Antimicrobial activity of Sesbania grandiflora flower polyphenol extracts on some pathogenic bacteria and growth stimulatory effect on the probiotic organism Lactobacillus acidophilus

Polyphenolic extracts (PE) of edible flower of Sesbania grandiflora were tested to evaluate its antimicrobial effect against some common pathogenic bacteria and growth promoting property against probiotic organism Lactobacillus acidophilus. The antimicrobial activity of S. grandiflora flower PE against selected pathogens was evaluated using both in vitro and in situ methods. In vitro studies suggested that PE has inhibitory effect against Staphylococcus aureus, Shigella flexneri 2a, Salmonella Typhi, Escherichia coli and Vibrio cholerae. The gram-positive organism S. aureus was the most sensitive organism to PE and minimum inhibitory concentration (MIC) was found to be 0.013 mg/mL where as the MIC of PE against V. cholerae was the highest (0.25 mg/mL). On the other hand PE showed growth promoting effect on the common probiotic bacterium L. acidophilus. The major finding was that S. grandiflora PE induced a significant biomass increase of L. acidophilus grown in liquid culture media. PE showed reduction of S. aureus growth in food (fish) during storage at 10°C. High performance liquid chromatography analysis showed that rutin, a major flavonoid of the PE diminished in the culture medium MRS broth with the growth of L. acidophilus.     

Increase in membrane permeability of electrolytes and betacyanin in beet root disc by fenitrothion

Effect of fenitrothion (phosphorothioic acid, 0,0-dimethyl 0-4-nitro-m-tolyl ester), an organophosphorous insecticide, on membrane permeability employing the leakage of betacyanin and electrolytes as the criteria were studied in beet root(Beta vulgaris) discs. The leakage of both betacyanin and electrolytes increased with increasing concentrations (10–150 ppm) of fenitrothion in the incubation medium. At 0.33 mM the increase in electrolyte leakage was approximately linear for the first 6h, while the increase in betacyanin leakage started with a lag of about 2 h. Long term incubation (24 h) showed a biphasic nature (in the semilog plot) for the increase in betacyanin leakage, while the increase in electrolyte leakage appeared more complex. In the control sample, the Arrhenius plots (25–50°C) of leakage showed a break at 40°C. In treated samples no break was observed, but the slope decreased (for both electrolyte and betacyanin leakage) as compared to the respective slopes in the control in the temperature region greater than 40°C. The results are discussed in terms of the possible effect of the insecticide on the active transport in plant membranes     

Structure of the Parainfluenza Virus 5 (PIV5) Hemagglutinin-Neuraminidase (HN) Ectodomain

Paramyxoviruses cause a wide variety of human and animal diseases. They infect host cells using the coordinated action of two surface glycoproteins, the receptor binding protein (HN, H, or G) and the fusion protein (F). HN binds sialic acid on host cells (hemagglutinin activity) and hydrolyzes these receptors during viral egress (neuraminidase activity, NA). Additionally, receptor binding is thought to induce a conformational change in HN that subsequently triggers major refolding in homotypic F, resulting in fusion of virus and target cell membranes. HN is an oligomeric type II transmembrane protein with a short cytoplasmic domain and a large ectodomain comprising a long helical stalk and large globular head domain containing the enzymatic functions (NA domain). Extensive biochemical characterization has revealed that HN-stalk residues determine F specificity and activation. However, the F/HN interaction and the mechanisms whereby receptor binding regulates F activation are poorly defined. Recently, a structure of Newcastle disease virus (NDV) HN ectodomain revealed the heads (NA domains) in a “4-heads-down” conformation whereby two of the heads form a symmetrical interaction with two sides of the stalk. The interface includes stalk residues implicated in triggering F, and the heads sterically shield these residues from interaction with F (at least on two sides). Here we report the x-ray crystal structure of parainfluenza virus 5 (PIV5) HN ectodomain in a “2-heads-up/2-heads-down” conformation where two heads (covalent dimers) are in the “down position,” forming a similar interface as observed in the NDV HN ectodomain structure, and two heads are in an “up position.” The structure supports a model in which the heads of HN transition from down to up upon receptor binding thereby releasing steric constraints and facilitating the interaction between critical HN-stalk residues and F.     

