Maslakov Georgy P, Kulishkin Nikita S, Surkova Alina A, Kulakova Milana A
Department of Embryology, St. Petersburg State University, Universitetskaya nab., 7-9, 199034 Saint-Petersburg, Russia.
Laboratory of Evolutionary Morphology, Zoological Institute RAS, Universitetskaya nab., 1, 199034 Saint-Petersburg, Russia.
J Dev Biol. 2021 Sep 4;9(3):37. doi: 10.3390/jdb9030037.
Hox genes are some of the best studied developmental control genes. In the overwhelming majority of bilateral animals, these genes are sequentially activated along the main body axis during the establishment of the ground plane, i.e., at the moment of gastrulation. Their activation is necessary for the correct differentiation of cell lines, but at the same time it reduces the level of stemness. That is why the chromatin of Hox loci in the pre-gastrulating embryo is in a bivalent state. It carries both repressive and permissive epigenetic markers at H3 histone residues, leading to transcriptional repression. There is a paradox that maternal RNAs, and in some cases the proteins of the Hox genes, are present in oocytes and preimplantation embryos in mammals. Their functions should be different from the zygotic ones and have not been studied to date. Our object is the errant annelid . This model is convenient for studying new functions and mechanisms of regulation of Hox genes, because it is incomparably simpler than laboratory vertebrates. Using a standard RT-PCR on cDNA template which was obtained by reverse transcription using random primers, we found that maternal transcripts of almost all Hox genes are present in unfertilized oocytes of worm. We assessed the localization of these transcripts using WMISH.
Hox基因是一些研究得最为深入的发育控制基因。在绝大多数两侧对称动物中，这些基因在原肠胚形成时，即在基平面建立过程中，沿着主体轴依次被激活。它们的激活对于细胞系的正确分化是必要的，但同时也降低了干性水平。这就是为什么原肠胚形成前胚胎中Hox基因座的染色质处于二价状态。它在H3组蛋白残基上同时携带抑制性和允许性表观遗传标记，导致转录抑制。存在一个悖论，即母体RNA，在某些情况下还有Hox基因的蛋白质，存在于哺乳动物的卵母细胞和植入前胚胎中。它们的功能应该与合子的功能不同，并且迄今为止尚未得到研究。我们的研究对象是游走多毛纲动物。这个模型便于研究Hox基因调控的新功能和机制，因为它比实验室脊椎动物简单得多。使用基于随机引物逆转录获得的cDNA模板进行标准RT-PCR，我们发现几乎所有Hox基因的母体转录本都存在于蠕虫的未受精卵母细胞中。我们使用全胚胎原位杂交（WMISH）评估了这些转录本的定位。
