The nucleoids of Escherichia coli, independently of the physiological state of the bacteria, are shown to be preserved as a fine-stranded fibrillar nucleoplasm by an OsO(4) fixation under defined conditions: acetate-veronal buffer pH 6, presence of Ca(++) and amino acids, stabilization with uranyl-acetate before dehydration. The same fixation procedure applied to the DNA of vegetative phage reveals a pool of homogeneous fibrillar structure very similar to the nucleoplasm. The "versene test," which produces a coarse coagulation of these plasms, emphasizes the similar behaviour of the pool and the nucleoids. The heads of mature phage are preserved in their true polyhedral shape by the standard fixation procedure, although they may be badly distorted when fixed under different conditions. Lanthanum nitrate and uranyl-acetate are shown to increase markedly the contrast of both phage and cytoplasm. The consequences of the fibrillar structure of the genetic material are discussed in relation to the probable division process.

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Electron microscope study of DNA-containing plasms. II. Vegetative and mature phage DNA as compared with normal bacterial nucleoids in different physiological states.

4Crawford, L. V., R. Dulbecco, M. Fried, L. Montagnier, and M. G. P. Stoker, these PNoCEEDINGS, 52, 148 (1964). Bourgaux, P., D. Bourgaux-Ramoisy, and M. G. P. Stoker, Virology, 25, 364 (1965). 6Black, P. H., and W. P. Rowe, these PROCEEDINGS, 50, 606 (1963). 7Diderholm, H., B. Stenkvist, J. Ponten, and T. Wesslen, Exptl. Cell Res., 37, 452 (1965). 8 Black, P. H., and W. P. Rowe, J. Nati. Cancer Inst., 32, 253 (1964). 9 Hopps, H. E., B. C. Bernheim, A. Nisalak, J. H. Tjio, and J. E. Smadel, J. Immunol., 91, 416 (1963). 10Black, P. H., E. M. Crawford, and L. V. Crawford, Virology, 24, 381 (1964). 11 Weil, R., Virology, 14 (1961). 12 Black, P. H., and W. P. Rowe, Virology, in press. 13 A clone of fibroblasts (C13), derived from the BHK-21 line,' was obtained from Professor M. Stoker, Giasgow, Scotland, and was used at the 80th-lOOth generations since cloning. 14 Pope, J. H., and W. P. Rowe, J. Exptl. Med., 120, 121 (1964). 16 Black, P. H., W. P. Rowe, H. C. Turner, and R. J. Huebner, these PROCEEDINGS, 50, 1148 (1963). 16 Defendi, V., J. Lehman, and P. Kraemer, Virology, 19, 592 (1963). 17 Black, P. H., and W. P. Rowe, Proc. Soc. Exptl. Biol. Med., 114, 721 (1963). 18 Gotlieb-Stematsky, T., and R. Shilo, Virology, 22, 314 (1964). 19 Dulbecco, R., personal communication. 20 Le Bouvier, G., personal communication. 21 Crawford, L. V., and P. H. Black, Virology, 24, 388 (1964). 22 Mayor, H. D., R. M. Jamison, and L. E. Jordan, Virology, 19, 359 (1963). 23Stoker, M., and P. Abel, in Cold Spring Harbor Symposia on Quantitative Biology, vol. 17, (1962), p. 375. 24 Black, P. H., unpublished data. 25 Vinograd, J., R. Bruner, R. Kent, and J. Weigle, these PROCEEDINGS, 49, 902 (1963).

https://www.pnas.org/content/pnas/54/4/1133.full.pdf

Mechanism of action of penicillins: a proposal based on their structural similarity to acyl-D-alanyl-D-alanine.

Type IV pili are remarkably strong, flexible filaments with varied roles in bacterial pathogenicity. All Gram-negative bacterial surfaces have type IV pili, which are polymeric assemblies of the protein pilin that evoke the host immune response and are potential drug and vaccine targets. Pilin structures that have been solved using X-ray crystallography and nuclear magnetic resonance, together with models for pilus architectures inferred from electron microscopy, fibre diffraction and computation, have established a molecular basis for assembly and multi-functionality, with implications for therapeutic interventions.

Type IV pilus structure and bacterial pathogenicity

These drugs, also called quinolones, include norfloxacin, ciprofloxacin, ofloxacin, enoxacin, and pefloxacin. We shall evaluate here the current status of the quinolones, considering mechanisms of action and resistance, activity in vitro, pharmacokinetics, clinical efficacy, adverse effects, and clinical uses

Fluoroquinolone antimicrobial agents.

Quinolines and structurally related heterocycles as antimalarials

Efficacy trial of a parenteral gonococcal pilus vaccine in men

The drug chloroquine is bactericidal for Bacillus megaterium; it inhibits DNA and RNA biosynthesis and produces rapid degradation of ribosomes and dissimilation of ribosomal RNA. Inhibition of protein synthesis is also observed, evidently as a secondary effect. Inhibition of DNA replication is proposed as a general mechanism of the antimicrobial action of chloroquine.

https://science.sciencemag.org/content/sci/151/3708/347.full.pdf

Chloroquine: Mode of Action

Quinacrine at a concentration of 8 x 10-4 mole per liter is bactericidal for Escherichia coli, blocks DNA synthesis, and inhibits the syntheses of RNA and protein strongly. At a concentration of 2x 10-4 mole per liter, the drug is bacteriostatic, the syntheses of protein and DNA (but not that of RNA) are partially inhibited, and the bacteria grow into giant filaments. Impairment of DNA replication is proposed as the mode of action of quinacrine.

https://science.sciencemag.org/content/sci/156/3775/655.full.pdf

Quinacrine (atebrin): mode of action.

http://science.sciencemag.org/content/sci/125/3238/119.full.pdf

Penicillin-induced lysis of Escherichia coli.

Interralations between nucleic acid and protein biosynthesis I. Synthesis and fate of bacterial nucleic acids during exposure to, and recovery from the action of chloramphenicol

Jennie Ciak

Papers

Efficacy trial of a parenteral gonococcal pilus vaccine in men

Chloroquine: Mode of Action

Quinacrine (atebrin): mode of action.

Penicillin-induced lysis of Escherichia coli.

Interralations between nucleic acid and protein biosynthesis I. Synthesis and fate of bacterial nucleic acids during exposure to, and recovery from the action of chloramphenicol