MS characterization of multiple forms of alpha-amylase in human saliva

Alpha-amylase is a major and well-characterized component of human saliva. Recent proteomic studies suggested that this protein could be observed in more than twenty spots on 2-D gels of salivary proteins. The aim of this work was to investigate this unexpected redundancy. 2-D gel electrophoresis was combined with systematic MALDI-TOF MS analysis. More than 140 protein spots identifying the alpha-amylase were shown to constitute a stable but very complex pattern. Careful analysis of mass spectra and simultaneous hierarchical clustering of the observed peptides and of the electrophoretic features of spots allowed one to define three major groups. A main class grouping 90 spots was shown to correspond to full length alpha-amylases that can be assumed to include isoforms and post-translationally modified forms, a subset of this class being demonstrated to be N-glycosylated. A second group included short alpha-amylases that are differently truncated in a non-random manner, very likely in the oral cavity. The last class grouped alpha-amylase forms showing both the N- and C-terminal sequences of the enzyme but displaying a molecular weight that was up to 50% lower than that of the native protein. It is speculated that the last group of alpha-amylase spots could correspond to proteins submitted to internal deletions prior to the secretion.     

Arsenic toxicity,mutagenesis, and carcinogenesis – a health risk assessment and management approach

A comprehensive analysis of published data indicates that arsenic exposure induces cardiovascular diseases, developmental abnormalities, neurologic and neurobehavioral disorders, diabetes, hearing loss, hematologic disorders, and various types of cancer. Although exposure may occur via the dermal, and parenteral routes, the main pathways of exposure include ingestion, and inhalation. The severity of adverse health effects is related to the chemical form of arsenic, and is also time- and dose-dependent. Recent reports have pointed out that arsenic poisoning appears to be one of the major public health problems of pandemic nature. Acute and chronic exposure to arsenic has been reported in several countries of the world where a large proportion of drinking water (groundwater) is contaminated with high concentrations of arsenic. Research has also pointed significantly higher standardized mortality rates for cancers of the bladder, kidney, skin, liver, and colon in many areas of arsenic pollution. There is therefore a great need for developing a comprehensive health risk assessment (RA) concept that should be used by public health officials and environmental managers for an effective management of the health effects associated with arsenic exposure. With a special emphasis on arsenic toxicity, mutagenesis, and carcinogenesis, this paper is aimed at using the National Academy of Science's RA framework as a guide, for developing a RA paradigm for arsenic based on a comprehensive analysis of the currently available scientific information on its physical and chemical properties, production and use, fate and transport, toxicokinetics, systemic and carcinogenic health effects, regulatory and health guidelines, analytical guidelines and treatment technologies.     

Comparative modelling of protein structure and its impact on microbial cell factories

Comparative modeling is becoming an increasingly helpful technique in microbial cell factories as the knowledge of the three-dimensional structure of a protein would be an invaluable aid to solve problems on protein production. For this reason, an introduction to comparative modeling is presented, with special emphasis on the basic concepts, opportunities and challenges of protein structure prediction. This review is intended to serve as a guide for the biologist who has no special expertise and who is not involved in the determination of protein structure. Selected applications of comparative modeling in microbial cell factories are outlined, and the role of microbial cell factories in the structural genomics initiative is discussed.     

An illustrated key to and diagnoses of the species of Histeridae (Coleoptera) associated with decaying carcasses in Argentina

A key to 16 histerid species associated with decaying carcasses in Argentina is presented, including diagnoses and habitus photographs for these species. This article provides a table of all species associated with carcasses, detailing the substrate from which they were collected and geographical distribution by province. All 16 Histeridae species registered are grouped into three subfamilies: Saprininae (twelve species of Euspilotus Lewis and one species of Xerosaprinus Wenzel), Histerinae (one species of Hololepta Paykull and one species of Phelister Marseul) and Dendrophilinae (one species of Carcinops Marseul). Two species are new records for Argentina: Phelister rufinotus Marseuland Carcinops troglodytes (Paykull). A discussion is presented on the potential forensic importance of some species collected on human and pig carcasses.     

