P. K. Pandey

Effect of orally administered azadirachtin on non-specific immune parameters of goldfish Carassius auratus (Linn. 1758) and resistance against Aeromonas hydrophila.

Modulation of the immune responses using active bio-ingredients as a possible prophylaxis measure has been novel prospect for aquaculture. The present study evaluated the effects of azadirachtin EC 25% on non-specific immune responses in goldfish Carassius auratus and resistance against pathogenic bacteria Aeromonas hydrophila. The experimental trial for effects of azadirachtin on immuno-haematoloical parameters in goldfish was conducted by feeding the various levels of azadirachtin as control T(0) (without azadirachtin), T(1) (0.1%), T(2) (0.2%), T(3) (0.4%), T(4) (0.8%) and T(5) (1.6%) for a period of 28 days. Fishes were challenged with A. hydrophila 28 days post feeding and relative percentage survival (%) was recorded over 14 days post infection. Immuno-haematoloical (total erythrocyte count, total leukocyte count, haemoglobin, packed cell volume, NBT activity, phagocytic activity, serum lysozyme activity, myeloperoxidase activity, total immunoglobulin) and serum biochemical parameters (serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) and blood glucose) of fishes were examined at 14 and 28 days of feedings. Fish fed with azadirachtin, showed significantly (p < 0.05) enhanced TEC, TLC, Total Ig, total protein, NBT activity, serum lysozyme activity and myeloperoxidase level in different treatment groups in comparison with control group. Similarly, SGOT, SGPT and blood glucose level were found to be significantly (p < 0.05) high but PCV and Hb did not differ significantly (p > 0.05) in the treatment groups compared to control groups. Azadirachtin at the concentration of 4 g kg(-1) showed significantly (p < 0.05) higher relative percentage survival (42.60%) when compared with the control against A. hydrophila infection. This study indicated that azadirachtin EC 25% (4 g kg(-1)) showed higher NBT activity, serum lysozyme, protein profiles, leukocyte counts and resistance against A. hydrophila infection and thus, can be used as a potential immunostimulant in aquaculture.

Assessment of mutagenic, hematological and oxidative stress biomarkers in liver of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) in response to sublethal verapamil exposure

Abstract The influx of pharmaceutical drugs and their metabolites have been reported to cause negative impact on aquatic biota. In this study, effects of long-term exposure of verapamil on mutagenic, hematological parameters and activities of the oxidative enzymes of Nile tilapia, Oreochromis niloticus were investigated for 60 days exposure at the concentrations of 0.29, 0.58 and 1.15 mg L−1 in the fish liver. The exposure resulted in significantly high (p < 0.05) micronuclei induction of peripheral blood cells at the peak on day 30 at 1.15 mg L−1. Compared with the control, there was significant increase (p < 0.05) in white blood cell counts and red blood cell distribution width (RDW), with a reduction in hemoglobin (Hb), red blood cell counts (RBCs), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) level as the concentration of the drug increased. The indices of oxidative stress biomarkers (lipid peroxidation and carbonyl protein) showed elevated level, depicting a positive correlation with both time and concentration. More so, the activity of energy-related parameter (Na+ -K+- ATPase) in the tissue was significantly inhibited (p < 0.05) at the end of 60 days exposure period. Further, the activity of catalase (CAT) was inhibited while reduced glutathione (GSH) level was decreased in the liver tissue. There was increase in the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione–S-transferase (GST) after 30 days at 0.29 mg L−1. The study demonstrated that prolonged exposure to verapamil at sublethal concentration can result in mutagenic effects and oxidative dysfunctions in O. niloticus.

Neurotoxic effects, molecular responses and oxidative stress biomarkers in Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) exposed to verapamil

