Adell Teresa, Grebenjuk Vladislav A, Wiens Matthias, Müller Werner E G
Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Universität Mainz, Duesbergweg 6, 55099 Mainz, Germany.
Dev Genes Evol. 2003 Sep;213(9):421-34. doi: 10.1007/s00427-003-0345-5. Epub 2003 Jul 24.
It is now well established that all metazoan phyla derived from one common ancestor, the hypothetical Urmetazoa. Due to the basal position of Porifera (Demospongiae) in the phylogenetic tree of Metazoa, studies on the mechanisms controlling the development of these animals can provide clues on the understanding of the origin of multicellular animals and on how the first organization of the body plan evolved. In this report we describe the isolation and genomic characterization of two T-box genes from the siliceous sponge Suberites domuncula. The phylogenetic analysis classifies one into the subfamily of Brachyury, Sd-Bra, and the second into the Tbx2 subfamily, Sd-Tbx2. Analyses of the Sd-Bra and Sd-Tbx2 sequences and their intron-exon structures demonstrate their basal position in the phylogeny of the T-box family, and allows us to hypothesize a model of the phylogenetic evolution of all T-box genes. Furthermore, we report the presence of two different products of alternative splicing of Sd-Bra, and demonstrate that they exist in different phosphorylation and glycosylation states in the sponge tissue. Sd-Bra expression in tissue and 3D-cell aggregates (primmorphs) is analyzed, suggesting that Sd-Bra might also have a role in Porifera morphogenesis.
现在已经明确，所有后生动物门都起源于一个共同祖先，即假设的原始后生动物。由于多孔动物门（寻常海绵纲）在后生动物系统发育树中的基部位置，对这些动物发育控制机制的研究可以为理解多细胞动物的起源以及身体结构的首次组织如何演化提供线索。在本报告中，我们描述了从硅质海绵Suberites domuncula中分离出的两个T-box基因及其基因组特征。系统发育分析将其中一个归类为短尾相关蛋白亚家族，即Sd-Bra，另一个归类为Tbx2亚家族，即Sd-Tbx2。对Sd-Bra和Sd-Tbx2序列及其内含子-外显子结构的分析表明它们在T-box家族系统发育中的基部位置，并使我们能够推测所有T-box基因的系统发育进化模型。此外，我们报告了Sd-Bra的两种不同可变剪接产物的存在，并证明它们在海绵组织中以不同的磷酸化和糖基化状态存在。分析了Sd-Bra在组织和三维细胞聚集体（原形体）中的表达，表明Sd-Bra可能在多孔动物形态发生中也发挥作用。