Scattered light intensity fluctuation in the canine ventricular myocardium: correlation with inotropic drug effect

Scattered light intensity fluctuation (SLIF) of coherent light by a strip of ventricular muscle during diastole is believed to be due to asynchronous cellular motion within the myocyte as a result of spontaneous release of Ca from the sacoplamic reticulum. Previous studies have shown a correlation between inotropic agents, such as ouabain and elevated extracellular Ca or decreased extracellular Na, and SLIF. The purpose of this study was to see if this correlation could be extended to other inotropic agents. The digitalis genin, ouabagenin, produces inotropy by increasing intracellular free Ca. In toxic concentrations the drug produces abnormal aftercontractions by spontaneous Ca release from the sarcoplasmic reticulum. On the other hand, the Ca channel agonist BAY k 8644 is also positively inotropic, but its effect is associated with a decrease in Ca release from the sarcoplasmic reticulum, manifested by conversion of "rest potentiation" to "rest depression." The effects of these inotropic agents on the power spectra of SLIF were dissimilar. Both frequency and amplitude of SLIF were increased after ouabagenin (1 microM), but these changes were most marked after the onset of toxicity, at which time contractility was decreased, rather than during the positive inotropic response. In contrast, BAY k 8644 (1 microM) decreased SLIF at all levels of inotropic response. The beta-adrenoceptor stimulant drug, dobutamine, and the adenylate cyclase activator, forskolin, produced minimal increase in SLIF at inotropic concentrations but caused a large increase in SLIF only after the onset of toxicity. These results suggest that SLIF is a better indicator of intracellular Ca overload and toxic oscillatory contractions in the presence of an inotrope and not of increased inotropy, per se.     

Mono(maleonitriledithiolene)molybdenum(IV) and Bis(μ-sulfido)-Bridged Dimolybdenum(V) Complexes with MoS Moiety

Mono(maleonitriledithiolene)sulfidomolybdenum(IV) complex, [MoS(S(4) )(mnt)](2-) (2; mnt=maleonitriledithiolene) was synthesized by the substitution reaction of a tetrasulfido ligand of the known [MoS(S(4) )(2) ](2-) (1) upon reaction with one or even excess equivalent of Na(2) (mnt) in aqueous MeCN solution in air. Surprisingly, 2 undergoes dimerization on treatment with alkyl halide such as MeI and PhCH(2) Br to form bis(μ-sulfido)dimolybdenum(V) species, [{MoS(mnt)}(2) (μ-S)(2) ](2-) (3). These complexes have been characterized by IR, UV/VIS spectroscopy, cyclic voltammetry, elemental analysis, and by X-ray crystal-structure analysis. Differences in the relative stability and electrochemical behavior of 1, 2, and 3 have been correlated with theoretical calculations at DFT level.     

Characterization of Novel Lipopeptides Produced by Bacillus tequilensis P15 Using Liquid Chromatography Coupled Electron Spray Ionization Tandem Mass Spectrometry (LC–ESI–MS/MS)

Microbes are known to interact and communicate with their neighbouring cells by releasing diverse types of low molecular weight diffusible metabolites. This paper describes the identification of iturins, fengycins and surfactins secreted by Bacillus tequilensis P15 isolated from sea coast of Jakhao, Kutch, India, using liquid chromatography coupled electron spray ionization tandem mass spectrometry. In methanol soluble fraction of acid precipitate harvested from cell free supernatant of B. tequilensis P15, 5 variants of iturins, 6 of fengycins and 39 surfactins could be identified. In particular, new surfactins with Ile/Leu at position 5 and Asp at position 6 in the peptide chain were discovered, which have not been previously reported. A novel class of novel surfactin consisting of Glu/methyl ester of Asp at position 5 in peptide chain was also identified. In addition, several linear forms of surfactins were also identified in the methanol soluble extracellular fraction of B. tequilensis P15. This is the first report on co-production of all the three classes of cyclic lipopeptides by a marine isolate B. tequilensis.     

The structural basis of mode of activation and functional diversity: a case study with HtrA family of serine proteases

HtrA (High temperature requirement protease A) proteins that are primarily involved in protein quality control belong to a family of serine proteases conserved from bacteria to humans. HtrAs are oligomeric proteins that share a common trimeric pyramidal architecture where each monomer comprises a serine protease domain and one or two PDZ domains. Although the overall structural integrity is well maintained and they exhibit similar mechanism of activation, subtle conformational changes and structural plasticity especially in the flexible loop regions and domain interfaces lead to differences in their active site conformation and hence in their specificity and functions.     

Differences in the flow and absorption cytometric DNA distributions of mouse hepatocytes and tumor cells

We have determined the DNA content, the ploidy levels, and the percentages of different cell types present in small and large mouse mammary tumors as well as in young and old mouse livers by using absorption and flow cytometry. Absorption cytometry data indicated a significant increase in the proportion of transformed G0/G1 cells in the tumors as compared to that of the stromal G0/G1 cells with progressive tumor growth. This increase was not detected by flow cytometry. In both young and old mouse livers, a small number of cells of higher ploidy (8C and 16C) were detected by absorption cytometry but were not apparent in histograms obtained by flow cytometry. Furthermore, changes in the proportions of liver cells of different ploidy with age were apparent in absorption cytometry data but not in flow cytometry data. In one mouse liver experiment, a 6C cell peak appeared in the flow cytometry histogram, but a direct measurement of DNA content by absorption cytometry failed to detect cells with such a peak. We therefore believe that some caution may be warranted in the use of flow cytometry alone for evaluation of DNA distributions and of the proportions of different types of cells in complex solid tissues.