Construction of selectable marker-removable plant expression vectors / 生物工程学报

The commonly used plant constitutive expression vector pBI121 was modified by insertion of two directly orientated lox sites each at one end of the selectable marker gene NPTII and by replacing the GUS gene with a sequence composed of multiple cloning sites (MCS). The resulting plant expression vector pBI121-lox-MCS is widely usable to accommodate various target genes through the MCS, and more importantly to allow the NPTII gene removed from transformed plants upon the action of the Cre recombinase. In addition, the CaMV 35S promoter located upstream of the MCS can be substituted with any other promoters to form plant vectors with expression features specified by the introduced promoters. Provided in this paper is an example that an enhanced phloem-specific promoter of the pumpkin PP2 gene (named dENP) was used to construct an NPTII-removable phloem-specific expression vector pBdENP-lox-MCS. Moreover, to facilitate screening of selectable marker-removed gene and the composite sequence is flanked by lox sites. Thus the selectable marker-free plants can be visually identified by loss of GFP fluorescence. The above newly created plant expression vectors can be used to develop selectable marker-removable transgenic plants for a variety of purposes.

Construction of vector of multiple loci gene targeting in leghorn chicken based on BAC with Cre/lox P system / 生物工程学报

Based on the sequence of BAC (Bacterial Artificial Chromosome) along with the Cre/lox P system, the gene-targeting vectors to multiple loci of the repetitive internal transcribed spacers between rDNA genes in Leghorn chicken were constructed. The key material of multiple loci gene targeting in vivo would be obtained. First, the plasmid of pYLSV-TDN with TK, HRDS2, and Neo genes was constructed. The TK-HRDS2-Neo DNA fragment obtained from the plasmid of pYLSV-TDN was digested by Not I/HindIII and inserted into the upstream of the lox P site of BAC plasmid for obtaining the selective vector of BAC-TDN. The expression vector of pYLVS-GID with EGFP, hIFN genes, and HRDS1 was then obtained. The plasmid of BAC-TDN-VS-GID was obtained by cotransformation of the selective vector of BAC-TDN and the expression vector of pYLVS-GID to E. coli NS3529 through the action of Cre/lox P system. The gene-targeting vector of BAC-TDN-GID to multiple loci of the ITS region in Leghorn chicken was obtained by cleaving the sequence of pYLVS with the homing endonuclease of I -Sce I and ligating with the linker of LS. The insertion and the insert direction of DNA fragments were identified by restriction digestion or PCR and sequencing in each clone. The significance of the technique ofgene-targeting vector to multiple loci are shown as follows. First, the targeting loci were increased to 100 - 300. Second, the problems of unstable expression of inserted genes were partially solved. Third, the need for safety against toxicity integration was resolved. Fourth, the forbidden zone of gene integrating on the repetitive DNA sequences was broken through.

Estudo da proteína de choque térmico GRP788 para o desenvolvimento de um sistema de receptor-ligante para o câncer de próstata / The use of the heat-shock protein GRP78 for the development of a receptor-ligant ssystem in prostate cancer

Terapêuticas mais eficazes são necessárias para o câncer de próstata avançado. A Proteína regulada pela glicose-78 (GRP78) foi recentemente descrita como sendo um possível marcador molecular para a doença. Neste estudo, avaliou-se a GRP78 no desenvolvimento de um sistema de receptor-ligante para o câncer de próstata. Inicialmente, foram criados dois fagos com afinidade à GRP78 e foi demonstrado que ambos se ligam especificamente à proteína in vitro e em células de câncer de próstata. Em seguida, mostrou-se que ambos os fagos com afinidade à GRP78 rastrearam xeno-tumores prostáticos in vivo, e finalmente mostrou-se que os fagos ligam-se especificamente à GRP78 em metástases ósseas de câncer de próstata humano /Improved therapies are needed for advanced prostate cancer. The Glucose-regulated protein-78 (GRP78) was recently described as molecular marker for prostate cancer. We hipothesized that GRP78 could be used in the development of a receptor-ligand system. We initially cloned two GRP78-targeting plasmids (WIFPWIQL and WDLAWMFRLPVG) into a fUSE5-based phage. We showed that both phage bound specifically to GRP78 in vitro and to intact prostate cancer cells, and was internalized by those cells. GRP78-binding phage showed a strong homing in vivo to human prostate cancer xenografts. Finally, we showed that both phage bound specifically to GRP78 expressed in human prostate cancer bone metastases...