Secretory responses in granular ducts and acini of submandibular glands in vivo to parasympathetic or sympathetic nerve stimulation in rats

Summary The roles of sympathetic and parasympathetic nerves in the secretion of saliva from submandibular glands of rats have been tested by electrical stimulation of either nerve for 1 h unilaterally in separate animals. The flows of saliva thereby induced and their protein content were monitored. Structural changes in each gland were assessed by light- and electron microscopy and compared with the unstimulated contralateral control gland, and the extent of the changes was determined morphometrically. Sympathetic nerve stimulation induced a relatively low flow of saliva that was rich in protein and was accompanied by extensive degranulation from both acinar and granular duct cells. In contrast parasympathetic nerve stimulation induced a considerable flow of saliva that had a low protein content and no detectable degranulation occurred from the secretory cells. It is possible, therefore, that some protein in parasympathetic saliva may have arisen from a non-granular pathway.     

Influence of Abscisic Acid on K+ absorption by leaf tissues ofSolanum tuberosum L. (cv. Bintje). Relation with calcium fluxes and with calmodulin

Previous results with potato leaf tissues revealed that a treatment with ABA (10^-4 M) induced an increase of K⁺ uptake (Suleimanet al., 1990a). In this study, we investigate the relationship between increased K⁺ uptake, Ca²⁺ fluxes and calmodulin by treating potato leaf discs with Ca²⁺ channel blockers (La³⁺, verapamil and nifedipine) and with calmodulin inhibitors (chlorpromazine, W₇: N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide, and compound 4880). We found : a) all these inhibitors decreased K⁺ uptake in the same ratio in tissues treated or not with ABA; b) a synergistic effect between ABA and the Ca²⁺ ionophore A 23187 on K⁺ uptake. The results suggest that the hormone may act on K⁺ uptake like a Ca²⁺ agonist, in accord with HUDDART’s hypothesis.     

Seropositivity and Serointensity of Toxoplasma gondii Antibodies and DNA among Patients with Schizophrenia

The aim of this cross sectional case control study was to examine the serofrequency and serointensity of Toxoplasma gondii (Tg) IgG, IgM, and DNA among patients with schizophrenia. A total of 101 patients with schizophrenia and 55 healthy controls from Sungai Buloh Hospital, Selangor, Malaysia and University Malaya Medical Center (UMMC) were included in this study. The diagnosis of schizophrenia was made based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). The presence of Tg infection was examined using both indirect (ELISA) and direct (quantitative real-time PCR) detection methods by measuring Tg IgG and IgM and DNA, respectively. The serofrequency of Tg IgG antibodies (51.5%, 52/101) and DNA (32.67%, 33/101) among patients with schizophrenia was significantly higher than IgG (18.2%, 10/55) and DNA (3.64%, 2/55) of the controls (IgG, P=0.000, OD=4.8, CI=2.2-10.5; DNA, P=0.000, OD=12.9, CI=2.17-10.51). However, the Tg IgM antibody between patients with schizophrenia and controls was not significant (P>0.005). There was no significant difference (P>0.005) in both serointensity of Tg IgG and DNA between patients with schizophrenia and controls. These findings have further demonstrated the strong association between the active Tg infection and schizophrenia.     

Enrichment of anaerobic heterotrophic thermophiles from four Azorean hot springs revealed different community composition and genera abundances using recalcitrant substrates

DGGE analysis combined with a metagenomic approach was used to get insights into heterotrophic anoxic enrichment cultures of four hot springs of Vale das Furnas, Portugal, using the recalcitrant substrate spent coffee ground (SCG). Parallel enrichment cultures were performed using the major components of spent coffee ground, namely arabinogalactan, galactomannan, cellulose, and proteins. DGGE revealed that heterotrophic thermophilic bacteria are highly abundant in the hydrothermal springs and significant differences in community composition depending on the substrate were observed. DNA, isolated from enrichment cultures of different locations that were grown on the same substrate were pooled, and the respective metagenomes were analyzed. Results indicated that cultures grown on recalcitrant substrate SCG consists of a totally different thermophilic community, dominated by Dictyoglomus. Enrichments with galactomannan and arabinogalactan were dominated by Thermodesulfovibrio, while cultures with casein and cellulose were dominated by Thermus. This study indicates the high potential of thermophilic bacteria degrading recalcitrant substrate such as SCG and furthermore how the accessibility to complex polymers shapes the bacterial community.

     

Structural basis for UBA-mediated dimerization of c-Cbl ubiquitin ligase

Ligand-induced down-regulation by the ubiquitin-protein ligases, c-Cbl and Cbl-b, controls signaling downstream from many receptor-tyrosine kinases (RTK). Cbl proteins bind to phosphotyrosine residues on activated RTKs to affect ligand-dependent ubiquitylation of these receptors targeting them for degradation in the lysosome. Both c-Cbl and Cbl-b contain a ubiquitin-associated (UBA) domain, which is important for Cbl dimerization and tyrosine phosphorylation; however, the mechanism of UBA-mediated dimerization and its requirement for Cbl biological activity is unclear. Here, we report the crystal structure of the UBA domain of c-Cbl refined to 2.1-A resolution. The structure reveals the protein is a symmetric dimer tightly packed along a large hydrophobic surface formed by helices 2 and 3. NMR chemical shift mapping reveals heterodimerization can occur with the related Cbl-b UBA domain via the same surface employed for homodimerization. Disruption of c-Cbl dimerization by site-directed mutagenesis impairs c-Cbl phosphorylation following activation of the Met/hepatocyte growth factor RTK and c-Cbl-dependent ubiquitination of Met. This provides direct evidence for a role of Cbl dimerization in terminating signaling following activation of RTKs.     

