Mechanism of catalase induction in Rhodopseudomonas spheroides: Role of porphyrin excretion

Summary Catalase induction in Rhodopseudomonas spheroides and three locally isolated strains of Rhodopseudomonas (TL-1, TL-4 and Rps. D) was studied. A correlation between the rate of excretion of porphyrin and the inducibility of the culture was observed. 8-hydroxyquinoline at 4x10^-5 M had no effect on Bchl synthesis but it inhibited porphyrin excretion and catalase induction in Rhodopseudomonas spheroides. 8-OH Q at this concentration partially inhibited Bchl synthesis and catalase induction in strain TL-1. The data indicate that the amount of catalase produced is dependent on the pool size of porphyrins.Abbreviations used ALA -amino laevulinic acid - Bchl Bacteriochlorophyll - EDTA Ethylene diamine tetra acetate - DMSO Dimethyl sulfoxide - 8-OH Q 8-hydroxyquinoline - nm nanometer - Rh. Rhodopseudomonas This work is part of a thesis submitted by K. T. Shanmugam in partial fulfillment of the requirements for the Ph. D. degree.     

Effect of Sublethal Heat on the Metabolic Activity of Staphylococcus aureus

Cells of Staphylococcus aureus MF-31 which have been heat-injured at 52 C have an altered metabolic activity. Analyses of whole-cell preparations by means of the Thunberg technique and Warburg manometry showed decreased dehydrogenase activity and oxygen uptake on a variety of substrates. In cell-free extracts prepared from injured cells, it was demonstrated that the specific activity of fructose diphosphate aldolase, lactate dehydrogenase, and butanediol dehydrogenase was less than that of extracts prepared from normal unheated cells. Recovery of the heat-injured cells in a suitable medium supported a return of the dehydrogenase activity and oxygen uptake, but the activity of the enzymes in cell-free extracts prepared from such partially recovered cells did not fully return to the level of normal (unheated) preparations. Addition of chloramphenicol or actinomycin D to the recovery medium, singly or in combination, retarded the return of the normal metabolic activity. Radiorespirometric experiments indicated that the percentage participation of the Embden-Meyerhoff Parnas and hexose monophosphate pathways remained the same for normal and heat-injured cells. The sublethal heat treatment decreased the catabolic capabilities of S. aureus and the production of selected end products associated with the metabolism of glucose.     

Production of Highly Labeled Adenoviruses

A method is described for increasing the incorporation of radioactive thymidine into adenovirus deoxyribonucleic acid by the use of amethopterin. In addition, a modified procedure is presented for the preparation of highly purified adenoviruses. This procedure, which employs enzymatic digestion of cellular debris, obviates the necessity for fluorocarbon treatment of crude virus suspensions, and routinely provides excellent recovery of virus.