Malate plays a crucial role in starch metabolism, ripening, and soluble solid content of tomato fruit and affects postharvest softening

Despite the fact that the organic acid content of a fruit is regarded as one of its most commercially important quality traits when assessed by the consumer, relatively little is known concerning the physiological importance of organic acid metabolism for the fruit itself. Here, we evaluate the effect of modifying malate metabolism in a fruit-specific manner, by reduction of the activities of either mitochondrial malate dehydrogenase or fumarase, via targeted antisense approaches in tomato (Solanum lycopersicum). While these genetic perturbations had relatively little effect on the total fruit yield, they had dramatic consequences for fruit metabolism, as well as unanticipated changes in postharvest shelf life and susceptibility to bacterial infection. Detailed characterization suggested that the rate of ripening was essentially unaltered but that lines containing higher malate were characterized by lower levels of transitory starch and a lower soluble sugars content at harvest, whereas those with lower malate contained higher levels of these carbohydrates. Analysis of the activation state of ADP-glucose pyrophosphorylase revealed that it correlated with the accumulation of transitory starch. Taken together with the altered activation state of the plastidial malate dehydrogenase and the modified pigment biosynthesis of the transgenic lines, these results suggest that the phenotypes are due to an altered cellular redox status. The combined data reveal the importance of malate metabolism in tomato fruit metabolism and development and confirm the importance of transitory starch in the determination of agronomic yield in this species.     

Intestinal Na(+)/Ca(2+) exchanger protein and gene expression are regulated by 1,25(OH)(2)D(3) in vitamin D-deficient chicks

The role of 1,25(OH)(2)D(3) on the intestinal NCX activity was studied in vitamin D-deficient chicks (-D) as well as the hormone effect on NCX1 protein and gene expression and the potential molecular mechanisms underlying the responses. Normal, -D and -D chicks treated with cholecalciferol or 1,25(OH)(2)D(3) were employed. In some experiments, -D chicks were injected with cycloheximide or with cycloheximide and 1,25(OH)(2)D(3) simultaneously. NCX activity was decreased by -D diet, returning to normal values after 50 IU daily of cholecalciferol/10 days or a dose of 1μg calcitriol/kg of b.w. for 15 h. Cycloheximide blocked NCX activity enhancement produced by 1,25(OH)(2)D(3). NCX1 protein and gene expression were diminished by -D diet and enhanced by 1,25(OH)(2)D(3). Vitamin D receptor expression was decreased by -D diet, effect that disappeared after 1,25(OH)(2)D(3) treatment. Rapid effects of 1,25(OH)(2)D(3) on intestinal NCX activity were also demonstrated. The abolition of the rapid effects through addition of Rp-cAMPS and staurosporine suggests that non genomic effects of 1,25(OH)(2)D(3) on NCX activity are mediated by activation of PKA and PKC pathways. In conclusion, 1,25(OH)(2)D(3) enhances the intestinal NCX activity in -D chicks through genomic and non genomic mechanisms.     

Roles of superoxide dismutase and catalase of Staphylococcus xylosus in the inhibition of linoleic acid oxidation

Streptomyces brasiliensis ATCC 23727 showed extensive sporulation when cultured in a liquid medium containing galactose and glutamic acid as carbon and nitrogen sources. Under such conditions, glycogen and trehalose are accumulated in the hyphae coinciding with spore formation. The results reported here suggest that glycogen accumulated in sporogenic hyphae is converted into trehalose during the final period of spore maturation. Glycogen is also accumulated in the hyphae when S. brasiliensis is cultured under conditions which did not support sporulation. Under such conditions, however, glycogen degradation is not accompanied by accumulation of trehalose. This suggest that the conversion of glycogen into trehalose might be a sporulation-specific event in streptomycetes.