Purification,characterization and chemical modification studies on a translation inhibitor protein from Luffa cylindrica

A ribosome-inactivating protein (RIP), luffin has been isolated from the seeds of Luffa cylindrica of Cucurbitaceae family by ammonium sulfate fractionation followed by cation exchange and gel-filtration chromatography. Extensive physico-chemical, immunological and biological characterizations were carried out on luffin and compared with that of gelonin. The molecular mass of luffin was -28 kDa as determined by gel-filtration chromatography and SDS-PAGE. The epsilon-NH2 group(s) of luffin were sequentially modified by N-succinimidyl 6-[3-(2-pyridyldithio) propionamido] hexanoate (LC-SPDP), N-succinimidyl-3-(2-pyridylthio)propionate (SPDP) and 2-iminothiolane (2IT) and their effect on immunoreactivity and ribosome inactivating property was evaluated. Modification of single amino group resulted in about 80% inhibition of immunoreactivity and more than 90% loss of protein synthesis inhibition activity. Modification of 2-3 amino groups further hampered both immunoreactivity and protein-synthesis inhibition property LC-SPDP modification played more pronounced effects on immunoreactivity and RIP activity than that of SPDP. However, 2IT modification retained both the immunoreactivity and RIP activity of luffin-LC-SPDP substantially. SPDP showed more pronounced effect on immunoreactivity and RIP activity as compared to 2IT. Therefore, it seems that the positive charge on lysine residues plays an important role in immunological as well as protein synthesis inhibitory effect of luffin.     

Humor modulates the mesolimbic reward centers

Humor plays an essential role in many facets of human life including psychological, social, and somatic functioning. Recently, neuroimaging has been applied to this critical human attribute, shedding light on the affective, cognitive, and motor networks involved in humor processing. To date, however, researchers have failed to demonstrate the subcortical correlates of the most fundamental feature of humor-reward. In an effort to elucidate the neurobiological substrate that subserves the reward components of humor, we undertook a high-field (3 Tesla) event-related functional MRI study. Here we demonstrate that humor modulates activity in several cortical regions, and we present new evidence that humor engages a network of subcortical regions including the nucleus accumbens, a key component of the mesolimbic dopaminergic reward system. Further, the degree of humor intensity was positively correlated with BOLD signal intensity in these regions. Together, these findings offer new insight into the neural basis of salutary aspects of humor.     

Glucocorticoid Stress Responses of Reintroduced Tigers in Relation to Anthropogenic Disturbance in Sariska Tiger Reserve in India

Tiger (Panthera tigris), an endangered species, is under severe threat from poaching, habitat loss, prey depletion and habitat disturbance. Such factors have been reported causing local extermination of tiger populations including in one of the most important reserves in India, namely Sariska Tiger Reserve (STR) in northwestern India. Consequently, tigers were reintroduced in STR between 2008 and 2010, but inadequate breeding success was observed over the years, thus invoking an investigation to ascertain physiological correlates. In the present study, we report glucocorticoid stress responses of the reintroduced tigers in relation to anthropogenic disturbance in the STR from 2011 to 2013. We found anthropogenic disturbance such as encounter rates of livestock and humans, distance to roads and efforts to kill domestic livestock associated with an elevation in fecal glucocorticoid metabolite (fGCM) concentrations in the monitored tigers. In this regard, female tigers seem more sensitive to such disturbance than males. It was possible to discern that tiger’s fGCM levels were significantly positively related to the time spent in disturbed areas. Resulting management recommendations include relocation of villages from core areas and restriction of all anthropogenic activities in the entire STR.     

