Parallel changes in brain tissue blood flow and mitochondrial function during and after 30 minutes of bilateral forebrain ischemia in the gerbil

Forebrain ischemia was induced in Mongolian gerbils by bilateral occlusion of the common carotid arteries for 30 minutes. These animals do not have a complete circulus arteriosus Willisii. Mitochondria were prepared from the forebrain tissue at the end of the 30 minutes occlusion period as well as at different time points after the release of the occlusion. Tissue blood flow in the forebrain was also determined by measuring the brain tissue accumulation of 14C-iodoantipyrine. Tissue blood flow in the forebrain decreased from a control level of 1.43 +/- 0.03 ml/min/gr to 0.13 +/- 0.03 ml/min/gr by the 30th minute of ischemia, increased to 1.12 +/- 0.25 ml/min/gr after 5 minutes of reflow, but decreased again to 0.41 +/- 0.07 ml/min/gr after 1 1/2 hours of reflow. Oxygen consumption rate of mitochondria prepared from the forebrain (glutamate + malate as substrates in the presence of ADP) was 98 +/- 13 nmoles O2/min/mg protein in control animals, decreased to 61 +/- 9 nmoles O2/min/mg protein after 30 minutes of occlusion, recovered to 106 +/- 9 nmoles O2/min/mg protein during the first 30 minutes of reperfusion. During extended reperfusion, mitochondrial respiratory activity declined reaching 20 +/- 5 nmoles O2/min/mg protein after 5 1/2 hours of reperfusion. Respiratory control ratio of the mitochondria (relative increase of respiration upon addition of ADP) was 9.2 +/- 1.3 in control animals, 7.0 +/- 1.5 after 30 minutes of carotid occlusion, 9.0 +/- 1.2 after 30 minutes of reperfusion, and 5.8 +/- 0.8 after 5 1/2 hours of reperfusion. Superoxide dismutase activity of the forebrain mitochondria was 5.10 +/- 0.7 I.U./mg protein in control animals, decreased to 3.3 +/- 1.6 I.U./mg protein after 30 minutes of occlusion and remained at this level throughout the reperfusion period. These data confirm earlier reports that deterioration of mitochondrial function may contribute to the development of ischemic and post-ischemic brain tissue damage. It also appears possible that postischemic damage of mitochondrial function develops secondary to postischemic deterioration of tissue blood flow.     

Microbiota,Phagocytic Activity,Biochemical Parameters and Parasite Control in Horses with Application of Autochthonous,Bacteriocin-Producing,Probiotic Strain Enterococcus faecium EF 412

Probiotics and Antimicrobial Proteins - The beneficial influence of bacteriocin-producing, probiotic, mostly non-autochthonous bacteria has already been reported in various animals. However, their...     

Mapping and genetic organization of pTiChry5, a novel Ti plasmid from a highly virulent Agrobacterium tumefaciens strain

Agrobacterium tumefaciens Chry5, a wild-type strain originally isolated from chrysanthemum, is unusually tumorigenic, particularly on soybean. We have mapped the Chry5 Ti plasmid by genomic walking and restriction endonuclease analysis, and have located its virulence, T-DNA, plasmid incompatibility, and l,l-succinamopine utilization loci. Southern analysis has revealed that about 85% of the Chry5 Ti plasmid is highly homologous to another Ti plasmid, pTiBo542. Although all the functions that we have located on pTiChry5 are encoded by pTiBo542-homologous regions, the two Ti plasmids differ in their genetic organization. The overall patterns of restriction sites in the plasmids also differ, with the exception of an approximately 12 kb segment of the virulence region, where the BamHI sites appear to be conserved. Complementation analysis has shown that deletion of a DNA segment which flanks the oncogenic T-DNA results in severe attenuation of virulence. This region also contains a sequence that is repeated in the Chry5 genome outside the Ti plasmid, and that is widely distributed in the Rhizobiaceae.     

Chemotaxis of the unicellular green algaDunaliella salina and the ciliatedTetrahymena pyriformis—effects of glycine,lysine, and alanine,and their oligopeptides

Chemotactic properties of amino acids (L-alanine, glycine and L-lysine) and their oligopeptides (10^–6M) and binding sites to these ligands were investigated in two unicellular models, the heterotrophicTetrahymena pyriformis and the auxotrophicDunaliella salina. Chemotaxis ofDunaliella induced by simple amino acids and their derivatives demonstrated that binding sites (receptors) for food molecules are not only present in the membrane but are also able to induce their basic physiological response. InTetrahymena, substances with special molecular structure and properties (polar, hydrophilic character of the signal peptide chain)-5-L-Lys, 5-Glywere required for chemoattraction, other peptides tested, lacking the required structure, were repellent. Divergences in chemotaxis and binding assays of both species suggest that trends of functional and binding parameters do not run parallel at this level of evolution.     

