Lysis

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

Formation of Extracellular Protein A by Staphylococcus aureus

Abstract: Staphylococcus aureus contains cell wall protein A as well as extracellular protein A. The two types of protein A have very similar amino acid compositions, electrophoretic mobilities and sizes. The release of extracellular protein A from exponentially growing bacteria is dependent on protein synthesis do novo and protein A is released directly after being synthesized on the ribosomes. Bacteria in the stationary phase, however, release protein A as a result of cell lysis. Protoplasts have been isolated which produce protein A as extensively as the intact bacteria but because of the absence of cell wall all the protein A is of the extracellular type. In the presence of puromycin, an enhancement of the formation of extracellular protein A is observed from cells also producing cell wall protein A.

Sulfhydryl groups and the oxygen effect on irradiated dilute solutions of enzymes and nucleic acids.

Abstract: DNA irradiated in cells has previously been shown to be more sensitive in the presence of oxygen. It is shown that enzymes in cells are similarly three times as radiosensitive under oxygenated conditions. A paradox then arises, since dilute solutions of enzymes and of DNA have been repeatedly shown to be without an oxygen effect, yet much of the radiation inactivation in a cell is caused by radical attack. It is shown that the radiosensitivity of DNA in preparations of lysed cells is oxygen-dependent. Furthermore, dilute solutions of DNA and of trypsin show an oxygen effect when SH-containing compounds are added. Possible mechanisms for the oxygen effect are discussed in light of these results. (auth)

High-quality plant DNA extraction for PCR: an easy approach.

Abstract: Polymerase chain reaction has found wide applications in modern research involving transformations and other genomic studies. For reproducible PCR results, however, the quantity and quality of template DNA is of considerable importance. A simple and efficient plant DNA extraction procedure for isolation of high-quality DNA from plant tissues is presented here. It requires maceration of plant tissue of about 1.0 cm(2) (e.g. of a leaf blade) in DNA extraction buffer (100 mM Tris-HCl, 100 mM EDTA, 250 mM NaCl) using 1.5-mL microfuge tubes, followed by cell lysis with 20% SDS, and DNA extraction with phenol: chloroform: iso-amyl alcohol (25:24:1). Hydrated ether is then used to remove polysaccharides and other contaminants from the DNA preparation. Average DNA yield is 20-30 microg cm(-2) for fresh tissues, and ratio of absorbance at 260 nm to absorbance at 280 nm is 1.5-1.8. The DNA is quite suitable for PCR using microsatellites, RAPD and specific markers for recombinant selection. Amplifications have been obtained for these markers by using template DNA extracted from fresh as well as frozen leaf tissues of various plants, including barley, oat, potato and tomato. DNA stored for more than 2 years has been successfully amplified with microsatellite markers, which shows suitability of this method after long-term storage of DNA. Besides, the ease of use and cost-effectiveness make the procedure attractive.

Macrophage-generated nitric oxide as cytotoxic factor in destruction of alginate-encapsulated islets. Protection by arginine analogs and/or coencapsulated erythrocytes.

Abstract: Isolated rat islets were microencapsulated in alginate beads of about 1.5 mm in diameter. These were cocultured with activated or resident peritoneal macrophages of syngeneic rats for 24 hr. Examination of the encapsulated islets by transmission electron microscopy showed that the islets were lysed by activated (80.0 +/- 12.8% of islets lysed), but not by resident, macrophages (17.5 +/- 12.2% lysis) despite encapsulation. Islet lysis was inhibited in a concentration-dependent manner by a specific nitric oxide-synthase inhibitor (0.5 mM NG-methyl-L-arginine: 5.9 +/- 3.9% lysis) in an L-arginine-reversible manner (0.5 mM NG-methyl-L-arginine + 10 mM L-arginine: 55.1 +/- 16.6% lysis). Incubation of encapsulated islets with 3 different nitric oxide-generating compounds also resulted in a concentration-dependent islet lysis. Coencapsulation of autologous erythrocytes was found to be an effective and easy way of protection from macrophage-mediated lysis. Protection was dependent upon the number of erythrocytes coencapsulated. This in vitro study demonstrates that nitric oxide secreted by activated macrophages is able to destroy islets despite encapsulation in alginate, and that both, inhibition of nitric oxide formation using enzyme inhibitors and scavenging of nitric oxide once formed exploiting the hemoglobin of autologous erythrocytes, protect encapsulated islets from destruction.