scholarly journals Distribution of Tetrodotoxin in Pacific Oysters (Crassostrea gigas)

Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 84
Author(s):  
Monika Dhanji-Rapkova ◽  
Andrew D. Turner ◽  
Craig Baker-Austin ◽  
Jim F. Huggett ◽  
Jennifer M. Ritchie
Keyword(s):  
Digestive Gland ◽  
Crassostrea Gigas ◽  
Safety Concern ◽  
Adductor Muscle ◽  
Marine Bivalve ◽  
Pacific Oysters ◽  
Heat Stable ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Production Area

A potent and heat-stable tetrodotoxin (TTX) has been found to accumulate in various marine bivalve species, including Pacific oysters (Crassostrea gigas), raising a food safety concern. While several studies on geographical occurrence of TTX have been conducted, there is a lack of knowledge about the distribution of the toxin within and between bivalves. We, therefore, measured TTX in the whole flesh, mantle, gills, labial palps, digestive gland, adductor muscle and intravalvular fluid of C. gigas using liquid chromatography-tandem mass spectrometry. Weekly monitoring during summer months revealed the highest TTX concentrations in the digestive gland (up to 242 µg/kg), significantly higher than in other oyster tissues. Intra-population variability of TTX, measured in the whole flesh of each of twenty animals, reached 46% and 32% in the two separate batches, respectively. In addition, an inter-population study was conducted to compare TTX levels at four locations within the oyster production area. TTX concentrations in the whole flesh varied significantly between some of these locations, which was unexplained by the differences in weight of flesh. This is the first study examining TTX distribution in C. gigas and the first confirmation of the preferential accumulation of TTX in oyster digestive gland.

scholarly journals Tissue- and substrate-dependent mitochondrial responses to acute hypoxia-reoxygenation stress in a marine bivalve Crassostrea gigas (Thunberg, 1793)

2021 ◽  
Author(s):  
Linda Adzigbli ◽  
Eugene P. Sokolov ◽  
Siriluck Ponsuksili ◽  
Inna M. Sokolova
Keyword(s):  
Digestive Gland ◽  
Crassostrea Gigas ◽  
Acute Hypoxia ◽  
Aquatic Organisms ◽  
Acid Oxidation ◽  
Ros Generation ◽  
Marine Bivalve ◽  
Ros Production ◽  
Succinate Oxidation ◽  
Hypoxia Reoxygenation

Hypoxia is a major stressor for aquatic organisms, yet intertidal organisms like the oyster Crassostrea gigas are adapted to frequent oxygen fluctuations by metabolically adjusting to shifts in oxygen and substrate availability during hypoxia-reoxygenation (H/R). We investigated the effects of acute H/R stress (15 min at ∼0% O2, and 10 min reoxygenation) on isolated mitochondria from the gill and the digestive gland of C. gigas respiring on different substrates (pyruvate, glutamate, succinate, palmitate and their mixtures). Gill mitochondria showed better capacity for amino acid and fatty acid oxidation compared to the mitochondria from the digestive gland. Mitochondrial responses to H/R stress strongly depended on the substrate and the activity state of mitochondria. In mitochondria oxidizing NADH-linked substrates exposure to H/R stress suppressed oxygen consumption and ROS generation in the resting state, whereas in the ADP-stimulated state, ROS production increased despite little change in respiration. As a result, electron leak (measured as H2O2 to O2 ratio) increased after H/R stress in the ADP-stimulated mitochondria with NADH-linked substrates. In contrast, H/R exposure stimulated succinate-driven respiration without an increase in electron leak. Reverse electron transport (RET) did not significantly contribute to succinate-driven ROS production in oyster mitochondria except for a slight increase in the OXPHOS state during post-hypoxic recovery. A decrease in NADH-driven respiration and ROS production, enhanced capacity for succinate oxidation and resistance to RET might assist in post-hypoxic recovery of oysters mitigating oxidative stress and supporting rapid ATP re-synthesis during oxygen fluctuations such as commonly observed in estuaries and intertidal zones.

Stegotricha enterikos gen.nov., sp.nov. (class Phyllopharyngea, order Rhynchodida), a parasitic ciliate in the digestive gland of Pacific oysters (Crassostrea gigas), and its distribution in British Columbia

1993 ◽  
Vol 71 (10) ◽  
pp. 2005-2017 ◽  
Author(s):  
S. M. Bower ◽  
G. R. Meyer
Keyword(s):  
British Columbia ◽  
Digestive Gland ◽  
Crassostrea Gigas ◽  
The Other ◽  
Binary Fission ◽  
New Family ◽  
Pacific Oysters ◽  
Wet Mount ◽  
The Family ◽  
Gland Tissue

Stegotricha enterikos gen.nov., sp.nov. is found in the lumen of the digestive gland tubules of Pacific oysters (Crassostrea gigas (Thunberg, 1793)), where it multiplies by transverse binary fission. Nondividing stages have an elongated ovoid body (49.8 ± 10.3 μm long and 18.1 ± 3.4 μm wide) covered by about 16 evenly spaced, slightly oblique kineties (ciliary rows), except for a small naked area on one side of the posterior end. One kinety, associated with the naked area, is unusual, with cilia spaced two to three times as far apart as in the other somatic kineties. A cytopharyngeal structure composed of radially arrayed overlapping sheets of microtubules occurs at the anterior end and occasionally encompasses extrusomes. The centrally located macronucleus is large (about 16 × 12 μm) and the micronucleus (about 2.5 μm in diameter) is either posterior or anterior to the macronucleus. Except for the extent of ciliation, S. enterikos is most closely affiliated with the family Ancistrocomidae. Instead of creating a new family, we suggest that the diagnosis of the Ancistrocomidae be expanded to include ciliates with complete ciliation. Stegotricha enterikos was found in 2.5–72.5% of the oysters (n = 40) sampled between November 1985 and March 1990 from 35 localities in British Columbia. Most infections (86%) were light (1–9 ciliates per wet mount of digestive gland tissue). However, there was no evidence of pathogenesis in 22 oysters with heavy infections (more than 25 ciliates per wet mount).

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