Stereoselective syntheses of a di-, tri-, and tetra-saccharide fragment of Shigella dysenteriae type 1 O-antigen using 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-glucopyranosyl chloride as a glycosyl donor.

Methyl 2,4-di-O-benzoyl-alpha-L-rhamnopyranoside (1) furnished a crystalline 3-O-bromoacetyl derivative that was treated with the dichloromethyl methyl ether-ZnCl2 reagent to give 2,4-di-O-benzoyl-3-O-bromoacetyl-alpha-L-rhamnopyranosyl chloride (3). Compounds 1 and 3 were condensed under the conditions of base-deficient, silver trifluoromethanesulfonate-mediated glycosylation to give a fully protected rhamnobioside, which on O-debromoacetylation afforded the disaccharide nucleophile 10. Similar condensation of 3 with methyl 3-O-benzoyl-4,6-O-benzylidene-alpha-D-galactopyranoside, followed by O-debromoacetylation and condensation of the thus formed methyl O-(2,4-di-O-benzoyl-alpha-L-rhamnopyranosyl)-(1----2)-4,6-O-benzylidene- 3-O-benzoyl-alpha-D-galactopyranoside again with 3, gave the trisaccharide glycoside. Subsequent O-debromoacetylation gave 17, having only HO-3(3) unsubstituted. Silver perchlorate-mediated glycosylations of 1, 10, and 17 with 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-glucopyranosyl chloride afforded, with high alpha stereoselectivity, protected di-, tri-, and tetra-saccharide glycosides. Subsequent hydrogenation, followed by N-acetylation and O-deacylation, afforded three oligosaccharide glycosides having nonreducing terminal 2-acetamido-2-deoxy-alpha-D-glucopyranosyl residues and comprising successively larger portions of the repeating unit of Shigella dysenteriae type 1 O-antigen.     

Heat shock protein synthesis of the cyanobacterium Synechocystis PCC 6803: purification of the GroEL-related chaperonin

Synechocystis PCC 6803 cells could be induced to synthesize four major HSPs with apparent molecular sizes of 70, 64, 15 and 14 kDa. Heat stress at 42.5 °C appeared to be the optimum temperature for HSP formation in cells grown at 30 °C.The relative rate of synthesis of HSP70 and HSP15 reached a maximum at 30 min after the temperature shift-up whereas the capability of cells to accumulate HSP64 and HSP14 continued through 2 h.The two most abundant HSPs, HSP70 and HSP64, were recognized on western blots by antibodies raised against authentic DnaK and GroEL from Escherichia coli. To furnish sufficient evidence for the assumption that HSP64 is a GroEL-related chaperonin, this protein was purified to homogeneity. There was a 76% sequence identity between the amino acid sequence of HSP64 and the corresponding protein in Synechococcus PCC 7942. Moreover, the purified HSP64 cross-reacted to anti-E. coli GroEL antibody. To our knowledge, this is the first report about the purification and partial protein sequencing of a cyanobacterial chaperonin.     

Identity of the antibiotic ramihyphin A and cyclosporin A

The antifungal antibiotic ramihyphin A, isolated fromFusarium solani strain S-435 in 1974, was shown to be identical with cyclosporin A.     

Rhizobium leguminosarum strains forming nitrogen-rich nodules inPisum sativum

The nodules which developed on the roots ofPisum sativum after inoculation withRhizobium leguminosarum bv.viciae strains showing a Hup⁺ symbiotic phenotype and/or a high relative efficiency of electron transfer to dinitrogen (RE) had a high nitrogen content of their tissue. In comparison with the nodules initiated by a strain possessing the Hup⁻ symbiotic phenotype or by an indigenous soilRhizobium population, the nitrogen-rich root nodules contained up to four times more nitrogen (9.2% of dry mass). In the nitrogen-rich nodules, total amino acid, and especially Ala, Lys and Phe contents were significantly increased. The nitrogen-rich nodule symbiotic phenotype (Nrn) was well expressed, irrespective of pea cultivars and host plant age. If a strain showing the Nrn phenotype was applied in double-strain inocula, a significant correlation was found between increasing rates of the strain and increasing percentage nitrogen content of nodule tissue in the nodulated plants.