Assessment of antibacterial activity of silver nanoparticles on Pseudomonas aeruginosa and its mechanism of action

Antimicrobial activity of silver nanoparticles is gaining importance due its broad spectrum of targets in cell compared to conventional antimicrobial agents. In this context, a UV photo-reduction method was used for the synthesis and the nanoparticles were characterized by UV–Visible spectroscopy, transmission electron microscopy, atomic force microscopy and thermogravimetric analysis techniques. The antibacterial activity of the synthesized silver nanoparticles was evaluated both in liquid and solid growth media employing various susceptibility assays on Pseudomonas aeruginosa, a ubiquitous bacterium. The dose dependent growth suppression by nanoparticles was studied with well diffusion method. By broth dilution method, the minimum inhibitory concentration (MIC) was found to be 2 μg/ml. It was observed that the bactericidal effect depends both on nanoparticle concentration and number of bacteria present. In our study, we could demonstrate the complete antibiofilm activity of silver nanoparticles at a concentration as low as 1 μg/ml. Our observations substantiated the association of reactive oxygen species and cell membrane damage in the antibacterial mechanism of silver nanoparticles. Our findings suggested that these nanoparticles can be exploited towards the development of potential antibacterial coatings for various biomedical and environmental applications.     

Ferulic acid with ascorbic acid synergistically extenuates the mitochondrial dysfunction during beta-adrenergic catecholamine induced cardiotoxicity in rats

Disruption of mitochondria and free radical mediated tissue injury have been reported during cardiotoxicity induced by isoproterenol (ISO), a beta-adrenergic catecholamine. The present study was designed to investigate the effect of the combination of ferulic acid (FA) and ascorbic acid (AA) on the mitochondrial damage in ISO induced cardiotoxicity. Induction of rats with ISO (150 mg/kg b.wt., i.p.) for 2 days resulted in a significant decrease in the activities of respiratory chain enzymes (NADH dehydrogenase and cytochrome c-oxidase), tricarboxylic acid cycle enzymes (isocitrate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, alpha-ketoglutarate dehydrogenase), mitochondrial antioxidants (GPx, GST, SOD, CAT, GSH), cytochromes (b, c, c1, aa3) and in the level of mitochondrial phospholipids. A marked elevation in mitochondrial lipid peroxidation, mitochondrial levels of cholesterol, triglycerides and free fatty acids were also observed in ISO intoxicated rats. Pre-co-treatment with the combination of FA (20 mg/kg b.wt.) and AA (80 mg/kg b.wt.) orally for 6 days significantly enhanced the attenuation of these functional abnormalities and restored normal mitochondrial function when compared to individual drug treated groups. Mitigation of ISO induced biochemical and morphological changes in mitochondria were more pronounced with a combination of FA and AA rather than the individual drug treated groups. Transmission electron microscopic observations also correlated with these biochemical parameters. Hence, these findings demonstrate the synergistic ameliorative potential of FA and AA on mitochondrial function during beta-adrenergic catecholamine induced cardiotoxicity and associated oxidative stress in rats.     

Synthesis, micellar properties, DNA binding and antimicrobial studies of some surfactant-cobalt(III) complexes

A new class of surfactant-cobalt(III) complex ions of the type, cis-[Co(X)(2)(C(14)H(29)NH(2))Cl](2+) (where X=ethylenediamine (en), or 2,2'-bipyridyl (bpy), or 1,10-phenanthroline (phen)) and cis-[Co(trien)(C(14)H(29)NH(2))Cl](2+) (trien=triethylenetetramine) were synthesized and characterized by IR, NMR, UV-visible electronic absorption spectra, elemental analysis and metal analysis. The critical micelle concentration (CMC) values of these surfactant-cobalt(III) complexes in aqueous solution were obtained from conductance measurements. Specific conductivity data (at 298, 308, 318 and 328 K) served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (DeltaG(0)(m), DeltaH(0)(m) and DeltaS(0)(m)). Interactions between calf thymus DNA and the surfactant-cobalt(III) complexes in aqueous solution have been investigated by electronic absorption spectroscopy, emission spectroscopy and viscosity measurements. The electrostatic interactions, van der Waals interactions and/or partial intercalative binding have been observed in these systems. The surfactant-cobalt(III) complexes were screened for their antibacterial and antifungal activities against various microorganisms. The results were compared with the standard drugs, Ciprofloxacin and Fluconazole respectively.     

Evaluation of anti-inflammatory activity of Alstonia macrophylla Wall ex A. DC. leaf extract.

Methanolic extract of dried leaves of Alstonia macrophylla Wall ex A. DC. and its fractions were investigated for its anti-inflammatory activity. The extract at a concentration of 200 mg kg(-1) and 400 mg kg(-1), p.o. and its fractions at 25 mg kg(-1) and 50 mg kg(-1), p.o. showed the significant dose dependent antiinflammatory activity in carrageenan and dextran-induced rats hind paw edema (acute models) as well as in cotton pellet-induced granuloma (chronic model) in rats. Anti-inflammatory activity of the tested extract and its fractions was comparable with that of the standard drug Indomethacin (10 mg kg(-1)).     

Genetic variation for VA mycorrhiza-dependent phosphate mobilisation in groundnut (Arachis hypogaea L.)

