Deletion analysis of the SUP35 gene of the yeast Saccharomyces cerevisiae reveals two non-overlapping functional regions in the encoded protein

SUP35is an omnipotent suppressor gene of Saccharomyces cerevisiae coding for a protein consisting of a C-terminal part similar to the elongation factor EF-1α and a unique N-terminal sequence of 253 amino acids. Twelve truncated versions of the SUP35 gene were generated by the deletion of fragments internal to the coding sequence. Functional studies of these deletion mutants showed that: (i) only the EF-1α-like C-terminal part of the Sup35 protein is essential for the cell viability; (ii) overexpression of either the N-terminal part of the Sup35 protein or the full-length Sup35 protein decreases translational fidelity, resulting in omnipotent suppression and reduced growth of [psi⁺] strains; (iii) expression of the C-terminal part of the Sup35 protein generates an antisuppressor phenotype; and (iv) both the N- or C-terminal segments of the Sup35 protein can bind to 80S ribosomes. Thus, the data obtained define two domains within the Sup35 protein which are responsible for different functions.     

Direct current electric field in some teleost species: Effect of medium salinity

Summary A direct current electric field up to 3 mV/ cm was recorded in 33 sea water around the fishMyoxocephalus brandti, Hexogrammos octogrammos, Enophrys diceraus, Pleuronectes stellatus, Bathimaste r derjugini, Sebastes scorpaeniformis. The body surface potentials were positive in relation to the external and internal media; they attained 10 mV and slowly varied near the mean value at every point. The potentials at the surface points of individual skin sections adjoining the oral and branchial cavities, the anal orifice and peripheral fin sections were normally characterized by polarities opposite to those of body surface potentials (in sea water they were negative in relation to the external medium).When placed in sea water during their fresh water cycle, the salmonOncorhynchus keta and the fresh water fishSalvelinus alpinus andMisgurnus fossilis had no d.c. field.In fresh water containing less than 0.03 salt, a d.c. field up to 25 mV/cm was recorded around all the above mentioned species. The potentials had an opposite polarity to that recorded in sea water.The distribution of potentials over the fish surface depends on the species. The potentials at some points of the body surfaces were found to vary when other fish or metal objects were placed in the aquarium.The parameters of the direct current electric field generated by a whole fish and by isolated skin pieces were identical and varied by the same law with changed medium salinity. Thus it may be assumed that the d.c. electric field around the fish is produced by active electrogenic ion transport mechanisms localized in the skin.     

Isolation and characterization of plasmid from the Bacillus brevis var. G.-B. cells

Summary The plasmid designated pAD1 was isolated from the cells of four variants of Bacillus brevis var. G.-B. The plasmid DNA has a molecular weight of about 47.1×10⁶ daltons and contains 43.4 mole % G+C. The bulk of pAD1 DNA (96–98%) is associated with the fraction of chromosome DNA and membranes.Restriction endonucleases SmaI, SalI and BamHI cleaved the plasmid DNA into two, two and six fragments, respectively. The cleavage map of the pAD1 genome has been constructed for these three endonucleases. Restriction enzymes EcoRI, HindIII, KpnI and PstI hydrolized the plasmid DNA into 16, 21, 10 and 9 fragments, respectively. The presence of repeated sequences in the plasmid genome was shown based on pAD1 DNA cleavage by these endonucleases.     

Der Einfluss von CCC auf die Entwicklung des Roggenhalmes

Field trials on the effect of chlorocholinechloride (CCC) on rye plants of the cultivar Danae and of a selected population “WRS” proved that rye principally shows as reaction analogous to wheat. The CCC-induced decrease of stalk length is due to the reduction of elongation growth of the 4th internode. This shortening effect is mainly the result of decreased cell extension and, in the middle internode, additionally of inhibited cell division in longitudinal direction. The shape of internodes is changed under the influence of CCC. Walls of parenchyma cells of CCC-treated plants are thinner and those of sclerenchyma cells are thicker compared with cell walls of control plants.      

Purification and characterization of recombinant Pneumocystis carinii thymidylate synthase

Gatalytically active Pneumocystis carinii thymidylate synthase is expressed to the extent of about 4% of the soluble protein in Escherichia coli χ2913 harboring plasmid pUETS-1.8 (U. Edman, J. C. Edman, B. Lundgren, and D. V. Santi, Proc. Natl. Acad. Sci. USA 86, 6503–6507, 1989). Ion-exchange, affinity, hydrophobic, and reactive dye agarose chromatography steps were explored to devise a large-scale purification protocol for P. carinii thymidylate synthase. Sequential DE52, Q-Sepharose, phenyl-Sepharose, and Cibacron Blue F3GA chromatography yielded enzyme that was homogeneous by SDS-PAGE in a yield of over 50%. The sequence of the first 10 amino acid residues of the purified protein was in accord with that predicted from the DNA sequence. Isoelectric focusing gave a pI of 6.2. Kinetic analysis of the purified enzyme revealed that the the K_m values were 4.7 ± 1.3 μM for dUMP and 15.7 ± 4.3 μM for 5,10-methylenetetrahydrofolate, similar to those of many other thymidylate synthases; the κ_cat of the most active preparation was 0.8 s⁻¹. The enzyme is stable for at least 2 months when stored at −80°C in the presence of 40% glycerol, Tris-HCl, and thiol.     

