The Nature and Radiation Sensitivity of the Long Forms of Escherichia coli Strain B/r

Open Access
Publisher Website
Google Scholar
Abstract
SUMMARY: By suitable adjustment of growth conditions in continuous cultures, organisms of Escherichia coli B/r with average lengths covering a wide range were produced and studied. From X-ray survival data it was concluded that radiosensitive sites were distributed along the length of an organism at intervals of 1-1.5 μ, whilst nuclear staining by the HCl-Giemsa method showed chromatinic bodies at an average spacing of 1.2 μ. Thus each nuclear body appeared to be a radiosensitive site. Lysozyme treatment did not reveal evidence of transverse membranes apart from those at visible ‘waists’. It was concluded that the longer organisms arose by the inhibition of the terminal stages of division. This inhibition did not affect the multiplication of the nuclear and cytoplasmic components, although there was considerable aggregation of nuclear material in irradiated organisms.