http://reposit.library.du.ac.bd:8080/xmlui/xmlui/handle/123456789/994 2026-04-06T21:30:03Z 2026-04-06T21:30:03Z Naher, Elmay http://reposit.library.du.ac.bd:8080/xmlui/xmlui/handle/123456789/1057 2019-11-13T03:43:36Z 2017-05-02T00:00:00Z

Fate of mitochondrial DNA (mtDNA) in zebrafish (Danio rerio)under oxidative stress Naher, Elmay Stress in various formssuch as extreme drought, temperature, salt intrusion, emergence of new pathogens, industrial chemicals discharge in to the aquatic system causing serious health problem of the fishes, which ultimately affect the expected production level in fisheries sector. All these environmental stress factors increase cellular reactive oxygen species (ROS) levelmainly superoxide(O2•−), hydroxyl radicals (OH•), hydrogen peroxide (H2O2) leading to secondary oxidative stress effects in fish. Under oxidative stress, ROS might affect the cellular macromolecules like protein, lipid, DNA etc. This study focused to examine the secondary effects of the environmental pollutants that is the oxidative stress on mitochondrial DNA (mtDNA) in fish. Tropical freshwater zebrafish (Danio rerio) was used as experimental model in this study and the oxidative stress was induced by H2O2treatment. Firstly we examined the acute toxicity of H2O2on zebrafish by estimating LC50 value which was not reported yet. The fishes were exposed to different concentrations of H2O2 for static acute toxicity test. The concentration-mortality (%) data were analyzed through Probit analysis to estimate the 96 h median lethal concentration (LC50) which was 257.494 µM. Secondly, the oxidative stress effect on mtDNA was examined in both H2O2 treated and non-treated zebrafish during 96 hours period. We have designed two sets of mtDNA specific primers to observe H2O2 stress effect in two specific zone of mtDNA, one is from 1 bp to 8500 bp and the other is 8244 bp to 16585 bp. After polymerase chain reaction we observed a probable nucleotide loss in mtDNA in fish under oxidative stress with the primer set 2. This oxidative damage was observed from 8266 bp to 16563 bp in both brain and egg cell of H2O2treated zebrafish. After in silico analysis, we found that this particular sequence consists of several hot spots which are repeated sequences and prone to oxidative damage. This study finds a potential sequence in mtDNA to find the oxidative damage in fish. Our findings might be the basis to develop a molecular biomarker to study the secondary oxidative stress effect due to any environmental pollutants. This thesis submitted to the Department of Fisheries, University of Dhaka in partial fulfillment of the requirements for the degree of Master in Science (MS) in Fisheries.

2017-05-02T00:00:00Z Tania, Hasna Ahmed http://reposit.library.du.ac.bd:8080/xmlui/xmlui/handle/123456789/1056 2019-11-13T03:42:17Z 2017-05-02T00:00:00Z

