Decreased GTP-stimulated adenylyl cyclase activity in HPRT-deficient human and mouse fibroblast and rat B103 neuroblastoma cell membranes

Defect of the purine salvage enzyme, hypoxanthine phosphoribosyl transferase (HPRT), results in Lesch-Nyhan disease (LND). It is unknown how the metabolic defect translates into the severe neuropsychiatric phenotype characterized by self-injurious behavior, dystonia and mental retardation. There are abnormalities in GTP, UTP and CTP concentrations in HPRT-deficient cells. Moreover, GTP, ITP, XTP, UTP and CTP differentially support Gs-protein-mediated adenylyl cyclase (AC) activation. Based on these findings we hypothesized that abnormal AC regulation may constitute the missing link between HPRT deficiency and the neuropsychiatric symptoms in LND. To test this hypothesis, we studied AC activity in membranes from primary human skin and immortalized mouse skin fibroblasts, mouse Neuro-2a neuroblastoma cells and rat B103 neuroblastoma cells. In B103 control membranes, GTP, ITP, XTP and UTP exhibited profound stimulatory effects on basal AC activity that approached the effects of hydrolysis-resistant nucleotide analogs. In HPRT- membranes, the stimulatory effects of GTP, ITP, XTP and UTP were strongly reduced. Similarly, in human and mouse skin fibroblast membranes we also observed a decrease in GTP-stimulated AC activity in HPRT-deficient cells compared with the respective controls. In mouse Neuro-2a neuroblastoma membranes, AC activity in the presence of GTP was below the detection limit of the assay. We discuss several possibilities to explain the abnormalities in AC regulation in HPRT deficiency that encompass various species and cell types.     

Murine cytomegalovirus interference with antigen presentation contributes to the inability of CD8 T cells to control virus in the salivary gland

Compared to other organs, murine cytomegalovirus (MCMV) replication in the salivary gland is uniquely resistant to CD8 T-cell control. The contribution of viral genes that interfere with antigen presentation (VIPRs) to this resistance was assessed using a mutant lacking MCMV's known VIPRs. Salivary gland titers of the VIPR-deficient virus were at least 10-fold lower than those of the wild type during the persistent phase of infection; the defect was reversed by depleting CD8 T cells. Thus, VIPRs contribute to CD8 T cells' inability to control virus in the salivary gland.     

Prevalence and pathology of the nematode Heterakis gallinarum, the trematode Paratanaisia bragai, and the protozoan Histomonas meleagridis in the turkey, Meleagris gallopavo

The prevalence of infection and associated pathology induced by two helminth and one protozoan species infecting Brazilian turkeys are reported. The intestinal nematode Heterakis gallinarum appeared with a prevalence of 70% in the infected birds, without gross lesions when not associated to the protozoan Histomonas meleagridis. Histological findings in the ceca were represented by the presence of H. gallinarum worms, intense chronic diffuse inflammatory processes with mononuclear and polymorphonuclear (heterophils) leucocyte infiltrations. The prevalence of the protozoan H. meleagridis associated to H. gallinarum was of 2.5% and microscopic examination revealed a severe inflammatory process in the liver and cecum with the presence of small clear areas with round eosinophilic parasites. Gross lesions were absent in turkeys infected with the renal digenetic trematode Paratanaisia bragai; the parasite was prevalent in 20% of the cases and cross-sections of the kidneys showed a remarkable distension of the collecting ducts with several worms in the lumen. The walls of the ducts presented a discrete heterophilic infiltrate among mononuclear cells.     

A Mutation in the luxS gene influences Listeria monocytogenes biofilm formation

Using a Vibrio harveyi reporter strain, we demonstrated that Listeria monocytogenes secretes a functional autoinducer 2 (AI-2)-like signal. A luxS-deficient mutant produced a denser biofilm and attached to a glass surface 19-fold better than the parent strain. Exogenous AI-2 failed to restore the wild-type phenotype to the mutant. It seems that an intact luxS gene is associated with repression of components required for attachment and biofilm formation.     

Water recycling by Amazonian vegetation: coupled versus uncoupled vegetation-climate interactions

To demonstrate the relationship between Amazonian vegetation and surface water dynamics, specifically, the recycling of water via evapotranspiration (ET), we compare two general circulation model experiments; one that couples the IS92a scenario of future CO2 emissions to a land-surface scheme with dynamic vegetation (coupled) and the other to fixed vegetation (uncoupled). Because the only difference between simulations involves vegetation coupling, any alterations to surface energy and water balance must be due to vegetation feedbacks. The proportion of water recycled back to the atmosphere is relatively conserved through time for both experiments. Absolute value of recycled water is lower in our coupled relative to our uncoupled simulation as a result of increasing atmospheric CO2 that in turn promotes lowering of stomatal conductance and increase in water-use efficiency. Bowen ratio increases with decreasing per cent broadleaf cover, with the greatest rate of change occurring at high vegetation cover (above 70% broadleaf cover). Over the duration of the climate change simulation, precipitation is reduced by an extra 30% in the coupled relative to the uncoupled simulations. Lifting condensation level (proxy for base height of cumulus cloud formation) is 520m higher in our coupled relative to uncoupled simulations.     

Evaluation of Antimicrobial Activity of Cashew Tree Gum

Crude and purified cashew tree gum were tested for their antimicrobial activity against bacteria, yeast and fungi. Their use was also evaluated as a carbon source for microbial growth. Cashew gum presented only a weak activity against Saccharomyces cerevisiae and no activity was observed against all other microorganisms tested. The possibility that removal of anacardic acid present in the raw gum during purification may explain the negative results obtained was discussed. When purified cashew tree gum was used as carbon source, only Listeria monocytogenes, Saccharomyces cerevisiae and Kluyveromyces marxianus did not grow after 5 days of incubation.     

Alkaline protease from <Emphasis Type="Italic">Bacillus sp.</Emphasis> isolated from coffee bean grown on cheese whey

Two strains of Bacillus, one from a culture collection (B. subtilis ATCC 6633) and a wild type (Bacillus sp. UFLA 817CF) isolated during coffee fermentation in the south of Minas Gerais, Brazil, were evaluated in relation to secretion of alkaline proteases. The strains were grown on nutrient broth, nutrient broth with sodium caseinate and nutrient broth with three different concentrations of cheese whey powder for 72 h. Samples were collected at 24-h intervals to evaluate the proteolytic activity, protein content and cell population. Maximum protease activity was observed after 24-h growth for both the microorganisms, a period that coincided with the end of the exponential phase. The specific activity values were, respectively, 839.8 U/mg for B. subtilis ATCC 6633 and 975.9 U/mg for Bacillus sp. UFLA 817CF. The 60% saturation presented the best results for specific protease activity in all the growth culture media tested with B. sp. UFLA 817CF. Bacillus sp. UFLA 817CF showed highest enzymatic activity at pH 9.0 and 40°C in the three culture media tested. The protease obtained from culture of the wild Bacillus strain presented stability at pH 7.0 and considerable heat stability at 40°C and 50°C, and could be an alternative for the industry to utilize cheese whey to produce proteolytic enzymes.     

Identification and molecular characterisation of a fibrinogen binding protein from <Emphasis Type="Italic">Streptococcus iniae</Emphasis>.

Background  

Binding of serum components by surface M-related proteins, encoded by the emm genes, in streptococci constitutes a major virulence factor in this important group of organisms. The present study demonstrates fibrinogen binding by S. iniae, a Lancefield non-typeable pathogen causing devastating fish losses in the aquaculture industry and an opportunistic pathogen of humans, and identifies the proteins involved and their encoding genes.