ZnO nanoparticles modulate the ionic transport and voltage regulation of lysenin nanochannels

Background

The insufficient understanding of unintended biological impacts from nanomaterials (NMs) represents a serious impediment to their use for scientific, technological, and medical applications. While previous studies have focused on understanding nanotoxicity effects mostly resulting from cellular internalization, recent work indicates that NMs may interfere with transmembrane transport mechanisms, hence enabling contributions to nanotoxicity by affecting key biological activities dependent on transmembrane transport. In this line of inquiry, we investigated the effects of charged nanoparticles (NPs) on the transport properties of lysenin, a pore-forming toxin that shares fundamental features with ion channels such as regulation and high transport rate.

Results

The macroscopic conductance of lysenin channels greatly diminished in the presence of cationic ZnO NPs. The inhibitory effects were asymmetrical relative to the direction of the electric field and addition site, suggesting electrostatic interactions between ZnO NPs and a binding site. Similar changes in the macroscopic conductance were observed when lysenin channels were reconstituted in neutral lipid membranes, implicating protein-NP interactions as the major contributor to the reduced transport capabilities. In contrast, no inhibitory effects were observed in the presence of anionic SnO₂ NPs. Additionally, we demonstrate that inhibition of ion transport is not due to the dissolution of ZnO NPs and subsequent interactions of zinc ions with lysenin channels.

Conclusion

We conclude that electrostatic interactions between positively charged ZnO NPs and negative charges within the lysenin channels are responsible for the inhibitory effects on the transport of ions. These interactions point to a potential mechanism of cytotoxicity, which may not require NP internalization.

     

Impact of long and short term irrigation of a sodic soil with distillery effluent in combination with bioamendments

The study reports the effects of irrigation of a sodic soil with post methanation effluent (PME) of a distillery. Impact of long term effluent irrigation in the field (10 years) and short term effluent irrigation using different doses of PME in the laboratory (30 days) was studied in combination with three bioamendments i.e. farmyard manure, brassica residues and rice husk. Impact on various soil properties like EC, pH, total organic carbon (TOC), total Kjeldahl nitrogen (TKN), available phosphorus, exchangeable K, Na, Ca, Cl, microbial population and soil enzyme activities were studied. Long term application of PME proved useful in significantly increasing TOC, TKN, K, P and soil enzymatic activities in the soil but tended to build up harmful concentration of Na, that could be chelated by bioamendments. In short terms studies, application of 50% PME along with bioamendments proved to be the most useful in improving the properties of sodic soil and also favoured successful germination and improved seedling growth of pearl millet.     

Regulation of mouse follicle development by follicle-stimulating hormone in a three-dimensional in vitro culture system is dependent on follicle stage and dose

The developmental requirements of ovarian follicles are dependent on the maturation stage of the follicle; in particular, elegant studies with genetic models have indicated that FSH is required for antral, but not preantral, follicle growth and maturation. To elucidate further the role of FSH and other regulatory molecules in preantral follicle development, in vitro culture systems are needed. We employed a biomaterials-based approach to follicle culture, in which follicles were encapsulated within matrices that were tailored to the specific developmental needs of the follicle. This three-dimensional system was used to examine the impact of increasing doses of FSH on follicle development for two-layered secondary (100-130 microm; two layers of granulosa cells surrounding the oocyte) and multilayered secondary (150-180 microm, several layers of granulosa cells surrounding the oocyte) follicles isolated from mice. Two-layered secondary follicles were FSH responsive when cultured in alginate-collagen I matrices, exhibiting FSH dose-dependent increases in follicle growth, lactate production, and steroid secretion. Multilayered secondary follicles were FSH dependent, with follicle survival, growth, steroid secretion, metabolism, and oocyte maturation all regulated by FSH. However, doses greater than 25 mIU/ml of FSH negatively impacted multilayered secondary follicle development (reduced follicle survival). The present results indicate that the hormonal and environmental needs of the follicular complex change during the maturation process. The culture system can be adapted to each stage of development, which will be especially critical for translation to human follicles that have a longer developmental period.     

Unusual microbial xylanases from insect guts

Recombinant DNA technologies enable the direct isolation and expression of novel genes from biotopes containing complex consortia of uncultured microorganisms. In this study, genomic libraries were constructed from microbial DNA isolated from insect intestinal tracts from the orders Isoptera (termites) and Lepidoptera (moths). Using a targeted functional assay, these environmental DNA libraries were screened for genes that encode proteins with xylanase activity. Several novel xylanase enzymes with unusual primary sequences and novel domains of unknown function were discovered. Phylogenetic analysis demonstrated remarkable distance between the sequences of these enzymes and other known xylanases. Biochemical analysis confirmed that these enzymes are true xylanases, which catalyze the hydrolysis of a variety of substituted beta-1,4-linked xylose oligomeric and polymeric substrates and produce unique hydrolysis products. From detailed polyacrylamide carbohydrate electrophoresis analysis of substrate cleavage patterns, the xylan polymer binding sites of these enzymes are proposed.     

Inhibitory effect of Terminalia chebula Retz. fruit extracts on digestive enzyme related to diabetes and oxidative stress

Terminalia chebula fruit extracts were prepared sequentially with hexane, ethyl acetate, methanol and methanol-water (70:30) and tested for their α-glucosidase inhibitory and antioxidant potential. The study resulted in the formulation of an extract with high α-glucosidase inhibitory potential (IC(50) 0.19 ± 0.03 μg mL(-1)) enriched with hydrolysable tannins. Also, each of the extract was chemically characterized by reversed-phase high-performance liquid chromatography on the basis of their marker compounds chebulagic acid, chebulinic acid and corilagin in order to give explanation to the significant activity shown by the extracts. The antioxidant potential of the highly active extract was evaluated in the cellular level also using superoxide dismutase, glutathione S-transferase and induced oxidative stress assays. The results indicated the possibility of using the extract as a nutraceutical health supplement in the management of type 2 diabetes.     

Review on proteomic analyses of benzo[a]pyrene toxicity

Benzo[a]pyrene (BaP), a five-ring polycyclic aromatic hydrocarbon, is a well-recognized environmental pollutant. Coal-processing waste products, petroleum sludge, asphalt, creosote, and tobacco smoke, all contain high levels of BaP. Exposure to BaP elicits many adverse biological effects, including tumor formation, immunosuppression, teratogenicity, and hormonal effects. In addition to the genetic damage caused by BaP exposure, several studies have indicated the disruption of protein-protein signaling pathways. However, contrary to the large number of studies on BaP-induced DNA damage, only few data have been gathered on its effects at the protein level. This review highlights all proteomic studies to date used for assessing the toxicity of BaP and its metabolites in various organ systems. It will also give an overview on the role proteomics may play to elucidate the mechanisms underlying BaP toxicity.