Anthropogenic and climatic impacts on the Kapotakkho river fisheries Bangladesh and adaptation strategies Tania, Hasna Ahmed Bangladesh has been identified as one of the most vulnerable countries due to climate change. On the other hand, anthropogenic impact on land and nature fuses impacts on the biophysical environment, biodiversity and distinctive resources. The river fisheries are also vulnerable due to climate and anthropogenic changes. Available researches on river fisheries have focused mainly on fish production, fish biodiversity, fishing gear and fishermen's livelihoods. This study assessed the socio-economic status of fishers and present non-fishers (who were fishers before) and the impacts and adaptation strategies to anthropogenic and climatic changes in the Kapotakkho river fisheries of Chowgachaupazila of Jessore district, Bangladesh. Data were collected through household interviews, semi-structure questionnaire, focus group discussions (FGD), oral history interviews and interviews with key informants between June and July 2016 from two fishing communities (Hazrakhana and Kalitola) of the Kapotakkho river. Secondary data (Climatic parameter; temperature, rainfall) were collected from Bangladesh metrological department (BMD), Agargaon, Dhaka-1207. Socio-economic status of respondents was studied in term of age structure, religion, level of education, housing condition, homestead and cultivable savings. The socio-economic status of present day non-fishers was found better than that of fishers while occasional fishers and part-time fishers were found better than those of full-time fishers. On contrast, the socio-economic status of respondents was found better in 2016 than in 1998. Both fishing communities are being exposed to the impacts of anthropogenic variables (dam construction, riverbank land use and urban runoff) and climatic variables (high temperature and low precipitation). However, volumes of water and fish habitat are being reduced. Quality of the waters was found deteriorated in 2016 than in 1998. Fish abundance was found reduced in 2016 than in 1998. This study also identified that some fishes are locally extinct and/or going to be extincted from the surveyed river. It was also found that mean catch is reduced by 9.90-folds in 2016 than in 1998. Income from fisheries related activities were found reduced by reduction in fish catch which in turn affecting the livelihoods of the fishers thus affecting their socio-economic status. To cope with the changing climate and man-made variability both fishing communities have taken multiple adaptation strategies. Some 88.3% respondents adapted adaptation strategies while rest did not. While 86.3% adopted diversification of livelihoods others increased fishing duration and use extra efficient fishing gears. Diversification of livelihoods included agriculture, fish trading; fish farming, small business and vehicle driving as prominent in both study sites. This has clearly demonstrated that agriculture is the most common adaptation strategy for fishers and non-fishers. The socio-economic statusof the river Kapotakkho fishers and fisheries has been affected by a number of anthropogenic and climatic hazards, and are being traditionally adapted to those impacts which are not sufficient for sustainable livelihoods and fisheries. Over the next few decades this situation may worsen as predicted by the latest scientific research and an improved level of responsiveness would be required. This thesis submitted to the Department of Fisheries, University of Dhaka in partial fulfillment of the requirements for the degree of Masters of Science (MS) in Fisheries.

2017-05-02T00:00:00Z Ray, Utpal Chandra http://reposit.library.du.ac.bd:8080/xmlui/xmlui/handle/123456789/1055 2019-11-12T09:12:53Z 2017-04-30T00:00:00Z

Genetic diversity of Hilsa and Chapila in Bangladesh using DNA barcodingand RAPD techniques Ray, Utpal Chandra Fisheries is one of the most important sectors in the socio-economic context of our country. Fishes are the major source of animal protein and it contributes about 60% of the animal protein intake. Tenualosa ilisha is the national fish of Bangladesh. “Jatka” are captured in a large quantity by artisanal fishers and sold on local markets as “chapila”. The main purposes of the study were morphological identification and genetic characterization of “chapila” and different species of “hilsa”. Morphometric study and DNA barcoding were used for species identification. Species identification based on the DNA sequence of a fragment of the cytochrome c oxidase subunit I gene in the mitochondrial genome, DNA barcoding, is widely applied to assist in sustainable exploitation of fish resources. RAPD (Randomly Amplified Polymorphic DNA) analyses were used to find out the genetic distances by ten arbitrary oligonucleotide RAPD primers. Four different species of chapila (Gudusia chapra), hilsa (Tenualosa ilisha), toli shad (Tenualosa toli) and big eye ilish (Ilisha megaloptera) were identified by morphometric study. But DNA barcoding shows there were two different species of Indian oil sardine (Sardinella longiceps) and kelee shad (Hilsa kelee). A total of 134 bands were produced in RAPD analysis among four species where 23 bands were polymorphic indicating 18.48% polymorphisms. The molecular size of the amplified DNA fragments ranged between 200 to 1480bp and 83unique RAPD bands were observed among four populations.The values of pair-wise genetic distances ranged between 0.5077 and 0.9933with some degrees of genetic variation among the populations.The highest genetic distance (0.9933) was found between Gudusia chapra and Sardinella longiceps. While the lowest genetic distance (0.5077) was found between Sardinella longiceps and Hilsa kelee.The UPGMA dendrogramsegregated the four populations in three major clusters viz. C1, C2 and C3. Clusters C1 and C2 comprised Sardinella longiceps and Hilsa kelee. On the other hand, Gudusia chapra created the new distant cluster C3. Results show that DNA barcoding is a reliable tool for species identification. Genetic diversity information may be used for improved breeding programme and conservation of those four populations. This thesis submitted to the Department of Fisheries, University of Dhaka in partial fulfillment of the requirements for the degree of Masters of Science (MS) in Fisheries.

