Charney Noah D, Kubel Jacob E, Woodard Craig T, Carbajal-González Blanca I, Avis Samantha, Blyth Julia A, Eiseman Charles S, Castorino John, Malone John H
Harvard Forest, Harvard University, Petersham, MA, USA.
Natural Heritage & Endangered Species Program, Massachusetts Division of Fisheries and Wildlife, Westborough, MA, USA.
BMC Dev Biol. 2019 Nov 12;19(1):21. doi: 10.1186/s12861-019-0202-z.
Animals with polyploid, hybrid nuclei offer a challenge for models of gene expression and regulation during embryogenesis. To understand how such organisms proceed through development, we examined the timing and prevalence of mortality among embryos of unisexual salamanders in the genus Ambystoma.
Our regional field surveys suggested that heightened rates of embryo mortality among unisexual salamanders begin in the earliest stages of embryogenesis. Although we expected elevated mortality after zygotic genome activation in the blastula stage, this is not what we found among embryos which we reared in the laboratory. Once embryos entered the first cleavage stage, we found no difference in mortality rates between unisexual salamanders and their bisexual hosts. Our results are consistent with previous studies showing high rates of unisexual mortality, but counter to reports that heightened embryo mortality continues throughout embryo development.
Possible causes of embryonic mortality in early embryogenesis suggested by our results include abnormal maternal loading of RNA during meiosis and barriers to insemination. The surprising survival rates of embryos post-cleavage invites further study of how genes are regulated during development in such polyploid hybrid organisms.
具有多倍体、杂交核的动物对胚胎发育过程中的基因表达和调控模型提出了挑战。为了了解这类生物如何进行发育，我们研究了钝口螈属单性蝾螈胚胎死亡的时间和发生率。
我们的区域实地调查表明，单性蝾螈胚胎死亡率的升高始于胚胎发育的最早阶段。尽管我们预计在囊胚期合子基因组激活后死亡率会升高，但在实验室饲养的胚胎中并未发现这种情况。一旦胚胎进入第一次分裂阶段，我们发现单性蝾螈与其两性宿主之间的死亡率没有差异。我们的结果与之前显示单性死亡率高的研究一致，但与报道中整个胚胎发育过程中胚胎死亡率持续升高的情况相反。
我们的结果表明，早期胚胎发育中胚胎死亡的可能原因包括减数分裂过程中RNA的母体装载异常和受精障碍。分裂后胚胎令人惊讶的存活率促使人们进一步研究在这类多倍体杂交生物的发育过程中基因是如何调控的。
