RESUMO
A beta actin cDNA of Tanichthys albonubes was isolated through the RT-PCR and RACE approach. The cDNA was 1,787-bp in length, including a 1,128-bp CDS, a 95-bp 5'UTR and a 564-bp 3'UTR. Genomic DNA containing the transcription region and 5'-flanking region was cloned based on the beta actin cDNA by Genome walker. A 3,000-bp beta actin gene promoter was then produced by PCR according to the sequences of the 5'-flanking region and the first intron. This promoter consisted of a 1,800-bp 5'-flanking region, and a 1,200-bp 5'-UTR. 3 transcription elements, CAAT box, CArG motif and TATA box were found in the 5'-flanking region. This promoter was inserted into the vector pDsRed2-1 and microinjected into fertilized eggs of Tanichthys albonubes to prove its transcription activity. The beta actin promoter and GH CDS of Tanichthys albonubes were then fused to construct an expression vector pTLA-GH. GH-transgenic Tanichthys albonubes was obtained by microinjection of the pTLA-GH into the fertilized eggs. Fast-growth individuals were observed in the transgenic group and the body weight of the largest individual was 2.1-fold that of the maximum in its non-transgenic siblings in 100 dph. In addition, a co-injection strategy was employed with pTLA-DsRed and pTLA-GH vector and proven to enhance the efficiency of GH-transgenic fish detection.
Assuntos
Actinas/genética , Cyprinidae/genética , Proteínas de Peixes/genética , Regiões 3' não Traduzidas , Regiões 5' não Traduzidas , Animais , Animais Geneticamente Modificados , Sequência de Bases , Clonagem Molecular , Regiões Determinantes de Complementaridade , Primers do DNA/genética , DNA Complementar/genética , DNA Complementar/isolamento & purificação , Vetores Genéticos , Hormônio do Crescimento/genética , Proteínas Luminescentes/genética , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Proteínas Recombinantes/genéticaRESUMO
Through PCR amplification, 1.3 kb of 5'-proximal promoter (TA, 1.3 kb) of the beta-actin gene of white cloud mountain minnow Tanichthys albonubes was obtained. Using Genome Walker, a 1.7 kb 5'-upstream sequence from the proximal promoter of the beta-actin gene was isolated, and a further promoter (3.0 kb in size) was amplified according to the isolated 5'-proximal and upstream sequences (TLA, 3.0 kb). Both the 1.3 kb and 3.0 kb promoters contain elements that were critical to the transcription activity of other species, including the CCAAT Box (-89 approximately -85), CArG Box (-59 approximately -49), TATA Box (-26 approximately -20). Results of putative transcription binding sites analysis of the promoters by software TRANSFAC 6.0 revealed the presence of E-box, several transcript binding sites NF-Y, SP1 (Stimulating Protein 1), AP1 (Activator Protein 1), and some more transcription binding sites existing in the further promoter. The two promoter sequences were inserted into the expression vector to construct the recombinant expression vector, pTA-DsRed and pTLA-DsRed, respectively. The vectors were microinjected into the fertilized eggs of Tanichthys albonubes and higher positive rate was obtained and stronger red fluorescence was observed in pTLA-DsRed transgenic fish. RT-PCR analysis showed that RFP (Red fluorescent protein) mRNA level in pTLA-DsRed transgenic fish was 35.7% higher than that of the pTA-DsRed transgenic fish of 15-days-post-hatched. The present study showed that both the proximal and further promoter sequences have effective transcription activities and the 3.0 kb promoter possesses higher potent activity than that of the 1.3 kb promoter.