Lysis

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

Biochemical and ultrastructural properties of osmotically lysed rat-liver mitochondria

Abstract: Isolated rat-liver mitochondria were osmotically lysed by suspension and washing 3 times in cold, distilled water. Pellets obtained by centrifugation at 105,000 g for 30 min were resuspended, fixed with glutaraldehyde and OsO(4), and embedded in Epon 812. Thin sections show the presence of two distinct membranous populations, each of which is relatively homogeneous in size and appearance. Swollen mitochondria ( approximately 1.5 micro in diameter), which have been stripped of their outer membranes, are largely devoid of matrix and normal matrix granules and are referred to as "ghosts." The smaller (0.2 to 0.4 micro in diameter), empty appearing, vesicular elements, derived primarily from the outer mitochondrial membrane, can be differentiated from the ghosts on the basis of their smaller size and complete absence of internal structures, especially cristae. Each membranous element is enclosed by a single, continuous membrane; the "double membrane" organization typical of intact mitochondria is not observed. These findings indicate that the outer membrane of rat-liver mitochondria is spatially dissociated from the inner mitochondrial membrane by osmotic lysis of the mitochondria in distilled water. Three parameters of structural and functional significance in freshly isolated rat-liver mitochondria have been correlated with the structural alterations observed: (a) chemical composition (total protein, lipid phosphate and total phosphate), (b) specific and total activities of marker enzymes for mitochondrial matrix and membranes (malate dehydrogenase (MDH), D-beta-hydroxybutyrate dehydrogenase (BDH) and cytochromes), and (c) integrated multienzyme functions (respiration, phosphorylation, and contraction). The data presented indicate that all mitochondrial membranes are completely conserved in the crude ghost preparation and that, in addition, about (1/3) of the matrix proteins (estimated by assays for MDH activity and protein) are retained. The study of integrated mitochondrial functions shows that a number of physiologically important multienzyme activities also are preserved in the water-washed preparation. The respiratory rate of ghosts per milligram of protein is 1.5 to 2.0 times that of intact mitochondria, which shows that the respiratory chain in the ghosts is functionally intact. The rate of phosphorylation is reduced, however, to about 25% of that measured in freshly isolated mitochondria and accounts for lowered P:O ratios using succinate as substrate (P:O ranges from 0.4 to 0.9). The phosphorylation of ADP to ATP is the only biochemical function, so far investigated, that is greatly affected by osmotic lysis. In addition, two lines of evidence suggest that the ghosts undergo an energy-dependent transformation resulting in contraction: (a) suspensions of the crude ghost preparation in 0.02 M Tris-0.125 M KCl medium show a marked increase in optical density upon the addition of ATP, and (b) ghost preparations incubated in ion-uptake medium in the absence of added calcium but in the presence of added ATP contain a large number of highly condensed ghosts (about 50% of the total profiles) when viewed as thin sections in the electron microscope. The correlated biochemical and morphological study presented here shows that the outer membrane of rat-liver mitochondria can be removed by controlled osmotic lysis without greatly impairing a number of integrated biochemical functions associated with the inner membrane.

Quantitative Influence of Antibody and Complement Coating of Red Cells on Monocyte-Mediated Cell Lysis

Abstract: Monocyte-mediated lysis in vitro of human red cells coated with measured amounts of immunoglobulin G (IgG) or complement were studied. 1,000-1,500 molecules of IgG anti-D are necessary to effect measurable lysis, and lysis increases linearly with increasing levels of antibody sensitization. 100 microgram/ml of IgG1 abolished lysis even at maximal levels of anti-D sensitization (15,000 molecules/cell). Two isoimmune IgG anti-A or anti-B antisera were 5 to 10-fold less efficient in promoting phagocytosis or lysis per molecule of IgG bound; however, because of the greater antigen density of A or B, more than 100,000 molecules IgG/cell could be bound, producing equivalent lysis to anti-D-coated cells. Although inhibition by IgG1 was similar at equivalent levels of sensitization with anti-A, anti-B, or anti-D at high levels of coating with anti-A or anti-B (not attainable with anti-D), lysis was not inhibited by IgG1. Cells coated with human complement components alone were not lysed by monocytes; however, complement coating augmented IgG-mediated lysis and reduced the quantity of anti-D necessary to produce lysis to less than 1,000 molecules/cell. After thorough degradation of C3b by serum to C3d, complement augmentation persisted.

