Mucus properties of Chinese carp and Indian carp: Physical barrier to pathogens

The study was aimed to investigate the probable role of mucus in reception and/or repulsion of Lernaea in Indian and Chinese major carps. Ctenophryngodon idella, Hypophthalmichthys moiltrix, Labeo rohita, Cirrhinus mrigala, Catla catla and Cyprinus carpio averaging 830±316 g each were collected and disinfected with KMnO4 (8.0ppm) for collections of contamination free mucus. Total protein contents and size categorization were determined by Bradford Micro Assay and SDS-PAGE analysis. Lectin and alkaline phosphatase activities were also measured by hemagglutination (HA) titer and alkaline phosphatase test, respectively. Protein concentrations were the highest in C. idella and C. catla and the lowest in C. carpio. Considering protein profiles mucus samples from C. catla contained the highest molecular weight proteins while C. carpio has one unique protein band of 14.13 kDa the weight of which resembles the weight of lysozyme, a protective element of mucus. Lectin activity was highest in C. idella indicative of low resistance while it was the lowest in H. molitrix. Alkaline phosphatase level was the highest in C. catla, and was the lowest in C. carpio.  Overall results indicted C. carpio as the most resistant species as it showed better values for the immune components. Higher values of protein contents and alkaline phosphatase for C. catla may be in favor of its higher susceptibility. These studies on mucus contents are good assessment indicators of the possibility of parasitic attacks in Chinese and Indian major carps.