Transforming Activity in Both Complementary Strands of Bacillus subtilis DNA

Abstract

Under conditions favoring single-strand transformation, the two complementary strands of Bacillus subtilis DNA, separated by differential complexing with polyriboguanylic acid, have identical transforming activity. Moreover separated single strands, upon renaturation with unmarked (recipient) DNA, form heteroduplex molecules with similar double-strand transformin activity. These findings bear upon the mechanism of DNA integration.

Autoradiographic Estimation of Competence and the Relationship between Competence and Transformability in Cultures of Bacillus subtilis

“…(I) Individual competent cells integrate the transforming strands predominantly in one specific strand of their genome. Although for the competent population as a whole, random strand integration has been reported for Bacillus subtilis (Chilton, 1967;Rudner, Karkas & Chargaff, I 968), Haemophilus infuenzae (Goodgal & Notani, I 968) and Diplococcus pneumoniae (Peterson & Guild, 1968), this does not necessarily exclude the possibility that cells which have absorbed a multiplicity of duplexes preferably integrate strands of the same polarity. (2) There is a high degree of heteroduplex repair with the donor strand as template.…”

Nucleic acid transport driven by ion gradient across cell membrane

“…(1) The cells are incubated with calcium salts and DNA at 0°C; Molecules of nucleic acids are transported across (2) The suspension is then warmed to 37°C. the membrane into the recipient cell at an early stage Viruses are initially adsorbed to receptors in the of genetic transformation, transfection, viral infection outer cell wall and then transfer their nucleic acid and conjugation.…”

“…Furthermore, direct proof that either strand of a DNA molecule can transform has been obtained in experiments with Bacillus subtilis DNA. The two strands of this DNA have been separated and each of them transformed B. subtilis cells to approximately the same extent [2,3].…”

Chemical Mutagens

“…The genetic effects of mutagen on single-stranded (denatured) DNA can Table 6). (IV) Kelly and Pritchard (1965) be evaluated directly (Postel andGoodgal, 1966, 1967;Chilton, 1967) or after renaturation (Horn and Herriott, 1962). For reasons not fully understood, single-stranded DNA yields mutations faster than native DNA only in some systems and for some mutagens (Horn and Herriott, 1962;Strack et al, 1964).…”

“…B. subtilis (Chilton, 1967). Competent B. subtilis are mixed with single-stranded DNA at a final level of 0.1 f-lgfml in the presence of 10-3 EDT A.…”