In September, 1996, paralytic toxicity was detected incultured oyster Crassostrea gigas and short necked clam Tapes japonica from Hamanako, Shizuoka, Prefecture concomitantry with the apperance of the toxic dinofragellata Alexandrium catenella. The toxicities were 7.9 MU/g for oyster and 10.2 MU/g for short necked clam. The toxin of the bivalves in Hamanako was found to be comprised GTX2 and GTX3 as major component.
Paralytic shellfish poison (PSP) infestation to bivalves due to toxic dinofllagate such as Alexandrium spp. has posed some serious problem on public health and fishery industry. Although their PSP infestation cannot be predicted completely, their PSP monitoring programs have been carried out to protect the consumer and the rear-farmer, from food poisoning and fishery damage, respectively, by the concerning prefectural agency. Therefore, three species of bivalves (mussel Mytilus edulis, hard clam Meretrix lamarckii, surf clam Pseudocardium sachalinensis) in Ibaraki were investigated on their toxicity and PSP composition, from 1990 to 1998 and for four successive years from 1993 to 1996 as well as in 1998, respectively. Further, in order to elucidate their toxification and detoxification mechanisms, the toxicity and PSP composition were investigated using anatomical parts of clams.
Monitoring programs for marine toxins in seafood were limited in large part to mouse bioassays in many countries. However, these assays were criticized from the viewpoints of animal welfare, cost, sensitivity, and efforts required for the assays. It is now clear that replacement of the assay would be desirable. Efforts are being made to develop new methods to replace or to complement mouse bioassays. Cell bioassay, one of those alternative assays, is reviewed here comparing with other methods.
A new polyether marine toxin, brevetoxin B1 and known brevetoxin, PbTx-3, were isolated from the New Zealand shellfish cockle, Austrovenus stutchbu'yi and brevetoxin B1 was elucidat-ed by comparison of its spectral data with those of brevetoxins B and use of NMR techniques. PbTx-2 and 3 were isolated from oyster, Crassostrea gigas, harvested in 1993 at Tiki Road, Coromandel Peninsula, and PbTx-3 also isolated from oysters collected at Rangaunu Harbour in February 1994 and June 1995.
Using spectral and chromatography methods mycotoxin production profiles were exanlined for 19 strains of 12 species of the genus Penicillium fungi. The mycotoxin profiles of the fungi, belonging to P. aurantiogriseum, P. chrysogenum. P. granulatum, P. spinulosum and P. vulpinum species, which were isolated from the various environments at various times, are differed from those, described earlier. Isolates of P. chrysogenum, P. griseofulvum and P. vulpinum produce the alkaloid nature mycotoxins, which were characteristic for these species. Mycofoxins were not detected in P glabrum, P. dangeardii and P. funiculosum species.
The objective of this study is to investigate the structural basis of apoptosis-inducing activity of T-2 toxin in HL-60 human promyelotic leukemia cells. DNA fragmentation pattern in gel electrophoresis and quantitative DNA assay were used to examine the apoptosis-inducing ability of T-2 and its metabolites. Of six kinds of mycotoxins tested, T-2 was found to be the most potent apoptotic agent. The rank order of the potency was T-2>HT-2 > 3'-OH-T-2=NEOS =3'-OH-HT-2=TOL=vehicle control. Since either hydroxylation of T-2 at carbon 3'(C-3') of isovaleryl group (3'-OH-T-2) or hydrolysis of T-2 at C-8 (NEOS) abrogated the apoptosis-inducing ability, it was suggested that intact isovaleryl group of T-2 molecule played an important role in induction of apoptosis in HL-60 cells in vitro.
A simple, rapid and economical minicolumn packed with “lahar” (a local adsorbent material) and Florisil, previously developed for aflatoxins in copra meal, was adopted for corn. In minicolumn experiments for corn, the efficiency of two extraction solvent systems : methanol-4% KCI solution (90+10) and methanol-water (90+10) and of two clarifying agents : 10% CuSO4 and 30% (NH4)2SO4 solutions, was evaluated. The modified minicolumn method using methanol-water (90+10) and 10% CuSO4 solution gave a distinct aflatoxin-derived blue fluorescent band in the Florisil layer under UV light, and was estimated to be applicable to corn at the detection limit of 5 μg/kg of aflatoxin.
The retinoblastoma tumor suppressor gene product, RB protein, is a negative regulator of cell growth and antagonizes c-Myc oncoprotein. We have previously reported that the c-myc gene expression is aberrantly elevated in rat hepatocellular carcinomas induced by aflatoxin B1 (AFB1). In this paper, to elucidate the significance of the overexpression of c-myc gene in AFB1 hepatocarcinogenesis, we analyzed the effects of a human RB cDNA expression vector, pSV2·RB, on the growth and tumorigenicity of Kagura-2 (K2) cells, which have been established from AFB1-induced rat hepatoma and overexpressing c-myc gene just as an original tumor. Even though any effects of exogeneous expression of RB gene on the transcriptional levels of c-myc and glutathione-S-transferase P (GST-P) genes were not detected, pSV2·RB-transfected K2 cells significantly reduced the ability to form colonies in semi-solid medium, and their growth rate was markedly decreased in a lower concentration of serum. Moreover, tumors that formed by the transfectants in nude mice were much smaller, but were histologically indistinguishable from those of parental K2 cells. These results indicate that the enforced expression of RB gene suppresses the growth of K2 cells in vitro and in vivo without any effects on the expression level of c-myc mRNA.
Five moldy corn samples were analyzed for Fusarium mycotoxins including 8-ketotrichothecenes, zeralenone (ZEA), and fumonisins and found to be heavily contaminated with these toxins. Among 8-ketotrichothecenes, deoxynivalenol (DON), 15-acetyl-DON, and nivalenol (NIV) were the major toxins rather than 3-acetyl-DON and 4-acetyl-NIV. In addition, one moldy corn sample was contaminated with iso-DON, which has the same molecular weight of DON. This is the first report iso-DON and DON as well as other Fusarium mycotoxins were occurred in moldy corn from Korea.