Acute hepatopancreatic necrosis disease (AHPND) of shrimps is a bacterial disease, first appeared in China in 2009 and causes mortality up to 100 % which usually occurs early (within approximately first 35 days) after stocking shrimp fry of black tiger shrimp, Penaeus monodon (Fabricius) and white leg shrimp, Litopenaeus vannamei (Boone). The purpose of this study was to isolate and identify the pathogenic strain of V. parahaemolyticus causing AHPND in cultured shrimps (P. monodon) using molecular techniques. After a disease outbreak in April 2017, shrimp samples were collected from three different locations of south-west shrimp farming region of Bangladesh viz. Satkhira, Khulna and Bagerhat districts. In this study, three selective media were used for primary isolation of V. parahaemolyticus. Among 28 primary isolates, representative14isolates were checked for the species-specific detection of V. parahaemolyticus using ldh primers and all of them were found to be positive. The isolates were further characterized to check their AHPND positivity using AP3 and AP4 primers. Four isolates showed positive results for both AP3 and AP4 which indicated that the isolates were AHPND positive. This study also report that all AHPND positive strains showed sensitivity to the antibiotics Tetracycline and Nalidixic Acid. The results of this study will help the farmers and policy makers to make plan to protect shrimps from AHPND and thereby sustain the shrimp farming in Bangladesh.

Cinnamon has different biological properties such as antioxidant, antimicrobial, antidiabetic and antiallergic. This study was carried out to investigate the effect of cinnamon as feed supplement on growth performances and bacterial load of Heteropneustes fossilis. Twenty fries were stocked in each 60 litre aquarium for a rearing period of 90 days. Commercial diet was used that contains 0.0% (control), 0.5%, and 1.0% cinnamon bark powder. The diet containing 1% cinnamon resulted in greater ADG, SGR, FCR and survival rate. Whereas, the diet containing 0.5% cinnamon resulted in greater condition factor and lower FCR. In most of the cases the diet containing 1% cinnamon showed lower amount of bacterial count than the controlled condition. Cinnamon could have an antibacterial activity antagonistic to Vibrio and Aeromonas as there was no count found in fish flesh samples after 90 days of culture. The findings of this study suggest that growth performances and bacterial load of H. fossilis were better in commercial feed containing cinnamon powder. It is recommended that fish farmers can use cinnamon as feed supplement to improve growth performance and reduce bacterial load during culture of H. fossilis.

Acute hepatopancreatic necrosis disease (AHPND) is an emerging shrimp disease caused by strains of Vibrio parahaemolyticus containing a unique virulent plasmid, responsible for substantial economic losses since 2009; caused up to 100% mortality in farmed shrimp Penaeus monodon. The purpose of this study was to isolate and identify the pathogenic strain of V. parahaemolyticus causing AHPND in cultured shrimp (Penaeus monodon) using classical and molecular techniques. Samples were collected from three different locations of south-west shrimp farming regions of Bangladesh viz. Sadar Upazilla of Satkhira; Mongla and Morrelganj under Bagerhat district. In this study, three selective media were used for primary isolation of V. parahaemolyticus. Among 46 primary isolates, 18 representative isolates were checked for the species-specific detection of V. parahaemolyticus using ldh primers and all of them were found to be positive. 16S rRNA gene sequencing were used to further confirm the isolates as V. parahaemolyticus. tdh primer was used to check human pathogenicity but all 18 isolates showed negative result. The isolates were further characterized to check their AHPND positivity using AP3 and AP4 primers. Ten isolates showed positive results for AP3 (55.56%) and 9 showed positive results for AP4 (50%) which indicated that the isolates were AHPND positive. This study also reported that all AHPND positive strains were resistant to the antibiotic gentamycin but sensitive to chloramphenicol, nalidixic acid, nitrofurantoin and tetracycline. The findings of this study will help the shrimp farmers and policy makers to take proper biosecurity measures to protect shrimps from AHPND and thereby sustain the shrimp production in Bangladesh. Dhaka Univ. J. Biol. Sci. 27(1): 57-68, 2018 (January)

The freshwater air-breathing swamp eel Monopterus spp. are native to the freshwater of Bangladesh and throughout the Indian subcontinent. To identify the different swamp eel species and to check the genetic diversity among them, a total of twelve swamp eel specimens were collected from four districts (Tangail, Bogura, Bagerhat and Sylhet) representing the four division of Bangladesh. The extracted DNA from twelve fish samples was amplified by the PCR technique for DNA barcoding and RAPD analysis. Among 12 specimens, 8 specimens showed a 95-100% similarity with M. cuchia species published in the NCBI GenBank database and BOLD system. The studied mct3 (collected from Tangail region), mcs1, mcs2 and mcs3 (collected from Sylhet region) specimens showed about 83% homology with Ophisternon sp. MFIV306-10 as per BLAST search; whereas BOLD private database showed 99% similarity with Ophisternon bengalense (Bengal eel). From the phylogenetic tree analysis, 8 samples were clustered with M. cuchia and 4 samples showed similarity with Ophisternon sp. MFIV306-10 and Ophisternon bengalense _ANGBF45828-19. In RAPD-PCR based analysis, it was found that the maximum genetic distance (1.6094) was observed between mcba2 and mcs3, while between mct1 and mct2, the minimum genetic distance was 0.000. A total of 192 bands, of which 35 were polymorphic with 17.88% polymorphisms among swamp eel species and the size of the amplified DNA fragments ranged from 250 to 1800 bp. The information on DNA barcoding and RAPD analysis help measure the genetic diversity among swamp eel species, ensure the reliability of the published taxonomic information, and initiate proper management programs to conserve these vulnerable species to meet future export demand. Asiat. Soc. Bangladesh, Sci. 46(2): 117-131, December 2020

Black tiger shrimp (Penaeus monodon Fabricius 1798) cultured in Bangladesh was investigated for the presence of microsporidian parasite. Histological section of hepatopancreas showed a large number of microsporidian spores under light microscopy. Spores under scanning electron microscope appeared oval shapes. Histology of infected shrimps showed severe degeneration of hepatopancreatic tubules. Early and late stage of microsporidian parasites in hepatopancreatic tubules were also observed. DNA extracted from the hepatopancreas of shrimps were subjected to PCR amplification using primers targeting microsporidian SSU rRNA gene. The PCR amplified an expected product of ~328 bp and the sequences showed 81 -82% identity with the Paranucleospora theridion reported from western Norway in 2008. Further screening of field samples was carried out using EHP-specific primers. DNA extracted from ten hepatopancreas samples of P. monodon were tested and none found to be positive for EHP (Enterocytozoon hepatopenaei). This is the first report for the identification of microsporidian parasites in cultured shrimp along the south-west region of Bangladesh.