• Journal of Pharmaceutical Investigation
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• v.26 no.4
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• pp.291-297
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• 1996

Liposomes of $pSV-{\beta}-Galactosidase$ vector plasmid DNA with various lipid composition were prepared by the thin-film method. Size distribution, shape and the efficiency of plasmid DNA encapsulation were investigated. Effect of sonication time on the plasmid DNA entrapment in liposomes and stability at $4^{\circ}C$ were also examined. Sizes of neutral liposomes were about 100-200 nm and above $1\;{mu}m$, and those of cationic liposomes were about 400-600 nm and above $1\;{mu}m$. Shapes of liposomes entrapped plasmid DNA were spherical. Proper sonication time for better entrapment was below 15 minutes and stability at $4^{\circ}C$ was decreased rapidly after 1 day. Plasmid DNA entrapments of complex liposomes of various lipids were higher than those of liposomes made from one sort of lipid. Plasmid DNA entrapments of cationic liposomes were higher than those of neutral liposomes.

• Journal of Sericultural and Entomological Science
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• v.39 no.1
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• pp.36-43
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• 1997

In order to express the FLP recombinase in B. mori cultured cell line, BmN-4, transient expression system using a heat shock protein gene (hsp70) promoter of Dorosophilla melnogaster was constructed. This vector was designated as pHsSV. Activity strength of the hsp70 promoter was compared with that of immediate early gene (IE-1) and polyhedrin gene of BmNPV employing the E. coli $\beta$-galactosidase gene as a reporter gene. The result showed that the pHs $\beta$-gal plasmid vector expressed the $\beta$-galactosidase at 2nd and 3rd day after the transfer of plasmid DNA into BmN-4 cells, which was similar to that of pIE1 $\beta$-gal vector, but different from that of a recombinant virus, vBm $\beta$-gal. For the construction of FLP recombinase transient expression vector, the FLP recombinase gene was cloned by polymerase chain reaction technique. To express the FLP recombinase, this gene was inserted into pHsSV plasmid vector, under the control of the hsp70 promotor, and tranfected in BmN-4 cells. The expressed FLP recombinase was estimated at 44kDa on a 12.5% SDS-PAGE.

• Journal of Sericultural and Entomological Science
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• v.40 no.1
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• pp.52-59
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• 1998

For the construction of plasmid and bmNPV sarrying the FRT recognition site for the FLP recombinases, we synthesized the wild type FRT dligonucleotides. The target FRT sequences consist of three 13bp repeated DNA sequences; two repeats in a direct orientation and one inverted relative to the other two. In addition, there is an 8bp spacer region between the repeats which determune the orientation of the FRT recombination site. In order to place the FRT site both in target BmNPV genome and the transfer vector, we constructed a plasmid, FRT site both in the target BmNPv genome and the transfer vector, we constructed a plasmid, pFRT$\beta$-gal, carrying the FRT sites within the cloning sites of pSV vector and a recombinant BmNPV, vFRTPH, carrying the FRT sites at a downstream of polyhedrin promotor, respectively. In order to test the functionality of the FLP/FRT site-specific recombination system, vFRTPH, pFRT$\beta$-gal and pHsFLP DNA were co-transfected into BmN-4 cells. The resulting recombinant virus was designated a vFRT$\beta$2-gal. From construction analysis of the vFRT$\beta$2-gal with PCR technique it was concluded that the entire pFRT$\beta$-gal plasmid with $\beta$-galactosidase gene and origines of replication flanked by two functional hybrid FRT sequences. The efficiency of recombination was 8.7%, which was higher than that(2.2%) of recombination between a conventional transfer vector and the wild type BmNPV.