RESUMO
Electrical conductance and other solution properties of aqueous solutions of a fluorine-containing poly(carboxylic acid), (poly(9H,9H-perfluoro-2,5-dimethyl-3,6-dioxa-8-nonenoic acid), PPFNA) were studied with special attention to the salt effect. This polymer dissociated strongly resulting in a low pH value in unneutralized state (beta=0, beta: degree of neutralization). The specific conductance was the highest at beta=0 and decreased as beta increased. A considerable increase in conductance was observed by titrating NaCl at low beta, because large amounts of bound protons were released by addition of NaCl. The amounts of released protons exceeded those originally dissociated at beta=0. Such an anomalous proton liberation suggests that this polymer is a fairly strong polyacid but not a typical one such as poly(styrene sulfonic acid). Under fully neutralized state (beta=1), however, the solution conductance was lower than the sum of the polymer and NaCl added, due to polyion-salt ion interaction.
Assuntos
Ácidos Carboxílicos/química , Flúor/química , Sais/química , Condutividade Elétrica , Concentração de Íons de Hidrogênio , Estrutura Molecular , Polímeros/química , Temperatura , Viscosidade , Água/químicaRESUMO
Spirulina platensis is one of the most commercially important species of microalgae. Thus, it is an attractive candidate for genetic manipulation and the development of novel practical applications. However, this process is hampered by the absence of a stable gene transfer system, specifically the limited number of suitable vectors and transformation methods available for this organism. Artificial transposon systems developed by extracting the essential elements from natural transposons have been extensively studied, and recently a mutated transposase and transposon system was reported to improve transformation efficiency by electroporation. We applied a modified transformation strategy using a natural Tn5 transposon, transposase, and cation liposome complex by electroporation to improve the transformation efficiency for Spirulina platensis strain C1 (Arthrospira sp. PCC9438). Aggregation of cells became visible after 3 weeks during 2.0 microg/ml chloramphenicol selection, and growth continued for more than 12 months. Transfected chloramphenicol acetyltransferase (CAT) genes were detected in the genomic DNA by Southern hybridization. Transformed cells demonstrated CAT activity, but non-transformed cells did not.
Assuntos
Cloranfenicol O-Acetiltransferase/genética , Cianobactérias/genética , Técnicas de Transferência de Genes , Transformação Genética/genética , Sequência de Bases , Southern Blotting , Cloranfenicol O-Acetiltransferase/metabolismo , Cianobactérias/metabolismo , Primers do DNA , Elementos de DNA Transponíveis/genética , Lipossomos , Dados de Sequência Molecular , Plasmídeos/genética , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Fatores de Tempo , Transposases/metabolismoRESUMO
Transformation of Escherichia coli is a basic technique for genetic engineering. We used a liposome-mediated lipofection method to transform electrocompetent E. coli cells which has little natural competence of foreign DNA without electroporation treatment, and got transformants with simple and quick treatment by a plasmid or a transposon and transposase complex.