Structure—activity relationships for chloro‐ and nitrophenol toxicity in the pollen tube growth test

—Acute toxicity of 10 chlorophenols and 10 nitrophenols with identical substitution patterns is analyzed with the pollen tubegrowth (PTG) test. Concentration values of 50% growth inhibition (IC50) between 0.1 and 300 mg/L indicate that the absolutesensitivity of this alternative biotest is comparable to conventional aquatic test systems. Analysis of quantitative structure–activityrelationships using lipophilicity (log Kow), acidity (pKa), and quantum chemical parameters to model intrinsic acidity, solvation interactions,and nucleophilicity reveals substantial differences between the intraseries trends of log IC50. With chlorophenols, a narcotictyperelationship is derived, which, however, shows marked differences in slope and intercept when compared to reference regressionequations for polar narcosis. Regression analysis of nitrophenol toxicity suggests interpretation in terms of two modes of action:oxidative uncoupling activity is associated with a pKa window from 3.8 to 8.5, and more acidic congeners with diortho- substitutionshow a transition from uncoupling to a narcotic mode of action with decreasing pKa and log Kow. Model calculations for phenolnucleophilicity suggest that differences in the phenol readiness for glucuronic acid conjugation as a major phase-II detoxication pathway have no direct influence on acute PTG toxicity of the compounds

Metabolic adaptation of two in silico mutants of Mycobacterium tuberculosis during infection

ABSTRACT: Background: Up to date, Mycobacterium tuberculosis (Mtb) remains as the worst intracellular killer pathogen. To establish infection, inside the granuloma, Mtb reprograms its metabolism to support both growth and survival, keeping a balance between catabolism, anabolism and energy supply. Mtb knockouts with the faculty of being essential on a wide range of nutritional conditions are deemed as target candidates for tuberculosis (TB) treatment. Constraint-based genome-scale modeling is considered as a promising tool for evaluating genetic and nutritional perturbations on Mtb metabolic reprogramming. Nonetheless, few in silico assessments of the effect of nutritional conditions on Mtb’s vulnerability and metabolic adaptation have been carried out. Results: A genome-scale model (GEM) of Mtb, modified from the H37Rv iOSDD890, was used to explore the metabolic reprogramming of two Mtb knockout mutants (pfkA- and icl-mutants), lacking key enzymes of central carbon metabolism, while exposed to changing nutritional conditions (oxygen, and carbon and nitrogen sources). A combination of shadow pricing, sensitivity analysis, and flux distributions patterns allowed us to identify metabolic behaviors that are in agreement with phenotypes reported in the literature. During hypoxia, at high glucose consumption, the Mtb pfkA-mutant showed a detrimental growth effect derived from the accumulation of toxic sugar phosphate intermediates (glucose-6-phosphate and fructose-6-phosphate) along with an increment of carbon fluxes towards the reductive direction of the tricarboxylic acid cycle (TCA). Furthermore, metabolic reprogramming of the icl-mutant (icl1&icl2) showed the importance of the methylmalonyl pathway for the detoxification of propionyl-CoA, during growth at high fatty acid consumption rates and aerobic conditions. At elevated levels of fatty acid uptake and hypoxia, we found a drop in TCA cycle intermediate accumulation that might create redox imbalance. Finally, findings regarding Mtb-mutant metabolic adaptation associated with asparagine consumption and acetate, succinate and alanine production, were in agreement with literature reports. Conclusions: This study demonstrates the potential application of genome-scale modeling, flux balance analysis (FBA), phenotypic phase plane (PhPP) analysis and shadow pricing to generate valuable insights about Mtb metabolic reprogramming in the context of human granulomas

Carbohydrate-active enzymes from the zygomycete fungus Rhizopus oryzae: a highly specialized approach to carbohydrate degradation depicted at genome level

<p>Abstract</p> <p>Background</p> <p><it>Rhizopus oryzae </it>is a zygomycete filamentous fungus, well-known as a saprobe ubiquitous in soil and as a pathogenic/spoilage fungus, causing Rhizopus rot and mucomycoses.</p> <p>Results</p> <p>Carbohydrate Active enzyme (CAZy) annotation of the <it>R. oryzae </it>identified, in contrast to other filamentous fungi, a low number of glycoside hydrolases (GHs) and a high number of glycosyl transferases (GTs) and carbohydrate esterases (CEs). A detailed analysis of CAZy families, supported by growth data, demonstrates highly specialized plant and fungal cell wall degrading abilities distinct from ascomycetes and basidiomycetes. The specific genomic and growth features for degradation of easily digestible plant cell wall mono- and polysaccharides (starch, galactomannan, unbranched pectin, hexose sugars), chitin, chitosan, β-1,3-glucan and fungal cell wall fractions suggest specific adaptations of <it>R. oryzae </it>to its environment.</p> <p>Conclusions</p> <p>CAZy analyses of the genome of the zygomycete fungus <it>R. oryzae </it>and comparison to ascomycetes and basidiomycete species revealed how evolution has shaped its genetic content with respect to carbohydrate degradation, after divergence from the Ascomycota and Basidiomycota.</p

