Lysis

About: Lysis is a research topic. Over the lifetime, 6072 publications have been published within this topic receiving 216978 citations.

Studies on the Regulation of Extracellular Enzyme Formation by Bacillus subtilis

Abstract: The paper describes how to prepare osmotically sensitive forms from the fungus Oospora lactis. The lytic enzyme from actinomycetes at a concentration of 25 mg/ml causes abundant formation of protoplasts at 36 degrees C and pH 7.5 within 10--15 min. The best stabilizing agent is 1 M NaCl solution or a mixture of 1 M NaCl with 1 M mannitol solution (1:1). In order to induce lysis of cell walls by the enzyme from Helix pomatia, the cells must be pretreated with a solution containing 40 mM tris (hydroxymethyl)-aminomethane, 5 mM EDTA and 0.2 M cysteine. The production of Oospora lactis protoplasts was accompanied with the liberation of lipase from the periplasmic space. The activity of lipase was 90% of the overall intracellular activity as was confirmed by the results of differential centrifugation of a homogenate prepared by mechanical disintegration of the cells. Since the Rf in disc electrophoresis, the pH optimum and the substrate specificity of exocellular lipase were identical with those of periplasmic lipase, the enzyme must be liberated without a change in the molecular weight.

The plasma membrane proteins Prm1 and Fig1 ascertain fidelity of membrane fusion during yeast mating.

Abstract: As for most cell–cell fusion events, the molecular details of membrane fusion during yeast mating are poorly understood. The multipass membrane protein Prm1 is the only known component that acts at the step of bilayer fusion. In its absence, mutant mating pairs lyse or arrest in the mating reaction with tightly apposed plasma membranes. We show that deletion of FIG 1, which controls pheromone-induced Ca2+ influx, yields similar cell fusion defects. Although extracellular Ca2+ is not required for efficient cell fusion of wild-type cells, cell fusion in prm1 mutant mating pairs is dramatically reduced when Ca2+ is removed. This enhanced fusion defect is due to lysis. Time-lapse microscopy reveals that fusion and lysis events initiate with identical kinetics, suggesting that both outcomes result from engagement of the fusion machinery. The yeast synaptotagmin orthologue and Ca2+ binding protein Tcb3 has a role in reducing lysis of prm1 mutants, which opens the possibility that the observed role of Ca2+ is to engage a wound repair mechanism. Thus, our results suggest that Prm1 and Fig1 have a role in enhancing membrane fusion and maintaining its fidelity. Their absence results in frequent mating pair lysis, which is counteracted by Ca2+-dependent membrane repair.

State of Adenovirus 2 Deoxyribonucleic Acid in the Nucleus and Its Mode of Transcription: Studies with Isolated Viral Deoxyribonucleic Acid-Protein Complexes and Isolated Nuclei

Abstract: Newly replicated adenovirus 2 deoxyribonucleic acid (DNA) can be isolated from the nucleus of HeLa cells by a gentle lysis procedure as a fairly homogeneous complex with a sedimentation of 73S. The viral DNA complex can be prepared completely free from host cell DNA. The viral complex is slightly active in ribonucleic acid (RNA) synthesis in vitro. Treatment of the complex with Pronase and sodium dodecyl sulfate converts the DNA to a form which sediments at 43S. Nuclei isolated from adeno-infected cells synthesize high-molecular-weight virus-specific RNA in vitro. Optimal RNA synthesis requires a divalent cation, preferentially manganese, and relatively high salt concentrations. The synthesis of virus-specific RNA by the isolated nuclei is strongly inhibited by low doses of alpha-amanitine. The latter experimental result is discussed in terms of the polymerase used to transcribe the adenovirus DNA in vivo.