Response of lentil to VA Mycorrhizal inoculation and plant available P levels of unsterile soils

Summary Responses of lentil in unsterile soils at low, medium and high levels of plant available soil P toGlomus fasciculatum inoculation were evaluated. It was observed that growth, dry matter accumulation, nodulation, and nitrogen fixation were considerably improved in VAM inoculated plants over uninoculated control at low and medium levels of plant available soil P.     

In vitro regeneration of plants from hypocotyl segments of Amaranthus paniculatus

Hypocotyl segments, 5 to 8 mm length from 4 to 7 day old seedlings, callused on B₅ medium supplemented with Kn (0.5 ppm) and NAA (0.1 ppm). Even without transfer, shoots were formed in such cultures. About 20% of the cultures produced multiple shoots. In medium with 1 ppm each of Kn and NAA direct shoots were formed at one end of the hypocotyl segment and callusing was initiated at the other end. The plants obtained in either medium formed roots and could be transferred to soil for further growth.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxy acetic acid - GA₃ gibberellic acid - Kn Kinetin - NAA naphthalene acetic acid     

Structural insights into thermostable direct hemolysin of Vibrio parahaemolyticus using single-particle cryo-EM

Thermostable direct hemolysin (TDH) is a ~19 kDa, hemolytic pore-forming toxin from the gram-negative marine bacterium Vibrio parahaemolyticus, one of the causative agents of seafood-borne acute gastroenteritis and septicemia. Previous studies have established that TDH exists as a tetrameric assembly in physiological state; however, there is limited knowledge regarding the molecular arrangement of its disordered N-terminal region (NTR)—the absence of which has been shown to compromise TDH's hemolytic and cytotoxic abilities. In our current study, we have employed single-particle cryo-electron microscopy to resolve the solution-state structures of wild-type TDH and a TDH construct with deletion of the NTR (NTD), in order to investigate structural aspects of NTR on the overall tetrameric architecture. We observed that both TDH and NTD electron density maps, resolved at global resolutions of 4.5 and 4.2 Å, respectively, showed good correlation in their respective oligomeric architecture. Additionally, we were able to locate extra densities near the pore opening of TDH which might correspond to the disordered NTR. Surprisingly, under cryogenic conditions, we were also able to observe novel supramolecular assemblies of TDH tetramers, which we were able to resolve to 4.3 Å. We further investigated the tetrameric and inter-tetrameric interaction interfaces to elaborate upon the key residues involved in both TDH tetramers and TDH super assemblies. Our current structural study will aid in understanding the mechanistic aspects of this pore-forming toxin and the role of its disordered NTR in membrane interaction.     

Ratiometric Ca+2 measurement in human recombinant muscarinic receptor subtypes using the Flexstation scanning fluorometer

In modern drug discovery, numerous assay formats are available to screen and quantitate receptor-ligand interactions. Radioactive assays are “gold standard” because they are fast, easy, and reproducible; however, they are hazardous, produce radioactive waste, require special lab conditions, and are expensive on a large scale. Thus, it provides a lot of importance to the “mix & measure” assays that have an optical readout. Fluorescence techniques are likely to be among the most important detection approaches used for high throughput screening due to their high sensitivity and amenability to automation. The aim of the present study was to determine the functional antagonistic affinities of standard muscarinic antagonists in CHO cells over expressing m1, m3, and m5 receptors and to compare them with the respective binding affinities. This study was further extended to elucidate that Ca⁺² measurement assays can serve as a functional screening tool for GPCRs. For this purpose, standard muscarinic receptor antagonists, namely, tolterodine, oxybutynin, and atropine were used. We determined and compard the IC₅₀ values of these three standard inhibitors in fura 2 AM loaded m1, m3, and m5 overexpressing CHO cells and in radioligand binding assay. Both the assays exhibited comparable rank order potencies of the standard inhibitors. This study suggests that Ca⁺² mobilization assays can be an alternate to radioligand binding assays.     

