Efficient in vitro plant regeneration through leaf base derived callus cultures of abiotic stress sensitive popular Asian Indica rice cultivar IR 64 (Oryza sativa L.)

A simple and efficient protocol has been developed for high frequency plant regeneration through callus cultures derived from leaf bases of abiotic stress sensitive Asian indica rice variety IR 64. Leaf base segments (4-5 mm diameter) were obtained from 6-day-old dark grown seedlings germinated on halfstrength Murashige and Skoog medium and cultured on MS medium supplemented with different concentrations of 2,4-Dichlorophenoxyacetic acid (2.2-18 μM) and Kinetin (0.2-1.7 μM). Among the various combinations, 13.5 μM 2,4-D and 1.3 μM Kn resulted in high callus induction frequency (87.5%) with a maximum fresh weight of 0.22 g per segment. The regeneration frequency was 75.5% with multiple shoots within 3 weeks of transfer on MS medium supplemented with 13.3 μM 6-benzylamino purine and 8 μM Naphthaleneacetic acid. The shoots readily rooted on half-strength MS medium without any hormonal supplements. In vitro regenerated plantlets with multiple shoots and roots were transferred to sterile soil and vermiculite mix and maintained in shade house for 30 days. Complete plantlets were then transferred to nursery and acclimatized to the external environment until seed set. RAPD profile reveals monomorphism and thus confirming the genetic stability of the regenerated plants. This method has the potential for both direct as well as indirect method of transformation for the production of genetically modified plants.     

Antipathogenic potential of marine <Emphasis Type="Italic">Bacillus</Emphasis> sp. SS4 on <Emphasis Type="Italic">N</Emphasis>-acyl-homoserine-lactone-mediated virulence factors production in <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> (PAO1)

Antipathogenic therapy is an outcome of the quorum-sensing inhibition (QSI) mechanism, which targets autoinducer-dependent virulent gene expression in bacterial pathogens. N-acyl homoserine lactone (AHL) acts as a key regulator in the production of virulence factors and biofilm formation in Pseudomonas aeruginosa PAO1 and violacein pigment production in Chromobacterium violaceum. In the present study, the marine bacterial strain SS4 showed potential QSI activity in a concentration-dependent manner (0.5–2 mg/ml) against the AHL-mediated violacein production in C. violaceum (33–86%) and biofilm formation (33–88%), total protease (20–65%), LasA protease (59–68%), LasB elastase (36–68%), pyocyanin (17–86%) and pyoverdin productions in PAO1. The light and confocal laser scanning microscopic analyses confirmed the reduction of the biofilm-forming ability of PAO1 when treated with SS4 extract. Furthermore, the antibiofilm potential was confirmed through static biofilm ring assay, in which ethyl acetate extract of SS4 showed concentration-dependent reduction in the biofilm-forming ability of PAO1. Thus, the result of this study clearly reveals the antipathogenic and antibiofilm properties of the bacterial isolate SS4. Through 16S rDNA analysis, the strain SS4 was identified as Bacillus sp. (GenBank Accession Number: GU471751).     

Theoretical and experimental studies of vibrational spectra and thermodynamical analysis of 3�?bromopropiophenone and 4�?bromo-3-chloropropiophenone

Quantum chemical calculations of molecular geometries, vibrational wavenumbers and thermodynamical properties of 3'-bromopropiophenone and 4'-bromo-3-chloropropiophenone were carried out using Hartree-Fock (HF) and density functional theory (DFT) using hybrid functional B3LYP with 6-31?G (d,p) as basis set. The optimized geometrical parameters obtained by HF and DFT calculations are in good agreement with the experimental FTIR and FT Raman spectral datas. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed simulated spectrograms.     

Quorum Sensing Inhibition in Pseudomonas aeruginosa PAO1 by Antagonistic Compound Phenylacetic Acid

In Pseudomonas aeruginosa, quorum sensing (QS) autoinducer known as acyl homoserine lactone (AHL) acts as a key regulator in the expression of pathogenic characters. In this work, the efficiency of phenylacetic acid (PAA) in reducing the production of AHL-dependent factors in P. aeruginosa PAO1 was studied. PAA at a concentration of 200?μg?ml(-1) displayed significant reduction in QS-dependent pyocyanin, exopolysaccharide, and protease and elastase production in PAO1. In swimming inhibition assay, PAA-treated PAO1 cells exhibited poor motility in swimming agar plate. In in vivo analysis, PAO1-preinfected Caenorhabditis elegans showed enhanced survival when treated with PAA. PAA at the QS inhibitory concentration showed no growth inhibitory activity on PAO1. Results of the present study revealed the potential of PAA as antipathogenic compound to prevent QS-dependent pathogenicity of P. aeruginosa.     

