Contaminação por mercúrio em sedimento e em moluscos do Pantanal, Mato Grosso, Brasil Mercury contamination in sediment and in molluscs of Pantanal, Mato Grosso, Brazil

<abstract language="eng">The total level of mercury detected in the sediment and in the tissues of molluscs from the Bento Gomes basin, although low, have shown that the mercury used in the gold mining activities in the Poconé wetlands has contaminated those aquatic habitats in Pantanal. From 69 sediment samples analyzed, 26 % (N = 18) have shown levels ranging from 0.01 to 0.25µg.g-1 of mercury (moist weight). Mercury levels analyzed in 54 samples of mollusc tissues (Ampullaria scalaris Orbigny, 1835; A. canaliculata Lamarck, 1819 and Marisa planogyra Pilsbry, 1933) have shown that 30% (N = 16) were contaminated with levels ranging from 0.02 to 1.16µg.g-1 moist weight. This study shows that the mercury used in digs for gold mining and released into the environment has reached the habitats of Pantanal spread from the sediment into the molluscs living in the region

Glândula submandibular de ratos com envelhecimento: observações ao microscópio eletrônico de varredura de alta resolução Submandibular gland of rats with ageing: observations with high resolution scanning electron microscopy

As características tridimensionais dos componentes intracelulares de células acinares e de ductos foram reveladas usando o método ósmio-DMSO-ósmio. As amostras foram maceradas em solução de tetróxido de ósmio diluído após a fratura na solução de dimetil sulfoxido. As lamelas do retículo endoplasmático granular são reveladas entremeadas por várias mitocôndrias. As lamelas do retículo endoplasmático granular são localizados ao redor dos núcleos na porção basal e estas estruturas são observadas em imagens tridimensionais de microscopia eletrônica de alta resolução.<br>The three-dimensional characteristics of the intracellular components of acinar and ductal cells were revealed using the osmium-DMSO-osmium method. The samples were macerated in diluted osmium after fractured in DMSO solution. The stacks of the rough endoplasmic reticulum are revealed intermingling by several mitochondria. The lamellae of the rough endoplasmic reticulum are located around the nuclei at basal portion and these structures are shown in three-dimensional HRSEM images