Pen shell (Atrina cf. japonica) resources have been devastated in Ariake Bay, Japan, and to facilitate the recovery of this species, there is an urgent need to fully understand the factors contributing to its high levels of mortality. Pen shells living in natural waters grow through successive life stages, and environmental factors may affect these bivalves differently at different stages.
View Article and Find Full Text PDFBeing the precursor of serotonin and melatonin, dietary supplementation with tryptophan (TRP) may modulates behavior, stress responses, and antioxidant capacity in fish. In this study, effects of Chattonella exposure on the swimming behavior and brain monoamine metabolism of yellowtail fed a commercial diet (control diet) or that enriched by 1.5% L-TRP (TRP + diet) were investigated.
View Article and Find Full Text PDFThe identification and quantification of okadaic acid (OA)/dinophysistoxin (DTX) analogues and pectenotoxins (PTXs) in samples collected from coastal locations around Japan were evaluated by liquid chromatography mass spectrometry. The species identified and analyzed included , , (), , , , , (), and . The dominant toxin found in was PTX2 although some samples contained DTX1 as a minor toxin.
View Article and Find Full Text PDFLactate dehydrogenase (LDH)-release assay was applied to estimate the toxic potential of harmful algal species at the cellular level. African green monkey kidney (Vero), yellowtail fin epithelia (MJF), and rainbow trout gill (RTgill-W1) cells were used as target cells. A live cell suspension of Karenia mikimotoi (SUO-1) induced the release of LDH from these cell lines, while the activity of another strain, FUK, was much lower.
View Article and Find Full Text PDFHeterocapsa circularisquama showed much higher toxic effects on short-necked clams than Chattonella marina. Clams exposed to H. circularisquama exhibited morphological changes concomitant with an accumulation of mucus-like substances in the gills, a profound reduction in filtration activity, and lysosomal destabilization in hemocytes.
View Article and Find Full Text PDFThe biological toxic potentials of aqueous extracts from the dinophycean flagellates Gymnodinium impudicum and Alexandrium affine and the raphidophycean flagellate Chattonella ovata were examined in both in vitro and in vivo systems. Interestingly, the extract from A. affine was the only one that showed potent cytotoxicities towards HeLa, Vero, and Neuro-2a cells in a concentration-dependent manner.
View Article and Find Full Text PDFTo elucidate the ichthyotoxic mechanism of the harmful dinoflagellate Cochlodinium polykrikoides, a bioassay using damselfish was conducted. After exposure to a live-cell suspension of C. polykrikoides, all the fish were died within 90 min.
View Article and Find Full Text PDFOur recent studies have demonstrated that the aqueous extract prepared from Alexandrium tamarense, a harmful red tide phytoplankton, showed cytotoxicity on Vero cells. In this study, the toxic substance was purified from the culture supernatant of A. tamarense.
View Article and Find Full Text PDFIn a previous study of ours, the superoxide scavenging activity of aqueous extracts from dinophycean red tide flagellates was detected by an electron spin resonance (ESR)-spin trapping method, but not by an L-012 (luminol analog)-dependent chemiluminescence (CL) method. To investigate the discrepancy between the two methods, the effect of ferric-protein complexes on superoxide scavenging activity was examined. The reduced signal intensity of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO)-OOH due to superoxide dismutase (SOD) did not change with the addition of horseradish peroxidase (HRP), while the reduced CL response due to SOD was restored by the addition of different concentrations of HRP.
View Article and Find Full Text PDFBiosci Biotechnol Biochem
May 2007
The antioxidant properties of aqueous extracts from the dinophycean flagellates Gymnodinium impudicum and Alexandrium affine and the raphidophycean flagellate Chattonella ovata were examined. An electron spin resonance (ESR)-spin trapping method coupled with steady state kinetic analysis showed that all of the extracts directly scavenge superoxide, and that the superoxide scavenging potential of any of the extracts was comparable to that of L-ascorbic acid. As for hydroxyl radical scavenging, the Fenton reaction and the method of ultraviolet radiation to hydrogen peroxide were used as hydroxyl radical generation systems.
View Article and Find Full Text PDFBiosci Biotechnol Biochem
March 2007
Recent studies indicate that some raphidophycean red tide flagellates produce substances able to scavenge superoxide, whereas there have been no reports on superoxide scavenger production by dinophycean red tide flagellates. In this study, we examined the superoxide-scavenging activity of aqueous extracts from dinophycean red tide flagellates, Gymnodinium spp., Scrippsiella trochoidea, and Karenia sp.
View Article and Find Full Text PDFStrain MS-02-063, gamma-proteobacterium, isolated from a coast area of Nagasaki, Japan, produced a red pigment which belongs to prodigiosin members. This pigment, PG-L-1, showed potent algicidal activity against various red tide phytoplanktons in a concentration-dependent manner. An understanding of a mechanism of PG-L-1 production by this marine bacterium may yield important new insights and strategies for preventing blooms of harmful flagellate algae in natural marine environments.
View Article and Find Full Text PDFWe found that the red tide dinoflagellate Karenia mikimotoi (Gymnodinium mikimotoi) generates reactive oxygen species (ROS). In chemiluminescence analysis using an O2- specific probe, a slightly lower but significant level of O2- was detected in a K. mikimotoi cell suspension as compared to one containing Chattonella marina, a well-known ROS-producing red tide phytoplankton.
View Article and Find Full Text PDFComp Biochem Physiol C Toxicol Pharmacol
August 2002
Cochlodinium polykrikoides, a harmful red tide dinoflagellate, is highly toxic to fish, but the toxic mechanism is still unknown. Recent study has suggested that C. polykrikoides generates reactive oxygen species (ROS) such as superoxide anion (O(2)(-)) and hydrogen peroxide (H(2)O(2)), and the ROS-mediated ichthyotoxicity has been proposed.
View Article and Find Full Text PDFHeterocapsa circularisquama (Dinophyceae), a red tide dinoflagellate, is toxic to bivalve molluscs such as the pearl oyster (Pinctada fucata), but no harmful effects of this alga on fish have been observed so far. We found that 7 strains of H. circularisquama showed hemolytic activities toward rabbit erythrocytes in a cell-density dependent manner, but to quite different extents.
View Article and Find Full Text PDFRed tides of Heterocapsa circularisquama (H. circularisquama), recently identified as a novel species of dinoflagellate, have frequently caused mass mortality of several species of bivalves in Japan, while no harmful effects of this flagellate on fish have been reported so far. We found that the cell-free ethanol extract prepared from H.
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