Publications by authors named "Chun Fai Yu"

Tetrodotoxin (TTX) is a potent neurotoxin isolated mainly from toxic puffer fish. To date, the TTX biosynthetic mechanism inside its hosts remains unresolved. Here, we hypothesize the TTX synthesis relies on the host gut microbiota, including the neglected non-culturable bacteria.

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A rapid and simple detection method for tetrodotoxin (TTX) in urine and plasma of patients with puffer fish poisoning was developed using commercially pre-packed solid-phase extraction (SPE) cartridges (C18 and weak cation exchange columns) and subsequent analyses by HPLC with UV detection. The detection limit of the standard TTX, TTX-spiked urine and plasma samples were all 10 ng/ml and the average TTX recovery in urine and plasma samples after SPE were 90.3 +/- 4.

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Article Synopsis
  • Fatal food poisonings from pufferfish in Cambodia have been ongoing for decades, with no previous documentation of the toxins or species involved.
  • Researchers studied three pufferfish species from the coastal waters of Sihanouk Ville, finding that two species, L. wheeleri and L. spadiceus, were non-toxic, while L. lunaris was toxic with elevated toxicity levels in all body tissues.
  • Tetrodotoxin (TTX) was identified as the primary toxin in L. lunaris, confirming it as a dangerous source of TTX and likely responsible for past poisonings in Cambodia.
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The toxicity of two species of wild Cambodian freshwater pufferfish of the genus Tetraodon, T. turgidus and Tetraodon sp., was investigated.

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Article Synopsis
  • The study examined the toxicity of the horseshoe crab Carcinoscorpius rotundicauda from Cambodia during both rainy and dry seasons.
  • The bioassay results indicated significant variability in toxicity levels, with tetrodotoxin (TTX) identified as the primary toxin, while no paralytic shellfish toxins were found.
  • Despite being classified as moderately toxic, the horseshoe crabs are deemed unsafe for human consumption, marking this research as the first on toxic marine seafood in Cambodian waters.
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Out of eight dominant discrete bacterial colonies isolated and purified from the toxic marine puffer fishes collected in Hong Kong waters, two novel species of non-sporing, non-acid-fast and chemoorganotrophic bacteria capable of producing tetrodotoxin (TTX, a potent non-protein neurotoxin), as well as one previously reported and confirmed TTX-producing bacterium. They were identified as Microbacterium arabinogalactanolyticum, Serratia marcescens and Vibrio alginolyticus, respectively, all of which are widely distributed in soils, sewage or marine environments. Each bacterial isolate (500 ml broth medium cultured in darkness without aeration for 10 days at 25 degrees C) could produce an amount of toxicity, after extraction and purification, ranging from 78.

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The toxicological profiles of two local common puffer fish, Takifugu niphobles (Jordan and Snyder) and Takifugu alboplumbeus (Richardson), collected in Hong Kong waters were investigated continuously for 14 months (June 1997-August 1998). Their annual spawning seasons (as evident by the enlargement of gonads and presence of eggs in the ovary) were found to be from October to February (four consecutive months) and December to February (two consecutive months), respectively. The toxicities of their internal organs were determined by standard mouse bioassay and expressed in terms of mouse units (MU).

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