Drug sensitivity of different bacteria isolated from various sources of drinking water from Bangalore District, India

A total of 150 isolates obtained from different sources of drinking water (Well, supply water, tube well) were subjected to invitro sensitivity test against 7 antimicrobial agents. The overall susceptibility of the isolates were highest in Ciprofloxacin (91.33) followed by Norfloxacin (86.66), Gentamicin (83.33) and Trimethoprime (74.66). Sensitivity to other antimicrobial agents tested in Furazolidone (23.33), Nalidixic acid (18.0) and Cefotaxime (6.6) was found to be less than 25. It was found that Cefotaxime was the least effective drug. © Global Science Publications

High fluoride content in ground water - A case study in Bagepalli, Kolar district, Karnataka state

High concentration of fluoride causes health hazards which is noticed in the study area. Increase in fluoride level leads to dental and skeletal fluorosis, whereas the decrease of the same leads to dental caries. Water samples were analyzed for various parameters like PH, Electrical conductance, Total dissolved solids, Alkalinity, Total hardness, Calcium, Magnesium, Phosphates, Sodium and Potassium. The maximum fluoride ion concentration analyzed was 6.2 mg/L and minimum 1.2 mg/L. The concentration of fluoride was beyond the permissible limits in all the samples analyzed. Suggestions have been made to ameliorate the adverse effect by incorporating various defluoridation techniques. Copyright Enviromedia

Effect of processing on the microstructure of finger millet by X-ray diffraction and scanning electron microscopy

Finger millet is one of the important minor cereals, and carbohydrates form its major chemical constituent. Recently, the millet is processed to prepare hydrothermally treated (HM), decorticated (DM), expanded (EM) and popped (PM) products. The present research aims to study the changes in the microstructure of carbohydrates using X-ray diffraction and scanning electron microscopy. Processing the millet brought in significant changes in the carbohydrates. The native millet exhibited A-type pattern of X-ray diffraction with major peaks at 2θ values of 15.3, 17.86 and 23.15, whereas, all other products showed V-type pattern with single major peak at 2θ values ranging from 19.39 to 19.81. The corresponding lattice spacing and the number of unit cells in a particular direction of reflection also reduced revealing that crystallinity of starch has been decreased depending upon the processing conditions. Scanning electron microscopic studies also revealed that the orderly pattern of starch granules changed into a coherent mass due to hydrothermal treatment, while high temperature short time treatment rendered a honey-comb like structure to the product. However, the total carbohydrates and non-starch polysaccharide contents almost remained the same in all the products except for DM and EM, but the individual carbohydrate components changed significantly depending on the type of processing

Isotope Hydrogeological Factors Control Transport of Radon-222 in Hard Rock Fractured Aquifer of Bangalore, Karnataka

Radon-222 is a daughter element of radium-226 and are member of the uranium decay series. Radon-222 concentrations in groundwater of Bangalore city in different geological units were measured in 42 tube wells. The study area is underlain by Granite, Migmatite, Granodiorite and Gneiss rock and many dolerite dykes. The radon-222 concentration in groundwater is widely varying and ranging from 14 to 1000 Bq/L with an average value of 172.4 Bq/L. Significant differences in the radon-222 concentrations in groundwater among geological units were observed. The radon-222 distribution in groundwater is related to the presence of uranium in aquifer materials of the various rock types. Uranium concentration in groundwater is ranging from 0.2 to 523 μg/L. Transport of radon-222 through bedrock by water depends mainly on the percolation of water through the pore and along fractured planes of the rocks. Rn-222 cannot travel farther than several hundred meters away from their origin because of its short half-life of 3.8 days. It may travel the farthest within fractured or fissured geological formation where groundwater movement is fastest. The study shows that radon concentration in groundwater is controlled by geohydrological and hydrochemical characteristics of the study area