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  • Alex J. Salazar-Medina, Leticia García-Rico, Karina D. García-Orozco, Elisa Valenzuela-Soto, Carmen A. Contreras-Vergara, Rodrigo Arreola, Aldo Arvizu-Flores,1 and Rogerio R. Sotelo-Mundo. Inhibition by Cu2+ and Cd2+ of a Mu-Class Glutathione S-Transferase from Shrimp itopenaeus vannamei. J BIOCHEM MOLECULAR TOXICOLOGY Volume 24, Number 4, 2010

    Glutathione S-transferases (GSTs) are a family of detoxifying enzymes that atalyze the conjugation of glutathione (GSH) to electrophiles, thereby increasing the olubility of xenobiotics and aiding its excretion from the cell. The present work presents the
    inhibition of a mu-class GST of the marine shrimp Litopenaeus vannamei by copper (Cu2+) and cadmium (Cd2+). The protein was overexpressed in bacteria and its enzymatic activity measured using 1-chloro- 2,4-dinitrobenzene. The mean inhibitory concentration (IC50) for shrimp GST against Cu2+ was 4.77 μM and for Cd2+ was 0.39 μM. A molecular model of the protein
    based on the crystal structure of a maize GST bound to cadmium showed that the metal binds in
    the GSH-binding site by coordination with Asp and Gln residues. These results are consistent with the experimental data and suggest that sublethal concentration of metals may affect the capacity of the organism to detoxify pesticides or xenobiotics.

    L. García-Rico, L. Tejeda-Valenzuela, A. Burgos-Hernández. Seasonal Variations in the Concentrations of Metals in Crassostrea corteziensis from Sonora, México. Bull Environ Contam Toxicol (2010) 85:209–213

    This study examines seasonal variations in the concentrations of Cd, Cu, Pb, and Hg in experimentally cultured Crassostrea corteziensis, an oyster species known to have high resistance to physical and chemical stressors. The highest levels of Cd (4.92 mg/kg), Cu (3.45 mg/kg), and Pb (0.67 mg/kg) were detected in oyster samples collected
    during the summer, while Hg concentrations were similar (0.03 to 0.04 mg/kg) throughout all seasons. Results indicate that except for Cd, Crassostrea corteziensis accumulates
    metals to levels below those recommended by the US. FDA and the Mexican government. For Cd, its concentration correlates more strongly with the temperature of the oyster’s environment rather than to the oyster growth cycle.

    Luıs Eliseo Ochoa-Valenzuela, Agustín Gómez-Alvarez, Leticia García-Rico and Arturo Israel Villalba-Atondo. Distribution of heavy metals in surface sediments of the
    Bacochibampo Bay, Sonora, Mexico
    Chemical Speciation and Bioavailability (2009), 21(4)

    The aim of this study was to determine the levels of heavy metals (Al, Cd, Cr, Cu, Fe, Mn and Pb) in the geochemical fractions of the coastal surface sediments from the Bacochibampo Bay in Sonora, Mexico. Two surveys were conducted (March and September) during 2004, at eight sampling stations inside the bay, and in three natural effluents discharged into this bay. The extraction of metals was carried out using a microwave oven method and the quantification was done by atomic absorption spectrophotometry. The highest detected concentration of total heavy metals in sediments was: Fe4Al4Mn4Pb4Cr4Cu4Cd, with the following concentration values: Fe (1.72%), Al (1.03%), Mn (416.31mg kg1), Pb (11.73mg kg1), Cr (11.41mg kg1), Cu (6.78mg kg1) and Cd (1.33mg kg1). The levels of total heavy metals (Al, Cr, Cu, Fe, Mn and Pb) were much less than the lowest observable effect level (LEL) which indicates that the sediments were not from polluted areas and that the origin of the metals was due to natural conditions. However, concentrations of Cd were much higher than the low effect level (LEL), over 40% of metal was detected in the exchangeable fraction and carbonates. The normalisation study showed a high degree of enrichment of Cd in all the sampling stations in the Bacochibampo Bay (samples EF 34– 87) and in the natural flows that discharge into this bay (samples EF 22–35%), which exceeds by several orders of magnitude the value of sample EF 1, which indicates that Cd is anthropogenically induced. Based on these results, it is important that precautionary measures are established, since the deposited Cd in these fractions may be potentially toxic, due to the physicochemical changes that occur in the environment. Thus, future studies will focus on identifying problems involved with Cd bioaccumulation in different trophic levels.

