Regulation of reduced nitrogen assimilation in Rhodobacter capsulatus E1F1

The phototrophic bacterium Rhodobacter capsulatus E1F1 assimilates ammonia and other forms of reduced nitrogen either through the GS/GOGAT pathway or by the concerted action of l-alanine dehydrogenase and aminotransferases. These routes are light-independent and very responsive to the carbon and nitrogen sources used for cell growth. GS was most active in cells grown on nitrate or l-glutamate as nitrogen sources, whereas it was heavily adenylylated and siginificantly repressed by ammonium, glycine, l-alanine, l-aspartate, l-asparagine and l-glutamine, under which conditions specific aminotransferases were induced. GOGAT activity was kept at constitutive levels in cells grown on l-amino acids as nitrogen sources except on l-glutamine where it was significantly induced during the early phase of growth. In vitro, GOGAT activity was strongly inhibited by l-tyrosine and NADPH. In cells using l-asparagine or l-aspartate as nitrogen source, a concerted induction of l-aspartate aminotransferase and l-asparaginase was observed. Enzyme level enhancements in response to nitrogen source variation involved de novo protein synthesis and strongly correlated with the cell growth phase.Abbreviations ADH l-alanine dehydrogenase - AOAT l-alanine:2-oxoglutarate aminotransferase - Asnase l-asparaginase - GOAT Glycine: oxaloacetate aminotransferase - GOGAT Glutamate synthase - GOT l-aspartate: 2-oxoglutarate aminotransferase - GS Glutamine synthetase - HPLC High-Pressure Liquid Chromatography - MOPS 2-(N-morpholino)propanesulfonic acid - MSX l-methionine-d,l-sulfoximine     

In vivo inhibition of nitrogenase by hydroxylamine in Rhodospirillaceae Role of nitric oxide

Rhodobacter capsulatus strains E1F1 and B10 and Rhodobacter sphaeroides DSM 158 did not use hydroxylamine as nitrogen source for growth but metabolized it mainly through the glutamine synthetase reaction. Hydroxylamine had a high toxicity for cells growing either under phototrophic or dark-aerobic conditions. l-methionine-d,l-sulfoximine partially inhibited hydroxylamine uptake and increased the inhibition time of nitrogenase activity by this nitrogen compound. Nitric oxide was also a powerful inhibitor of nitrogenase in intact cells of R. capsulatus. Since low amounts of NO were produced from hydroxylamine, short-term inhibition of nitrogenase in the presence of this compound could be mediated in vivo by nitric oxide.Abbreviations GS glutamine synthetase - MSX l-methionine-d,l-sulfoximine - MTA mixed alkyltrimethylammonium bromide     

Biomarkers of toxicity in Clarias gariepinus exposed to sublethal concentrations of polycyclic aromatic hydrocarbons

Physiological, biochemical and histological indices in Clarias gariepinus broodstock, and teratogenic indices in embryos exposed to sublethal concentrations of naphthalene, phenanthrene and pyrene were investigated in 2014 using a static-renewal bioassay protocol. Phenanthrene (1.41 mg l^?1) was the most toxic, followed by pyrene (1.53 mg l^?1) and naphthalene (7.21 mg l^?1), based on 96 h LC50 values. Hepatosomatic indices were significantly higher in naphthalene- and pyrene-treated males compared with solvent controls, whereas fecundity in females was significantly lower by factors of 2.4 (naphthalene), 2.8 (phenanthrene) and 2.4 (pyrene), compared with controls. Catalase levels were lower in female phenanthrene-treated fish compared with controls. Histological alterations observed in PAH-treated fish include oedema, inflammatory cells, epithelial lifting and hyperplasia in the gills, vacuolation, haemosiderin pigments and sinusoidal congestion in the liver, and degenerated zona radiata in the ovary. Teratogenic effects were not observed, as evidenced by the lack of histological alterations in embryos spawned from pre-exposed broodstock. Sex-specific responses and the utility of biomarkers at cellular and individual levels of organisation are therefore demonstrated for holistic evaluations of polycyclic aromatic hydrocarbons in ecotoxicological studies.     

