Phage, Colicins, and Macroregulatory Phenomena

Luria, Salvador E.

doi:10.1126/science.168.3936.1166

Cited by 37 publications

(16 citation statements)

References 29 publications

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“…Studies of the killing action of bacteriocins have indicated that the adsorption of a single particle may be sufficient to kill a susceptible cell. Luria (21) termed this "quantal" killing to distinguish it from the "molar" bactericidal activity of the classical antibiotics. Sensitive bacteria are thought to be killed by bacteriocins in a two-step process.…”

Section: Bactericidal Action Of Streptocin A--preliminary Experimentmentioning

confidence: 99%

Group a Streptococcal Bacteriocin

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Dajani

Wannamaker

et al. 1973

The Journal of Experimental Medicine

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The bacteriocins are an intriguing potpourri of bactericidal antibiotics, having a wide range of different genetic determinants, physicochemical properties, and killing mechanisms (1). Bacteriocinogeny seems an almost universal property of bacteria and various strains of most species have now been shown to produce bacteriocins. Although there have been several reports of bacteriocin-like inhibition produced by Group A streptococci on solid media (2-4), progress in this field has been hampered by the inability to demonstrate the active bacteriocin in broth cultures.A streptococcal bacteriocin was recently obtained in cell-free form following "freeze-thaw" extraction of the liquor from cultures grown on Oxoid ToddHewitt agar (4, 5). The producer organism was a Group A beta-hemolytic streptococcus (strain FF-22) and the bacteriocin was correspondingly named streptocin A. The present communication is concerned with the isolation and purification of streptocin A from broth cultures of this same producer strain and an investigation of the mode of action of the bacteriocin against a susceptible Group A streptococcus. Several properties of the bacteriocin are compared with those of a bacteriocin produced by a strain of phage type 71 Staphylococcus aureus. Materials and MethodsBacterial Strains.--Group A streptococcus strain FF-22 (5) and S. aureus strain C55 (6) were the organisms used for the production of the streptococcal and staphylococcal bacteriocins. Various other strains were utilized as indicators in studies of the specificity of the range of bactericidal activity of these bacteriocins. Group A streptococcus strain PF 1643 (6) is an indicator sensitive to both streptocin A and staphylococcin. S. aureus strain 502A (6)

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Section: Bactericidal Action Of Streptocin A--preliminary Experimentmentioning

confidence: 99%

Group a Streptococcal Bacteriocin

Tagg

Dajani

Wannamaker

et al. 1973

The Journal of Experimental Medicine

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“…Certain amplification processes undoubtedly take place at the level of the genome-one is welldocumented (19) and others have been proposed (20). However, other amplification processes are known, both in procaryotic (21) and eucaryotic (22) cells, which appear to involve alterations in, and operate directly on, the preformed machinery of the cell (often membranes), rather than involving, directly and primarily, alterations in the regulation of gene function.…”

Section: Endogenous Protein Synthesismentioning

confidence: 99%

Zoospore Germination in Blastocladiella emersonii: Cell Differentiation without Protein Synthesis?

Soll

Sonneborn

1971

Proc. Natl. Acad. Sci. U.S.A.

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Evidence is presented to suggest that several early events of zoospore germination in the water mold, Blastocladiella emersonii, are not dependent upon concomitant protein synthesis. The events involve abrupt, dramatic changes in cell architecture. On account of this evidence, as well as evidence available from other sources, we question whether differential protein synthesis provides an exclusive and sufficient mechanism for phenotypic change (i.e., cell differentiation). Rather, we argue that mechanisms for bringing about structural alterations in the preformed machinery of the cell should also be given attention.One common thread runs through virtually all current thinking regarding the mechanism(s) of cellular differentiationnamely, that cells change phenotype (i.e., differentiate) as a result of differential protein synthesis. Our intention in this paper is certainly not to discredit the usefulness of this hypothesis, but rather to call into question whether this form of phenotypic control provides an exclusive and sufficient mechanism for cellular differentiation.The organism under study is the water mold Blastocladiella emersonii. We have focused attention particularly on the sequence of cellular changes involved in zoospore germination, primarily because this sequence is characterized by dramatic, abrupt changes in cell structure, and because zoospore populations can be induced to germinate rapidly and semisynchronously (1). A sequence of four morphologically distinct cell types can be unambiguously resolved (see Fig. 1 and refs.

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“…Bacteriocins are proteins excreted by bacteria which prevent the growth of other related bacteria. The colicins produced by E. coli [1] have been most extensively studied and many gram-positive organisms also produce a wide range of bacteriocins [2], including the lactic acid bacteria. Characterization of bacteriocins from gram-positive bacteria poses additional problems in that other inhibitory substances are also produced, for exam-Correspondence to: C.A.…”

Section: Introductionmentioning

confidence: 99%