Development of programmable small DNA-binding molecules with epigenetic activity for induction of core pluripotency genes

Epigenetic modifications that govern the gene expression are often overlooked with the design of artificial genetic switches. N-Methylpyrrole-N-methylimidazole (PI) hairpin polyamides are programmable small DNA binding molecules that have been studied in the context of gene regulation. Recently, we synthesized a library of compounds by conjugating PI polyamides with SAHA, a chromatin-modifier. Among these novel compounds, PI polyamide-SAHA conjugate 1 was shown to epigenetically activate pluripotency genes in mouse embryonic fibroblasts. Here, we report the synthesis of the derivatives of conjugate 1 and demonstrate that these epigenetically active molecules could be developed to improve the induction of pluripotency factors.     

A regio- and stereoselective 1,3-dipolar cycloaddition for the synthesis of new-fangled dispiropyrrolothiazoles as antimycobacterial agents

A series of dispiropyrrolothiazoles compounds were synthesized using 1,3-dipolar cycloaddition and were screened for antimycobacterial activity against Mycobacterium tuberculosis H₃₇Rv and INH resistant M. tuberculosis strains. Two of them were showing good activity with MIC of less than 1 μM. Compound (5f) was found to be the most active with MIC of 0.210 and 8.312 μM respectively.     

Inhibition of quorum sensing regulated biofilm formation in Serratia marcescens causing nosocomial infections

Serratia marcescens is an opportunistic pathogen causing severe urinary tract infections in hospitalized individuals. Infections of S. marcescens are of great concern because of its increasing resistance towards conventional antibiotics. Quorum sensing (QS)-a cell to cell communication-system of S. marcescens acts as a global regulator of almost all the virulence factors and majorly its biofilm formation. Since, the QS system of S. marcescens directly accords to its pathogenesis, targeting QS system will provide an improved strategy to combat drug resistant pathogens. In the present study, QS system of S. marcescens has been used as target and its inhibition has been studied upon exposure to bioactives from coral associated bacteria (CAB). This study also emphasises the potential of CAB in producing bioactive agents with anti-QS and antibiofilm properties. Two CAB isolates CAB 23 and 41 have shown to inhibit biofilm formation and the production of QS dependent virulence factors like prodigiosin, protease, lipase and swarming motility. The study, on the whole explicates the potential of QS system as a target to treat drug resistant bacterial infections.     

Collagen adsorption on quercetin loaded polycaprolactone microspheres: approach for "stealth" implant

We recently experimented with collagen coating on the surface of quercetin loaded polycaprolactone microspheres by simple adsorption technique to mimic extra cellular matrix and reduce immune or inflammatory responses at the site of implants. The collagen immobilization on polymeric scaffold surfaces through various surface modification techniques was the current scenario to improve bio-integration of the polymers with the in vivo system. Nevertheless, it requires other chemicals or processing methods to modify the surface of polymers to immobilize the collagen covalently. Here protein adsorption principle is used for the coating of collagen onto the surface of solid microspheres and characterized. Optical, ATR-FTIR, SEM analysis confirm collagen coating. The reduction in burst release of the quercetin from the PCL microspheres further confirms its presence and role in the controlled release. The results indicate that the adsorption technique can be the simple strategy to coat collagen on the surface of polyester implants to develop stealth implant in shorter time with low cost technology.     

Purification, immobilization, and characterization of nattokinase on PHB nanoparticles

In this study, nattokinase was purified from Bacillus subtilis using ion exchange chromatography and immobilized upon polyhydroxybutyrate (PHB) nanoparticles. A novel strain isolated from industrial dairy waste was found to synthesize polyhydroxyalkanoates (PHA) and the strain was identified as Brevibacterium casei SRKP2. PHA granules were extracted from 48 h culture and the FT-IR analysis characterized them as PHB, a natural biopolymer from B. casei. Nanoprecipitation by solvent displacement technique was used to synthesize PHB nanoparticles. PHB nanoparticles were characterized using transmission electron microscopy and particle size ranged from 100–125 nm. Immobilization of nattokinase upon PHB nanoparticles resulted in a 20% increase in the enzyme activity. Immobilization also contributed to the enhanced stability of the enzyme. Moreover, the activity was completely retained on storage at 4 °C for 25 days. The method has proven to be highly simple and can be implemented to other enzymes also.