Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types

Abstract

Biologists have long attempted by chemical means to induce in higher organisms predictable and specific changes which thereafter could be transmitted in series as hereditary characters. Among microSrganisms the most striking example of inheritable and specific alterations in cell structure and function that can be experimentally induced and are reproducible under well defined and adequately controlled conditions is the transformation of specific types of Pneumococcus. This phenomenon was first described by Gri~th (1) who succeeded in transforming an attenuated and non-encapsulated (R) variant derived from one specific type into fully encapsulated and virulent (S) cells of a heterologous specific type. A typical instance will suffice to illustrate the techniques originally used and serve to indicate the wide variety of transformations that are possible within the limits of this bacterial species.Gri~th found that mice injected subcutaneously with a small amount of a living 1~ culture deri, ed from Pneumococcus Type H together with a large inoculum of heat-killed Type III (S) cells frequently succumbed to infection, and that the heart's blood of these animals yielded Type HI pneumococci in pure culture. The fact that the P~ strain was avirulent and incapable by itself of causing fatal bacteremia and the additional fact that the heated suspension of Type HI cells eoataincd no viable organisms brought convincing evidence that the 1~ forms growing under these conditions had newly acquired the capsular structure and biological specificity of Type III pneumococci.The original observations of Griffith were later confirmed by Neufeld and Levinthal (2), and by Banrherm (3) abroad, and by Dawson (4) in this laboratory. Subsequently Dawson and Sia (5) succeeded in inducing transformation in ~tro. This they accomplished by growing R cells in a fluid medium containing anti-R serum and heat-killed encapsulated S cells. They showed that in the test tube as in the animal body transformation can be selectively induced, depending on the type specificity of the S cells used in the reaction system. Later, Alloway (6) was able to cause

Bright Fluorescent Streptococcus pneumoniae for Live-Cell Imaging of Host-Pathogen Interactions

“…Besides potentially limiting diffusion of the fluorescent proteins by localizing them to the nucleoid (see below), we have shown previously by highthroughput sequencing of RNA transcripts (RNA-Seq) that hlpA is highly transcribed (40). The fusion constructs were integrated into the pathogenic encapsulated S. pneumoniae D39 genetic background (41), resulting in strains JWV500 (HlpA-GFP) and MK119 (HlpA-RFP) (Fig. 1A).…”

An Overview of Genome Organization and How We Got There: from FISH to Hi-C

“…We have since come to recognize that DNA is the genetic material containing all the information essential for life and the basis for heredity (2). The human genome is divided into 46 DNA molecules, or chromosomes, consisting of pairs of chromosomes 1 to 22 (autosomes), numbered sequentially according to their size, and of two sex chromosomes that determine whether an individual is male or female (Fig.…”

Ethanol-Induced Alcohol Dehydrogenase E (AdhE) Potentiates Pneumolysin in Streptococcus pneumoniae

“…The bacterial strains (Escherichia coli and S. pneumoniae) and plasmids used in this study are shown in Table 1. Encapsulated S. pneumoniae D39 (serotype 2; NCTC7466) (22) and WU2 (serotype 3) (23) strains and their isogenic ⌬adhE (serotype 2 and 3), ⌬rex (serotype 2), and ⌬spxB (serotype 2) mutants were used. The mutants were created using an ermB cassette inserted opposite to the target gene orientation to disrupt its expression (24).…”