[Tetrodotoxin Content of the Small Gastropod Nassarius sufflatus].

Severe tetrodotoxin (TTX) poisoning due to small gastropods has been documented in Japan. In this study, we investigated the TTX content of the muscles and viscera of Nassarius sufflatus collected off the coast of Futaoi Island, Shimonoseki, Yamaguchi Prefecture, Japan, to prevent the occurrence of TTX poisoning caused by this small gastropod. Live specimens were obtained, and their muscles and viscera were collected. Test solutions were prepared from tissues of specimens and analyzed for TTX by HPLC-fluorescence detection. TTX was detected in both tissues at concentrations ranging from <0.1 to 18.2 µg/g for muscle and <0.1 to 130.7 µg/g for viscera. These results suggested that N. sufflatus accumulates TTX not only in its viscera but also in its muscles, and that precautions should be taken to prevent food poisoning due to this gastropod.

[Toxicity of Takifugu exascurusCollected from the Sea of Kumano].

Marine pufferfish Takifugu exascurus is not approved for human consumption due to the lack of information on its toxicity. To clarify the toxicity of T. exascurus, ten live specimens were collected from the Sea of Kumano, Japan, and the toxicity and tetrodotoxin (TTX) concentration were determined using mouse bioassay and high performance liquid chromatography-fluorescence detection (HPLC-FLD), respectively. Toxicity was observed in the skin, liver, and ovaries, but the testes and muscle were non-toxic (<10 MU/g). On the other hand, HPLC-FLD revealed that TTX was detected in the muscle in two of the 10 specimens (1.4 and 1.5 MU/g). Based on the results, TTX is the main toxic component contributing to toxicity in T. exascurus.

Similarity in the Structure of tetD-Carrying Mobile Genetic Elements in Bacterial Strains of Different Genera Isolated from Cultured Yellowtail.

Structure analysis was performed on the antibiotic-resistance-gene region of conjugative plasmids of four fish farm bacteria.The kanamycin resistance gene, IS26, and tetracycline resistance gene (tetA(D)) were flanked by two IS26s in opposite orientation in Citrobacter sp. TA3 and TA6, and Alteromonas sp. TA55 from fish farm A. IS26-Inner was disrupted with ISRSB101. The chloramphenicol resistance gene, IS26 and tetA (D) were flanked by two IS26s in direct orientation in Salmonella sp. TC67 from farm C. Structures of tetA (D) and IS26 were identical among the four bacteria, but there was no insertion within the IS26-Inner of Salmonella sp. TC67. Horizontal gene transfer between the strains of two different genera in fish farm A was suggested by the structure homologies of mobile genetic elements and antibiotic resistance genes.

Antioxidant activities of two sericin proteins extracted from cocoon of silkworm (Bombyx mori) measured by DPPH, chemiluminescence, ORAC and ESR methods.

Recent efforts have focused on the use of sericin proteins extracted from cocoons of silkworm as a healthy food source for human consumption. In this study, we focused on the antioxidative properties of sericin proteins. The antioxidative properties were measured in sericin proteins extracted from the shell of the cocoon, designated hereafter as white sericin protein and yellow-green sericin protein, as well as bread without sericin protein and bread to which white sericin powder had been added using four measurement methods: 1,1-Diphenyl-2-picrylhydrazyl (DPPH), chemiluminescence, oxygen radical absorbance capacity (ORAC) and electron spin resonance (ESR). High antioxidative properties of sericin proteins were indicated by all four methods. A comparison of the two types of sericin proteins revealed that yellow-green sericin protein exhibited high antioxidative properties as indicated by the DPPH, chemiluminescence and ORAC methods. By contrast, a higher antioxidative property was determined in white sericin protein by the ESR method. Consequently, our findings confirmed that sericin proteins have antioxidative properties against multiple radicals. In addition, the antioxidative property of bread was enhanced by the addition of sericin powder to the bread. Therefore, findings of this study suggest that sericin proteins may be efficiently used as beneficial food for human health.

Molecular orientation and multilayer formation in the adsorbed film of 1H,1H,10H,10H-perfluorodecane-1,10-diol at the hexane/water interface; pressure effect on the adsorption of fluoroalkane-diol.