Fabrication of an amperometric d-amino acid biosensor based on nickel hexacyanoferrate polypyrrole hybrid film deposited on glassy carbon electrode

A nickel hexacyanoferrate polypyrrole film was synthesized through an electrochemical two-step methodology leading to a very stable and homogenous robust hybrid film. A highly sensitive, specific and rapid amperometric d-amino acid biosensor was constructed by immobilizing d-amino acid oxidase on this film deposited over the surface of a glassy carbon electrode. The modified electrode was characterized by scanning electron microscopy, electrochemical impedance spectroscopy and Fourier transform infrared spectrophotometry. The biosensor showed optimum response within 1 s, when operated at 50 mV s^?1 in 0.01 M Tris HCl buffer, pH 7.0 at 30 °C. The biosensor exhibited excellent sensitivity with a detection limit of 1.5 µM (S/N = 3) for d-amino acids and wider linear range, 20–500 µM. Analytical recovery of added d-alanine (5 and 10 mM) in serum samples was 98.00 and 98.80 %, respectively. Within-batch and between-batch coefficients of variation in serum samples were 1.36 and 2.77 %, respectively. The enzyme electrode was used more than 50 times over 2 months, when stored at 4 °C. The proposed modified electrode exhibited sufficient mechanical and electrochemical stability and high sensitivity compared to earlier electrochemical d-amino acid biosensors. Interference by ascorbic acid and uric acid, the main interfering species in the biological samples, was negligible.     

On the PsbS-induced quenching in the plant major light-harvesting complex LHCII studied in proteoliposomes

Photosynthesis Research - Non-photochemical quenching (NPQ) in photosynthetic organisms provides the necessary photoprotection that allows them to cope with largely and quickly varying light...     

Modelling family 2 cystatins and their interaction with papain

Cystatins are extensively studied cysteine protease inhibitors, found in wide range of organisms with highly conserved structural folds. S-type of cystatins is well known for their abundance in saliva, high selectivity and poorer activity towards host cysteine proteases in comparison to their immediate ancestor cystatin C. Despite more than 90% sequence similarity, the members of this group show highly dissimilar binding affinity towards papain. Cystatin M/E is a potent inhibitor of legumain and papain like cysteine proteases and recognized for its involvement in skin barrier formation and potential role as a tumor suppressor gene. However, the structures of these proteins and their complexes with papain or legumain are still unknown. In the present study, we have employed computational methods to get insight into the interactions between papain and cystatins. Three-dimensional structures of the cystatins are generated by homology modelling, refined with molecular dynamics simulation, validated through numerous web servers and finally complexed with papain using ZDOCK algorithm in Discovery Studio. A high degree of shape complementarity is observed within the complexes, stabilized by numerous hydrogen bonds (HB) and hydrophobic interactions. Using interaction energy, HB and solvent accessible surface area analyses, we have identified a series of key residues that may be involved in papain–cystatin interaction. Differential approaches of cystatins towards papain are also noticed which are possibly responsible for diverse inhibitory activity within the group. These findings will improve our understanding of fundamental inhibitory mechanisms of cystatin and provide clues for further research.     

Comparative study of key phosphorus and nitrogen metabolizing enzymes in mycorrhizal and non-mycorrhizal plants of Dendrobium chrysanthum Wall. ex Lindl.

The role of mycorrhizal fungi in overcoming nutrient limitation to plant growth by enhancing nutrient acquisition, especially phosphorus (P) and nitrogen (N), is well documented. However, in orchids, the importance of mycorrhizal fungi in nutrient acquisition is not as extensively studied as in other plants. Therefore, an in vitro culture system to study the effects of mycorrhizal association on P and N metabolizing enzymes, viz., acid phosphatase, alkaline phosphatase, nitrate reductase (NR), nitrite reductase (NiR) and glutamine synthetase (GS) in Dendrobium chrysanthum was developed. After 90 days of mycorrhizal treatment, activities of acid phosphatase, alkaline phosphatase, NR, NiR and GS were higher in mycorrhizal plantlets than in control plantlets. The hardened plantlets that were initially treated with mycorrhiza under in vitro conditions also showed higher activities of the enzymes investigated. These mycorrhizal plantlets showed higher survival (96.33 %), shoot length (3.7 cm) and shoot fresh weight (0.359 g) as compared to control after 120 days of hardening. The results presented in this study suggest that mycorrhizal association might have increased the assimilation of P and N in D. chrysanthum plantlets, indicating the importance of mycorrhiza in orchids.     

On race: 34 conversations in a time of crisis

The purpose of this Research Note is to offer an analysis of the goals and achievements of former President Clinton's Initiative on Race from its announcement in June 1997 through spring 2000. This Initiative was the first attempt in nearly thirty years by a United States' President to seriously and systematically address the issue of "race". Three conclusions emerge: first, the Clinton Race Initiative accomplished more than most social scientists and the public are aware of; second, the Initiative is incomplete because the President has not released his own proposed book-length analysis on race; and, third, a number of structural and political factors significantly limited the "success" of the Initiative.