Comparative analysis of Rhipicephalus tick salivary gland and cement elementome.

Rhipicephalus spp. (Acari: Ixodidae) ticks are obligate hematophagous arthropods, which constitute a model for the study of vector-host interactions. The chemical composition or elementome of salivary glands (SG) and cement provides information relevant for the study of protein-based complex multifunctional tissues with a key role in tick biology. In this study, we characterized the elementome of cement cones in Rhipicephalus sanguineus collected from naturally infested dogs and in SG and cement of R. bursa collected from experimentally infested rabbits at different feeding stages. The elementome was characterized using scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The results showed the identification of up to 14 chemical elements in the cement, and suggested tick/host-driven differences in the cement elementome between tick species and between SG and cement within the same species. By still unknown mechanisms, ticks may regulate cement elementome during feeding to affect various biological processes. Although these analyses are preliminary, the results suggested that N is a key component of the cement elementome with a likely origin in SG/salivary proteins (i.e., Glycine (C2H5NO2)-rich superfamily member proteins; GRPs) and other tick/host-derived components (i.e. NAPDH). Future research should be focused on tick elementome and its functional implications to better understand cement structure and function.