SYMPOSIUM ON THE ROLE OF CELL FRAGMENTS IN METABOLIC REACTIONS

The present symposium can be considered a toplasts proved to be unsuitable for more exlogical extension of the symposium on "Cellular tensive experiments, however, since on incubaOrganization in Relation to Function" held in tion they became as impermeable as whole cells Houston last year. In that symposium, emphasis to large molecules, and thus lost enzyme-forming was placed on the location of various specific ability in the treated protoplasts could not be enzymes in subcellular particles of microbial restored by insertion of DNA or RNA. It was cells that had been fragmented by different profound, however, that a sudden "shocking" of the cedures. Many of the enzymes examined were protoplasts by dilution with water, and subsethose involved in respiration and oxidative phosquent centrifugation, yielded a pellet that was phorylation. This symposium was concerned amenable to considerable manipulation. Such with organized structures of disrupted cells that preparations were also treated in various ways function in the synthesis of the macromolecules to remove DNA and RNA; again it was found deoxyribonucleic acid (DNA), ribonucleic acid that removal of almost all of the DNA had little (RNA), and protein. A particulate system that effect on protein synthesis, whereas removal of catalyzes a nonoxidative, light-induced phosRNA either by extraction with NaCl or treatphorylation was also discussed. ment with RNAase resulted in a large decrease Spiegelman, in a discussion of "Macromolecuin protein synthesis. The resolution and some of lar Synthesis in Subcellular Fractions of Bacthe characteristics of these preparations were terial Protoplasts," gave an extensive review of discussed in individual papers in other sessions the work emanating from his laboratory during of this meeting. The main observations reported the past several years on the synthesis of RNA, were that such shocked preparations could be DNA, and protein. made from Escherichia coli as well as B. megaWith Bacillus megaterium, conditions were terium. With proper supplementation, these found that would permit the preparation of preparations were able to effect the net synthesis protoplasts in such a condition that DNA and of DNA, RNA, and protein. For the synthesis of RNA could be selectively removed and the reboth DNA and RNA, there was an absolute resultant effect on enzyme-synthesizing capacity quirement for the presence of amino acids. These of the preparation could be measured. Up to 99 observations confirm previous reports of the per cent of the DNA could be removed without amino acid requirements for nucleic acid synany loss in enzyme-forming ability, but removal thesis in whole cells. of 30 per cent or more of the RNA led to a Fraser and Mahler discussed in detail their rather large inhibition of enzyme synthesis. Prowork on the synthesis of T2 and T3 bacterio1 This symposium was held at the Fifty-seventh phage in preinfected protoplasts of E. coli. ProtoGeneral Meeting of the Society of American Bacplasts were prepared from infected cells by teriologists in Detroit, Michigan, on April 30, 1957. treatment with lysozyme and versene. The inParticipants were: Sol Spiegelman, Department of fected protoplasts, unlike the original infected Bacteriology, University of Illinois, Urbana, Illicells, were found to be permeable to DNAase nois; Dean Fraser and H. R. Mahler, Departments and RNAase. However, the action of these enof Bacteriology and Chemistry, Indiana University, zymes in removing the homologous nucleic acids Bloomington, Indiana; Albert Frenkel) Donald D. proved to be dependent on the particular past Hickman and Lucille Smith, Department of Botany, history of the protoplasts and on other less conUniversity of Minnesota, Minneapolis, Minnesota, trollable factors. Since the work with protoplasts and Johnson Research Foundation, University of of infected cells was not always reproducible, Pennsylvania, Philadelphia, Pennsylvania. 2 Operated by Union Carbide Nuclear Company attempts were made to study the behavior of for the U. S. Atomic Energy Commission. infected protoplasts that had been shocked in