Pharmaceutical drugs and their metabolites are detected in aquatic ecosystems and have been reported to cause ecotoxicological consequences to resident aquatic organisms. The study investigated the effects of acute and long-term exposure to verapamil on activities of acetylcholinesterase and antioxidant enzymes as well as mRNA expression of stress-related genes in brain and muscle tissues of Nile tilapia, Oreochromis niloticus. The 96h LC50 of verapamil to O. niloticus was 2.29mgL-1. Exposure to sub-lethal concentrations of verapamil (0.14, 0.29 and 0.57mgL-1) for period of 15, 30, 45 and 60days, led to inhibition of acetylcholinesterase activities in the brain and muscle of the fish. The activities of the oxidative enzymes such as the catalase, superoxide dismutase and glutathione peroxidase were also inhibited in both the tissues while there was an increase in the activities of glutathione-S-transferase and reduced glutathione in the muscle after 15 days at 0.29mgL-1. Lipid peroxidation and carbonyl protein showed elevated level, indicating a positive correlation with both time and concentration. The activities of energy-related biomarker (Na+-K+-ATPase) in both the tissues were significantly inhibited (p<0.05) compared with the control. Transcription of catalase (cat), superoxide dismutase (sod) and heat shock proteins 70 (hsp70) were up-regulated in both the tissues after the study period. Prolonged exposure to sub-lethal verapamil can result in oxidative stress, up-regulation of stress-related genes and neurotoxicity in O. niloticus.

Isolation and Characterization of Phenanthrene-Degrading Bacteria from PAHs Contaminated Mangrove Sediment of Thane Creek in Mumbai, India

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs), including phenanthrene, are commonly found as pollutants in soils, estuarine, and sediments, as well as in terrestrial and other aquatic ecosystems. In this context, the phenanthrene-degrading bacteria were isolated and characterized in contaminated mangrove surface sediment, on the coast of Thane Creek, Mumbai, India by enrichment method, using phenanthrene as the sole source of carbon and energy. The phylogenetic diversity of the isolates were evaluated by 16S rRNA gene analysis and characterized as Bacillus mojavensis strain KSS001, Bacillus firmus strain KSS002, Bacillus flexus strain KSS003, Bacillus vietnamensis strain KSS004, and Bacillus amyloliquefaciens strain KSS005. Each isolate was grown on the phenanthrene up to 100 mg/L and the biodegradation ability was evidenced using a gas chromatography–flame ionization detector. Further, the mean value of phenanthrene degradation by 5 bacterial isolates after incubation in mineral salt medium for 7 days was 63% at 100 mg/L. The study reports that mangrove sediments of Thane Creek, Mumbai, contain a diverse population of phenanthrene-degrading bacteria that have the potential and capability to degrade PAHs contaminated sites, and are consequently recommended for bioremediation.

A prospective of epidemiological intervention in investigation and management of argulosis in aquaculture

Argulus, an obligate macroectoparasite, infests a wide range of fishes causing severe economic loss to aquaculture industry. The application of chemotherapeutants is the most common approach to combat argulosis. But it is very expensive and has a range of negative impacts on the host and environment. An alternative to the extensive use of chemotherapeutics is to restrict Argulus infestation by adopting a range of biosecurity and quarantine measures. However, before adopting these measures it is essential to adequately understand the complex interaction among the host, parasite and environment, in order to identify key factors affecting parasite dynamics and to formulate a possible management strategy. Epidemiology provides key tools to advance our understanding of diseases and allows bringing convergence in controlling the disease. Compared to terrestrial diseases, relatively few epidemiological studies have been conducted to investigate aquatic animal diseases. For Argulus spp., the complex real-world dynamics of transmission, reproduction and the host specificity and the role of these parasites as a vector for various pathogens are very complex to develop an effective epidemiological framework. This review principally focuses on the application of epidemiological concepts, providing insights about the sampling frame, commenting upon the use of simple deterministic susceptible-infected-removed models and examines the determinants of transmission and spread of argulosis. Further, this paper describes the risk factors associated with Argulus infestation and the importance of risk analysis in intervention against its epizootics. Overall, this review is intended to highlight the need for development of a more extensive epidemiological approach to combat argulosis in aquaculture.

In vitro evaluation of natural and synthetic substrate for biofilm formation and their effect on water qualities.

The present study evaluated the natural and synthetic substrate for biofilm formation in in vitro condition and their effect on physico-chemical parameters of water. The four different treatments i.e., control (without substrate), T1 (sugarcane bagasse), T2 (PVC), T3 (coconut husk) and T4 (bamboo strips) as substrates were used for assessment of biofilm formation and heterotrophic bacterial growth. Physico-chemical parameters of water and total platecolonies were estimated at weekly intervals for five weeks. Results of dissolved oxygen, total alkalinity, as well as nutrients like ammonia-nitrogen, nitrate-nitrogen and nitrite-nitrogen showed significant (p