Wnt signaling in the processes of segmentation and elongation in the beetle Tribolium castaneum

Abstract

Introduction: In most arthropods segments form sequentially from a posterior growth zone in an anterior to posterior fashion, just like vertebrate somites arise from presomitic mesoderm. In both phyla, segmentation relies on the dynamic expression of cyclic genes belonging to the same signaling pathways. However, much of what we know about segmentation in arthropods comes from RNAi-based loss of function analysis, with the corresponding unwanted early effects. Furthermore, it has not been always possible to relate the phenotype obtained with the specific affected part of the process. Material and Methods: Transgenic nuclear GFP-line, embryo culture (dissected and bisected Tribolium eggs) and in-situ hybridization, to test the inhibition (IWP-3) and activation (LiCl) of Wnt signaling pathway during specific time intervals. Results: The activation and inhibition of Wnt signaling pathway affect axis elongation in dissected and bisected embryos, as well as partially disrupts convergent movements toward the ventral midline. At the same time we are analyzing the expression patterns of the two oscillatory genes known in Tribolium (odd-skipped and even-skipped), by in-situ hybridization. Discussion: By incubating the embryos with different drugs at specific time intervals during segmentation, we want to determine the role of different signaling pathways, Wnt pathway included, during embryonic elongation and segmentation, compared to what happens in vertebrates and other arthropods.