Collaborative Research: Life History Variation in Copepods: Modulation through Chromatin Diminution and Endoreduplication

[0080921]本研究探讨水生微甲壳类动物对基因组DNA的大量损失、获得和重组的反应。重点是胚胎染色质减少-基因组的大小减少和重组，并对核内重复进行额外的探索性研究-核DNA扩增而没有随后的有丝分裂。PI将研究体细胞和生殖细胞谱系中DNA含量的变化是否可以通过对基因组体积大小的影响来解释发育时间和胚胎和成年身体大小的变化。研究将包括重建Cyclopidae的系统发育，并使用系统发育无关的对比来测试成虫体细胞DNA含量与发育速度和成虫体型的相关进化。pi将调查胚胎中大量的种系DNA是否可能在发育过程中最需要这种转录物的时候提高蛋白质转录率。DNA的定量变化将使用细胞光度法和同位素标记的DNA和RNA前体来测量。桡足类是研究基因组大规模变化进化的理想工具，因为它们的基因组大小在物种之间差异很大，调节它们DNA含量的机制是已知的，它们的生活史变化和种群生物学已经得到了很好的研究，它们的染色体也可以进行定量和比较分析。桡足类动物可能是海洋中数量最多的多细胞生物，是许多鱼类的主要食物，因此在全球生态中起着重要作用。

0080921Rasch This research investigates responses of aquatic microcrustaceans to massive losses, gains, and reorganizations of genomic DNA. The focus is on embryonic chromatin diminution - reduction in size and reorganization of the genome, with additional exploratory research on endoreduplication - the amplification of nuclear DNA without subsequent mitosis. The PI's will investigate whether variation in DNA content in somatic and germ cell lineages can explain variation in developmental time and embryonic and adult body sizes through effects on bulk size of the genome. Research will include reconstruction of a phylogeny of the Cyclopidae and use of phylogenetically-independent contrasts to test for correlated evolution of adult somatic DNA content with developmental rate and adult body size. The PIs will investigate whether large amounts of germline DNA in embryos make possible higher rates of protein transcription at times during development when there is greatest need for such transcripts. Quantitative changes in DNA will be measured using cytophotometry and isotopically labeled DNA and RNA precursors. Copepods are ideal for examining evolution of large-scale changes in the genome because their genome size varies greatly among species, mechanisms that modulate their DNA contents are known, their life history variation and population biology are well studied, and their chromosomes are amenable to quantitative and comparative analyses. Copepods may be the most abundant multicellular organisms in the oceans, are a primary diet item of many fish, and thus play a major role in global ecology.