Theses (Ph.D.)

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ASSESSMENT OF PRODUCTIVITY OF FRESHWATER FISH PONDS
(KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR - 585401, 2019) KISHOR, C.,; A.T.RAMCHANDRANAIK
Four farm ponds of different agro-climatic regions viz, Dakshina Kannada and Shivamogga districts were selected for the study. The selected ponds were from designated as Coastal ponds from Dakshina Kannada (ponds P1 and P2) and Malnad ponds from Shivamogga (ponds P3 and P4). Physico-chemical and biological characteristics of water from selected farm ponds were assessed. The results showed variation in different water quality parameters. The water temperature ranged from 24.30 to 32.10 oC, pH from 5.60 to 9.35, Transparency from 7.1 to 30.40 cm, Dissolved oxygen from 3.1 to 11.34 mg/l, Alkalinity from 24 to 166 mg/l, Carbon dioxide from 1.11 to 13.74mg/l, Ammonianitrogen from 0.29 to 18.65 μg at./l and Phosphate-phosphorus from 0.21 to 5.34 μg at./l. A total of 3 genera of phytoplankton (Cyanophyta, Chlorophyta, and Bacillarophyta) were found dominant groups. The pond sediment characteristics such as temperature, pH, electrical conductivity, organic carbon, available phosphorus, available potassium, total nitrogen and textural compositions were within the range suited for freshwater farming. Quantitative and qualitative analyses of phytoplankton showed that plankton content was moderate. The gross primary productivity ranges from (14.45-184.45 mg C/m3/hr). Maximum net primary productivity (136.23 mg C/m3/hr) was recorded during March in pond P3 and Community respiration ranged from 0.31 to 127.94 mg C/m3/hr. Highest concentration of Chl-a (3.75 mg/l) was recorded in pond P4 in March while lowest was in pond P2 (0.19 mg/l) in January. Zooplankton abundance was belonging to 5 classes viz, Rotifera, Protozoa, Copepoda, Cladocera and Ostracod. Average numbers of zooplankton varied from farm ponds (P1&P2) was 176 to 10368 Cells/m3 and in (P3&P4) was 1579 to 21797 Cells/m3. Highest concentration of Chl-a (3.75 mg/l) was recorded in pond P4 in March while lowest was in pond P2 (0.19 mg/l) in January. Average growth rate and average body weight of three major carps such as Catla (Catla catla), Rohu (Labeo rohita) and Common carp (Cyprinus carpio) was recorded for 16 months. Maximum growth in terms of length and weight of catla, rohu and common carp was from pond P3 and P4 (52.75cm and 1080.71g, 44.40cm and 954.19g and 48.43cm and 1023.18g respectively). Key words: Farm ponds, Physico-chemical characteristics, Plankton diversity, Primary productivity, Chl-a, Indian major carps.
Open Access
DEVELOPMENT OF THERAPEUTIC PHAGE CONSORTIA TO MANAGE AEROMONAS HYDROPHILA INFECTION IN AQUACULTURE SYSTEMS
(KARNATAKA VETERINARY, ANIMAL & FISHERIES SCIENCES UNIVERSITY, BIDAR, 2021) NITHIN, M. S.,; S.K.GIRISH
Motile Aeromonas Septicemia has contributed to severe economic loss in several aquaculture fish species such as carps, tilapia, salmons, and catfishes. In the present study, water and diseased fish samples were collected. Diseased fishes had a clinical sign such as enlarged abdomen, reddening, dropsy, fin rot and haemorrhages on the body surface. The etiological agent was identified as Aeromonas hydrophila and other Aeromonas spp. through biochemical and molecular methods. Further, Multiple Antibiotic Resistance (MAR) index showed >0.2 for the isolated A. hydrophila (n=35), which indicates the property of multidrug resistance. Therefore, as a preliminary approach to develop bio-control measure, novel lytic bacteriophages (phages AhFM1-AhFM22) were isolated from different water systems. Transmission electron microscopy (TEM) confirms that the lytic phages AhFM1 to AhFM11 & AhFM12 belong to family of Myoviridae and Siphoviridae respectively. Interestingly, phages (AhFM1- AhFM11) displayed adsorption in the range of 70 to 96%; latent period 15 to 25 min and burst 65 ± 27 PFU/host cell to 348 ± 13 PFU/host cell. The phages were stable over broad array of physicochemical parameters (temperatures, salinity, pH and chloroform). The novel bacteriophage-based strategies viz., prophylactic and therapeutic approach (injection, oral and immersion) to prevent and treat A. hydrophila infection were studied for first time in India. Prophylactic application in injection, immersion and feed impregnated phages showed 100%, 95.11% and 93.11% survival than the challenged untreated fishes. Therapeutic approach (injection) has resulted in 100% survival in initial (0 and 24) hours of treatment and delay in therapy resulted in 80% and 75% survival at 48 and 72 hr respectively. These findings support that phages (AhFM1-AhFM11) can be used to treat/control A. hydrophila infection in cultured fishes and have an immense capability to develop as a substitute to antibiotics
Open Access
REVERSE-VACCINOLOGY APPROACH TO DEVELOP VACCINE AGAINST RED SEA BREAM IRIDOVIRUS (RSIV)
(KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR, 2022) PUNEETH, T. G.,; S.K.GIRISH
Reverse vaccinology (RV) is a modern technique that accelerates the discovery of potential vaccine candidates suitable in vaccine development. Red sea bream iridovirus (RSIV) is the etiological agent responsible for Red sea bream iridovirus disease (RSIVD) in fish leading to huge economic losses to the aquaculture industry. The present study was aimed to screen, isolate, characterize RSIV genome and develop a vaccine candidate using the RV approach to control the RSIV infection. In this study RSIV was isolated from a moribund Asian sea bass cultured in estuarine cages. The PCR amplification and sequencing results of the DNA polymerase gene showed similarity with the sequences of RSIV strains from other countries. Experimental infection studies revealed 100% mortality in the RSIV challenged Asian sea bass on 6th day post infection (dpi). Histopathogical observations in the spleen, kidney and liver tissues were similar to that of typical RSIV infection. Replication efficiency test in the fish cell lines revealed that the RSIV could infect eleven cell lines with viral titers ranging from 102.6 to 106.3 TCID50/ml. The Illumina Hiseq sequencing of RSIV revealed that the complete genome size of RSIV is 111,557 bp with GC content of 53%. The phylogenetic analysis of the 26 core genes including Major capsid protein indicated that the virus belong to the genus Megalocytivirus of the RSIV-Genotype II. The genome encoded 114 ORFs of which 38 ORFs were predicted as functional proteins while the rest were hypothetical proteins. Of the 114, two proteins (MCP and ORF036) were identified as potential vaccine candidates using the RV strategy. The vaccine targets were cloned and expressed in Escherichia coli BL21 (DE3) cells. Asian sea bass vaccinated (injection method) with purified recombinant proteins, MCP and ORF036 emulsified with ISA763 adjuvant showed protection against RSIV infection with relative percentage survival of 76.7% and 63%, respectively.
