Abstract
The crassispirids are a large branch of venomous marine gastropods whose venoms have not been investigated previously. We demonstrate that crassispirids comprise a major group of toxoglossate snails in a clade distinct from all turrids whose venoms have been analyzed. The isolation and biochemical definition of the first venom component from any crassispirid is described. Crassipeptide cce9a from Crassispira cerithina (Anton, 1838) was purified from crude venom by following biological activity elicited in young mice, lethargy and a lack of responsiveness to external stimuli. Using Edman sequencing and mass spectrometry, the purified peptide was shown to be 29 amino acid residues long, with the sequence: GSCGLPCHENRRCGWACYCDDGICKPLRV. The sequence assignment was verified through the analysis of a cDNA clone encoding the peptide. The peptide was chemically synthesized and folded; the synthetic peptide was biologically active and coelution with the native venom peptide was demonstrated. When injected into mice of various ages, the peptide elicited a striking shift in behavioral phenotype between 14 and 16 days, from lethargy to hyperactivity.