节仍然存在根本性的问题。 在发育的最后幼年阶段，C. Finmarchicus或者进行终末蜕皮（即，蜕皮成成虫）或垂直迁移到深处并开始滞育。这种发育途径的差异对C。finmarchicus种群动态，但由于C. finmarchicus，像所有其他桡足类在家庭哲水蚤，不可靠进入滞育在实验室。此外，大多数温带种群的哲水蚤桡足类在一年内有多个世代，在繁殖和发展的时间，导致显着的异质性年龄结构的变化。因此，这些异质种群的实地采样产生的桡足类的混合物，准备滞育，正在为终端蜕皮，或尚未准备的命运。在这样的人群中滞育准备的研究是非常困难的。为了能够直接调查影响滞育开始的因素，我们需要可靠地预测个体桡足类的命运（进入滞育或继续成熟到成年）在异质种群的标记。幸运的是，C。在晚春，挪威海岸外的finmarchicus是非常同步的，由注定要经历滞育的幼年桡足类组成。 该项目将使用高通量454焦磷酸测序来识别这些桡足类在滞育过程中表达变化的基因。与挪威研究人员合作，研究人员还将在独特的连续培养中饲养桡足类，并进行额外的转录分析，以确定在桡足类准备终末蜕皮时表达变化的基因。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稳定的滞育标记物，可用于研究更异质的温带种群的滞育起始。尽管经过几十年的研究，我们仍然不知道触发滞育的过程，因此无法模拟哲水蚤桡足类的种群动态，一代这是我们对海洋生态系统的理解中一个长期存在的众所周知的差距，在这一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是足够一致的，可以作为滞育准备的可靠指标。这个基本假设还有待验证;因此，这项工作是有风险的，但有潜在的高回报，适合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达给广大受众。滞育准备生物标志物的开发和应用将最终使模型制作者能够参数化滞育，并提高生态系统模型预测人类对海洋和气候变化的影响所带来的变化的能力

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