In silico analysis of Myoglobin in Channa striata

Myoglobin is a cytoplasmic hemoprotein, expressed solely in cardiac myocytes and oxidative skeletal muscle fibers, that reversibly binds O₂ by its heme residue. Myoglobin is an essential oxygen-storage hemoprotein capable of facilitating oxygen transport and modulating nitric oxide homeostasis within cardiac and skeletal myocytes. Functionally, myoglobin is well accepted as an O₂- storage protein in muscle, capable of releasing O₂ during periods of hypoxia or anoxia. There is no evidence available regarding active sites, ligand binding sites, antigenic determinants and the ASA value of myoglobin in Channa striata. We further document the predicted active sites in the structural model with solvent exposed ASA residues. During this study, the model was built by CPH program and validated through PROCHECK, Verify 3D, ERRAT and ProSA for reliability. The active sites were predicted in the model with further ASA analysis of active site residues. The discussed information thus provides the predicted active sites, ligand binding sites, antigenic determinants and ASA values of myoglobin model in Channa striata.     

The ESAT-6 Protein of Mycobacterium tuberculosis Interacts with Beta-2-Microglobulin (β2M) Affecting Antigen Presentation Function of Macrophage

ESAT-6, an abundantly secreted protein of Mycobacterium tuberculosis (M. tuberculosis) is an important virulence factor, inactivation of which leads to reduced virulence of M. tuberculosis. ESAT-6 alone, or in complex with its chaperone CFP-10 (ESAT-6:CFP-10), is known to modulate host immune responses; however, the detailed mechanisms are not well understood. The structure of ESAT-6 or ESAT-6:CFP-10 complex does not suggest presence of enzymatic or DNA-binding activities. Therefore, we hypothesized that the crucial role played by ESAT-6 in the virulence of mycobacteria could be due to its interaction with some host cellular factors. Using a yeast two-hybrid screening, we identified that ESAT-6 interacts with the host protein beta-2-microglobulin (β2M), which was further confirmed by other assays, like GST pull down, co-immunoprecipitation and surface plasmon resonance. The C-terminal six amino acid residues (90–95) of ESAT-6 were found to be essential for this interaction. ESAT-6, in complex with CFP-10, also interacts with β2M. We found that ESAT-6/ESAT-6:CFP-10 can enter into the endoplasmic reticulum where it sequesters β2M to inhibit cell surface expression of MHC-I-β2M complexes, resulting in downregulation of class I-mediated antigen presentation. Interestingly, the ESAT-6:β2M complex could be detected in pleural biopsies of individuals suffering from pleural tuberculosis. Our data highlight a novel mechanism by which M. tuberculosis may undermine the host adaptive immune responses to establish a successful infection. Identification of such novel interactions may help us in designing small molecule inhibitors as well as effective vaccine design against tuberculosis.     

Detection of Vibrio cholerae O1 in the aquatic environment by fluorescent-monoclonal antibody and culture methods

Vibrio cholerae O1 in plankton samples collected from ponds and rivers between February 1987 and January 1990 in Matlab, Bangladesh, was detected by the fluorescent-monoclonal antibody (FA) technique. Samples were collected at sites which were monitored fortnightly (fixed sites) as well as at sites that were part of a case-control study. FA results were compared with those obtained by conventional culture methods (CM). A total of 876 samples were collected; V. cholerae O1 was detected in 563 samples (64.27%) by the FA method and in 3 samples (0.34%) by CM. Of the fixed-site plankton samples, 439 (63.62%) were positive by FA and none were positive by CM. Of the 93 case sites sampled on the day after the occurrence of a case of cholera, 73 (78.49%) were positive for V. cholerae O1 by FA and 3 (3.2%) were positive by CM. In comparison, of the 93 first-day sample collections at control sites at the time a case of cholera occurred, only 51 (54.83%) were positive by FA and none were positive by CM. From the data, it is concluded that V. cholerae O1 is present throughout the year in the ponds and rivers of Bangladesh that were examined in this study and that V. cholerae can be detected by FA but not always by CM. The FA procedure was found to be very useful in detecting V. cholerae in plankton, with which it was associated and often occurred in large numbers in the nonculturable stage. Thus, studies investigating the significance of the role of environmental factors in the epidemiology of cholera can be performed effectively by using FA. Such studies are in progress.     

