Cell population dynamics and somatic change

Effects of Enzymatic Deoxyribonucleic Acid Digests on Population Changes and Deoxyribonucleic Acid Synthesis of Pneumococci

“…Limited efforts to detect antagonists capable of interfering with the DNA + deoxyribonuclease-promoted enhancement of growth of virulent pneumococci showed that elevated Ca++ levels (20 ,g per ml or more), kinetin riboside, and salmine are capable of producing such effects in vitro and in vivo (Braun, 1958).…”

“…In the course of recent studies with Brucella species, it had been found that this typical direction of population changes, i. e., from R -÷ S, in vivo, could be duplicated in vitro provided deoxyribonucleic acid (DNA) + deoxyribonuclease were added to the culture medium (Braun and Whallon, 1954;Braun, 1956). It subsequently was demonstrated that this selective effect was independent of the source of the DNA, could not be reproduced by any known DNA breakdown product, and involved a capability of the virulent S cells to convert a DNA product of relatively large molecular size into a toxic factor for avirulent non-S cells (Braun et at., 1957b;Braun, 1958). A cursory survey among a few bacterial species, including Diplococcus pneumoniae, Salmonella typhosa, Staphylococcus aureus, and Vibrio comma, indicated that the selective effects in vitro of DNA + deoxyribonuclease were not restricted to brucellae.…”

SMALL-CELL SEGREGANTS FROM A POSSIBLY HOMOZYGOUS DIPLOID STRAIN OF ESCHERICHIA COLI

“…The conditions that stimulate or trigger the haploidization process in the diploid may be similar, in some respects, to those reported by Braun and co-workers for inducing population changes in Brucella. [Refer to the publications of W. Braun (1953Braun ( , 1958 for reviews describing environmental conditions that induce population changes in Brucella species.] When smoothcolony-forming (S) cells of Brucella abortus were grown in a closed-culture system, they found that rough-colony-type (R) cells appeared after 5 days of incubation.…”

Biodynamic effects of oligonucleotides.

“…In Brucella, nonsmooth (avirulent) to smooth (virulent) population changes in DNA digest-supplemented cultures involve the production of an inhibitor for nonsmooth cells as indicated in Fig. 1 (5,10). In contrast, with gram-positive bacterial species, a direct stimulation of the multiplication of the virulent type (S type in the case of pneumococci, coagulasepositive type in the case of staphylococci, "matt," type in the case of streptococci) is produced by DNA fragments (5,27,28); the avirulent types (R, coagulase-negative, and glossy, respectively) do not respond to such supplementation ( Fig.…”