title: Synthesis of macromolecules in synchronously grown Arthrobacter.
abstract: The synchronous growth of Arthrobacter has not yet been studied. We have shown that synchrony of A. crystallopoietes and A. globiformis cultures can be achieved in a liquid synthetic medium by inoculating a fresh medium with cells taken from an advanced stationary phase culture. DNA content measurements and pulsed incorporations of tritiated thymidine have been used to show that DNA synthesis occurs in a stepwise manner in these synchronized cultures. The use of absorbance of cultures as a monitor of synchronized cell growth was especially useful since cells did not separate during the exponential phase. The breaks in the absorbance versus time curve indicated a slow-down in mass synthesis. Protein and RNA synthesis occurred in two waves during the time necessary for a doubling of cell mass: a first increase was observed at the beginning of the DNA replication; after a slow-down, a second sharp increase occurred after the replication of DNA. These results are discussed in relation to previous data on the existence of a differential transcription during the development of A. crystallopoietes.
mesh_terms: D001173:Arthrobacter / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis*; D004269:DNA, Bacterial / Q000096:biosynthesis*; D007700:Kinetics; D012329:RNA, Bacterial / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial