Search

In invertebrates, the prophenoloxidase (proPO) pathway is involved in the phenol-like antioxidant production against invading pathogens. Overproduction of melanin and phenolic substances leads to the disruption of hemocytes (own host cells); therefore, there is a prerequisite to regulate the antioxidant production, which is performed by the proteases and proPO-associated cell adhesion protein peroxinectin (PX). PX is a macromolecular structure consisting of protein involved in the proPO pathway, which is a potential target in the regulatory mechanism in crustaceans. In the proPO cascade, pattern recognition proteins initiate the proPO cascade by the consequent reaction, and PX is involved in the key step in the regulatory mechanism of phenoloxidase enzyme synthesis. In the present study, Indian white shrimp Fenneropenaeus indicus PX ( Fein-PX) gene sequence was used. Upregulation of Fein-PX was determined using immunostimulants β-glucan (agonists) and examined its expression by quantitative RT-PCR. To find the downregulation or negative regulation of Fein-PX, inhibitors were screened, and its 3D model provides molecular insights into the rationale inhibitor design for developing an effective molecule against Fein-PX. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the present study, chitosan-ZnO composite was synthesized by stirring of chitosan purified from mud crab Scylla serrata shells with zinc chloride and sodium hydroxide. The physicochemical characteristics of chitosan-ZnO composite were studied using UV-Vis spec, Fourier transform infrared, X-ray diffraction and scanning electron microscopy. Chitosan-ZnO composite formation was confirmed by the functional groups stretching and bending vibrations in Fourier transform infrared. Scanning electron microscopy results showed the synthesized chitosan-ZnO composite was rod-like structure. X-ray diffraction results represent the hexagonal shape and crystalline size (30–60 nm) of zinc oxide in the chitosan-ZnO composite. Antibacterial activity of chitosan-ZnO composite demonstrated the effective growth control of a Gram-negative Vibrio parahaemolyticus and Gram-positive Bacillus lechiniformis bacteria isolated from aquatic environments. Light microscopy and confocal laser scanning microscopy also evidenced the antibiofilm activity of chitosan-ZnO composite against the V. parahaemolyticus and B. lechiniformis at the concentration of 40 and 60 µg/ml, respectively. [ABSTRACT FROM AUTHOR]

White Spot Syndrome Virus causes viral disease in crustaceans and generates a significant burden in the developing nations. Biochemical and immunological assays were performed in WSSV infected Penaeus semisulcatus which were monitored in different salinity conditions. Continuous exposure of shrimps to WSSV showed a reduced life span, indicating the pathogenicity in Penaeidae species. Hence, this study is intended to investigate the protective antioxidant potential of the innate immune system consisting biochemical and morphological alterations. Penaeus semisulcatus challenged with white spot syndrome virus (5.5 × 104 copy number; WSSV) reared at different salinity 5, 15, 25 (control) and 35 g/L were examined after 0-120 h for immunological parameters such as total hemocyte count (THC), phenoloxidase (PO) and respiratory burst (RB) and alkaline and acid phosphatase activities. After 72 h, the WSSV injected P. semisulcatus tissues were histopathologically sectioned and stained. This study would be helpful to understand host-pathogen interaction and envisages the improvement of better management practices in shrimp aquaculture system. [ABSTRACT FROM AUTHOR]

Ruta graveolens silver nanoparticles (AgNPs) showed the color change within 30 min and characterized using UV-visible spectra, Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). UV-visible spectrum of R. graveolens AgNPs showed the sharp peak at the wavelength of 440-560 nm. XRD patterns confirmed that crystalline nature of R. graveolens AgNPs and FTIR results revealed that phytochemical reaction of these R. graveolens is responsible for the synthesis of AgNPs. TEM results showed the size of the R. graveolens AgNPs around 30-50 nm with spherical and triangular nature. Further, the antibacterial and antibiofilm activity of R. graveolens AgNPs showed the effective inhibitory activity against clinically important Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. Our findings suggest that R. graveolens AgNPs can be exploited toward the development of potential antibacterial agents for various biomedical and environmental applications. [ABSTRACT FROM AUTHOR]

