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Biomedical subjects

R N Doetsch

Publications and source records attributed to R N Doetsch.

At least 37 records · Page 2Linked to original sources
PubMed1969

Motility tracks: technique for quantitative study of bacterial movement.

A method for recording movements of bacteria in time and space on a single photograph is described. Quantitative information on the behavior of various motile organisms may easily be obtained for comparative studies. The method possesses certain advantages over cinematography, and illustrations of applications of the technique are presented.

Bacillus↗
PubMed1969

Relationship between cell wall, cytoplasmic membrane, and bacterial motility.

High-resolution electron microscopy of polarly flagellated bacteria revealed that their flagella originate at a circular, differentiated portion of the cytoplasmic membrane approximately 25 nm in diameter. The flagella also have discs attaching them to the cell wall. These attachment discs are extremely resistant to lytic damage and are firmly bound to the flagella. The cytoplasm beneath the flagellum contains a granulated basal body about 60 nm in diameter, and a specialized polar membrane. The existence of membrane-bound basal bodies is shown to be an artifact arising from adherence of cell wall and cytoplasmic membrane fragments to flagella in lysed preparations. Based on structures observed, a mechanism to explain bacterial flagellar movement is proposed. Flagella are considered to be anchored to the cell wall and activated by displacement of underlying cytoplasmic membrane to which they are also firmly attached. An explanation for the membrane displacement is given.

Bacteria↗
PubMed1969

Effect of respiratory inhibitors on the motility of Pseudomonas fluorescens.

The translational motility of Pseudomonas fluorescens was weakly inhibited by oligomycin, Dicumarol, 2,4-dinitrophenol, 2n-heptyl-4-hydroxyquinoline N-oxide, and potassium cyanide. Atabrine and antimycin A together with potassium cyanide immediately immobilized this bacterium, but antimycin A alone was without effect. Gramicidin D also immobilized P. fluorescens, but its action was inhibited by K(+) and NH(4) (+) ions. In like manner, the effect of p-chloromercuribenzoate could be counteracted with cysteine, thereby suggesting the involvement of -SH groups in flagellar motility processes. It appears that the energy required for motility of P. fluorescens is generated by oxidative phosphorylation mediated by the cytochrome system.

Adenosine Triphosphate↗
PubMed1966

Some singular properties of bacterial flagella, with special reference to monotrichous forms.

Roberts, F. F., Jr. (University of Maryland, College Park), and R. N. Doetsch. Some singular properties of bacterial flagella, with special reference to monotrichous forms. J. Bacteriol. 91:414-421. 1966.-Heat (60 C for 30 min), 10 m acetamide, and 8 m urea all brought about rapid and complete dissolution of flagella from monotrichous bacteria; hence, these flagella respond similarly to those of peritrichous forms. Chloramphenicol (10(3) mug/ml) inhibited regeneration of flagella in all peritrichously flagellated cultures; however, monotrichous forms were able to regenerate their flagella in a concentration 10(2) times that required to inhibit multiplication. Peritrichous bacteria did not synthesize flagella when infected by lytic bacteriophages. In these experiments, the time from infection to lysis was sufficient for uninfected controls to resynthesize their flagella. Monotrichous bacteria, however, in all but one instance, were able to resynthesize their flagella before lysis occurred. A study of flagella resynthesis in a non-nutritive milieu indicated that only a small amount of flagellum precursor is present in any given cell. The effect of temperature on synthesis of flagella indicated that, although some bacteria multiply and are motile at a given temperature, they are unable to resynthesize their flagella at that same temperature. This strongly suggests that initial flagellum synthesis and flagellum regeneration are not necessarily identical processes.

Amides↗