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Chromosome Replication Related to Cell Division and Increase in Cell Mass In Synchronized Cultures of Nelsseria Meningitidis
Author(s) -
Jyssum Kaare
Publication year - 1972
Publication title -
acta pathologica microbiologica scandinavica section b microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0365-5563
DOI - 10.1111/j.1699-0463.1972.tb00053.x
Subject(s) - cell division , biology , genetics , chromosome , locus (genetics) , neisseria meningitidis , mutant , strain (injury) , population , replication (statistics) , cell , gene , virology , bacteria , demography , anatomy , sociology
Synchronous growth of Neisseria meningitidis Strain M1 was obtained after release from prolonged chloramphenicol inhibition. Chromosome replication was examined by enumerating mutants induced with nitrosoguanidine in successive samples from the cultures and correlated with cell division as measured by colony‐forming units, and with growth as evaluated by increase in absorbancy. A transformable (genetically competent) variant of the test strain was compared with a non transformable (genetically incompetent) one. The two variants have been found to differ with regard to chromosome replication, presumably by having different origin and direction of replication. The experiments indicate that cell division in both variants starts when the same, definite region or locus on the chromosome is replicated. This region seems to be located close to the origin (or terminus) of replication postulated for the non transformable variant. The rate of increase in absorbancy is abruptly approximately doubled 5–7 minutes after the start of cell division, whereas it is constant during the division cycle. The sudden enhancement of the rate does not occur when the density of the population is higher than corresponding to about A = 0.600, although growth continues at higher densities. Some implications of these findings have been discussed.