    Leticia García-Rico, Johanna Leyva-Perez, Martin E. Jara-Marini. Content and daily intake of copper, zinc, lead, cadmium, and mercury from dietary supplements in Mexico. Food and Chemical Toxicology 45 (2007) 1599–1605.BAJAR PDF

    This study investigates the presence of Cu, Zn, Cd, Pb, and Hg in 24 dietary supplements purchased in different health stores across the city of Hermosillo, located in the northwest of Mexico. Analysis of metals was done by microwave digestion and atomic absorption
    spectroscopy. The most abundant elements in dietary supplements were Cu (<0.19–137.85 lg/g) and Zn (<2.83–4785.71 lg/g), followed by Pb (<0.003–66.32 lg/g), Cd (<0.001–2.90 lg/g), and Hg (<0.24–0.85 lg/g). The estimated daily intakes of metals were below those recommended by WHO and the Institute of Medicine, showing that little risk from heavy metals is associated with the consumption of the dietary supplements analyzed. However, some products presented more than 10% of the tolerable daily intake of Pb, indicating that production processes should be improved.

    L. García-Rico, Mercedes Valenzuela Rodríguez, Jara-Marini M (2006). Geochemistry of Mercury in sediment of Oyster Areas in Sonora, Mexico. Marine Pollution. 52: 453-458.

    M.E. Jara-Marini and L. García-Rico (2006). Distribution of arsenic in three geochemical fractions of surface sediments from coastal sites of Sonora, Mexico (Gulf of California). Bull. Environ. Contam. 76:677-683.

    Leticia García-Rico, María Sonia Soto-Cruz, Martín E. Jara-Marini, Agustín Gómez- Álvarez. (2004) Fracciones geoquímicas de Cd, Cu y Pb en sedimentos marinos superficiales de zonas ostrícolas del estado de Sonora, México. Rev. Int. Contam. Amb. 3(20):159-167.

    L. García-Rico, S. Wilson-Cruz, M.C. Frasquillo-Félix, M.E. Jara-Marini. (2003). Total Metals in Intertidal Surface Sediment of oyster culture areas in Sonora, Mexico. Bull. Environ. Contam. 70(6):1235-1241.

    García-Rico, L., Frasquillo-Félix, Carmen, Robles-Burgueño, M. R. y Jara-Marini. (2002). Determination of cadmium and zinc and its relationship to metallothionein levels in swine kidney. Rev. Int. Cont. Ambient. 18 (4):157-162. BAJAR PDF

    García-Rico, L., Ramos. R. E. , Vivian, J. 2001. Determination of Total Metals in Cultivated Oysters (Crassostrea gigas) from the Northwest Coast of Mexico by Microwave Digestion and Atomic Absorption Spectrometry. JOURNAL OF AOAC INTERNATIONAL VOL. 84, NO. 6, 2001. pp.1909-1913.

    Bivalves such as oysters often accumulate heavy metals, and therefore can be used to monitor
    changes of pollutant concentrations in the environment. Cultivated oysters from the northwest coast of Mexico are widely used for human consumption and thus have an important commercial value. Information was gathered on the concentration of these elements in oysters Crassostrea gigas) cultivated on the coast of Sonora. Oysters were randomly collected from April to october 1997, from 6 different locations (65 individuals per site) in 4 different months. Metals were determined by microwave digestion followed by atomic absorption spectroscopy. The mean values (mg/g fresh weight)for each metal were: Cd, 0.76; Cu, 3.64; Zn, 17.71; Pb, 0.50; As, 0.05; Hg, 0.03; and Se, 0.21. The results show that, except for Cd, concentrations of
    regulated metals were under the maximum permitted values specified by regulatory agencies of
    Mexico and were comparable to those reported from other areas.

    García-Rico, L., Robles-Burgueño, M. R. y Valenzuela-Soto, E. 1999. Las metalotioneínas y el metabolismo del cadmio en mamíferos. Rev. Int. Cont. Ambient. Vol.15.No.2.

    García-Rico, L. y Jara Marini, M. E. 1996. Aplicación de Microondas en la Digestión de Hígado de Bovino para la Cuantificación de Metales Pesados. Rev. Int. Contam. Ambient. Vol. 12, No. 1.

    Las metalotoneinas y su relación con la toxicidad del cadmio en los animales. BAJAR PDF


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