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PubMed1957

Transformation reactions between Pneumococcus and three strains of Streptococci.

Reciprocal transformation reactions to streptomycin resistance have been demonstrated between pneumococcus and 2 strains of viridans streptococci, which by the usual bacteriological criteria are distantly related to pneumococcus. Desoxyribonucleic acid (DNA) extracts of a strain of streptomycin-resistant Streptococcus salivarius have been found capable of transforming pneumococcus and two strains of viridans streptococci but the strain itself was not transformed by autologous or heterologous DNA extracts. The two strains of viridans streptococci were more efficient than pneumococcus as receptors of both autologous and heterologous transforming principles. It is inferred, therefore, that efficiency of transformation does not necessarily indicate closeness of relationship among bacteria. The efficiency of transforming principles (TP's) from three streptococcal strains to induce streptomycin resistance in pneumococcus increased following their reduplication in pneumococcus. At the same time the efficiency of two of these TP's to transform streptococcus was reduced. Resistance to optochin (ethylhydrocupreine), a characteristic of most streptococci, can be transferred to pneumococcus, a naturally susceptible species, by transformation reactions.

Carrier Proteins↗
PubMed1958

The development in vitro of particles from cytoplasm. II. Particles from hemoglobin and deoxyribonucleic acid.

Spherical particles, 1 to 10 microns in diameter, resulted from the incubation at 37 degrees C. of distilled water lysates of erythrocytes with deoxyribonucleic acid (DNA). The particles consisted of 88 per cent hemoglobin and 12 per cent DNA (dry weight basis). An unknown factor, presumably an enzyme, present only in fresh red cell lysates, was required for particle development. Particle size was a function of the pH of the reaction mixture. The pH range was 4.8-5.8. It was possible to trap extraneous proteins and polysaccharides in pockets within the hemoglobin particles during their development to the exclusion of some of the hemoglobin. The amount of any one substance so trapped was proportional to its concentration in the reaction mixture. Some practical applications of the particles, as a means for making particulate various soluble substances (enzymes, antigens, antibiotics), are suggested.

Cytoplasm↗