Open Access
TOXICOLOGICAL CHARACTERISATION OF TITANIUM DIOXIDE (TIO2) AND SILICON DIOXIDE (SIO2) NANOPARTICLES IN PEARLSPOT (ETROPLUS SURATENSIS)
(KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR – 585 401, 2022) SHEETHAL K. U.,; lakkshmipathi
Growing production and use of nanoparticles unavoidably results in their accumulation in oceans, rivers, and other bodies of water, posing a threat to the ecosystems health. The gradual introduction of these nanoparticles into the environment has prompted concern about the dynamics and toxic effects of these xenobiotics in various ecosystems, either alone or in combination with other contaminants which could alter their toxicity. This study evaluates the toxicity of joint effects of these different nanoparticles (Titanium dioxide and Silicon dioxide). The acute toxicity of 96 h of LC50 value of TiO2 NPS, SiO2 NPs and Combination of TiO2 +SiO2 NPs for Etroplus suratensis fingerlings was calculated and found to be 160.42 ppm, 128.93 ppm and 61.88 ppm. For sublethal toxicity, the fingerlings were exposed to two sub lethal concentrations i.e., 1/10th and 1/5th of LC50 up to 56 days. Experimental results of accumulation showed that the uptake TiO2 NPs concentration in vital organs were in the order brain> gills> liver> kidney> muscle. Similarly in SiO2 NPs it was liver> gills> brain> muscle> kidney. In combination of TiO2 + SiO2 NPs the highest accumulation was recorded in liver> brain> muscle> gill> kidney. Significant increase in RBC count and WBC was noticed. While, haemoglobin, PCV, MCV, MCH and MCHC showed decreased in fingerlings exposed to NPs. Significant changes was observed enzymatic antioxidants in treatment and control groups. The histology results reveled that TiO2 and SiO2 NPs cause severe damage to morphology of gills, liver, brain, muscle and brain compared that with control group. The study suggested that sublethal concentration of TiO2 and SiO2 NPs altered the hemetological, enzymatic and histological parameters and exerts stress to the fish. Key words: Nanoparticles, TiO2 NPs, SiO2 NPs, Hemetology, Histology, Enzymes
Open Access
TOXICOLOGICAL EFFECTS OF OXYTETRACYCLINE ON COMMON CARP, CYPRINUS CARPIO
(KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR, 2022) SHRUTHI; LAKSHMIPATHI
Oxytetracycline (OTC), an antibacterial agent, is extensively used in aquaculture practices all over the world. Tetracycline class of antibiotics alone were marketed to the maximum extent of 39,74,179 kg in 2019 which is about 66% of the medically important drug. Despite of its use, the toxicity of OTC to freshwater fish has been investigated. In this study, Common carp (Cyprinus carpio) were exposed to different concentrations (25, 50, 75, and 100 mg kg−1 diet) of OTC for a period of 60 days, during which fish were killed at the end of every 15 days to analyse certain haematological, enzymological and histological parameters. During the exposure period, a mixed trend was observed in haemoglobin (Hb), haematocrit, mean cell volume, mean cellular Hb, and mean cellular Hb concentration, whereas decreased red blood cell countand increased white blood cell, haemoglobin, haematocrit, mean cell volume, mean cellular Hb, mean cellular Hb concentrationwas noticed. Enzymes such as Aspartate aminotransferase, Alanine aminotransferaseand Lactate dehydrogenase that are metabolically important were studied in order to know alterations in any carbohydrate or protein metabolism due to chronic toxicant exposure. A biphasic trend was observed in the enzymatic levels of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase in the vital organs (gill, liver and muscle) of fish. In gill, activities of AST and LDH increased but that of ALT decreased. Thus enzyme activity is based on organ sensitivity to toxicant and rate of disturbances in carbohydrate metabolism. Along with haematological and enzymatic changes severe histological changes in the gills and liver were observed in fish treated with oxytetracycline. Histological investigations have long been recognized to be reliable biomarkers of stress in fish. 120 Furthermore, the observed histological alterations appear to be result of several physio-metabolic disordersconsequence of the biochemical and molecular modes of action of OTC. The alterations of these parameters lead to the conclusion that these parameters may be used as biomarkers in monitoring OTC toxicity in aquatic environment. KEYWORDS: Oxytetracycline, Cyprinus carpio, Haematology, Enzyme, Histology

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