Meeting Abstract
Segmentation is a key characteristic of the phylum Arthropoda and linked to the evolutionary success of this lineage. The formation of segments requires the activity of the Wnt family of secreted proteins, as inferred from functional data in model organisms such as Drosophila melanogaster (fruit fly) and Tribolium castaneum (flour beetle). Comparable data are, however, limited in lineages like Chelicerata (e.g., spiders, mites), the sister group to the rest of the arthropods. Here we examined the inhibition of canonical Wnt signaling in the cobweb spider Parasteatoda tepidariorum using parental RNA interference against the single-copy Wnt-1 co-receptor arrow (arr; vertebrate homolog: LRP5 and LRP6), which is known to be a key member of the canonical Wnt-signaling pathway in holometabolous insects. We describe defects in germband formation and segmentation incurred by arr knockdown in developing spider embryos, using cell division, segment boundary, and apoptosis markers to assess the effect of the knockdown. We additionally compare our data to known phenotypes in the fruit fly and the flour beetle toward evaluating the conservation of arr function across insects and arachnids.