Induction of oxidative stress and histopathological changes by sub-chronic doses of triazophos

The effect of triazophos (O, O-diethyl O-1-phenyl-1 H-1, 2, 4-triazol-3-yl phosphorothioate), a widely used insecticide was studied on the induction of oxidative stress and histological alterations at sub-chronic doses in male albino rats. Oral administration of triazophos at concentrations of 1.64, 3.2 and 8.2 mg/kg body wt for 30 days produced dose as well as time-dependent increase in the lipid peroxidation (determined by malondialdehyde levels) and glutathione-S-transferase (GST) activity in serum with aconcomitant decrease in ferric reducing ability of plasma (FRAP) and blood glutathione (GSH) content. Histopathological examination of liver of triazophos-treated rats showed significant and progressive degenerative changes as compared to control, which could be due to induction of oxidative stress. However, no significant histopathological changes were observed in spleen, kidney and brain at either dose of triazophos with respect to control. These results indicated that oral administration of triazophos was associated with enhanced lipid peroxidation and compromised antioxidant defence in rats in dose and time-dependent manner. Thus the present study demonstrated for the first time the role of oxidative stress as the important mechanism involved in the stimulation of hepatic histoarchitectural alterations at sub-chronic doses of triazophos in rats.     

Semi-synthetic aristolactams—inhibitors of CDK2 enzyme

Several analogs of aristolochic acids were isolated and derivatized into their lactam derivatives to study their inhibition in CDK2 assay. The study helped to derive some conclusions about the structure–activity relation around the phenanthrin moiety. Semi-synthetic aristolactam 21 showed good activity with inhibition IC₅₀ of 35 nM in CDK2 assay. The activity of this compound was comparable to some of the most potent synthetic compounds reported in the literature.     

Direct shoot bud induction and plant regeneration in <Emphasis Type="Italic">Capsicum frutescens</Emphasis> Mill.: influence of polyamines and polarity

Direct shoot bud induction and plant regeneration was achieved in Capsicum frutescens var. KTOC. Aseptically grown seedling explants devoid of roots, apical meristem and cotyledons were inoculated in an inverted position in medium comprising of Murashige and Skoog (Physiol Plant 15:472–497, 1962) basal medium supplemented with 2-(N-morpholine) ethanesulphonic acid buffer along with 2.28 μM indole-3-acetic acid, 10 μM silver nitrate and either of 13.31–89.77 μM benzyl adenine (BA), 9.29–23.23 μM kinetin, 0.91–9.12 μM zeatin, 2.46–9.84 μM 2-isopentenyl adenine. Profuse shoot bud induction was observed only in explants grown on a media supplemented with BA (26.63 μM) as a cytokinin source and 19.4 ± 4.2 shoot buds per explant was obtained in inverted mode under continuous light. Incorporation of polyamine inhibitors in the culture medium completely inhibited shoothoot bud induction. Incorporation of exogenous polyamines improved the induction of shoot buds under 24 h photoperiod. These buds were elongated in MS medium containing 2.8 μM gibberellic acid. Transfer of these shoots to hormone-free MS medium resulted in rooting and rooted plants were transferred to fields. This protocol can be efficiently used for mass propagation and presumably also for regeneration of genetically transformed C. frutescens.     

Importance of partially unfolded conformations for Mg(2+)-induced folding of RNA tertiary structure: structural models and free energies of Mg2+ interactions

RNA molecules in monovalent salt solutions generally adopt a set of partially folded conformations containing only secondary structure, the intermediate or I state. Addition of Mg2+ strongly stabilizes the native tertiary structure (N state) relative to the I state. In this paper, a combination of experimental and computational approaches is used to estimate the free energy of the interaction of Mg2+ with partially folded I state RNAs and to consider the possibility that Mg2+ favors "compaction" of the I state to a set of conformations with a higher average charge density. A sequence variant with a drastically destabilized tertiary structure was used as a mimic of I state RNA; as measured by small-angle X-ray scattering, it adopted a progressively more compact conformation over a wide Mg2+ concentration range. Average free energies of the interaction of Mg2+ with the I state mimic were obtained by a fluorescence titration method. To interpret these experimental data further, we generated molecular models of the I state and used them in calculations with the nonlinear Poisson-Boltzmann equation to estimate the change in Mg2+-RNA interaction free energy as the average I state dimensions decrease from expanded to compact. The same models were also used to reproduce quantitatively the experimental difference in excess Mg2+ between N and I states. On the basis of these experiments and calculations, I state compaction appears to enhance Mg2+-I state interaction free energies by 10-20%, but this enhancement is at most 5% of the overall Mg2+-associated stabilization free energy for this rRNA fragment.     

