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.     

Internal anatomy and ultrastructure of the male reproductive organization of the Sesarmid crab Muradium tetragonum (1798)—(Decapoda: Brachyura)

Sesarmid crab, Muradium tetragonum, considered a key detritus consumer plays a significant role in the nutrient cycling and energy flow in most of the mangrove environments. Morphological and ultrastructural organization of the M. tetragonum male reproductive system are characterized through transmission electron microscopic studies. Adult males (3.2–4.2 cm) with dark violet carapace and white-tipped cheliped were procured alongside the coastal areas of Tanjavur district, Tamil Nadu, India. The morphological analysis highlights the male gonads to be bilaterally symmetrical and anterolaterally located inside the cephalothorax. A pair of elongated testes lying attached to the hypodermis of the carapace leads to a long highly coiled vas deferens categorized into three distinct regions (Proximal vas deferens, Middle vas deferens and distal vas deferens) structurally and functionally with Posterior vas deferens receiving sac-like accessory glands. It gets followed by an ejaculatory duct and ends with the penile papillae at the coxae's base of the fifth peripod. Structural modifications were observed in the ultrastructure of vas deferens envisage (considering) its functional role in storing spermatophores, active absorption and assisting the secretory activity. Spermatophores, witnessed as spherical bodies are bounded by a dense double wall. Aflagellate, immotile and spherical spermatozoa that measuring 3.6 μm in diameter encompasses a complex acrosome cupped by a nucleus. Moreover, perforatorium and the extending nuclear arms with chromatin, as displayed in the experimental organism M. tetragonum, are in synergy with that of certain brachyurans as specified in the study. Hence, the current study assessing the morphology and ultrastructure parameters of the male gonads could be useful in understanding the physiology of sexual maturation, annual cyclic changes, tracing the phylogenetic relationship among species and enhancing the brood-stock management.