Jyotirmayee Pradhan

The effect of Euglena viridis on immune response of rohu, Labeo rohita (Ham.).

The study evaluated the effect of dietary doses of Euglena viridis on the immune response and disease resistance of Labeo rohita fingerlings against infection with the bacterial pathogen Aeromonas hydrophila. L. rohita fingerlings were fed with diet containing 0 (Control), 0.1 g, 0.5 g, 1.0 g Euglena powder kg(-1) dry diet for 90 days. Biochemical (serum total protein, albumin, globulin, albumin:globulin ratio), haematological (WBC, RBC, haemoglobin content) and immunological (superoxide anion production, lysozyme, serum bactericidal activity) parameters of fish were examined after 30, 60 and 90 days of feeding. Fish were challenged with A. hydrophila 90 days post-feeding and mortalities were recorded over 10 days post-infection. The results demonstrate that fish fed with Euglena showed increased levels of superoxide anion production, lysozyme, serum bactericidal activity, serum protein and albumin (P < 0.05) compared with the control group. Following challenge with A. hydrophila less survivability was observed in the control group (56.65%) than the group fed the experimental diets. The group fed 0.5 g Euglena kg(-1) dry diet showed the highest percentage survival (75%). These results indicate that Euglena stimulates the immunity and makes L. rohita more resistant to A. hydrophila infection.

Effect of β-glucan on the immune response of early stage of Anabas testudineus (Bloch) challenged with fungus Saprolegnia parasitica

The present study was carried out to study the effect of different dosages of β-glucan suspension on immune response and disease resistance in Anabas testudineus spawns against a fungal pathogen Saprolegnia parasitica. Eight day old spawns were exposed for 3 h in four different dosages of β-glucan suspension in phosphate buffered saline at the rate of 0, 5, 10, 15 mg l-1. The cell suspension of spawn was assayed for total protein, acid phosphate, lysozyme, bactericidal and NBT activity. The spawns were then challenged with 3x105 CFU ml-1 of S. parasitica. The survivability percentage and immunological parameters were assayed upto day 7. Exposure of fish for 3h to all the concentrations of β-glucan recorded a significant enhancement in the immunological parameters such as lysozyme activity, bactericidal activity and NBT activity by the end of day 7. The challenge study indicated least mortality in the groups exposed to 10 mgl-1 and 15 mgl-1 but 15 mgl-1 gives little higher survivability. Thus 3 h exposure of β-glucan suspension could reduce the mortality and increase the immunity of A. testudineus spawns against S. parasitica.

Effects of supplementation diet containing Microcystis aeruginosa on haematological and biochemical changes in Labeo rohita infected with Aeromonas hydrophila.

An experiment of 100 days duration was conducted to test the effect of Microcystis aeruginosa in Labeo rohita against Aeromonas hydrophila. The rohu fingerlings (22 ± 2 g) were fed with the experimental diets incorporated with different concentrations of M. aeruginosa @ 0 g kg-1, 0.5 g kg-1, 1 g kg-1 and 5 g kg-1. Replicate groups of fish were fed for three month daily @4% body weight. At an interval of 30 days blood and serum samples were assayed for different haematological [total erythrocyte count (TEC), total leucocyte count (TLC), haemoglobin] and biochemical [blood glucose, serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP)] parameters. Significantly (p ≤ 0.05) increased haemoglobin content and TLC was observed in Microcystis treated group. It was observed that the serum AST activity was significantly (p ≤ 0.05) decreased to all the treated groups of fish as compared to control on entire assay period. Serum ALT activity was significantly (p ≤ 0.05) different to all the treated groups of fish on day 60, on day 90 and on day 10 (except group B) bacterial post challenge as compared to control. After 90 days, fish were challenged with A. hydrophila and mortality (%) was recorded up to day 10 post challenge. Highest percentage of survival (72%) was noticed in the group fed 1.0 g Microcystis kg-1 dry diet. The present study suggests that the administration of bluegreen algae, Microcystis aeruginosa supplementation diets for 100 days protects the hematological and biochemical parameters in L. rohita from A. hydrophila.