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

哈里斯这项研究调查了水生微型甲壳动物对基因组DNA的大量丢失、获得和重组的反应。重点放在胚胎染色质的缩小和基因组的重组上，另外还有关于内复制的探索性研究--在没有随后有丝分裂的情况下扩增核DNA。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影响基因组的体积大小来解释发育时间以及胚胎和成年身体大小的变化。研究将包括重建环鱼科的系统发育，并使用与系统发育无关的对比来测试成体DNA含量与发育速度和成体大小的相关性进化。PI将调查胚胎中大量的生殖系DNA是否可能在发育过程中最需要蛋白质转录的时候产生更高的蛋白质转录速率。DNA的定量变化将使用细胞光度学和同位素标记的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不同物种之间差异很大，调节它们DNA含量的机制是已知的，它们的生活史变异和种群生物学得到了很好的研究，它们的染色体可以进行定量和比较分析。桡足类可能是海洋中最丰富的多细胞生物，是许多鱼类的主要食物，因此在全球生态中发挥着重要作用。

0084854Harris 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.