Meeting Abstract
Black widow spiders (genus Latrodectus) are infamous for their exceptionally potent venom, which in addition to insect toxins contains the vertebrate neurotoxin α-latrotoxin. α-Latrotoxin is an unusual metazoan toxin because it forms exogenous calcium channels in vertebrate neurons, triggering massive neurotransmitter release in injected victims. However, α-latrotoxin is just one of at least 20 latrotoxin paralogs, all of which are strongly and specifically expressed in the venom glands of the Western black widow (L. hesperus). Interestingly, the phylogenetic distribution of the large latrotoxin family is extremely narrow, being limited to a few genera of the same family (Theridiidae), suggesting its recent origin. In addition to latrotoxins, black widow venom also contains other classes of toxins, some of which may be unique to theridiids. Here we present analyses of newly sequenced spider genomes, including a genome from the house spider (Parasteatoda tepidariorum), a close relative of black widows that produces far less toxic venom. Bioinformatic surveys of toxin genes in the house spider genome, along with gene expression (RNA-Seq) studies of venom glands from multiple species suggest large differences in venom protein composition among closely related species. Moreover, phylogenetic analyses of latrotoxins and other toxin families suggest extensive and recent lineage-specific evolution of venom genes, along with substantial shifts in tissue specific expression among species. We will discuss these findings in terms of their adaptive significance for black widow ecology, and for deciphering the physiological activities and biomedical utility of black widow venom.
