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Lysis
About: Lysis is a research topic. Over the lifetime, 6072 publications have been published within this topic receiving 216978 citations.
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TL;DR: The same procedure developed for Escherichia coli was also successful for purifying intact flagella from Bacillus subtilis for the purification of intact flagescens free from detectable cell wall, membrane, or cytoplasmic material.
Abstract: A procedure is described for the purification of bacterial flagella in the form of a filament-hook-basal body complex (intact flagella) free from detectable cell wall, membrane, or cytoplasmic material. Spheroplasts produced with lysozyme and ethylenediaminetetraacetic acid were lysed with Triton X-100, and the flagella were purified by (NH4)2SO4 precipitation, differential centrifugation, and CsCl gradient centrifugation. As much as 40% of the flagella were recovered, and they contained about one basal body per 4 to 6 μm of flagella. The same procedure developed for Escherichia coli was also successful for purifying intact flagella from Bacillus subtilis.
165 citations
TL;DR: Direct evidence obtained at the single cell level shows that a single effector lymphocyte is required and sufficient for the destruction of a single target cell and that killer cells which have been responsible for the lysis of a given target cell can lyse a second and even a third time.
Abstract: Isolation and characterization of individual functionally reactive cytotoxic T lymphocytes have been achieved. Peritoneal exudate cytotoxic lymphocytes were obtained from BALB/c mice injected with EL4 tumor cells. Lymphocyte tumor cell conjugation was promoted by centrifugation. Individual conjugates comprised of one lymphocyte bound to one tumor cell were isolated with a micropipette. The ultrastructure of isolated killer lymphocytes and the lysis of conjugated target cells were analyzed. The cytotoxic lymphocytes are small cells with an indented nucleus which is poor in peripheral chromatin and rich in rough nuclear sap. The cytoplasm contains one-membrane-bound lysosome-like granules and clusters of ribosomes, but no rough endoplasmatic reticulum. The Golgi apparatus is well developed. Direct evidence obtained at the single cell level shows that a single effector lymphocyte is required and sufficient for the destruction of a single target cell and that killer cells which have been responsible for the lysis of a given target cell can lyse a second and even a third time.
164 citations
TL;DR: The isolation procedure described here is relatively brief and relies on the powerful proteolytic activity of proteinase K combined with the denaturing ability of the ionic detergent SDS.
Abstract: There are a number of different procedures for the preparation of genomic DNA. They all start with some form of cell lysis, followed by deproteinization and recovery of DNA. The main differences between various approaches lie in the extent of deproteinization and in molecular weight of the DNA produced. The isolation procedure described here is relatively brief and relies on the powerful proteolytic activity of proteinase K combined with the denaturing ability of the ionic detergent SDS.
164 citations
TL;DR: The morphological evidence suggests that the initial binding of the antibiotic disrupts the packing order of lipopolysaccharide of the outer membrane, which ultimately forms holes in the cell envelope and can lead to cell lysis, which makes aminoglycoside drugs particularly effective antibiotics.
Abstract: The mode of action of gentamicin has traditionally been considered to be at the 30S ribosomal level. However, the inhibition of bacterial protein synthesis alone appears to be insufficient to entirely explain the bactericidal effects. Bacteriolysis is also mediated through perturbation of the cell surface by gentamicin (J.L. Kadurugamuwa, J.S. Lam, and T.J. Beveridge, Antimicrob. Agents Chemother. 37:715-721, 1993). In order to separate the surface effect from protein synthesis in Pseudomonas aeruginosa PAO1, we chemically conjugated bovine serum albumin (BSA) to gentamicin, making the antibiotic too large to penetrate through the cell envelope to interact with the ribosomes of the cytoplasm. Furthermore, this BSA-gentamicin conjugate was also used to coat colloidal gold particles as a probe for electron microscopy to study the surface effect during antibiotic exposure. High-performance liquid chromatography confirmed the conjugation of the protein to the antibiotic. The conjugated gentamicin and BSA retained bactericidal activity and inhibited protein synthesis on isolated ribosomes in vitro but not on intact cells in vivo because of its exclusion from the cytoplasm. When reacted against the bacteria, numerous gentamicin-BSA-gold particles were clearly seen on the cell surfaces of whole mounts and thin sections of cells, while the cytoplasm was devoid of such particles. Disruption of the cell envelope was also observed since gentamicin-BSA and gentamicin-BSA-gold destabilized the outer membrane, evolved outer membrane blebs and vesicles, and formed holes in the cell surface. The morphological evidence suggests that the initial binding of the antibiotic disrupts the packing order of lipopolysaccharide of the outer membrane, which ultimately forms holes in the cell envelope and can lead to cell lysis. It is apparent that gentamicin has two potentially lethal effects on gram-negative cells, that resulting from inhibition of protein synthesis and that resulting from surface perturbation; the two effects in concert make aminoglycoside drugs particularly effective antibiotics. Images
164 citations
TL;DR: It is concluded that apoptosis is primarily induced in CV‐1 cells but may be arrested by membrane lysis, depending on the incubation protocol.
Abstract: Photosensitization using the tumor-localizing porphyrin Photofrin® induces cell death both in vitro and in vivo, but the mechanism of cell death is not well understood. Cell lysis (necrosis) and apoptosis have both been observed. The latter seems restricted mainly to lymphoma and epithelial cell lines. To check the influence of the incubation protocol on the cell death mechanism, CV-1 cells were loaded with Photofrin using two different protocols. In both protocols, photosensitized CV-1 cells underwent severe morphological changes before cell death. Many cells treated with protocol 1 (24 h with 1 μ g/mL of Photofrin in culture medium) underwent apoptosis, as demonstrated by plasma membrane blebbing and fragmentation into vesicles, condensation of the chromatin and fragmentation of the nucleus with oligonucleosomic degradation of the DNA. In contrast, cells treated with protocol 2 (1 h with 10 μg/mL of Photofrin in phosphatebuffered saline) lysed instead of fragmented, without oligonucleosomic degradation of the DNA. This type of cell death looks much like necrosis. However, early morphological changes suggest that it is, in fact, apoptosis stopped by plasma membrane leakage. It is concluded that apoptosis is primarily induced in CV-1 cells but may be arrested by membrane lysis, depending on the incubation protocol.
164 citations