A feeding study to probe the uptake of Maitotoxin by snapper (Pagrus auratus)

• Feeding experiments were used to determine Maitotoxin uptake in carnivorous fish.
• Maitotoxins can accumulate in Pagrus auratus viscera, liver and muscle.
• Genetic tools confirm the presence of Gamberdiscus australes in P. auratus viscera.

The role of ciguatoxins (CTX) in Ciguatera fish poisoning (CFP) has been investigated previously, but little is known about Maitotoxin (MTX) and whether it plays a significant role in causing human illness. The MTXs are known to have slightly higher potency than CTXs when administered intraperitoneally in mice, but are less potent when administered orally, due to their water solubility. It is not known whether MTXs accumulate in carnivorous fish tissues, and to investigate this further fish feeding trials with snapper (Pagrus auratus) were undertaken. Replicate P. auratus were fed with juvenile mullet (Aldrichetta forsteri) injected with a pellet of a known quantity of Gambierdiscus australes, which is a known producer of MTX. The levels of MTX in different fish tissues were determined using two newly developed sensitive LC–MS/MS assays for MTX that monitor either a specific cleavage fragment (generated from micro-scale oxidation of the intact toxin) or the intact toxin itself. The investigations revealed the presence of MTX in P. auratus viscera, liver and muscle samples. The presence of Gambierdiscus-related genes in P. auratus digestive organs was confirmed using DNA amplification technology.