Zymographic assay of plant diamine oxidase on entrapped peroxidase polyacrylamide gel electrophoresis. A study of stability to proteolysis

A zymographic assay of diamine oxidase (DAO, histaminase, EC 1.4.3.6), based on a coupled peroxidase reaction, and its behavior at proteolysis in simulated gastric and intestinal conditions, are described. The DAO activity from a vegetal extract of Lathyrus sativus seedlings was directly determined on sodium dodecyl sulfate polyacrylamide electrophoretic gels containing entrapped horseradish peroxidase, with putrescine as substrate of histaminase and ortho-phenylenediamine as co-substrate of peroxidase. The accumulation of azo-aniline, as peroxidase-catalyzed oxidation product, led to well-defined yellow-brown bands on gels, with intensities corresponding to the enzymatic activity of DAO. After image analysis of gels, a linear dependency of DAO content (Coomassie-stained protein bands) and of its enzymatic activity (zymographic bands) with the concentration of the vegetal extract was obtained. In simulated gastric conditions (pH 1.2, 37 °C), the DAO from the vegetal extract lost its enzymatic activity before 15 min of incubation, either in the presence or absence of pepsin. The protein pattern (Coomassie-stained) revealed that the DAO content from the vegetal extract was kept almost constant in the simulated intestinal fluid (containing pancreatin or not), with a slight diminution in the presence of pancreatic proteases. After 10 h of incubation at 37 °C, the DAO enzymatic activity from the vegetal extract was 44.7% in media without pancreatin and 13.6% in the presence of pancreatin, whereas the purified DAO retained only 4.65% of its initial enzymatic activity in the presence of pancreatin

Non-antibiotic quorum sensing inhibitors acting against N-acyl homoserine lactone synthase as druggable target

YesN-acylhomoserine lactone (AHL)-based quorum sensing (QS) is important for the regulation of proteobacterial virulence determinants. Thus, the inhibition of AHL synthases offers non-antibiotics-based therapeutic potentials against QS-mediated bacterial infections. In this work, functional AHL synthases of Pseudomonas aeruginosa LasI and RhlI were heterologously expressed in an AHL-negative Escherichia coli followed by assessments on their AHLs production using AHL biosensors and high resolution liquid chromatography–mass spectrometry (LCMS). These AHL-producing E. coli served as tools for screening AHL synthase inhibitors. Based on a campaign of screening synthetic molecules and natural products using our approach, three strongest inhibitors namely are salicylic acid, tannic acid and trans-cinnamaldehyde have been identified. LCMS analysis further confirmed tannic acid and trans-cinnemaldehyde efficiently inhibited AHL production by RhlI. We further demonstrated the application of trans-cinnemaldehyde inhibiting Rhl QS system regulated pyocyanin production in P. aeruginosa up to 42.06%. Molecular docking analysis suggested that trans-cinnemaldehyde binds to the LasI and EsaI with known structures mainly interacting with their substrate binding sites. Our data suggested a new class of QS-inhibiting agents from natural products targeting AHL synthase and provided a potential approach for facilitating the discovery of anti-QS signal synthesis as basis of novel anti-infective approach.University of Malaya High Impact Research (HIR) Grant (UM-MOHE HIR Grant UM.C/625/1/HIR/MOHE/CHAN/14/1, no. H-50001-A000027) given to K.G.C. and National Natural Science Foundation of China (no. 81260481) given to H.W

Cyanamide mode of action during inhibition of onion (Allium cepa L.) root growth involves disturbances in cell division and cytoskeleton formation

Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). Its phyotoxic effect on plant growth was examined on roots of onion (Allium cepa L.) bulbs. Water solution of cyanamide (2–10 mM) restricted growth of onion roots in a dose-dependent manner. Treatment of onion roots with cyanamide resulted in a decrease in root growth rate accompanied by a decrease in accumulation of fresh and dry weight. The inhibitory effect of cyanamide was reversed by its removal from the environment, but full recovery was observed only for tissue treated with this chemical at low concentration (2–6 mM). Cytological observations of root tip cells suggest that disturbances in cell division may explain the strong cyanamide allelopathic activity. Moreover, in cyanamide-treated onion the following changes were detected: reduction of mitotic cells, inhibition of proliferation of meristematic cells and cell cycle, and modifications of cytoskeleton arrangement

Testosterone therapy induces molecular programming augmenting physiological adaptations to resistance exercise in older men

