Diet overlap of non‐native common carp and native Nile tilapia: A potential cause for population reduction of Nile tilapia stock in Lake Ziway, Ethiopia

This study was aimed to produce recombinant growth hormone (rGH) from giant grouper (Epinephelus lanceolatus), giant gouramy (Osphronemus gouramy) and common carp (Cyprinus carpio) and compare their bioactivity potential by means of inducing the growth hormone of juvenile Nile tilapia (Oreochromis niloticus) as the model. DNA fragment encoding mature GH protein of giant grouper (El-mGH), giant gouramy (Og-mGH) and common carp (Cc-mGH) was amplified by PCR method. The purified PCR products were ligated to pCold-1 to generate pCold/El-mGH, pCold/OgmGH, and pCold/Cc-mGH protein expression vector, respectively. Each of the expression vectors was transformed into the Escherichia coli BL21. E. coli BL21 was cultured using 2xYT medium and protein production was induced by cold shock at 15±1oC for overnight. The inclusion bodies of E. coli transformants containing protein expression vector were isolated by sonication method, and rGH production was analyzed by SDS-PAGE. Juvenile of Nile tilapia of average body weight of 12.41±3.28 g was intramuscularly injected once a week for 4 weeks with 1 μg inclusion body containing rGH per gram fish body weight. The result showed that rGH in molecular weight of about 25 kDa was obtained. Fish injected with rGH of El-mGH, Cc-mGH and Og-mGH grew 20.94%, 18.09%, and 16.99% faster, respectively, compared with the control. This result indicated that the three rGH produced in E. coli possessed biological activity when tested on Nile tilapia and further research is needed to find its effect on the growth of other aquaculture fish species.

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PERBEDAAN DAYA TAHAN NON SPESIFIK LIMA SPESIES IKAN AIR TAWAR TERHADAP INFEKSI Aeromonashydrophila

Jurnal Perikanan Universitas Gadjah Mada ◽

10.22146/jfs.9031 ◽

2003 ◽

Vol 5 (2) ◽

pp. 1

Author(s):

H. Syakuri ◽

Triyanto Triyanto ◽

K. H. Nitimulyo

Keyword(s):

Antibacterial Activity ◽

Common Carp ◽

Antibody Titer ◽

Fish Species ◽

Nile Tilapia ◽

Clarias Gariepinus ◽

Causative Factor ◽

African Catfish ◽

Skin Mucus ◽

Time To Death

Fish naturally has a non-specific defense against several pathogens. The non-specific defense is anatomical and physiological function that varies according to genetical and environmental factor. The differences of non-specific defense against Aeromonas hydrophila infection were studied in blackfinpacu (Colossoma macropomum), gourami (Osphronemus goramy), common crap (Cyprinus carpio), African catfish (Clarias gariepinus), and red nile tilapia (Orochromis sp.). This study also examined the differences on several parameters of non-specific defense, including differentiation anc number of leucocytes, serum total, titer of antibody, and antibacterial activity of skin mucus.The fishes were intramuscularly infected at the media lethal doses for common carp (7,4 x 108cfu/fish). Pathological changes, survival rate, and mean time to death were observed every day. The observation of non-specific defense parameters were carried out prior and at seven day after infection.The results showed thahblackfinpacu was the most resistant species against A. hydrophila infection. African catfish and red nile tilapia were most resistant than gourami and common carp. The antibody titer and percentage of thrombocytes were the causative factor for the difference of the resistence against A. hydrophila. The five fish species also showed differences on leucocytes number, monocytes and eosinophiles percentage, and serum total, but they did not showed the differences of neutrophile percentage. The skin mucus of all fish species did not exhibited antibacterial activity against A. hydrophila. This study also found increase in antibody titer and leucocytes number after A. hydrophila infection.

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