Surface plasmon resonance biosensor for dopamine using D3 dopamine receptor as a biorecognition molecule

In modern biomedical technology, development of high performance sensing methods for dopamine (DA) is a critical issue because of its vital role in human metabolism. We report here, a new kind of bioaffinity sensor for DA based on surface plasmon resonance (SPR) using a D(3) dopamine receptor (DA-RC) as a recognition element. A conjugate of DA was synthesized using bovine serum albumin (BSA) protein and was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The biosensor surface was constructed by the immobilization of the DA-BSA conjugate onto an SPR gold surface by physical adsorption. Atomic force microscopy (AFM) investigations revealed that the DA-BSA conjugate was homogeneously distributed over the sensor surface. Specific interaction of the DA-RC with the immobilized DA-BSA conjugate was studied by SPR. Based on the principle of indirect competitive inhibition, the biosensor could detect DA in a linear dynamic range from 85 pg/ml (ppt) to 700 ng/ml (ppb). The biosensor was highly specific for DA and showed no significant interference from potent interferences such as ascorbic acid (AA), uric acid (UA) and other DA analogues viz., 3,4 dihydroxyphenyl acetic acid (DOPAC) and 3-(3,4 dihydroxyphenyl)-alanine (DOPA). The sensor surface displayed a high level of stability during repeated regeneration and affinity reaction cycles. Since this biosensor is simple, effective and is based on utilization of natural receptor, our study presents an encouraging scope for development of portable detection systems for in-vitro and in-vivo measurement of DA in clinical and medical diagnostics.     

Synthesis, structural analysis, and SAR studies of triazine derivatives as potent, selective Tie-2 inhibitors

A novel class of selective Tie-2 inhibitors was derived from a multi-kinase inhibitor 1. By reversing the amide connectivity and incorporating aminotriazine or aminopyridine hinge-binding moieties, excellent Tie-2 potency and KDR selectivity could be achieved with 3-substituted terminal aryl rings. X-ray co-crystal structure analysis aided inhibitor design. This series was evaluated on the basis of potency, selectivity, and rat pharmacokinetic parameters.     

Existing and emerging detection technologies for DNA (Deoxyribonucleic Acid) finger printing, sequencing, bio- and analytical chips: a multidisciplinary development unifying molecular biology, chemical and electronics engineering

The current status and research trends of detection techniques for DNA-based analysis such as DNA finger printing, sequencing, biochips and allied fields are examined. An overview of main detectors is presented vis-à-vis these DNA operations. The biochip method is explained, the role of micro- and nanoelectronic technologies in biochip realization is highlighted, various optical and electrical detection principles employed in biochips are indicated, and the operational mechanisms of these detection devices are described. Although a diversity of biochips for diagnostic and therapeutic applications has been demonstrated in research laboratories worldwide, only some of these chips have entered the clinical market, and more chips are awaiting commercialization. The necessity of tagging is eliminated in refractive-index change based devices, but the basic flaw of indirect nature of most detection methodologies can only be overcome by generic and/or reagentless DNA sensors such as the conductance-based approach and the DNA-single electron transistor (DNA-SET) structure. Devices of the electrical detection-based category are expected to pave the pathway for the next-generation DNA chips. The review provides a comprehensive coverage of the detection technologies for DNA finger printing, sequencing and related techniques, encompassing a variety of methods from the primitive art to the state-of-the-art scenario as well as promising methods for the future.