Expression of hunchback protein in a subset of ectodermal teloblasts of the oligochaete annelid Tubifex

The early expression patterns of hunchback protein (T-hb protein) were examined in the oligochaete Tubifex, using an antibody raised to the LZF2 protein in leech. This antibody recognizes a 60-kDa polypeptide in the Tubifex embryo. Before teloblastogenesis, T-hb protein is expressed in every cleavage-stage blastomere. At the completion of teloblastogenesis, the only cells expressing T-hb are a fraction of the micromere-derived epithelial cells. During gastrulation, nuclear T-hb is seen in spreading micromere-derived epithelial cells and also in a subset of ectodermal teloblasts. Comparisons of these results with those from other annelids suggest that hb expression in the early cleavage blastomeres and the micromere-derived epithelium are features highly conserved among annelids. In contrast, hb expression in teloblasts appears to be an innovation evolved in the oligochaetes.