Members of the sortase enzyme super family decorate the surfaces of Bacillus anthracis cell wall with proteins that play key roles in microbial pathogenesis and its biofilm formation. Bacillus anthracis Sortase-A (Ba-SrtA) is a potential target for new therapeutics as it is required for B. anthracis survival and replication within macrophages. An understanding of the binding site pocket and substrate recognition mechanism by SrtA enzymes may serve to be beneficial in the rational development of sortase inhibitors. Here, the LPXTG signal peptide-based competitive inhibitors are screened against the Ba-SrtA and compounds with reasonable inhibition, specificity, and mechanisms of inactivation of SrtA have been covered. The screened compounds are experimentally validated against the phylogenetically similar Gram-positive pathogen B. cereus. In situ microscopic visualizations suggest that these screened compounds showed the microbial and biofilm inhibitory activity against B. cereus. It facilitates the further development of these molecules into useful anti-infective agents to treat infections caused by B. anthracis and other Gram-positive pathogens. These results provide insight into basic design principles for generating new clinically relevant lead molecules. It also provides an alternative strategy where a screened ligand molecule can be used in combination to battle increasingly against the Gram-positive pathogens. [ABSTRACT FROM AUTHOR]

Lipopolysaccharide and β-1,3 glucan-binding protein (LGBP) is a family of pattern-recognition transmembrane proteins (PRPs) which plays a vital role in the immune mechanism of crustaceans in adverse conditions. Fenneropenaeus indicus LGBP-deduced amino acid has conserved potential recognition motif for β-1,3 linkages of polysaccharides and putative RGD (Arg-Gly-Asp) cell adhesion sites for the activation of innate defense mechanism. In order to understand the stimulating activity of β-1,3 glucan (β-glucan) and its interaction with LGBP, a 3D model of LGBP is generated. Molecular docking is performed with this model, and the results indicate Arg71 with strong hydrogen bond from RGD domain of LGBP. Moreover, from the docking studies, we also suggest that Arg34, Lys68, Val135, and Ala146 in LGBP are important amino acid residues in binding as they have strong bonding interaction in the active site of LGBP. In our in vitro studies, yeast agglutination results suggest that shrimp F. indicus LGBP possesses sugar binding and recognition sites in its structure, which is responsible for agglutination reaction. Our results were synchronized with the already reported evidence both in vivo and in vitro experiments. This investigation may be valuable for further experimental investigation in the synthesis of novel immunomodulator.

Haemocyanin is an important non-specific immune protein present in the hemolymph of invertebrates, which have the ability to recognize the microbial pathogens and trigger the innate immune system. In this study, we isolated and purified the haemocyanin using gel filtration chromatography and investigated its microbial recognition mechanism against the invading pathogens. Kuruma shrimp Marsupenaeus japonicus haemocyanin showed the single band with a molecular weight of 76 kDa on SDS-PAGE and its molecular mass was analysed through the MALDI. Pathogen recognition mechanism of M. japonicus haemocyanin was detected through bacterial agglutination, agglutination inhibition and prophenoloxidase activity. M. japonicus haemocyanin agglutinate all human blood RBC types and showed the bacterial agglutination against all tested Gram positive Staphylococcus aureus, Enterococcus faecalis and Bacillus subtilis and Gram negative Pseudomonas aeruginosa, Proteus vulgaris and Vibrio parahaemolyticus at the concentrations ranging from 30 to 50 μg/ml. Agglutination was inhibited by 50-200 mM of N-acetylneuraminic acid, a-D-glucose, D-galactose and D-xylose. Our results suggest that, 76 kDa subunit of M. japonicus haemocyanin recognize the pathogenic surface proteins which are present on the outer membrane of the bacteria and mediates the bacterial agglutination through haemocytes. This bacterial agglutination was visualized through Confocal Laser Scanning Microscopy (CLSM). This present study would be helpful to explore the importance of haemocyanin in innate immune response of M. japonicus and its eliciting pathogen recognition mechanism leads to the development of innate immunity in crustaceans.