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R A JENSEN

Publications and source records attributed to R A JENSEN.

At least 19 recordsLinked to original sources
PubMed1963

ELECTROKINETICS AND CELL PHYSIOLOGY. 1. EXPERIMENTAL BASIS FOR ELECTROKINETIC CELL STUDIES.

Jensen, Roy A. (The University of Texas M. D. Anderson Hospital and Tumor Institute, Houston) and Felix L. Haas. Electrokinetics and cell physiology. I. Experimental basis for electrokinetic cell studies. J. Bacteriol. 86:73-78. 1963.-The stable and regular electrokinetic pattern displayed by Bacillus subtilis cell populations was presented as the basis for precisely controlled experimental procedures. The course of electrokinetic behavior characteristic of a cell population was one which paralleled the overall physiology of the culture. The prospects of capitalizing upon this biological feature of the cell were considered in cases where portions of a cell population were separable with respect to some distinct physiological criterion. Such cell fractions may be associated with a discrete and detectable difference in the net charge residing upon the bacterial cell surface. Within a limited pore-size range, membrane filters lost or retained cells, depending upon the electrostatic interaction between cell and filter disc. Fractionation on membrane filters proved to be adjustable and could be controlled by selecting the proper ionic strength in the culture medium. Procedures of this kind have potential for the development of preparative techniques or, alternatively, as experimental vehicles for kinetic analysis.

Bacillus subtilis↗
PubMed1963

ELECTROKINETICS AND CELL PHYSIOLOGY. II. RELATIONSHIP OF SURFACE CHARGE TO ONSET OF BACTERIAL COMPETENCE FOR GENETIC TRANSFORMATION.

Jensen, Roy A. (The University of Texas M. D. Anderson Hospital and Tumor Institute, Houston) and Felix L. Haas. Electrokinetics and cell physiology. II. Relationship of surface charge to onset of bacterial competence for genetic transformation. J. Bacteriol. 86:79-86. 1963.-A reliable cell fractionation scheme, which is sensitive to the electrokinetic properties of Bacillus subtilis cells, has been described in detail. Recipient cell populations, characterized by a wide range of competency for transformation to independence of nutritional markers, were subjected to electrokinetic fractionation. Results indicated that (i) physiological competency is directly related to the electrical charge on the cell surface, (ii) newly competent cells carry a maximal negative charge, (iii) the newly competent cell appears with spontaneous abruptness, (iv) a kinetic flow of competent cells from the highly charged fractions to the lower charged fractions indicates the progressive loss of the surface charge maintained by a competent cell, and (v), by token of the latter statement, cells competent to undergo transformation do so within a range of surface-charge values.

Bacillus subtilis↗