The Nuclear Structures of Protocaryotic Organisms (Bacteria and Cyanophyceae)

Bacterial growth and the cell envelope.

“…It would appear at present that, as might be expected, similar morphology and disturbance VOL. 34,1970 a When shifted to the permissive temperature, septation will still occur in the presence of 100 uAg of chloramphenicol per ml. b When shifted to the permissive temperature, septation is random and nuclear segregation is disturbed.…”

“…Cytological evidence has suggested that the membranes and the DNA are connected in grampositive and gram-negative bacteria (28,33,34,61,62,120,122). This connection is often to the infolding of the membranes known as the mesosomes, but undoubtedly the attachment can also be directly with the cytoplasmic membrane.…”

“…In assessing whether the DNA is attached to the mesosomes or to the cytoplasmic membrane (120), it should be borne in mind that the sac of the mesosome is in fact continuous with the cytoplasmic membrane. When protoplasts of B. subtilis are examined, the DNA then appears to be directly attached to the bounding membrane (34,121), presumably because the internal membranes of the mesosome have been everted and the mesosome sac expanded into the cytoplasmic membrane. Similarly, when some strains of B. subtilis are exposed to semi-anaerobic conditions, the mesosomes disappear and the DNA appears to be attached to the cytoplasmic membrane (62,120).…”

Deoxyribonucleic Acid Distribution in Bacillus subtilis Independent of Cell Elongation

“…The Jacob model was based in part upon the zonal synthesis of Streptococcus wall antigens (8), a mechanism of surface growth not yet convincingly demonstrated to exist in many other bacterial species. Furthermore, the attachment of bacterial DNA to the cell membrane shown by electron microscopy (10,14,24,26) and biochemically (12,29) is not really strong support for the Jacob model, for little is known about the linear extension of membrane in relationship to overlying surface.…”

Physiology and cytological chemistry blue-green algae.

“…On the other hand, Fuhs (253, confirmed by 333) asserted that there are one, two, four, or eight "genomes" per cell, increasing in from the end of an 0. amoena filament. He has suggested that many large-celled bluegreen algae contain multiple copies of their genome per cell (257). Consistent with this view point are the observations that hair cells of Calothrix braunii appear to contain about one-fifth and two-fifths as much DNA as actively growing vegetative cells, according to quantitative fluorescent microscopy (776a), and that the average amount of DNA per cell of A. variabilis can vary 7.5-fold as a function of growth rate (804).…”