Highly selective and sensitive coumarin–triazole‐based fluorometric ‘turn‐off’ sensor for detection of Pb2+ ions

Exposure to even very low concentrations of Pb²⁺ is known to cause cardiovascular, neurological, developmental, and reproductive disorders, and affects children in particular more severely. Consequently, much effort has been dedicated to the development of colorimetric and fluorescent sensors that can selectively detect Pb²⁺ ions. Here, we describe the development of a triazole‐based fluorescent sensor L5 for Pb²⁺ ion detection. The fluorescence intensity of chemosensor L5 was selectively quenched by Pb²⁺ ions and a clear color change from colorless to yellow could be observed by the naked eye. Chemosensor L5 exhibited high sensitivity and selectivity towards Pb²⁺ ions in phosphate‐buffered solution [20 mM, 1:9 DMSO/H₂O (v/v), pH 8.0] with a 1:1 binding stoichiometry, a detection limit of 1.9 nM and a 6.76 × 10⁶ M^?1 binding constant. Additionally, low‐cost and easy‐to‐prepare test strips impregnated with chemosensor L5 were also produced for efficient of Pb²⁺ detection and proved the practical use of this test.     

Excitation transfer and trapping kinetics in plant photosystem I probed by two-dimensional electronic spectroscopy

Photosystem I is a robust and highly efficient biological solar engine. Its capacity to utilize virtually every absorbed photon’s energy in a photochemical reaction generates great interest in the kinetics and mechanisms of excitation energy transfer and charge separation. In this work, we have employed room-temperature coherent two-dimensional electronic spectroscopy and time-resolved fluorescence spectroscopy to follow exciton equilibration and excitation trapping in intact Photosystem I complexes as well as core complexes isolated from Pisum sativum. We performed two-dimensional electronic spectroscopy measurements with low excitation pulse energies to record excited-state kinetics free from singlet–singlet annihilation. Global lifetime analysis resolved energy transfer and trapping lifetimes closely matches the time-correlated single-photon counting data. Exciton energy equilibration in the core antenna occurred on a timescale of 0.5 ps. We further observed spectral equilibration component in the core complex with a 3–4 ps lifetime between the bulk Chl states and a state absorbing at 700 nm. Trapping in the core complex occurred with a 20 ps lifetime, which in the supercomplex split into two lifetimes, 16 ps and 67–75 ps. The experimental data could be modelled with two alternative models resulting in equally good fits—a transfer-to-trap-limited model and a trap-limited model. However, the former model is only possible if the 3–4 ps component is ascribed to equilibration with a “red” core antenna pool absorbing at 700 nm. Conversely, if these low-energy states are identified with the P₇₀₀ reaction centre, the transfer-to-trap-model is ruled out in favour of a trap-limited model.

     

High frequency conversion of non-embryogenic synseeds and assessment of genetic stability through ISSR markers in <Emphasis Type="Italic">Gymnema sylvestre</Emphasis>

The present study describes the first attempt of exploiting encapsulation technology for high plantlet recovery, short-term storage and conservation of Gymnema sylvestre—an antidiabetic liana. Indole-3-butyric acid (IBA) pretreated nodal segments (NS) were encapsulated in sodium alginate (Na₂-alginate) matrix and the optimal culture conditions were evaluated in terms of maximum conversion capacity of synseeds into complete plantlets. Highest conversion frequency of synseeds was obtained on Murashige and Skoog’s (MS) medium supplemented with 5.0 µM 6-benzyladenine (BA). Augmentation of Na₂-alginate matrix with plant growth regulators (PGRs) and additive further improved in vitro conversion rates and the synthetic endosperm composed of 3% Na₂-alginate in MS?+?2.5 µM BA?+?2.5 µM gibberellic acid (GA₃)?+?50 µM adenine sulphate (AdS) stimulated maximum recovery (88.2?±?0.48%) of complete plantlets from synseeds. Studies on short term cold storage of synseeds showed that nutrient encapsulation maintains the viability of NS for a storage period of 8 weeks. Ex-vitro conversion of synseeds was also carried out on soilrite and vermicompost (3:1) mixture under culture room conditions. Monomorphic DNA profiles produced through Inter-Simple Sequence Repeat (ISSR) markers confirmed the genetic uniformity between synseed derived and mother plantlets.     

