Meeting Abstract

118.3  Monday, Jan. 7  Exploring the silk and the silk-like venom from the spitting spider Scytodes thoracica. CORREA, S.*; ZOBEL-THROPP, P.; BINFORD, G.; SUTER, R.; GARB, J.E.; University of Massachusetts Lowell; Lewis and Clark College; Lewis and Clark College; Vassar College; University of Massachusetts Lowell scorr006@ucr.edu

Scytodids have evolved a unique way to capture prey from a distance. Scytodids spit an adhesive glue from their fangs onto prey. The ejected material contains long, fibrous strands with structural similarities to abdominal spider silk. We characterized venom and silk gland proteins from a spitting spider species, Scytodes thoracica, to determine its composition and possible evolutionary connections between the silk-like venom and their abdominal silk proteins (spidroins). We identified two novel spidroins: S. thoracica fibroin 1 and 2 showing the characteristics of all known spidroins, including repetitive sequences and conserved C-terminal domains. Amino acid composition analyses indicate that S. thoracica fibroin 1 is the major component of the major ampullate silk from this species. S. thoracica dragline silk was found to have high toughness, but was not as tough as previously described. Phylogenetic analyses suggest that proteins comprising spider dragline silk evolved independently, and is attributed to multiple gene duplication events. Forty percent of S. thoracica venom gland cDNAs encoded a family of glycine rich peptides, whereas another 17% of venom cDNAs encoded putative venom toxins. No venom cDNAs were homologous to spidroins, but the high expression of glycine-rich peptides suggest they constitute a major component of the Scytodes venom spit. Results indicate that scytodids evolved a unique way of synthesizing a fibrous silk-like material from their venom glands using novel proteins, supporting the proposed novel silk gene hypothesis.