Purification of restriction endonuclease XcyI from Xanthomonas cyanopsidis

A new Type II restriction endonuclease XcyI, purified from Xanthomonas cyanopsidis 13D5, is an isoschizomer of SmaI and XmaI that cleaves at the nucleotide sequence 5'-C decreases CCGGG-3' of double-stranded DNA. The single restriction activity present in this strain permits rapid purification of 8000 units of cleavage activity from 10 g of freshly harvested cells. The resulting XcyI preparation is free of contaminating nuclease activities that interfere with in vitro manipulation of DNA.     

Antigen of "serum sickness" type of heterophile antibodies in human sera: indentification as gangliosides with N-glycolylneuraminic acid.

Antigen of “serum-sickness” type of heterophile antibodies in pathologic human sera was purified from equine and bovine erythrocyte stroma. The chemical nature of this antigen was glycosphingolipids with N-glycolylneuraminic acid. The antigen of equine erythrocytes was identified as hematoside with N-glycolylneuraminic acid, GlNeu(α, 2–3)Gal(β, 1–4)Glc(β,1-1) ceramide and the antigen of bovine erythrocytes was N-glycolylneuraminyl-paragloboside, GlNeu (α,2–3)Gal(β,1–4)GlcNAc(β,1–3)Gal(β,1–4)Glc(β,1-1) ceramide. The results indicate that “serum-sickness” antibodies react with a common disaccharide moiety of non-reducing end of the both glycosphingolipids.     

EDTA and oxalic acid — two useful agents for narcotizing fragile and rapid microzooplankton

EDTA and oxalic acid in concentrations of about 0.5 mM immobilize several microzooplankton organisms in Baltic Sea water (salinity 5–7 ). Both agents can be used to narcotize ciliates (Mesodinium rubrum, Askenasia sp. and Halteria sp.) and some rotifers (Synchaeta spp.).     

Phospholipid methylation affects immunoglobulin E-mediated histamine and arachidonic acid release in rat leukemia basophils

Antigenic stimulation of rat basophilic leukemia cells sensitized with immunoglobulin E causes the release of histamine as well as arachidonic acid and its metabolites. The release of these substances is preceded by an increase in phospholipid methylation. Inhibition of phospholipid methylation is correlated to the inhibition of histamine release. Inhibition of methylation also reduces arachidonate release. Phospholipid methylation appears to be associated with both histamine secretion and the release of arachidonate and its metabolites.     

Modification of oligosaccharide-lipid synthesis and protein glycosylation in glucose-deprived cells

Incubation of vesicular stomatitis virus-infected glucose-starved baby hamster kidney cells with [³⁵S]methionine results in the synthesis of all viral proteins. However, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and tryptic peptide mapping, the G protein is abnormally glycosylated. Metabolic labeling of the oligosaccharide-lipid precursors with [³H]mannose for 15 min, followed by Chromatographic and enzymatic analysis, indicates that the radiolabeled lipid-linked oligosaccharides are devoid of glucose in contrast to the glucosylated oligosaccharide-lipids synthesized by cells grown in the presence of glucose. Also, in contrast to control cells, examination of the glycopeptide fraction reveals the presence of [³H]mannose-labeled glycopeptides which are resistant to erado-β-N-acetylglucos-aminidase H and are smaller in size than glycopeptides from mature vesicular stomatitis virus. In order to observe these effects, a minimum time of 5 h of glucose deprivation is necessary and the addition of 55 μm glucose or mannose to the medium reverses these effects. These results indicate that vesicular stomatitis virus-infected BHK cells deprived of glucose are unable to glucosylate the oligosaccharide-lipid intermediates and, consequently, are unable to glycosylate the G protein normally.     

In vitro construction of a recombinant adenovirus Ad2:Ad5

A hybrid virus containing the left half of the Ad5 genome and the right half of the Ad2 genome has been constructed by ligating together in vitro the BamHI.-A fragment of Ad5 (map co-ordinates 0–59.5) to the-SawHI-A fragment of Ad2 (map coordinates 59.5–100), and using this DNA to transfect susceptible cells. Viable progeny virus has been obtained which grows as well as the parental virus without any requirement for helper virus, and probably contains a hybrid hexon polypeptide consisting of the major part of the Ad5 hexon with an Ad2 carboxy terminus.     

Oxygen consumption during the fenton-type reaction between hydrogen peroxide and a ferrous-chelate (Fe2+-DTPA)

The Fenton-type reaction between ferrous diethylenetriamine pentaacetic acid (Fe²⁺-DTPA, 50–200 μM) and H₂O₂ (20–1000 μM) in phosphate buffer at pH 7.0 results in consumption of dissolved oxygen. This observation differs from many prior reports that oxygen is liberated when more concentrated solutions of H₂O₂ are decomposed by iron salts. The rate and total quantity of oxygen consumed were dependent upon the concentrations of ferrous chelate, H₂O₂, and excess DTPA. Evidence is provided that both the ferrous-DTPA chelate and free DTPA can participate in the oxygen-consuming reactions. Oxygen was also consumed during the Fenton reaction between ferrous ions and H₂O₂ when DTPA and phosphate buffer were omitted. Under these conditions, oxygen evolution was observed at higher H₂O₂ concentrations (e.g., 400 μM). The consumption of oxygen during the Fenton-type reaction of an iron chelate at neutral pH may be relavant to events that take place in biologic systems.