In the preceding paper, the isolation and some characteristics of a pneumococcus manifesting binary capsulation were described (1). This organism, which was shown to produce two capsular polysaccharides, was derived by transformation of a non-capsulated mutant of pneumococcus Type III with deoxyribonucleates (DNA) of pneumococcus Type I. A noteworthy property of the SI-III cell is the production by it of approximately normal amounts of Type III polysaccharide in contrast to the markedly diminished or absent production of this substance by the cell from which it was derived. Two hypotheses to account for the restitution of the synthesis of Type III polysaccharide by the cell manifesting binary capsulation are readily apparent. Either that part of the genome controlling synthesis of Type III polysaccharide has been restoled to normal in the process of cellular transformation to the binary capsular state or the increased production of Type III polysaccharide results from the simultaneous presence within the cell of the mutated Type III capsular genome and the normal Type I capsular genome. Distinction between these two hypotheses may be made by a study of genetic properties of DNA from the SLIII cell. In experiments in which DNA from cells with a binary capsule was applied to noncapsulated organisms derived from a strain of pneumococcus Type II, cells of the mutant S-m phenotype, SI cells and, rarely, SI-III cells were recovered. No organisms of the SIII phenotype have ever been observed in an experiment of this kind.

No abstract

No abstract

No abstract