Hayward David C, Miller David J, Ball Eldon E
Centre for Molecular Genetics of Development & Research School of Biological Sciences, Australian National University, P.O. Box 475, 2601, Canberra, ACT, Australia.
Dev Genes Evol. 2004 May;214(5):257-60. doi: 10.1007/s00427-004-0398-0. Epub 2004 Mar 17.
Although corals are nominally diploblastic, the early development of Acropora millepora involves a process that clearly resembles gastrulation in higher metazoans. This similarity at the morphological level led us to search for the Acropora equivalents of genes whose key roles in gastrulation are conserved across the higher Metazoa. We here report the characterisation of one such gene, snail, which in both Drosophila and the mouse is expressed in cells undergoing an epithelial-mesenchyme transition and/or morphogenetic movements. In addition to an N-terminal SNAG domain, the Acropora snail protein contains four zinc fingers with sequences diagnostic for members of the snail protein subfamily. In situ hybridisation reveals expression in epithelial tissue in the central portion of one side of the flattened pre-gastrulation embryo, which continues to express snail as it is engulfed by its opposite layer. Comparison to snail expression during gastrulation in bilaterians such as Drosophila reveals striking similarities and suggests mechanistic, and possibly evolutionary, links between the processes of mesoderm formation in bilaterians and endoderm formation in the Cnidaria.
虽然珊瑚名义上是双胚层动物，但多孔鹿角珊瑚的早期发育涉及一个明显类似于高等后生动物原肠胚形成的过程。这种形态学水平上的相似性促使我们去寻找在高等后生动物中参与原肠胚形成且作用关键的同源基因。我们在此报告了一个这样的基因——蜗牛基因（snail）的特征，该基因在果蝇和小鼠中均在经历上皮 - 间充质转化和/或形态发生运动的细胞中表达。除了一个N端的SNAG结构域外，多孔鹿角珊瑚的蜗牛蛋白还包含四个锌指结构，其序列是蜗牛蛋白亚家族成员的诊断特征。原位杂交显示，在扁平的原肠胚形成前胚胎一侧的中央部分的上皮组织中有表达，当该组织被其相对层吞噬时，仍持续表达蜗牛基因。与果蝇等两侧对称动物原肠胚形成过程中蜗牛基因的表达相比，显示出惊人的相似性，并暗示了两侧对称动物中中胚层形成过程与刺胞动物中内胚层形成过程之间的机制联系，甚至可能是进化联系。
