Casano C, Ragusa M, Cutrera M, Costa S, Gianguzza F
Dipartimento di Biologia Cellulare e dello Sviluppo, Università di Palermo, Italy.
Int J Dev Biol. 1996 Oct;40(5):1033-41.
In Paracentrotus lividus sea urchin embryos, at blastula stage, there is an abrupt increase in the abundance of alpha and beta tubulin transcripts in particular of the PI beta 1, PI beta 2 and PI alpha 2 forms. In order to assign specific functions to the various embryonic tubulin genes, we have used whole-mount in situ hybridization to determine spatial patterns of expression of five different alpha and beta tubulin embryonic genes. The PI beta 3 transcripts, as previously shown for PI alpha 2, start to localize in a few founder cells from which the neurogenic territory differentiates. The other four embryonic tubulin mRNAs (PI beta 1/2 and PI alpha 1/10), are localized in the ciliated band- and gut-territory. These territories originate by morphogenetic processes, which occur in late embryogenesis in the sea urchin and depend on cellular interactions. In particular, the interactions between the oral and aboral ectoderm specify the position of the ciliated band, whereas the invagination of the vegetal plate forms the gut territory. We suppose that the increase in alpha and beta tubulin transcripts could be functionally related to these two morphogenetic events. Our results show in fact that specific tubulin isotypes, or a mix of them, are expressed in and mark the ciliated band and the neighboring oral/aboral ectoderm cells of the ciliated band, in addition to the cells of the gut territory. The same localization of all these tubulin transcripts has been confirmed by whole-mount in situ hybridization experiments performed on embryos treated with agents able to induce deciliation or exogastrulation. Furthermore a putative correlation of PI beta 2 with cilium formation has been shown by the results obtained on deciliated embryos.
在紫球海胆胚胎的囊胚期，α和β微管蛋白转录本的丰度会突然增加，尤其是PIβ1、PIβ2和PIα2形式。为了确定各种胚胎微管蛋白基因的特定功能，我们使用了全胚胎原位杂交技术来确定五个不同的α和β胚胎微管蛋白基因的表达空间模式。正如之前对PIα2的研究所示，PIβ3转录本开始定位于少数神经源区域从中分化出来的奠基细胞中。其他四种胚胎微管蛋白mRNA（PIβ1/2和PIα1/10）则定位于纤毛带和肠道区域。这些区域是通过形态发生过程形成的，这些过程发生在海胆胚胎发育后期，并且依赖于细胞间相互作用。特别是，口侧和反口侧外胚层之间的相互作用决定了纤毛带的位置，而植物极板的内陷形成了肠道区域。我们推测α和β微管蛋白转录本的增加可能在功能上与这两个形态发生事件相关。事实上，我们的结果表明，特定的微管蛋白亚型或它们的混合物，除了在肠道区域的细胞中表达外，还在纤毛带以及纤毛带相邻的口侧/反口侧外胚层细胞中表达并标记这些细胞。在用能够诱导去纤毛或外胚层外翻的试剂处理的胚胎上进行的全胚胎原位杂交实验证实了所有这些微管蛋白转录本的相同定位。此外，在去纤毛胚胎上获得的结果表明PIβ2与纤毛形成可能存在相关性。
