Abstract
Ciguatera fish poisoning (CFP) is an illness contracted through the ingestion of seafood containing ciguatoxins. It is prevalent in tropical regions worldwide, including in Australia. Ciguatoxins are produced by some species of Gambierdiscus. Therefore, screening of Gambierdiscus species identification through quantitative PCR (qPCR), along with the determination of species toxicity, can be useful in monitoring potential ciguatera risk in these regions. In Australia, CFP is prevalent in tropical Queensland and increasingly in sub-tropical regions of Australia, but has a report rate of approximately 10%. Yet the identity, distribution and abundance of ciguatoxin producing Gambierdiscus spp. is largely unknown. In this study, we developed a rapid qPCR assay to quantify the presence and abundance of Gambierdiscus lapillus, a likely ciguatoxic species first described from Australia. We assessed the specificity and efficiency of the qPCR assay. The assay was tested on 25 environmental samples from the Heron Island reef in the southern Great Barrier Reef, a ciguatera endemic region, to determine the presence and patchiness of this species across samples from Chnoospora sp., Padina sp. and Sargassum sp. macroalgal hosts.
Highlights
Benthic dinoflagellates of the genus Gambierdiscus Adachi & Fukuyo produce ciguatoxins (CTX), which can accumulate in humans via consumption of contaminated seafood and cause ciguatera fish poisoning (CFP) (Fig 1)
While genomic DNA was visible for each strain on the agarose gel and the DNA could be amplified via PCR (SSU PCR amplification, Table 5), no cross-reaction was observed for genetically closely related species G. belizeanus, G. cheloniae, G. pacificus and G. scabrosus
The results presented highlight the importance of carefully verifying quantitative PCR (qPCR) assays based on rRNA genes using multiple local strains as their target gene copy numbers might vary, but qPCR assay to detect Gambierdiscus lapillus the necessity and possible issues that can arise while constructing “absolute” standard curves
Summary
Benthic dinoflagellates of the genus Gambierdiscus Adachi & Fukuyo produce ciguatoxins (CTX), which can accumulate in humans via consumption of contaminated seafood and cause ciguatera fish poisoning (CFP) (Fig 1). The symptoms of CFP are largely gastrointestinal and neurotoxic, in severe cases, further complications such as cardiovascular or severe neurological symptoms can appear [5]. In the most extreme cases, CFP can result in death [6]. Species of Gambierdiscus are predominantly epiphytic, growing on macroalgae and other substrates such as coral detritus.
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