Phospholipid dependence of rat liver microsomal acyl: CoA synthetase and acyl-CoA : 1-Acyl-sn-glycero-3-phosphocholine O-acyltransferase

Summary Investigations were performed on the influence of the phospholipid composition and physicochemical properties of the rat liver microsomal membranes on acyl-CoA synthetase and acyl-CoA : 1-acyl-sn-glycero-3-phosphocholine O-acyltransferase activities. The phospholipid composition of the membranes was modified by incubation with different phospholipids in the presence of lipid transfer proteins or by partial delipidation with exogenous phospholipase C and subsequent enrichment with phospholipids. The results indicated that the incorporation of phosphatidylglycerol, phosphatidylserine and phosphatidylethanolamine induced a marked activation of acyl-CoA synthetase for both substrates used—palmitic and oleic acids. Sphingomyelin occurred as specific inhibitor for this activity especially for palmitic acid. Palmitoyl-CoA: and oleoyl-CoA : lacyl-sn-glycero-3-phosphocholine acyltransferase activities were found to depend on the physical state of the membrane lipids. The alterations in the membrane physical state were estimated using two different fluorescent probes—1,6-diphenyl-1,3,5-hexatriene and pyrene. In all cases of membrane fluidization this activity was elevated. On the contrary, in more rigid membranes obtained by incorporation of sphingomyelin and dipalmitoylphosphatidylcholine, acyltransferase activity was reduced for both palmitoyl-CoA and oleoyl-CoA. We suggest a certain similarity in the way of regulation of membrane-bound acyltransferase and phospholipase A₂ which both participate in the deacylation-reacylation cycle.     

Lipid status association with 25-hydroxy vitamin D: Cross sectional study of end stage renal disease patients

BackgroundSome observational studies indicate an association of 25-hydroxy vitamin D (25(OH)D) insufficiency and atherogenic cholesterol concentrations. The aim of this study was to investigate relationship between 25(OH)D concentrations and lipid parameters in end stage renal disease (ESRD) patients, separately for predialysis, hemodialysis and peritoneal dialysis patients.MethodsWe have adjusted 25(OH)D concentrations for seasonal variability with cosinor analysis, and performed all further analysis using these corrected 25(OH)D concentrations. Concentrations of 25(OH)D and the lipid parameters were determined in 214 ESRD patients and 50 control group participants. The analysis included the measurement of 25(OH)D by HPLC, apolipoprotein (Apo) AI, ApoB and Lp(a) by nephelometry, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) by spectrophotometry and manually calculated ApoB/ApoAI and LDL-C/HDL-C ratio.ResultsESRD patients with adjusted 25(OH)D concentrations of 50 nmol/L had significantly higher TC (P = 0.005) and ApoAI (P = 0.049). Significantly higher HDLC (P = 0.011) and ApoAI (P = 0.020) were found in hemodialysis patients with the 25(OH)D concentrations of 50 nmol/L. The other analyzed lipid parameters differed significantly between predialysis, hemodialysis and peritoneal dialysis patients with 25(OH)D concentrations of < 50 nmol/L.ConclusionsOur study indicate the significant relationship between 25(OH)D repletion and optimal concentrations of lipid parameters in ESRD patients. Further research is necessary to explain whether joint evaluation of vitamin D status and lipid abnormalities could improve cardiovascular outcome in ESRD patients.     

Conditioning adhesive contacts between the neutrophils and the endotheliocytes by Staphylococcus aureus

We have developed a model for evaluating the integral intercellular interactions in the “endotheliocyte‐neutrophil” system and have shown the high variability of adhesion contacts in different donors associated with different expression profiles of neutrophils. Two methods (forсe spectroscopy‐spectroscopy and scanning ion‐conductance microscopy) showed a decrease in the rigidity of the membrane‐cytoskeletal complex of neutrophils under the influence of Staphylococcus aureus 2879 M. Adding this strain to the “endotheliocyte‐neutrophil” system caused a statistically significant decrease in the adhesion force and adhesion work, which indicates a change in the expression profile and physicochemical properties of membranes of both types of interacting cells (neutrophils and endotheliocytes).