Xie et al. wrote:ABSTRACT
Fish venom remains a virtually untapped resource. There are so few fish toxin sequences for reference, which increases the difficulty to study toxins from venomous fish and to develop efficient and fast methods to dig out toxin genes or proteins. Here, we utilized Chinese yellow catfish (
) as our research object, since it is a representative species in Siluriformes with its venom glands embedded in the pectoral and dorsal fins. In this study, we set up an in-house toxin database and a novel toxin-discovering protocol to dig out precise toxin genes by combination of transcriptomic and proteomic sequencing. Finally, we obtained 15 putative toxin proteins distributed in five groups, namely Veficolin, Ink toxin, Adamalysin, Za2G and CRISP toxin. It seems that we have developed a novel bioinformatics method, through which we could identify toxin proteins with high confidence. Meanwhile, these toxins can also be useful for comparative studies in other fish and development of potential drugs.
Using gene sequences and similarities, the authors identified 15 proteins from the Chinese yellow catfish that MIGHT be venom toxins. The 15 proteins were similar to the following types of known toxins:
Veficolin: First identified in snake venom and then Anguimorpha lizard; its function is not clearly characterized. Proteins shaped like this are associated with the disease scurvy. The authors infer that the veficolin might cause scurvy as well, which "is in accordance with the symptoms caused by getting stuck by those spines from the Chinese yellow catfish."
Ink Toxins: Ink toxins isolated from sea hares can act as antimicrobial and antitumor agents. Cells exposed to ink toxins die within 6–8 hours by production of high amounts of hydrogen peroxide, inducing a form of oxidative stress.
Adamalysin: This protein requires zinc and calcium for its activity; it's a toxin protein first isolated from the venom of Eastern diamond back rattlesnake (Crotalus adamanteus).
Zn-2-Glycoprotein (ZaGP): This protein is reportedly involved in both inhibition of tumor growth and proliferation; the toxin's structure is highly homologous to a major histocompatibility complex class I (MHC-I) superfamily, which may function importantly in immunity. ZaGP may have some protective effects in tumor patients and prevent the cancer progression.
Cysteine-Rich Secretory Proteins Toxin (CRISP): Recent research has revealed that CRISPs are widely distributed in snake venom and that they inhibit smooth muscle contraction and some ion channels, producing lethargy, paralysis and hypothermia.