Risk Factors for MDR and XDR-TB in a Tertiary Referral Hospital in India

Background

India has a high burden of drug resistant TB, although there are few data on XDR-TB. Although XDR-TB has existed previously in India, the definition has not been widely applied, and surveillance using second line drug susceptibility testing has not been performed. Our objective was to analyze clinical and demographic risk factors associated with isolation of MDR and XDR TB as compared to susceptible controls, at a tertiary center.

Methodology/Findings

Retrospective chart review based on positive cultures isolated in a high volume mycobacteriology laboratory between 2002 and 2007. 47 XDR, 30 MDR and 117 susceptible controls were examined. Drug resistant cases were less likely to be extrapulmonary, and had received more previous treatment regimens. Significant risk factors for XDR-TB included residence outside the local state (OR 7.43, 3.07-18.0) and care costs subsidized (OR 0.23, 0.097-0.54) in bivariate analysis and previous use of a fluoroquinolone and injectable agent (other than streptomycin) (OR 7.00, 95% C.I. 1.14-43.03) and an initial treatment regimen which did not follow national guidelines (OR 5.68, 1.24-25.96) in multivariate analysis. Cavitation and HIV did not influence drug resistance.

Conclusions/Significance

There is significant selection bias in the sample available. Selection pressure from previous treatment and an inadequate initial regimen increases risk of drug resistance. Local patients and those requiring financial subsidies may be at lower risk of XDR-TB.     

Vertebrate slow skeletal muscle actin - conservation, distribution and conformational flexibility

The existence of a unique sarcomeric actin is demonstrated in teleosts that possess substantial amounts of slow skeletal muscle in the trunk. The slow skeletal isotype is conserved. There is one amino acid substitution between Atlantic herring slow skeletal actin and the equivalent in salmonids. Conversely, the intra-species variation is considerable; 13 substitutions between different herring skeletal isotypes (slow versus fast). The isomorphisms (non-conservative underlined: residues, 2, 3, 103, 155, 160, 165, 278, 281, 310, 329, 358, 360 and 363) are restricted to sub-domains 1 and 3 and include the substitution Asp-360 in 'slow' to Gln in 'fast' which results in an electrophoretic shift at alkaline pH. The musculature of the trunk facilitates the preparation of isoactins for biochemical study. Herring slow skeletal G-actin (Ca.ATP) is more susceptible to thermal, and urea, -induced denaturation and subtilisin cleavage than that in fast skeletal, but more stable than the counterpart in salmonids (one substitution, Gln354Ala) highlighting the critical nature of actin's carboxyl-terminal insert. Fluorescent spectra of G-actin isoforms containing the isomorphism Ser155Ala in complexation with 2'-deoxy 3' O-(N'-Methylanthraniloyl) ATP infer similar polarity of the nucleotide binding cleft. An electrophoretic survey detected two skeletal actins in some (smelt and mackerel) but not all teleosts. One skeletal muscle actin was detected in frog and bird.     

Herpetomonas roitmani (Fiorini et al., 1989) N. Comb.: A Trypanosomatid with a Bacterium-like Endosymbiont in the Cytoplasm

The trypanosomatid previously described as Crithidia roitmani is characterized here at the ultrastructural and biochemical levels. The data indicates that the parasite belongs to the Herpetomonas genus, and we therefore suggest the flagellate to be denominated as Herpetomonas roitmani n. comb. Cladistic analysis of isoenzyme data generated by eight different enzymes showed that the parasite presented a distinct banding pattern and could be grouped with some Herpetomonas spp., but not with Crithidia spp., used as reference strains. Accordingly, when the parasites were grown for longer periods in Roitman's defined medium, expontaneous differentiation from promastigotes to opisthomastigotes (typical of the Herpetomonas genus) occurred. Transmission electron microscopy revealed the presence of bacterium-like endosymbionts in the cytoplasm of all evolutive forms of the parasite. All morphological alterations characteristic of endosymbiont-bearing trypanosomatids could be observed.     

