Venum duct CDNA library sequences of two marine gastropods (Gemmula speciosa and Gemmula sogodensis): Similarity and divergence

• Main Authors: Heralde, Francisco M., III, Lapid, Carlo, Olivera, Baldomero M., Santos, Ameurfina D.
• Format: text
• Published: Animo Repository 2007
• Subjects: Turridae; Antisense DNA; Marine toxins; Biology
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/6863
• Institution: De La Salle University

Toxin studies in marine gastropods have taken large leaps since molecular techniques became widely available more than twenty years ago. The Conus toxicology which benefited largely form this breakthrough, has established the basic knowledge of the nature and properties of marine gastropod toxins and toxin genes. Recently, another group of venomous gastropods, the turrids, has become the focus of several studies. Comparative toxinological work with coniids has been done through shotgun cloning of toxin sequences from cDNA library venom duct tissues. Here, we report that employing an analogous strategy of shotgun cloning of toxin genes from the venom duct cDNA library, we are able to isolate toxin and non tpxins sequences from the two species of Indo-Pacific Turrinae, namely: Gemmula speciose (Reeve, 1843), collected form Batangas and Gemmula sogodensis (Olivera, 2005) collected form Sogod, Cebu. The 30 clone sequences analyzed from each library yielded overlap for two putative toxin genes (i.e., P-like type 1 and type 2) (approximately 6%). Clones gspxg1 and gsg816 code for P-like type 1 and clones gsp118, gsp21c and gsg818 code for P-like type 2. The “P-like toxin” nomenclature adapted was based on P-conotoxin – a three disulfide-bearing conopeptide with the first of its forms (tx9a) isolated in C. textile and found to exhibit spasmodic symptomatology in mice (i.e., hypersensitivity to touch, hyperactivity and convulsion). Toxin sequences characteristic of O-like, I-like and RGD peptides were also isolated but did not show overlap between the species. The presence of expressed toxin genes in the venom duct tissues indicates the dynamic use of these genes for prey hunting strategy. Hence, not only are the sequences shown to exhibit the disulfide pattern reminiscent of conotoxins, the overlap denotes similar use of the toxins in turrid envenomation of its prey, the polychaetes. The occurnece of other toxin sequences reflects the species diversification strategy and awaits rationalization in the context of the organism’s total prey-hunting physiology.