The adsorption of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC10diol) at the hexane solution/water interface was investigated by the measurement of interfacial tension gamma as a function of pressure p and concentration m1 and the thermodynamic data analysis. The results obtained were compared with those of 1H,1H,2H,2H-perfluorodecanol (TFC10OH) in order to clarify the effect of molecular orientation on the structure and property of the adsorbed film from the viewpoint of volume change of adsorption. The interfacial pressure pi versus mean area per adsorbed molecule A curve revealed two types of phase transitions among expanded, parallel condensed, and multilayer states. The A value in the condensed state and the transition pressure between the expanded and condensed states were larger for FC10diol than for TFC10OH, which manifests the different molecular orientation that the dispersion interaction between hydrophobic chains is weaker in the parallel orientation of FC10diol than in the perpendicular orientation of TFC10OH. The partial molar volume of FC10diol in the condensed state nu1H.C is slightly larger than that of TFC10OH, although the partial molar volume in the hexane solution is much smaller for FC10diol than for TFC10OH. This supports the view that the fluorocarbon chains of FC10diol remain in their contact with hexane even in the condensed film because of the parallel molecular orientation. The partial molar volume in the nu1H,M was very close to the molar volume of solid FC10diol nu1S and smaller than that of nu1H.C at the condensed-multilayer phase transition, and increased gradually with molecular piling. This substantiates that FC10diol molecules are densely packed in a first few layers just above the phase transition and a little loosely packed in the upper layers of the multilayer with increasing molecular piling. Furthermore, the volume change associated with adsorption from the solid FC10diol Delta(nu)(S) evaluated from the gamma versus p curve under the existence of solid deposit was positive and showed a minimum against concentration for the multilayer state. This is primarily due to the minimum in interfacial density at the solubility limit Gamma1H,S and thus due to the minimum in nu1H,M.

Molecular orientation and multilayer formation of 1H,1H,8H,8H-perfluorooctane-1,8-diol at the air/water interface.

The surface tension of the aqueous solution of 1H,1H,8H,8H-perfluorooctane-1,8-diol (FC(8)diol) was measured as a function of temperature and concentration under atmospheric pressure. The interfacial density and the entropy and energy of adsorption were evaluated and compared to those obtained for the adsorption of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC(10)diol) at the hexane solution/water interface. The surface tension curves show a break point corresponding to a phase transition of the adsorbed FC(8)diol film. The value of mean area per adsorbed molecule A just below the phase transition indicated the formation of a parallel condensed monolayer, and that above the phase transition suggested the spontaneous formation of a multilayer. The multilayer of FC(8)diol is less compressible and shows a smaller increase in layering with pi compared to FC(10)diol. This is probably because the surface force is repulsive for the hexane/FC/water interface, while it is attractive for the air/FC/water interface. The partial molar entropy change of adsorption is positive in the condensed FC(8)diol film, while it is negative in the condensed FC(10)diol film, which is reasonably explained in terms of the difference in entropy change accompanied by desolvation around the hydrophobic chain. From the viewpoints of the energetic stabilization accompanied by adsorption for the FC(8)diol system, the contribution from the replacement of air/water contact with air/fluorocarbon and fluorocarbon/water contacts and that from the molecular ordering in the adsorbed film is almost equal in case of the condensed monolayer, while in the multilayer the latter is comparatively larger than the former due to the hydrogen bonding between hydroxyl groups and the dispersion interaction among the ordered hydrophobic chains.

Cr(VI) reduction from contaminated soils by Aspergillus sp. N2 and Penicillium sp. N3 isolated from chromium deposits.

Aspergillus sp. N2 and Penicillium sp. N3 are chromate-resistant filamentous fungi that were isolated from Cr(VI) contaminated soil based on their ability to decrease hexavalent chromium levels in the growth medium. After 120 h of growth in a medium containing 50 ppm Cr(VI) at near neutral pH, Aspergillus sp. N2 reduced the Cr(VI) concentration by about 75%. Penicillium sp. N3 was able to reduce the Cr(VI) concentration by only 35%. However, Penicillium sp. N3 reduced the Cr(VI) concentration in the medium by 93% under acidic conditions. Interestingly, the presence of Cu(II) enhanced the Cr(VI) reducing ability of Aspergillus sp. N2 and Penicillium sp. N3 at near neutral pH. Aspergillus sp. N2 and Penicillium sp. N3 reduced the Cr(VI) concentration in the growth medium to a virtually undetectable level within 120 h. For both Aspergillus sp. N2 and Penicillium sp. N3, mycelial seed cultures were more efficient at Cr(VI) reduction than conidium seed cultures. The mechanisms of Cr(VI) reduction in Aspergillus sp. N2 and Penicillium sp. N3 were enzymatic reduction and sorption to mycelia. Enzymatic activity contributed significantly to Cr(VI) reduction. Aspergillus sp. N2 and Penicillium sp. N3 reduced the levels of Cr(VI) in polluted soil samples, suggesting that these strains might be useful for cleaning up chromium-contaminated sites.