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1.  Cytological Studies of Deoxyribonucleic Acid Replication in Escherichia coli 15T−: Replication at Slow Growth Rates and After a Shift-Up into Rich Medium 
Journal of Bacteriology  1970;104(1):401-409.
We examined the gross nuclear morphology of Escherichia coli 15T− grown in different media with doubling times ranging from 22 to 270 min. In slowly growing cells, deoxyribonucleic acid synthesis was measured by autoradiography and shown to occur with greatest probability during the first two-thirds of the division cycle. In such cells, segregation occurred later, at the end of the division cycle rather than at the end of deoxyribonucleic acid replication. Nuclear regions in L-broth cells (22-min doubling time) cannot correspond to separate chromosomes but probably represent regions of replication activity. Segregation of template nucleotide strands was measured after a shift-up from proline M9 or glucose M9 media into L broth. A model is presented to account for the pattern of segregation observed.
PMCID: PMC248226  PMID: 4919753
2.  Effect of Actinomycin D on the Transfer of Ribonucleic Acid from Nucleus to Cytoplasm in Lactobacillus acidophilus 
Journal of Bacteriology  1970;101(3):1005-1013.
After starvation for deoxyribosides, the deoxyribonucleic acid (DNA) of Lactobacillus acidophilus is restricted to a localized region of the cell. 3H-uracil is first incorporated into such a restricted region but subsequently is found throughout the cell. This spread occurs despite the absence of protein synthesis and a major reduction in the rate of ribonucleic acid (RNA) synthesis. However, blocking RNA synthesis with actinomycin D restricts incorporation to a localized region of the cell. It is concluded that uracil is first incorporated into RNA in the bacterial nucleus from which it subsequently spreads through the cell. Actinomycin D could prevent this spread by preventing the completion of RNA molecules, which therefore do not dissociate from the DNA template.
PMCID: PMC250422  PMID: 4985583
3.  Segregation of Deoxyribonucleic Acid in Bacteria: Association of the Segregating Unit with the Cell Envelope 
Journal of Bacteriology  1967;94(2):415-421.
Cells of the gram-positive organism Lactobacillus acidophilus R-26 were labeled with 3H-thymine to measure the segregation of radioactive deoxyribonucleic acid (DNA) into daugher cells. Such cells were found to contain 8 conserved units of DNA which would correspond to two replicating chromosomes per cell. Fluorescent antibody (FA) against this organism was used to demonstrate that portions of the cell surface (2 to 4 units per cell) were conserved during growth and division. The permanent association of DNA with these conserved cell surface units was measured by combining autoradiography with FA techniques. DNA synthesized immediately before FA labeling was not associated with the fluorescent cell surface, whereas DNA synthesized a generation previously was. The results are consistent with a model in which DNA becomes permanently fixed to the cell surface when it is first used as a template.
PMCID: PMC315056  PMID: 4962703

Results 1-3 (3)