The Coral Symbiomics Lab
Red Sea Research Center
Division of Biological and Environmental Science and Engineering

Publications in 2008

Wnt8 Is Required for Growth-Zone Establishment and Development of Opisthosomal Segments in a Spider

​McGregor, Pechmann, Schwager, Feitosa, Kruck, Aranda and Damen, “Wnt8 Is Required for Growth-Zone Establishment and Development of Opisthosomal Segments in a Spider,” Current Biology 18, no. 20 (2008).
McGregor Alistair P., Pechmann Matthias, Schwager Evelyn E., Feitosa Natália M., Kruck Sarah, Aranda Manuel, Damen Wim G. M.
The Wnt genes encode secreted glycoprotein ligands that regulate many developmental processes from axis formation to tissue regeneration [1]. In bilaterians, there are at least 12 subfamilies of Wnt genes [2]. Wnt3 and Wnt8 are required for somitogenesis in vertebrates 3, 4, 5, 6, 7 and are thought to be involved in posterior specification in deuterostomes in general [8]. Although TCF and β-catenin have been implicated in the posterior patterning of some short-germ insects 9, 10, the specific Wnt ligands required for posterior specification in insects and other protostomes remained unknown. Here we investigated the function of Wnt8 in a chelicerate, the common house spider Achaearanea tepidariorum[11]. Knockdown of Wnt8 in Achaearanea via parental RNAi caused misregulation of Delta, hairy, twist, and caudal and resulted in failure to properly establish a posterior growth zone and truncation of the opisthosoma (abdomen). In embryos with the most severe phenotypes, the entire opisthosoma was missing. Our results suggest that in the spider, Wnt8 is required for posterior development through the specification and maintenance of growth-zone cells. Furthermore, we propose that Wnt8, caudal, and Delta/Notch may be parts of an ancient genetic regulatory network that could have been required for posterior specification in the last common ancestor of protostomes and deuterostomes.