Dietary Supplementation of Selenium-Enriched Probiotics Enhances Meat Quality of Broiler Chickens (<Emphasis Type="Italic">Gallus gallus domesticus</Emphasis>) Raised Under High Ambient Temperature

We investigated the effects of selenium-enriched probiotics (SP) on broiler meat quality under high ambient temperature and explore their underlying mechanisms. A total of 200 1-day-old male broiler chicks (Ross 308) were randomly allotted to four treatment groups, each with five replicates, in groups of ten birds. These birds were fed a corn-soybean basal diet (C), a basal diet plus probiotics supplementation (P), a basal diet plus Se supplementation in the form of sodium selenite (SS, 0.30 mg Se/kg), and a basal diet with the addition of selenium-enriched probiotics (SP, 0.30 mg Se/kg). The experiment lasted for 42 days. The birds were sacrificed by cervical dislocation, and the breast muscles were removed for further process. Our results showed that SP diet significantly increased (p < 0.05) the physical (pH, colors, water holding capacity, drip loss, shear force) and sensory characteristics of breast meat. All P, SS, and SP supplementation enhanced the antioxidant system by increasing (p < 0.05) the Se concentrations, glutathione (GSH) levels, activities of glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) whereas decreasing (p < 0.05) malondialdehyde (MDA) levels, with SP being higher than P and SS. Moreover, SP diet significantly upregulated (p < 0.05) the mRNA levels of glutathione peroxidase genes (GPx1, GPx4) while it downregulated heat stress biomarkers such as heat shock protein (HSP) 70 as compared to C, P, and SS diets. In conclusion, our findings suggest that SP may function as beneficial nutritive supplement that is capable of improving meat quality during the summer season.     

Association of multiple-antibiotic-resistance profiles with point and nonpoint sources of Escherichia coli in Apalachicola Bay.

A total of 765 Escherichia coli isolates from point and nonpoint sources were collected from the Apalachicola National Estuarine Research Reserve, and their multiple-antibiotic-resistance (MAR) profiles were determined with 10 antibiotics. E. coli isolates from point sources showed significantly greater resistance (P < 0.05) to antibiotics and higher MAR indices than isolates from nonpoint sources. Specifically, 65 different resistance patterns were observed among point source isolates, compared to 32 among nonpoint source isolates. Examples of this contrast in MAR profiles included percentages of isolates with resistance to chlortetracycline-sulfathiazole of 33.7% and to chlortetracycline-penicillin G-sulfathiazole of 14.5% for point source isolates versus 15.4 and 1.7%, respectively, for nonpoint source isolates. MAR profile homology, based on coefficient similarity, showed that isolates from point sources were markedly more diverse than isolates from nonpoint sources. Seven clusters were observed among point source isolates, with a coefficient value of approximately 1.8. In contrast, only four clusters were observed among nonpoint source isolates. Covariance matrices of data displayed six very distinct foci representing nonpoint source E. coli isolates. Importantly, E. coli isolates obtained directly from human and animal feces also clustered among point and nonpoint sources, respectively. We conclude that E. coli MAR profiles were associated with point and nonpoint sources of pollution within Apalachicola Bay and that this method may be useful in facilitating management of other estuaries.     

On the distributive pattern of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in the medulla oblongata of the golden hamster (Mesocricetus auratus). A study on the topographical and functional linkages of the two enzymes

Histochemical study on the distributive patterns of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), amongst the constituents of the medulla oblongata of golden hamster (Mesocricetus auratus), viewed through the angle of the possible topographical and functional linkage of the two enzymes, have provided identical set-ups of AChE and BChE in many of the nuclei, fibers and tracts. In the case of AChE in many instances the results further point out that there is a balance of the enzymatic activity between the nuclei and the associated processes. On the other hand, in relation to BChE activity, the nuclei and their processes do not seem to be linked through such a histochemical factor. A detailed discussion on the significance of AChE relationship between the neurons and their processes from the functional point of view, against the data available in the literature, has been incorporated in the present study. Histoenzymologically, the ranges of the activities of AChE and BChE amongst the neurons and their processes are so closely related that such components are mirror images of each other in histochemical patterns. Naturally, such results have led to a detailed discussion in the contribution culminating in a proposition that AChE and BChE (amongst the locales studied) seems to be intimately linked in the neuro-physiological functioning undergoing in the regions of the medulla oblongata of golden hamster.