2017-04-30T00:00:00Z Eshik, Md. Moatavi Enan http://reposit.library.du.ac.bd:8080/xmlui/xmlui/handle/123456789/1054 2019-11-12T09:11:33Z 2017-04-30T00:00:00Z

Molecular identification and characterization of Vibrio parahaemolyticus causing Acute Hepatopancreatic Necrosis Disease in cultured Shrimp Eshik, Md. Moatavi Enan Acute Hepatopancreatic Necrosis Disease (AHPND), also called Early Mortality Syndrome (EMS), is a recently emergent shrimp bacterial disease caused by strains of Vibrio parahaemolyticus that contain a unique virulent plasmid, resulted in substantial economic losses since 2009.AHPND has caused severe mortalities up to100% in farmed populations of marine shrimp Penaeus monodon. The purpose of this thesis work was to identify and characterize the pathogenic strain of V. parahaemolyticus causing EMS in cultured shrimp using classical and molecular techniques. To conduct this work, shrimp samples were collected from three different locations of south-west shrimp farming region of Bangladesh viz.Sadar Upazilla of Satkhira district, Mongla and Morrelganj Upazilla under Bagerhat district. The shrimp samples were processed for microbial load count and to isolateV. parahaemolyticus strains. Four types of bacteriological culture media were used to enumerate the Total Bacterial count (TBC), Total Vibrio count (TVC). Besides Classical microbiology, molecular approaches (16S rRNAgene sequencing, pathogenic gene PCR using AP3 and AP4 primers) wereperformed to identify the pathogenic strains of V. parahaemolyticus causing AHPND in cultured shrimp. Shrimp suffering from AHPND showed significantly atrophy of hepatopancreas (HP), pale to white hepatopancreas due to pigment loss in connective tissue capsules and guts with discontinuous or no contents. In this study, TBC, TVC on TCBS and on HiChrome showed little variation of AHPND affected shrimp. TBC was found highest(6.37×108cfu/g) in shrimp of Satkhira Sadar Upazilla, whereas highest number of Total Vibrio on TCBS agar (2.40×107 cfu/g) was found in shrimp of Mongla Upazilla. In this study, among 46 isolates, representative eighteen isolates were checked for the species-specificdetection of V. parahaemolyticus using ldh primers; and tdhprimerswere used for the detection of human pathogenicity of V. parahaemolyticus. Detection of ldh gene fragment in the isolates showed positive result for ldhbut isolates were negative for human toxigenic gene tdh. The representative isolates were also subjected to 16S rRNA gene sequencing and were identified as V. parahaemolyticus. Multiple sequence alignment was performed to find out the polymorphic sites among the sequenced strains with considering 1386 bp nucleotides where 1.15 % dissimilarities were observed.Six strains (Vp2, Vp4, Vp21, Vp27, Vp35 and Vp39) were highly similar to each other but dissimilar to only two sites (34, 35 bp) on their polymorphic region. Phylogenetic analysis also confirmed the taxonomic positionof the isolates as V. parahaemolyticus. On the other hand, 18 V. parahaemolyticus isolates were further characterized to check the AHPND positivity using AP3 and AP4 primer. Twelve isolates showed positive result for AP3 and fourteen isolates for AP4 primer that indicate those isolates were AHPND positive which caused EMS in cultured shrimp.This study also reported that all the representative strainsof AHPND positive V. parahaemolyticuswere resistant to Gentamycin whereas all the strain showed sensitivity to Chloramphenicol, Nalidixic Acid,Nitrofurantion and Tetracycline. This report also agreed with the mortalities of shrimp that occurred within 30 days after stocking in shrimp farms of three different south-west regions of Bangladesh which caused by AHPND positive V. parahaemolyticus;and to the best of my knowledge, this is the first report of this shrimp pathogen in Bangladesh. This thesis submitted to the department of Fisheries, University of Dhaka in the partial fulfillment of the requirements for the degree of Master of Science (MS) in Fisheries.

2017-04-30T00:00:00Z