Sociodemographic,behavioral, and biological variables related to weight loss in native hawaiians and other pacific islanders

Objective:

Native Hawaiians and other Pacific Islanders (NHs/PIs) have a high obesity prevalence compared to other ethnic groups. We examined socio‐demographic, behavioral, and biological factors related to ≥3% weight loss in 100 overweight/obese NHs/PIs who completed a lifestyle intervention.

Design and Methods:

Data were from 56 Native Hawaiians, 22 Chuukese, and 22 Other Pacific Islanders who participated in a randomized controlled trial of the Partnership for Improving Lifestyle Intervention (PILI) 'Ohana Project. All completed a 3‐month weight loss program (WLP) to initiate weight loss and were then randomized into either a 6‐month family/community focused WLP called the PILI Lifestyle Program (PLP; n = 49) or a standard behavior WLP (SBP; n = 51). We collected baseline, 3‐ and 9‐month follow‐up data on socio‐demographics, weight (kg), a 6‐min. walk test, dietary fat, exercise frequency, and blood pressure.

Results and Conclusion:

Based on ANCOVA or logistic fit, ethnicity, sex, initial weight loss, fat in diet at baseline, change in systolic blood pressure, and intervention type were significantly associated (P ≤ .05) with ≥3% weight loss at 9‐month follow‐up. A logistic regression model indicated that Chuukese (OR = 6.04; CI = 1.14–32.17) and participants who had more weight loss in the first 3‐months (OR = 1.47; CI = 1.22–1.86) and who were in the PLP (OR = 4.50; CI = 1.50–15.14) were more likely to achieve ≥3% weight loss [model; χ² (7, N = 100) = 45.50, P < .0001]. The same lifestyle intervention does not benefit all NHs/PIs equally, possibly due to differences in acculturation status and social support. The findings also point to the importance of initial weight loss to sustain motivation toward long‐term weight loss maintenance.     

Effect of Methanolic extract of Musa sapientum leaves on Gastrointestinal Transit time in Normal and Alloxan induced Diabetic rats: Possible Mechanism of Action

Disorders of gastrointestinal motility have been associated with Diabetes mellitus. Hyperglycaemia particularly has been reported to inhibit gastrointestinal transit time while glibenclamide, a sulphonylurea and insulin, both increased transit time. Musa sapientum has also been reported as an antidiabetic agent but there is dearth of information on the effect of this plant on gastrointestinal motility. This study was therefore carried out to investigate the effect of methanolic extract of Musa sapientum leaves (MEMSL) on Gastrointestinal Transit time (GITT) in male albino rats with and without hyperglycaemia and to elucidate possible mechanism by which this extract functions. Fifty five albino rats were divided into 11 groups of five animals each. All animals were fasted for 24hrs before the begining of the experiment. Group 1 served as control; while the remaining groups (2 - 11) were treated with 250mg/kg; 500mg/kg MEMSL; diabetic control; diabetic treated with 250mg/kg; 500mg/kg MEMSL; diabetic treated with glibenclamide (5mg/kg); normal rats treated with Nifedipine (50mg/kg); normal rats treated with calcium chloride (CaCl2) only (10mg/kg); groups 10 and 11 were both pretreated with CaCl2 and subsequently treated with 250mg/kg and 500mg/kg MEMSL respectively. All plant extracts used for treatments were dissolved in normal saline and administered orally using orogastric tube. Charcoal meal was used as marker in the estimation of GITT. The study showed significant decrease in GITT in the normal rats treated with 250mg/kg and 500mg/kg of extract. However, in the diabetic rats treated with 500mg/kg MEMSL, there was significant increase in GITT and this is comparable with the gut response to glibenclamide (5mg/kg). Musa sapientum extract produced significant decrease in transit time in the calcium chloride pre-treated normal rats and this is comparable to the effect observed in Nifedipine treated group. The significant reduction in GITT produced by MEMSL in the normal rats reflects a strong possibility of MEMSL acting as calcium channel antagonist through the voltage gated calcium channel which may be due to the presence of alkaloids, saponins, cardenolides. There is the possibility of the extract acting as an inhibitor of potassium channel at higher concentration as observed in glibenclamide treated groups. Keywords: Musa Sapientum, Gastrointestinal transit time, Alloxan diabetes.