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Start date: 2022Has files: No

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    Microbiological Quality and Heavy Metal Concentrations in Slipper Oyster (Crassostrea iredalei) Cultured in Major Growing Areas in Capiz Province, Western Visayas, Philippines: Compliance with International Shellfish Safety and Sanitation Standards
    Pakingking, Rolando; Hualde, Lilibeth; Peralta, Ernestina; Faisan, Joseph; Usero, Roselyn (International Association for Food Protection, 2022)
    The increasing demand for slipper oyster (Crassostrea iredalei) has propelled farmers to expand oyster cultivation areas in the Philippines, chiefly for local consumption and feasibly for export overseas. As filter feeders, oysters can accumulate pathogens from the surrounding waters, and these pathogens can cause foodborne diseases in consumers. Therefore, oyster farming areas must be monitored for microbiological quality and heavy metal concentrations. In the present study, the microbiological quality of oysters and their growing waters in the major oyster farming areas of the Cogon and Palina Rivers and Cabugao Bay (in Roxas City and the Municipality of Ivisan, respectively, Capiz Province, Western Visayas, Philippines) were examined monthly during the wet (May to October) and dry (November to April) seasons over 12 months. Regardless of the sampling period, high levels of fecal coliforms in the water and Escherichia coli in oysters were found, clearly illustrating that these oyster growing areas would meet only the class B standard under the European Union classification system and would be considered “prohibited” for growing oysters under the U.S. classification system. Although Salmonella was occasionally detected in oysters, Vibrio cholerae was not detected and Vibrio parahaemolyticus was within acceptable limits. The heavy metal concentrations in oyster meat were also determined during the wet (July) and dry (March) seasons. Zinc and copper were the most abundant metals detected, and concentrations of lead, cadmium, mercury, and chromium were below the regulatory limits set by the European Union and the U.S. Food and Drug Administration. These oyster culture areas should be rehabilitated immediately to improve the microbiological quality of the oysters. Oysters harvested from these sites must be depurated or relayed to ensure quality and safety. Copyright ©, International Association for Food Protection
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    Comparative biochemical characterization of pufferfish saxitoxin and tetrodotoxin-binding protein (PSTBP) homologs in the plasma from four Takifugu species: Conservation of heat-stable PSTBP orthologs having three and two tandemly repeated lipocalin domains in genus Takifugu
    Zhang, Yafei; Ueno, Mikinori; Tatsuno, Ryohei; Takatani, Tomohiro; Shimasaki, Yohei; Arima, Kazunari; Sedanza, Mary Grace; Yamaguchi, Kenichi; Oshima, Yuji; Arakawa, Osamu (Elsevier, 2025)
    To study the relationship between domain characteristics of pufferfish saxitoxin and tetrodotoxin binding protein (PSTBP) proteoforms and their thermal stability, a comparative biochemical characterization of PSTBPs from the plasma of four Takifugu species (T. flavipterus, T. pardalis, T. alboplumbeus and T. rubripes) was conducted by Western blot analysis. The heat-tolerance tetrodotoxin (TTX)-binding ability of PSTBP proteoforms in T. rubripes plasma was verified by ultrafiltration and liquid chromatography tandem mass spectrometry (LC-MS/MS). These results suggest that the heat-stable PSTBP proteoforms, composed of three and two tandemly repeated lipocalin domains, are genetically conserved and ubiquitous in the genus Takifugu. This study builds on our knowledge of the structural and functional properties of PSTBP proteoforms, which is vital for understanding how toxins are transmitted and accumulate in organisms and is essential for evaluating the potential risks of toxins in seafood.
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    Structural, electronic, and optical properties of copper doped monolayer molybdenum disulfide: A density functional theory study
    Ducut, Melsa Rose D.; Rojas, Kurt Irvin M.; Bautista, Reilly V.; Arboleda, Nelson B. Jr. (Elsevier, 2025)
    We conducted first-principles calculations to investigate the effect of doping monolayer molybdenum disulfide (MoS2) with Cu in its structural, electronic, and optical properties. We found that Cu doping changes the material from an n-type semiconductor into a p-type semiconductor by shifting the Fermi energy level towards the valence band in all variations of concentration and site. The absorption coefficient, photoconductivity, and reflectivity calculations indicate that Cu-doped MoS2 is sensitive to violet light. In addition, Cu doping elevates the sensitivity of the material to low-energy light. These results show that Cu-doped MoS2 can be used in optoelectronic applications.