Nine cultivars of groundnut (Arachis hypogaea L.) were grown in a soil poor in available N or P. There was clearly genetic variation of characteristics indicative of VA mycorrhiza-dependent phosphate mobilisation, namely, VA mycorrhiza fungal spore count (SC), percentage of infection (IF) by VA mycorrhizal fungi (VAMF) and acid and alkaline phosphatase activities. Among the cultivars, one was non-nodulating with low values for all characteristics and in another experiment, this non-nodulating cultivar, one of its parents (PI 259747), a national check (Robut 33-1) and the highest yielding cultivar among the original nine (NFG 7), were grown and investigated for various P-mobilising properties and yield. The linear regression coefficient of pod yield on % VAMF infection was significant in both the experiments. Additionally, many of the correlation coefficients of pod yield and VAM dependent characteristics were positive and significant. From consideration of published evidence, it seems possible to breed for the desirable reinforcing effects of infestation, by VAMF and Rhizobium that can ultimately improve the productivity of groundnuts.     

Iodoestrogens, syntheses, and interaction with uterine receptors.

The rationale for undertaking the present study was to evaluate the utility of iodoestradiol analogs made highly radioactive with iodine isotopes in (a) the non-invasive differentiation of estrogen-dependent from estrogen-independent breast tumors, (b) spread of metastases containing estrogen receptors, and (c) potential application in therapeutic irradiation of target tissues. In the present paper, the model syntheses of a number of nonradioactive 127I-estrogen analogs are described. The analogs were tested for their ability to displace (compete with) [3H]estradiol from receptor sites. The most active compounds, 16beta-iodoestra-1,3,5(10)-triene-3,17 beta-diol (17) and 6-iodoestra-1,3,5(10),6-tetraene-3,17 beta-diol (10b), showed a relative binding affinity of 0.57 and 0.49, respectively.     

Spermatozoa input concentrations and RNA isolation methods on RNA yield and quality in bull (Bos taurus)

Sperm RNA can be used to understand the past spermatogenic process, future successful fertilization, and embryo development. To study the sperm RNA composition and function, isolation of good quality RNA with sufficient quantity is essential. The objective of this study was to assess the influence of sperm input concentrations and RNA isolation methods on RNA yield and quality in bull sperm. The fresh semen samples from bulls (n = 6) were snap-frozen in liquid nitrogen and stored at −80 °C. The sperm RNA was isolated using membrane-based methods combined with TRIzol (RNeasy + TRIzol and PureLink + TRIzol) and conventional methods (TRIzol, Double TRIzol, and RNAzol RT). Based on fluorometric quantification, combined methods resulted in significantly (P < 0.05) higher total RNA yields (800–900 ng/30–40 × 10⁶) as compared with other methods and yielded 20 to 30 fg of RNA/spermatozoon. The quality of RNA isolated by membrane-based methods was superior to that isolated by conventional methods. The sperm RNA was observed to be intact as well as fragmented (50–2000 bp). The study revealed that the membrane-based methods with a cocktail of lysis solution and an optimal input concentration of 30 to 40 million sperm were optimal for maximum recovery of RNA from bull spermatozoa.     

Development of new cytoplasmic-genetic male-sterile lines in pigeonpea from crosses betweenCajanus cajan (L. Millsp. andC. scarabaeoides (L.) Thouars

Exploitation of hybrid vigour is quite possible in cross-pollinated crops. However, pigeonpea is a grain legume crop with a moderate level of cross-pollination (20-70%), which is mainly aided by insect pollinators. As a first step, hybrids based on genetic male sterility (GMS) were developed in pigeonpea, but the hybrid seed production technique is not farmer-friendly, because in the hybrid seed production plot 50% of the population, which are male-fertile in the female rows, have to be eliminated in time before contamination. This requires skilled labour and is a time-consuming process, which increases the cost of hybrid seed production. Therefore, the objective of this study was to develop cytoplasmic-genetic male-sterile (CGMS) lines in pigeonpea through wide hybridization, which would be very suitable for hybrid seed production. Two CGMS lines, viz. CORG 990052 A and CORG 990047, were developed by interspecific hybridization of Cajanus cajan and C. scarabaeoides. Restorers were identified and three CGMS-based pigeonpea hybrids were developed. The hybrid COPH 3 is found to be promising in Tamil Nadu State, India.     

Munc18-1 is critical for plasma membrane localization of syntaxin1 but not of SNAP-25 in PC12 cells

Although Munc18-1 was originally identified as a syntaxin1–interacting protein, the physiological significance of this interaction remains unclear. In fact, recent studies of Munc18-1 mutants have suggested that Munc18-1 plays a critical role for docking of secretory vesicles, independent of syntaxin1 regulation. Here we investigated the role of Munc18-1 in syntaxin1 localization by generating stable neuroendocrine cell lines in which Munc18-1 was strongly down-regulated. In these cells, the secretion capability, as well as the docking of dense-core vesicles, was significantly reduced. More importantly, not only was the expression level of syntaxin1 reduced, but the localization of syntaxin1 at the plasma membrane was also severely perturbed. The mislocalized syntaxin1 resided primarily in the perinuclear region of the cells, in which it was highly colocalized with Secretogranin II, a marker protein for dense-core vesicles. In contrast, the expression level and the plasma membrane localization of SNAP-25 were not affected. Furthermore, the syntaxin1 localization and the secretion capability were restored upon transfection-mediated reintroduction of Munc18-1. Our results indicate that endogenous Munc18-1 plays a critical role for the plasma membrane localization of syntaxin1 in neuroendocrine cells and therefore necessitates the interpretation of Munc18-1 mutant phenotypes to be in terms of mislocalized syntaxin1.