Department of Biology, University of New Brunswick, Fredericton, NB, Canada.
J Exp Zool B Mol Dev Evol. 2021 Sep;336(6):496-510. doi: 10.1002/jez.b.23069. Epub 2021 Jul 12.
Ploidy transitions through whole genome duplication have shaped evolution by allowing the sub- and neo-functionalization of redundant copies of highly conserved genes to express novel traits. The nuclear:cytoplasmic (n:c) ratio is maintained in polyploid vertebrates resulting in larger cells, but body size is maintained by a concomitant reduction in cell number. Ploidy can be manipulated easily in most teleosts, and the zebrafish, already well established as a model system for biomedical research, is therefore an excellent system in which to study the effects of increased cell size and reduced cell numbers in polyploids on development and physiology. Here we describe a novel technique using confocal microscopy to measure genome size and determine ploidy non-lethally at 48 h post-fertilization (hpf) in transgenic zebrafish expressing fluorescent histones. Volumetric analysis of myofiber nuclei using open-source software can reliably distinguish diploids and triploids from a mixed-ploidy pool of embryos for subsequent experimentation. We present an example of this by comparing heart rate between confirmed diploid and triploid embryos at 54 hpf.
通过全基因组复制的倍性转变，允许高度保守基因的冗余拷贝进行亚功能化和新功能化，从而表达新的特征，从而塑造了进化。多倍体脊椎动物中的核质比（n:c）得到维持，导致细胞变大，但通过细胞数量的相应减少来维持体型。大多数硬骨鱼的倍性可以很容易地进行操作，而斑马鱼已经作为生物医学研究的模型系统得到很好的建立，因此是研究多倍体中细胞大小增加和细胞数量减少对发育和生理影响的极佳系统。在这里，我们描述了一种使用共聚焦显微镜的新技术，该技术可在转染表达荧光组蛋白的斑马鱼受精后 48 小时（hpf）非致死性地测量基因组大小并确定倍性。使用开源软件对肌纤维核进行体积分析，可以可靠地区分二倍体和三倍体与胚胎的混合倍性群体，以便进行后续实验。我们通过比较 54 hpf 时确认的二倍体和三倍体胚胎的心率来举例说明这一点。