Land-use change and soil type are drivers of fungal and archaeal communities in the Pampa biome

The current study aimed to test the hypothesis that both land-use change and soil type are responsible for the major changes in the fungal and archaeal community structure and functioning of the soil microbial community in Brazilian Pampa biome. Soil samples were collected at sites with different land-uses (native grassland, native forest, Eucalyptus and Acacia plantation, soybean and watermelon field) and in a typical toposequence in Pampa biome formed by Paleudult, Albaqualf and alluvial soils. The structure of soil microbial community (archaeal and fungal) was evaluated by ribosomal intergenic spacer analysis and soil functional capabilities were measured by microbial biomass carbon and metabolic quotient. We detected different patterns in microbial community driven by land-use change and soil type, showing that both factors are significant drivers of fungal and archaeal community structure and biomass and microbial activity. Fungal community structure was more affected by land-use and archaeal community was more affected by soil type. Irrespective of the land-use or soil type, a large percentage of operational taxonomic unit were shared among the soils. We accepted the hypothesis that both land-use change and soil type are drivers of archaeal and fungal community structure and soil functional capabilities. Moreover, we also suggest the existence of a soil microbial core.     

Cysteine protects freshly isolated cardiomyocytes against oxidative stress by stimulating glutathione peroxidase

Cysteine has been implicated in myocardial protection, although this is controversial and constrained by limited knowledge about the effects of cysteine at the cellular level. This study tested the hypothesis that a physiologically relevant dose of l-cysteine could be safely loaded into isolated cardiomyocytes leading to improved protection against oxidative stress. Freshly isolated adult rat ventricular cardiomyocytes were incubated for 2 h at 37°C with (cysteine incubated) or without (control) 0.5 mM cysteine prior to washing and suspension in fresh cysteine-free media. Cysteine incubated cells had higher intracellular cysteine levels compared to controls (9.6 ± 0.78 vs. 6.5 ± 0.65 nmol/mg protein, P < 0.02, n = 6 ± SE). Cell homeostasis indicators were similar in the two groups. Cysteine incubated cells had significantly higher glutathione peroxidase (GPx) activity (1.11 ± 0.23 vs. 0.54 ± 0.1 U/mg protein, P < 0.05, n = 5 ± SE) and significantly greater expression of GPx-1 (5.01 ± 0.48 vs. 3.01 ± 0.25 OD units/mm², P < 0.05, n = 4 ± SE) compared to controls. Upon exposure to H₂O₂, cysteine incubated cells generated fewer reactive oxygen species and took longer to show contractile changes and undergo hypercontracture. However, when cells were exposed to H₂O₂ in the presence of 0.05 mM of the GPx inhibitor mercaptosuccinic acid, this increased the control cells’ susceptibility to H₂O₂ and completely abolished the cysteine mediated protection. These results suggest a new role for cysteine in myocardial protection involving stimulation of glutathione peroxidase.     

Purification of xanthine dehydrogenase from rat liver: a rapid procedure with high enzyme yields

Xanthine dehydrogenase (EC 1.2.1.37) was purified approximately 1000-fold from liver homogenates of adult male Sprague-Dawley rats. Enzyme recovery was good (greater than 20% of the starting activity was obtained), and the homogeneously pure enzyme had a molecular mass of approximately 300,000 Da. The purified protein exhibited a specific activity of 2470 units/mg protein and spectral properties identical to those of the best preparations of this enzyme reported by other investigators. Routine preparations of this enzyme also possess higher dehydrogenase:oxidase ratios (typically between 5 and 6) than do other xanthine dehydrogenase preparations so far reported in the literature. Maximum dehydrogenase:oxidase ratios, greater than 10, could be obtained from this procedure if only peak dehydrogenase fractions from the chromatography columns were saved. The present small-scale purification method, which can be completed in 48-60 h, utilizes ammonium sulfate fractionation, Sephadex G-200 column chromatography, Blue Dextran-Sepharose column chromatography, and preparative gel electrophoresis.     

Rac1 Activation in Podocytes Induces Rapid Foot Process Effacement and Proteinuria

The kidney''s vital filtration function depends on the structural integrity of the glomerulus, the proximal portion of the nephron. Within the glomerulus, the architecturally complex podocyte forms the final cellular barrier to filtration. Injury to the podocyte results in a morphological change called foot process effacement, which is a ubiquitous feature of proteinuric diseases. The exact mechanism underlying foot process effacement is not known, but recently it has been proposed that this change might reflect activation of the Rac1 GTPase. To test this hypothesis, we generated a podocyte-specific, inducible transgenic mouse line that expressed constitutively active Rac1. When the Rac1 transgene was induced, we observed a rapid onset of proteinuria with focal foot process effacement. Using superresolution imaging, we verified that the induced transgene was expressed in damaged podocytes with altered foot process morphology. This work sheds new light on the complex balance of Rho GTPase signaling that is required for proper regulation of the podocyte cytoskeleton.     

Interference of seed dressing on groundnut nodulation

Aldrex T enhanced the mean number of groundnut nodules due to in vitro application at a higher than field concentration (6 g/kg groundnut kernels). Dressing at lower and agricultural applications (1.5 and 3, respectively) not only depressed but also considerably delayed nodule formation. This feature was demonstrated by the great losses in nodule number and weight as well. The latter picked up after 11 weeks to equate that of the controls. Interference of the fungicide in nodulation was highly significant at the sixth week of sowing. An insignificant increase in the number of root nodules was recorded at the tenth week of plant growth thus signifying recovery ofRhizobium from aldrex sensitivity. Dressing at 6 g/kg seeds did not affect the number and weight of nodules particularly after the fourth week of groundnut growth. Subsequently a highly significant increase in nodule weight was noticed.Nitrate and nitrite yield of nodules was favourably affected when kernels received twice the agricultural dose when compared with the non-dressed controls.