Mairin Lemus

Histopathological changes in gill, liver and kidney of neotropical fish Colossoma macropomum exposed to paraquat at different temperatures.

This work focused on the histological alterations in gill, liver and kidney of fish Colossoma macropomum exposed to different temperatures (18°C, 29°C, 35°C) with 10mg/L of herbicide Paraquat (PQ), during 21 days. The fish exhibited histopathological changes in these tissues; the most important alteration in gills was telangiectasis. Liver showed debris accumulation inside cytoplasm hepatocytes, karyolysis, karyohesis and a decrease in the size of sinusoids. Hyperplasia of melanomacrophagic centers (MMC) and an increase in basophils were observed in kidney. The lesion inducing by PQ and the damage in tissue depended of temperature exposure fish. The severity of lesions clearly differed among organs with the liver showing the most extensive damages followed in order by the kidney and gills. In PQ/18°C group it was observed the changes in the pattern of lesions, with kidney showing higher damage followed gills and liver.

Paraquat and temperature affect nonspecific immune response of Colossoma macropomum

This study evaluated the effect of paraquat (PQ) and temperature on hematological parameters and nonspecific immune system of fish Colossoma macropomum (Cachama). Juveniles were used for all experiments. Fish were exposed to three temperatures (18, 28, 35°C) and 10mg/L PQ during 21 days (PQ LC(50) 96h was of 48.05mg/L). Hematological (Hb, Ht, VCM, HCM and CHCM and RBC) and immunological parameters (WBC, differential count of white cells, phagocytes, and bacterial killing by phagocytes) were analyzed for 7, 14 and 21 days. Fishes PQ exposed at 18°C decreased Hb, MCH and MCHC; we observed sickle erythrocytes in control group at 18°C, and in PQ-exposed groups at 18 and 35°C. Immunological parameters were not affected by temperature. Neutrophils decreased significantly in all PQ-exposed groups. Bacterial killing by phagocytes decreased in 18 and 35°C PQ-groups; a synergistic interaction was shown between PQ and temperature on WBC and lymphocytes. These results indicate that PQ affected neutrophils counts independently of temperature exposure; the temperature exerted a synergistic effect on PQ toxicity in lymphocyte counts and phagocytic response and besides nonspecific immune response, PQ and temperature affects hematological parameters such as Hb, MCH, MCHC and erythrocytes morphology.

Niveles de mercurio en sedimentos de la zona costera de El Oro, Ecuador

The total content of Hg was evaluated in surface sediments at three localities in the coastal area of the province of El Oro, Ecuador. In each locality nine area of sampling were established, in which the total solids (ST), humidity (H), organic matter (MO) and Hg was analyzed. The Hg concentration was determined by atomic absorption spectrophotometry, by hydride generation with atomization in a quartz cell. The concentrations of Hg showed signifi cant differences between localities, with the largest concentration in the Huayla estuary (range: 6,57-7,61 mg kg-1) and the lowest in Bajo Alto (range: 3,46-4,83 mg kg-1). The levels of Hg in sediments suggest a clear anthropic incorporation in the three localities of the coastal profi le of the province of El Oro, which represent a risk to the biota and human health.

Contenido de boro en plantaciones de café ("Coffea arabica" L.) en dos localidades cafetaleras de Venezuela

Con el objetivo de determinar el estatus de boro en plantaciones de cafe (Coffea arabica L.) para Venezuela se muestrearon dos localidades cafetaleras venezolanas. Con veinte unidades experimentales por area se tomaron muestras de plantas de cafe y sus respectivos suelos en las localidades de Santa Cruz de Mora (Estado Merida) y Caripe (Estado Monagas), durante la epoca de cosecha para determinar el contenido de boro sin el suministro de algun aditivo contentivo del elemento en estudio. Las muestras de suelo y tejido de planta se trataron mediante un procedimiento de extraccion en caliente con acido nitrico previo a la determinacion espectrofotometrica de boro con azometina-H usando un sistema de flujo continuo. El tratamiento estadistico de los datos obtenidos para el contenido del elemento en las muestras de frutos y hojas fueron 24,96 ± 2,39; 75,86 ± 2,79 μg g-1 (Santa Cruz de Mora) y 9,56 ± 1,12; 29,08 ± 2,15 μg g-1 (Caripe) masa, seca respectivamente, los cuales muestran diferencias significativas en el contenido de boro tanto entre localidades como entre tejidos (p < 0,001), mientras que en suelos fueron 9,08 ± 1,38 μg g-1 (Santa Cruz de Mora) y 4,42 ± 0,95 μg g-1 masa seca, los cuales muestran diferencias significativas entre localidades (p < 0,001). Estos resultados indicaron valores de referencia para el contenido del elemento mayores en Santa Cruz de Mora (Estado Merida) que en Caripe (Estado Monagas).

Variación temporal de las variables físico-químicas y biomasa fitoplanctónica en aguas superficiales de la zona costera de Chacopata, NE Venezuela (Mar Caribe)

To understand the dynamics of some physico-chemical variables and phytoplankton biomass the Atlantic surface waters of coast Chacopata (Northeastern Venezuel...