Chromosome replication in Bacillus subtilis cultures growing at different rates.

Bacterial Genome Sizes Determined by DNA Renaturation Studies

“…Likewise, the genome size of Salmonella pullorurn (2.8 x 109 daltons) corresponds fairly well to the 2.4 to 3.0 x 109 daltons determined chemically as the corrected DNA content per cell nucleoid in S. typhimurium (Maalare & Kjeldgaard, 1966). The DNA content per cell nucleoid in resting cells or in uninucleated spores are particularly well investigated in several Bacillus species (Fitz-James & Young, 1959; Dennis & Wake, 1966; Eberle & Lark, 1967). The best possible value for the genome size of Bacillus species obtained from these investigations is about 3 x 109 daltons, which agrees well with the 2.6 to 2.8 x 109 daltons obtained for our three species.…”

Slow growing Bacillus subtilis: deoxyribonucleic acid replication in turbidostat cultures

“…The molecular weight of B. subtilis nuclear body at different growth rates was also determined (Table 3). It ranges from 2.87 x lo9 to 3.85 x lo9 daltons and is comparable to the results reported by others (Eberle and Lark 1967;Wake 1973). The genome (nuclear body) molecular weight, calculated from their equation (assuming D = 0 to GT-C), ranges from 2.8 x lo9 to 9.9 x lo9 daltons which is also inconsistent with the results reported in the literature.…”

“…The duration of tures (Table 1). Generation time data from the liter-the C period increased slower than the duration of ature for B. subtilis (Eberle and Lark 1967) are the generation time.…”

“…these data by first determining the amount of DNA per nuclear body, dividing by l/ln 2 to correct for ongoing replication (Eberle and Lark 1967;Maalge and Kjelgaard 1966), and multiplying by Avogadro's number to express the results in daltons (see Table 3). The values ranged from 2.9 x lo9 to 3.8 x lo9 daltons, a result comparable to that reported for B. subtilis (Dennis and Wake 1966; Eberle and Lark 1967;Wake 1973).…”

TherepMutation III. Altered Structure of the ReplicatingEscherichia coliChromosome

“…There are more growing forks in the rep -/2 mutant. To confirm that there were more x 02 x replicating forks in the rep chromosome than in E 2 E the rep+ chromosome, and to measure the u a average number of growing forks per cell, we I z/1 used an autoradiographic technique that deter-m ines the number of labeled cells as a function * 0 of the number of generations after a short pulse I __ _ _ of pH]thymidine (8,15). A culture in exponen-* 0 0.l 0.2 tial growth was exposed to [3H]thymidine fora a (Millipore Corp.) with warm medium, and resuspended in warm medium at zero time.…”