Proteomic analysis of hepatic tissue of ciguatoxin (CTX) contaminated coral reef fish Cephalopholis argus and moray eel Gymnothorax undulatus

Ciguatera fish poisoning is a global human food-borne illness caused by the consumption of coral reef fish contaminated with ciguatoxins (CTXs). Some reef fishes, such as groupers and moray eels, are more toxic than others. We hypothesized that fish containing CTXs could produce special proteins or detoxification proteins as a strategy for survival during the accumulation of CTXs. The objective of this study was to characterize the differential proteomes of the toxic and nontoxic hepatic tissue of grouper, Cephalopholis argus and moray eel, Gymnothorax undulatus, which had elevated levels of CTXs. A combination of two dimensional electrophoresis and mass spectrum approaches was employed for preliminary screening of the liver proteome of wild-caught individuals. In C. argus with elevated CTXs, the expression level of cytoskeleton proteins was increased, whereas those of ubiquitin enzymes, ATP related enzymes, and telomerase reverse transcriptase were greatly reduced. In CTX-containing G. undulatus, the proteins involved in Ca2+ binding, detoxification, antiapoptosis, immune defense, enhanced cell survival and proliferation were elevated. In both toxic fish species, the ATP synthase subunit beta and cytochrome c were down-regulated. However further study is needed to assess their potential roles in the resistance mechanism to contamination by CTXs. In conclusion, the comparative proteomic analysis revealed that CTXs induced influx/efflux of Na+ or Ca2+ changes in fish liver, with a concomitant interference with signal transduction, metabolomics processes, detoxification, antiapoptosis, immune defense, enhanced cell survival and proliferation etc.

► We used two 2-DE and MS approaches for preliminary screening of CTX contaminated coral reef fishes.
► In each species, the ATP synthase subunit beta and cytochrome c were down-regulated.
► Potential roles in the resistance mechanism to contamination by CTXs.