RESUMO
The correlation between electrotransformation and electropermeability was studied in yeast cells following the modification of their membranes by treatment with n-alcohols. It was found that the number of transformed cells decreased with increase of chain length of the alcohols used as follows: methanol < ethanol < propanol < butanol. The electropermeability was unaffected by the prepulse n-alcohol treatment. The lack of a unidirectional link between permeability and transformation leads to the assumption that the mechanism of DNA introduction into the cell could not be interpreted solely as a result of the existence of pores.
Assuntos
Álcoois/farmacologia , Saccharomyces cerevisiae/efeitos dos fármacos , Biotecnologia , Permeabilidade da Membrana Celular/efeitos dos fármacos , DNA Fúngico/genética , Eletricidade , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Transformação Genética/efeitos dos fármacosRESUMO
Electrofusion between cells of yeast strains with different genetic markers are investigated. The yield of fusion products depends strongly on the field conditions and the different compounds in the fusion media.
Assuntos
Eletricidade , Protoplastos/fisiologia , Saccharomyces cerevisiae/fisiologia , Fusão Celular , Eletroforese , Glicerídeos/farmacologia , Hibridização Genética/fisiologia , Mutação , Micologia/métodos , Saccharomyces cerevisiae/efeitos dos fármacos , Soroalbumina Bovina/farmacologiaRESUMO
Erythrocytes suspended in a medium of low ionic strength lyse under the effect of an exponential electrical pulse. The percentage of haemolysed cells decreases several-fold in the presence of divalent cations. The protective action of the ions studied increases in the following order: Ca++, Mg++, Zn++. It is assumed that divalent ions bind to the negative charges of the lipid and protein molecules and reduce their electrostatic repulsion, which results in stabilization of the membranes.
Assuntos
Cálcio/fisiologia , Membrana Eritrocítica/fisiologia , Magnésio/fisiologia , Zinco/fisiologia , Citratos/sangue , Condutividade Elétrica , Hemólise , Técnicas In VitroRESUMO
Dielectrophoretic velocities of human red blood cells in an axisymmetric field were measured as a function of the applied voltage and the distance from the axis of symmetry. The voltage of the alternating electric field (frequency 2 MHz), applied between two concentric cylindrical metal electrodes (outer and inner radii 0.24 and 1 mm, respectively), was varied up to 19 V. Two kinds of mediums were used: (a) 90% of 2.1% glycine solution and 10% of 5.5% glucose solution and (b) 5.4% sorbitol solution. The results have shown that in both mediums the cell velocities are proportional to the square of the applied voltage and inversely proportional to the cube of the distance from the axis of symmetry, as predicted by the theory. The coefficient of proportionality (dielectrophoretic coefficient) is on the order of 10(-25) A2S4kg-1. It depends on the donor of red blood cells and might be used for diagnostic purposes. These results will be used in future investigations of membrane adhesion, stability and fusion.