Studies on lysosomes. v. the effects of streptolysins and other hemolytic agents on isolated leucocyte granules.

Abstract: Granules from rabbit peritoneal leucocytes were prepared in 0.3 M sucrose as an optically homogeneous suspension with the aid of heparin. Lysis of the granules in vitro was followed by measurement of decreases in the apparent absorbance of the suspensions at 520 mµ and was accompanied by solubilization of beta-glucuronidase from the particles. Streptolysins O and S from hemolytic streptococci lysed the granules at 20°C; the initial rate of lysis by streptolysin O was greater than that by streptolysin S. Cysteine activated, and specific antibody inhibited, streptolysin O; antimycin and bovine serum albumin inhibited streptolysin S. The granules were not lysed by any other streptococcal exotoxins. Lysis was irreversible and depended neither upon oxidative phosphorylation, nor upon intact respiration. The granules were also lysed by lysolecithin, at concentrations from 2 x 10-6 M to 1 x 10-4 M; bovine serum albumin and antimycin also inhibited this lytic agent. Such other hemolytic agents and procedures as vitamin A, non-ionic detergents, and ultraviolet irradiation also disrupted leucocyte granules. In susceptibility to lysis and other properties, the granules of white cells resembled erythrocytes. Leucocyte granules differed from mitochondria in that they did not appear to take up or extrude water reversibly; they were unaffected by thyroxine, phosphate, or metabolic substrate. The studies are compatible with the hypotheses that white cell granules are similar to lysosomes isolated from other tissues, and that they share common surface properties with erythrocytes.

Properties of the Hemolytic Activities of Escherichia coli.

Abstract: Some properties of the cell-free and cell-associated hemolysins of Escherichia coli were studied. Several strains of E. coli that were isolated from intestines of pigs with edema disease produce large quantities of cell-free hemolysin when grown in the presence of an extract of meat. The component of meat that stimulates production of cell-free hemolysin is not extracted by lipid solvents and is not dialyzable. The cell-free hemolysin is an acidic substance that occurs in two forms. It is inactivated by trypsin but not by lecithinase, lysozyme, ribonuclease, or deoxyribonuclease, shows optimum activity between pH 7 and 8, and requires calcium ion for activity. It does not appear to be an enzyme. The kinetics of the lytic reaction are most consistent with the hypothesis that one molecule of cell-free hemolysin is sufficient to lyse one erythrocyte and that it is inactivated in the lytic reaction. The cell-free hemolysin does not sufficiently damage the cell during the prelytic period to cause lysis after the hemolysin-calcium-erythrocyte complex has been disrupted. The cell-associated hemolysin was not separated from the cell by autolysis, freezing, sonic treatment, or treatment with trypsin or lysozyme. It appears to be closely associated with the metabolic status of the cell. Organisms that are highly hemolytic under usual conditions of assay immediately lose most of their hemolytic capability in the presence of sodium cyanide, streptomycin, nalidixic acid, and rifampin.

Induction of bacterial lysis by penicillin.

Abstract: In the past decade penicillin has become increasingly important clinically, and a great deal has been learned about the action of this antibiotic on susceptible organisms (Florey et al., 1949). Numerous effects have been described in microorganisms exposed to penicillin; however, it is likely that most of these are a consequence of some primary process not yet well understood. Cooper (1956) has reviewed data on the primary action of penicillin and has suggested that a number of effects may follow an initial damage to the osmotic barrier of the cell. Demonstration of interference with transport processes are consistent with this view (Cooper, 1955; Gale and Taylor, 1947). The work to be reported here bears out this hypothesis and gives evidence of very early changes in the osmotic barriers of Escherichia coli and Bacillus megaterium exposed to penicillin. The conclusion is drawn from experimental data that formation of a substance, very likely an enzyme, is induced by penicillin, that this substance attacks the bacterial membrane and cell lysis ensues.