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PubMed1953

Control by factors distinct from the S transforming principle of the amount of capsular polysaccharide produced by type III pneumococci.

Pneumococci can possess the normal S transforming principle and yet produce amounts of capsular polysaccharide much less than would be expected if the quantity formed depended only on the nature of the S transforming principle.

Dietary Carbohydrates↗

PubMed1953

Morphologic variation in pneumococcus. I. An analysis of the bases for morphologic variation in pneumococcus and description of a hitherto undefined morphologic variant.

The problem of morphologic variation in pneumococcus has been reviewed and the desirability of studying such variation through an examination of bacterial cells rather than of bacterial colonies has been pointed out. To further this objective, a new terminology to describe the morphologic variants of pneumococcus, potentially applicable to other bacterial species, has been proposed. A hitherto undefined morphologic variant of pneumococcus, the filamentous capsulated (fil+ S+) variant, has been defined and its relationship to the three previously recognized non-filamentous capsulated (fil- S+), nonfilamentous non-capsulated (fil- S-), and filamentous non-capsulated (fil+ S-) variants has been presented.

Streptococcus pneumoniae↗

PubMed1953

Morphologic variation in pneumococcus. II. Control of pneumococcal morphology through transformation reactions.

The interaction of each of the four morphologic variants of pneumococcus with the transforming principles of the heterologous morphologic variants of the same species has been studied and has resulted in the isolation of eighteen of the twenty variants predicted to arise through such interactions. The analogy of the findings to the recombination of independently heritable characters in sexually reproducing forms has been noted.

Streptococcus pneumoniae↗

PubMed1963

INTRASPECIES AND INTERSPECIES TRANSFORMATION REACTIONS IN PNEUMOCOCCUS AND STREPTOCOCCUS.

The efficiency of transformation of pneumococcus and a strain of viridans streptococcus (strain D) to streptomycin resistance is influenced by the species in which the mutation to resistance occurred, as well as by the species in which the mutated gene has been replicated. Pneumococcus and streptococcus strain D transform in higher frequency with DNA that has been replicated in bacteria of the same species than with DNA from the heterologous species. However, the difference between the frequencies of interspecific and intraspecific transformation is much greater with pneumococcus as receptor than with streptococcus. In addition pneumococcus transforms in higher frequency with wholly homologous (pneumococcal) DNA than with DNA from pneumococci that have replicated the streptococcal Sm(r) gene. Pneumococcus is transformed in lower frequency by wholly heterologous (streptococcal) DNA than by DNA from streptococci that have replicated the pneumococcal Sm(r) gene. Streptococcus behaves similarly in that wholly homologous (streptococcal) DNA transforms it more efficiently than when the transforming fragment contains a pneumococcal moiety. Streptococcus is transformed in the same or lower frequency by wholly heterologous (pneumococcal) DNA than by DNA from pneumococci that have replicated the streptococcal Sm(r) gene. When erythromycin resistance was used as genetic marker instead of streptomycin resistance, similar results were found.

DNA↗

PubMed1957