Toxic Flatworm Egg Plates Serve as a Possible Source of Tetrodotoxin for Pufferfish

Okabe, Taiki; Oyama, Hikaru; Kashitani, Maho; Ishimaru, Yuta; Suo, Rei; Sugita, Haruo; Itoi, Shiro

doi:10.3390/toxins11070402

Cited by 36 publications

(25 citation statements)

References 37 publications

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“…Culturing, isolating and testing these bacterial species, in particular picocyanobacteria, for toxin production would be a logical next step in the search to identify the source of TTX in marine organisms. It has recently been shown that DNA from toxic flatworms were detected in the intestinal content of juvenile pufferfish (Okabe et al, 2019). So alternatively, it is also feasible that P. australis could source TTX from ingesting larvae, eggs, or pieces of the highly toxic sea slug P. maculata and flatworm Stylochoplana sp., which are common throughout New Zealand, Japan and Europe (Miyazawa et al, 1987;Salvitti et al, 2015;Turner et al, 2018).…”

Section: Conclusion and Future Researchmentioning

confidence: 99%

Seasonal and Spatial Variations in Bacterial Communities From Tetrodotoxin-Bearing and Non-tetrodotoxin-Bearing Clams

et al. 2020

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Tetrodotoxin (TTX) is one of the most potent naturally occurring compounds and is responsible for many human intoxications worldwide. Paphies australis are endemic clams to New Zealand which contain varying concentrations of TTX. Research suggests that P. australis accumulate the toxin exogenously, but the source remains uncertain. The aim of this study was to identify potential bacterial TTX-producers by exploring differences in bacterial communities in two organs of P. australis: the siphon and digestive gland. Samples from the digestive glands of a non-toxic bivalve Austrovenus stutchburyi that lives amongst toxic P. australis populations were also analyzed. Bacterial communities were characterized using 16S ribosomal RNA gene metabarcoding in P. australis sourced monthly from the Hokianga Harbor, a site known to have TTXbearing clams, for 1 year, from ten sites with varying TTX concentrations around New Zealand, and in A. stutchburyi from the Hokianga Harbor. Tetrodotoxin was detected in P. australis from sites all around New Zealand and in all P. australis collected monthly from the Hokianga Harbor. The toxin averaged 150 µg kg −1 over the year of sampling in the Hokianga Harbor but no TTX was detected in the A. stutchburyi samples from the same site. Bacterial species diversity differed amongst sites (p < 0.001, F = 5.9) and the diversity in siphon samples was significantly higher than in digestive glands (p < 0.001, F = 65.8). Spirochaetaceae (4-60%) and Mycoplasmataceae (16-78%) were the most abundant families in the siphons and the digestive glands, respectively. The bacterial communities were compared between sites with the lowest TTX concentrations and the Hokianga Harbor (site with the highest TTX concentrations), and the core bacterial communities from TTX-bearing individuals were analyzed. The results from both spatial and temporal studies corroborate with previous hypotheses that Vibrio and Bacillus could be responsible for the source of TTX in bivalves. The results from this study also indicate that marine cyanobacteria, in particular picocyanobacteria (e.g., Cyanobium, Synechococcus, Pleurocapsa, and Prochlorococcus), should be investigated further as potential TTX producers.

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Section: Conclusion and Future Researchmentioning

confidence: 99%

Seasonal and Spatial Variations in Bacterial Communities From Tetrodotoxin-Bearing and Non-tetrodotoxin-Bearing Clams

et al. 2020

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“…Our previous report showed that the pufferfish T. alboplumbeus inhabiting an intertidal zone of Hayama effectively acquired the toxins by feeding on Pl. multitentaculata , and its eggs and planktonic larvae [ 19 , 44 ]. Although the biomass of Pr.…”

Section: Resultsmentioning

confidence: 99%

First Detection of Tetrodotoxins in the Cotylean Flatworm Prosthiostomum trilineatum

et al. 2021

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Several polyclad flatworm species are known to contain high levels of tetrodotoxin (TTX), but currently TTX-bearing flatworms seem to be restricted to specific Planocera lineages belonging to the suborder Acotylea. During our ongoing study of flatworm toxins, high concentrations of TTXs were detected for the first time in the flatworm Prosthiostomum trilineatum, suborder Cotylea, from the coastal area of Hayama, Kanagawa, Japan. Toxin levels were investigated by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS), revealing that this species contains comparable concentrations of toxins as seen in planocerid flatworms such as Planocera multitentaculata. This finding indicated that there may be other species with significant levels of TTXs. The distribution of TTXs among other flatworm species is thus of great interest.

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“…with the accumulation of tetrodotoxin in various aquatic species (Magarlamov et al, 2017;Turner et al, 2017;Leao et al, 2018). On a different line, ingestion of toxic flatworm eggs had also been suggested as the source of tetrodotoxin in pufferfish Takifugu alboplumbeus (Okabe et al, 2019). Further, since tetrodotoxin-producing strains have been isolated from skin slime and kidneys of pufferfish (Campbell et al, 2009), toxin-producing microbes could be present in other body parts of horseshoe crab instead of gut.…”

Section: Discussionmentioning

confidence: 99%

Hemolymph Proteomics and Gut Microbiota of Horseshoe Crabs Tachypleus tridentatus and Carcinoscorpius rotundicauda

Leung

Nong

et al. 2020

Front. Mar. Sci.

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Horseshoe crabs are a group of marine chelicerates that contain only four extant species, some of which are endangered. Their hemolymph has been widely used in medical applications for endotoxin detection. Nevertheless, there is limited information on the profiles of their hemolymph proteins and their gut microbial diversity. In this study, we performed the first detailed investigation of the hemolymph proteomics and gut microbiota of two Asian horseshoe crabs Tachypleus tridentatus and Carcinoscorpius rotundicauda. Among the identified proteins being cataloged in the juvenile and adult hemolymph, unexpectedly, sesquiterpenoid signaling pathway proteins including Heat shock protein 83 (HSP83), Chd64, and a juvenile hormone binding protein (JHBP) were revealed. This provides evidence for the presence of functional sesquiterpenoid hormonal systems in these marine chelicerates. consumption of certain horseshoe crab species often leads to tetrodotoxin poisoning and the horseshoe crab is thought to possess a tetrodotoxin resistance mechanism. As such, sodium channels were analyzed and found to have critical amino acid residues that are similar to the toxin resistant pufferfish sodium channels. The source of the toxin is unknown so we investigated the gut microbiota, and found that Clostridium and Vibrio were the most dominant bacteria in T. tridentatus and C. rotundicauda, respectively. Together, this study provides a framework for further understanding of sesquiterpenoids and gut microbiota of these marine chelicerates.

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Toxic Flatworm Egg Plates Serve as a Possible Source of Tetrodotoxin for Pufferfish

Cited by 36 publications

References 37 publications

Seasonal and Spatial Variations in Bacterial Communities From Tetrodotoxin-Bearing and Non-tetrodotoxin-Bearing Clams

Seasonal and Spatial Variations in Bacterial Communities From Tetrodotoxin-Bearing and Non-tetrodotoxin-Bearing Clams

First Detection of Tetrodotoxins in the Cotylean Flatworm Prosthiostomum trilineatum

Hemolymph Proteomics and Gut Microbiota of Horseshoe Crabs Tachypleus tridentatus and Carcinoscorpius rotundicauda

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