Interaction investigations of crustacean β‐GBP recognition toward pathogenic microbial cell membrane and stimulate upon prophenoloxidase activation

In invertebrates, crustaceans' immune system consists of pattern recognition receptors (PRRs) instead of immunoglobulin's, which involves in the microbial recognition and initiates the protein–ligand interaction between hosts and pathogens. In the present study, PRRs namely β‐1,3 glucan binding protein (β‐GBP) from mangrove crab Episesarma tetragonum and its interactions with the pathogens such as bacterial and fungal outer membrane proteins (OMP) were investigated through microbial aggregation and computational interaction studies. Molecular recognition and microbial aggregation results of Episesarma tetragonum β‐GBP showed the specific binding affinity toward the fungal β‐1,3 glucan molecule when compared to other bacterial ligands. Because of this microbial recognition, prophenoloxidase activity was enhanced and triggers the innate immunity inside the host animal. Our findings disclose the role of β‐GBP in molecular recognition, host–pathogen interaction through microbial aggregation, and docking analysis. In vitro results were concurred with the in silico docking, and molecular dynamics simulation analysis. This study would be helpful to understand the molecular mechanism of β‐GBP and update the current knowledge on the PRRs of crustaceans. Copyright © 2014 John Wiley & Sons, Ltd.     

Examine the characterization of biofilm formation and inhibition by targeting SrtA mechanism in Bacillus subtilis: a combined experimental and theoretical study

A unified coarse-grained model of three major classes of biological molecules—proteins, nucleic acids, and polysaccharides—has been developed. It is based on the observations that the repeated units of biopolymers (peptide groups, nucleic acid bases, sugar rings) are highly polar and their charge distributions can be represented crudely as point multipoles. The model is an extension of the united residue (UNRES) coarse-grained model of proteins developed previously in our laboratory. The respective force fields are defined as the potentials of mean force of biomacromolecules immersed in water, where all degrees of freedom not considered in the model have been averaged out. Reducing the representation to one center per polar interaction site leads to the representation of average site–site interactions as mean-field dipole–dipole interactions. Further expansion of the potentials of mean force of biopolymer chains into Kubo’s cluster-cumulant series leads to the appearance of mean-field dipole–dipole interactions, averaged in the context of local interactions within a biopolymer unit. These mean-field interactions account for the formation of regular structures encountered in biomacromolecules, e.g., α-helices and β-sheets in proteins, double helices in nucleic acids, and helicoidally packed structures in polysaccharides, which enables us to use a greatly reduced number of interacting sites without sacrificing the ability to reproduce the correct architecture. This reduction results in an extension of the simulation timescale by more than four orders of magnitude compared to the all-atom representation. Examples of the performance of the model are presented.

Vibriostatic effects of probiotic Bacillus licheniformis Dahb1 and its molecular phylogeny resolved through RAPD markers

The in vitro vibriostatic effects of probiotic Bacillus licheniformis strains (Dahb1 to Dahb7) from both wild and commercial sources were evaluated against pathogenic Vibrios isolated from shrimp hatcheries and farms. Agar antagonism assay results showed that, out of seven B. licheniformis strains, strain Dahb1 showed the biggest inhibitory zone (6–12 mm) tested against 162 isolates of Vibrio spp. viz., V. harveyi (53 isolates), V. anguillarum (42 isolates), V. vulnificus (31 isolates) and Photobacterium damselae ssp. damselae (36 isolates) obtained from Penaeus monodon culture hatcheries and ponds. The genetic status of these seven strains were analyzed through randomly amplified polymorphic DNA analysis using 18 random primers. Of the 18 primers studied, only 6 generated repeatable polymorphic DNA bands with sizes ranging from 250 to 1,000 bp in seven isolates of B. licheniformis. The dendrogram generated from resolved gel profiles showed two major branches with three clusters. The results of the present study allow us to conclude that B. licheniformis Dahb1 can be used as an effective probiotic to control Vibrios. Field studies are needed to evaluate probiotic efficiency to control diseases in aquatic organisms.     

Effect of Amino Acid Substitution in the Penaeus monodon LGBP and Specificity Through Mutational Analysis

International Journal of Peptide Research and Therapeutics - Lipopolysaccharide and β-1,3-glucan-binding protein (LGBP) is a pattern recognition protein (PRP) purified from the Penaeus monodon...     

Abundance of potentially pathogenic micro-organisms in Penaeus monodon larvae rearing systems in India

Monodon baculovirus (MBV), external fouling organisms (EFO) and bacteria (especially Vibrio species) were monitored during 1996–1997 at nine different Penaeus monodon rearing hatcheries in India. Total cultivable heterotrophic bacteria, Vibrio-like-bacteria, presumptive Vibrio harveyi, Vibrio anguillarum, Vibrio vulnificus counts were determined from shrimp eggs, post larvae, rearing tank water, source sea water, feed (Artemia nauplii and microencapsulated feed). The MBV infected post larvae and their environment showed higher Vibrio-like-bacteria than uninfected post larvae. An over-whelming predominance of presumptive Vibrio harveyi and Vibrio anguillarum was observed in post larval rearing tank water, MBV infected and uninfected post larvae. Vibrio-like-bacteria in Artemia nauplii clearly showed the possible source of these pathogenic bacteria in the hatchery environments. Quantitative analysis of Vibrio-like-bacteria in hatcheries revealed that when the Vibrio-like-bacteria increases to 2 × 10² CFU mortality of the post larvae occurs. Abundance of these micro-organisms in hatchery samples indicated that they are opportunistic pathogens which can invade the shrimp tissue, subsequently cause disease when the post larvae were under stressful conditions.     

The immune response of tilapia Oreochromis mossambicus and its susceptibility to Streptococcus iniae under stress in low and high temperatures

Mozambique tilapia Oreochromis mossambicus acclimated to 27 degrees C were then held at 19, 23, 27 (control), 31 and 35 degrees C, and were examined for non-specific cellular and humoral responses after 12-96 h. Total leucocyte count decreased significantly when fish were transferred to 19 and 23 degrees C after 48 and 96 h, and when transferred to 35 degrees C over 12-96 h, respectively. Respiratory burst decreased significantly when fish were transferred to 19, 31 and 35 degrees C over 24-96 h, whereas phagocytic activity and phagocytic index decreased significantly when fish were transferred to low temperatures (19 and 23 degrees C) and high temperatures (31 and 35 degrees C) over 12-96 h. Lysozyme activity decreased significantly when fish were transferred to 19 degrees C after 12-96 h, but increased significantly when transferred to 31 and 35 degrees C over 48-96 h. Alternative complement pathway (ACH(50)) also decreased significantly when transferred to 19 and 23 degrees C after 12h, but increased significantly when transferred to 31 and 35 degrees C after 24h. In another experiment, tilapia reared at 27 degrees C were injected intraperitoneally with Streptococcus iniae at a dose of 1 x 10(7)colony-forming units (cfu)fish(-1), and then reared onward at water temperatures of 19, 23, 27 (control), 31 and 35 degrees C. Over 48-168 h, the cumulative mortality of S. iniae-injected fish held in 19 and 35 degrees C was significantly higher than that of injected-fish held in 23, 27 and 31 degrees C. It is concluded that transfer of tilapia O. mossambicus from 27 degrees C to low temperatures (19 and 23 degrees C) after 12h, and transfer of fish from 27 degrees C to high temperatures (31 and 35 degrees C) reduced their immune capability. Moreover, tilapia under temperature stress at 19 and 35 degrees C from 27 degrees C decreased its resistance against S. iniae.