Background: The andropause is associated with declines in serum testosterone (T), loss of muscle mass (sarcopenia) and frailty. Two major interventions purported to offset sarcopenia are anabolic steroid therapies and resistance exercise training (RET). Nonetheless, the efficacy, and physiological and molecular impacts of T therapy adjuvant to short-term RET remain poorly defined.Methods: Eighteen non-hypogonadal healthy older men, 65-75 y, were assigned in a random double-blinded fashion to receive, bi-weekly, either placebo (P, saline, n=9) or T (Sustanon 250 mg, n=9) injections over 6-weeks whole-body RET (3-sets of 8-10 reps at 80% 1-RM). Subjects underwent dual-energy x-ray absorptiometry, ultrasound of vastus lateralis (VL) muscle architecture, and knee-extensor isometric muscle force tests; VL muscle biopsies were taken to quantify myogenic/anabolic gene expression, anabolic signalling, muscle protein synthesis (D2O) and breakdown (extrapolated).Results: T adjuvant to RET, augmented total fat free mass (FFM) (P=0.007), legs fat free mass (P=0.02), and appendicular FFM (P=0.001) gains, while decreasing total fat mass (P=0.02). Augmentations in VL muscle thickness, fascicle length, and quadriceps cross-section area with RET occured to a greater extent in T (P less than 0.05).Total strength (P=0.0009) and maximal voluntary contract (e.g. knee extension at 70°) (P=0.002) increased significantly more in the T group. Mechanistically, both muscle protein synthesis rates (T: 2.13±0.21%·day−1 vs. P: 1.34±0.13%·day−1, P=0.0009) and absolute breakdown rates (T: 140.2±15.8 vs. P: 90.2±11.7g·day-1, P=0.02) were elevated with T therapy, which led to higher net turnover and protein accretion in the T group (T: 8.3±1.4g·day-1 vs. P: 1.9±1.2 g·day-1, P=0.004). Increases in ribosomal biogenesis (RNA:DNA ratio); mRNA expression relating to T metabolism (Androgen Receptor: 1.4-fold; Srd5a1: 1.6-fold; AKR1C3: 2.1-fold; HSD17β3: 2-fold); IGF-1-signalling (IGF-1Ea (3.5-fold), IGF-1Ec (3-fold) and myogenic regulatory factors (MRF); as well the activity of anabolic signalling (e.g. mTOR, AKT, RPS6; P less than 0.05) were all upregulated with T therapy. Only T up-regulated mitochondrial citrate synthase activity (P=0.03) and transcription factor A (Tfam) (1.41±0.2-fold, P=0.0002), in addition to PGC1-α mRNA (1.19±0.21-fold, P=0.037).Conclusions: Administration of T adjuvant to RET enhanced skeletal muscle mass and performance, while upregulating myogenic gene programming, myocellular translational efficiency and capacity - collectively resulting in higher protein turnover, and net protein accretion. T coupled with RET is an effective short-term intervention to improve muscle mass/ function in older non-hypogonadal men

Benzoxazinoids in Root Exudates of Maize Attract Pseudomonas putida to the Rhizosphere

Benzoxazinoids, such as 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA), are secondary metabolites in grasses. In addition to their function in plant defence against pests and diseases above-ground, benzoxazinoids (BXs) have also been implicated in defence below-ground, where they can exert allelochemical or antimicrobial activities. We have studied the impact of BXs on the interaction between maize and Pseudomonas putida KT2440, a competitive coloniser of the maize rhizosphere with plant-beneficial traits. Chromatographic analyses revealed that DIMBOA is the main BX compound in root exudates of maize. In vitro analysis of DIMBOA stability indicated that KT2440 tolerance of DIMBOA is based on metabolism-dependent breakdown of this BX compound. Transcriptome analysis of DIMBOA-exposed P. putida identified increased transcription of genes controlling benzoate catabolism and chemotaxis. Chemotaxis assays confirmed motility of P. putida towards DIMBOA. Moreover, colonisation essays in soil with Green Fluorescent Protein (GFP)-expressing P. putida showed that DIMBOA-producing roots of wild-type maize attract significantly higher numbers of P. putida cells than roots of the DIMBOA-deficient bx1 mutant. Our results demonstrate a central role for DIMBOA as a below-ground semiochemical for recruitment of plant-beneficial rhizobacteria during the relatively young and vulnerable growth stages of maize

Phytotoxic Effects of (±)-Catechin In vitro, in Soil, and in the Field

BACKGROUND: Exploring the residence time of allelochemicals released by plants into different soils, episodic exposure of plants to allelochemicals, and the effects of allelochemicals in the field has the potential to improve our understanding of interactions among plants. METHODOLOGY/PRINCIPAL FINDINGS: We conducted experiments in India and the USA to understand the dynamics of soil concentrations and phytotoxicity of (+/-)-catechin, an allelopathic compound exuded from the roots of Centaurea maculosa, to other plants in vitro and in soil. Experiments with single and pulsed applications into soil were conducted in the field. Experimental application of (+/-)-catechin to soils always resulted in concentrations that were far lower than the amounts added but within the range of reported natural soil concentrations. Pulses replenished (+/-)-catechin levels in soils, but consistently at concentrations much lower than were applied, and even pulsed concentrations declined rapidly. Different natural soils varied substantially in the retention of (+/-)-catechin after application but consistent rapid decreases in concentrations over time suggested that applied experimental concentrations may overestimate concentrations necessary for phytotoxicity by over an order of magnitude. (+/-)-Catechin was not phytotoxic to Bambusa arundinacea in natural Indian soil in a single pulse, but soil concentrations at the time of planting seeds were either undetectable or very low. However, a single dose of (+/-)-catechin suppressed the growth of bamboo in sand, in soil mixed with organic matter, and Koeleria macrantha in soils from Montana and Romania, and in field applications at 40 microg l(-1). Multiple pulses of (+/-)-catechin were inhibitory at very low concentrations in Indian soil. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that (+/-)-catechin is highly dynamic in natural soils, but is phytotoxic well below natural concentrations measured in some soils and applied at low concentrations in the field. However, there is substantial conditionality in the effects of the allelochemical

Beyond altruism: A case for compensated surrogate motherhood

Commercial surrogacy is prohibited in many countries, and there are a number of convincing reasons why it should remain so. We accept the reasons, but argue that fairness requires that surrogates be compensated for their labour as well as the risks they undertake. It is a mistake to equate compensated surrogacy with commercial surrogacy. In order to safeguard against the risk of exploitation and other harmful and unethical practices, we propose organizing surrogacy along the lines of professions such as nursing and teaching. This would involve establishing a professional body, which will be charged with the task of regulating fees , licensing, and monitoring clinics that offer surrogacy services, and screening and registering surrogates. We think a similar model can be used in the case of live organ donation as well as gamete and embryo donation