Transcriptomic Identification of Toxic Components of Catfish Venoms

Recent research has indicated that over 2,500 fish species (or ≈ 10% of all known species) possess venom glands associated with specialized teeth, or fin, opercular, and/or or cleithral spines. The secretions produced by these glands cause a wide array of physiological effects in vertebrate organisms, including severe pain, cardiovascular, neuromuscular, and general cytolytic effects, and, as might be expected, have been shown to have significant impacts on the predator/prey interactions of the species that produce them. In spite of this, however, the venoms of fishes have received comparatively little attention from scientists relative to those of other venomous organisms, to the point that we lack even the most basic information regarding venom composition, toxin identity, and genetic architecture of venom production for nearly all venomous fish species.

Over half of all venomous fish species are catfishes, which possess venom glands lining the spines that are found along the front edges of their pectoral and/or dorsal fins. Using comparative next generation RNA sequencing of fin spines and histologically similar fin tissues, we will compare the gene transcripts that code for protein production in these two tissue types and, by using bioinformatic methods to eliminate transcripts that both have in common, identify only those transcripts that are unique to venom gland cells. Additional examination of these transcripts, in conjunction with information gained from earlier studies and proteomic sequencing, will allow us to identify those transcripts that code for venom proteins, as well as the genes that are responsible for the production of these venom protein RNAs. These results will provide the first insight into the genetic mechanisms underlying venom production in a group of venomous fishes, and will serve as a springboard for future studies in this developing area of research.