Anaerobic ureolytic bacteria from caecal content and soft faeces of rabbit

Forty strains of ureolytic bacteria were isolated from the caecal content and soft faeces of seven rabbits by the anaerobic roll tube method and were characterized. The isolates were identified with Clostridium coccoides, Cl. innocuum, Peptostreptococcus productus, P. micros, Peptococcus magnus, Fusobacterium russii and Fusobacterium sp. Urease activity of representative strains of the various species was also determined. The study indicated that strongly-ureolytic anaerobic bacteria are present in the caecum of the rabbit.     

Artifactual phosphate binding due to impurities in [32P]orthophosphate

Many commercial preparations of [32P]orthophosphate contain radioactive impurities that interfere with binding and transport studies in biological systems. One type of impurity is micro-particulate whereas another may be pyrophosphate. Methods of removing these impurities from radiolabeled orthophosphate solutions are described.     

A new micronucleus test using peripheral blood erythrocytes of the newt Pleurodeles waltl to detect mutagens in fresh-water pollution

A model micronucleus test system using peripheral blood erythrocytes from larvae of Pleurodeles waltl is described. The most suitable larval stage for testing chemical treatments was determined. Larvae were reared in water containing one of the 4 compounds: benzo[a]pyrene (BaP), ethyl methanesulphonate (EMS), diethyl sulphate (DES) and N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). Response curves as a function of treatment duration over a period of 16 days were plotted for 3 different concentrations of the 4 compounds in order to optimize conditions for a low dose micronucleus test. This model can be used as a monitoring system for the detection of fresh water pollution and can also be employed for clastogen screening of chemical compounds. The test is sensitive, reliable and easy to use.     

The self determinants recognized by human virus-immune T cells can be distinguished from the serologically defined HLA antigens

The self specificity of human influenza virus-immune cytotoxic T cells has been analyzed in order to clarify the relationship between the self antigens that they recognize and the serologically defined HLA-A and -B antigens. Virus-immune effectors from HLA-A2-positive donors were tested on panels of virus-infected target cells from donors who were either HLA-mismatched or matched only for HLA-A2. Virus-immune T cells from 11 out of 11 A2-positive donors lysed all A2-matched virus-infected target cells (and no HLA-mismatched targets), except that each of these effector cells consistently failed to lyse virus-infected target cells from one A2-positive donor (designated M7). Although the A2 specificity of donor M7 could also be distinguished from the A2 antigen of other donors by alloimmune cytotoxic T cells, no differences in the A2 antigen of donor M7 could be defined by extensive serologic analyses. These results indicate that there is a strong but incomplete association between a self antigen recognized by virus-immune T cells and the serologically defined HLA-A2 specificity.     

Cellular fatty acid composition of Leuconostoc oenos

The cellular fatty acid composition of 70 lactic acid bacteria was examined by capillary gas chromatography. Fifty-four Leuconostoc oenos strains, including three reference, type strains from the other Leuconostoc spp., nine Pediococcus spp. and two Lactobacillus spp. were studied. Eighteen fatty acids were determined, of which 10 were identified by gas chromatography-mass spectrometry. The relative percentages of the 18 fatty acids of the Leuconostoc strains were analyzed numerically and grouped using the unweighted pair-group method. Results show that four clusters could be defined at r = 0.920, with five strains unassigned. The major fatty acids of the Leuc. oenos strains were found to be palmitic acid (C16:0), palmitoleic acid (C16:1–9), oleic acid (C18: 1–9), vaccenic acid (C18: 1–11), dihyrosterculic acid (C19-cyclopropane-9) and lactobacillic acid (C19-cyclopropane-11). It was mainly on the basis of the amounts of oleic acid and the C19-cyclopropane fatty acids that the strains of Leuc. oenos could be distinguished from each other. This is the first report of the occurrence of dihydrosterculic acid in lactic acid bacteria. For the majority of Leuc. oenos strains, the result obtained with the cellular fatty acid analysis confirmed the phenotypic relationships.     

ATP-dependent proteolysis of hemoglobin alpha chains in beta-thalassemic hemolysates is ubiquitin-dependent

beta-Thalassemia is an inherited human disorder which is characterized by a deficient production of hemoglobin beta chains and an attendant accumulation of structurally normal alpha chains in the erythropoietic cells. The objective of this work is to understand the mechanism of intracellular proteolysis of these excess alpha chains. Dialyzed stroma-free hemolysates (32 mg/ml hemoglobin) of blood reticulocytes from four individuals with beta-thalassemia intermedia were incubated with human hemoglobin 3H-alpha chains (0.13 mg/ml) at 37 degrees C in a reaction mixture supporting protein degradation. In the presence of ATP and an ATP-generating system, the fraction of alpha chain 3H radioactivity made acid-soluble after 4 h ranged from 4 to 12% among the different hemolysates; in the absence of ATP or when hemolysates of normal human erythrocytes were used, only 1 to 2% of the 3H-alpha chains were degraded. It is likely that the ATP-dependent proteolysis of 3H-alpha chains in the beta-thalassemic hemolysates corresponds to the ATP-dependent turnover of newly synthesized soluble alpha chains in intact beta-thalassemic reticulocytes observed previously (Shaeffer, J. (1983) J. Biol. Chem. 258, 13172-13177) because of the following similarities between the two systems: (a) free 3H-alpha chains, but not 3H-labeled tetrameric hemoglobins, were readily degraded; (b) the rate of 3H-alpha chain proteolysis in the cell-free system was at least one-half of that observed for the turnover of newly synthesized alpha chains (t1/2 approximately 6 h) in intact cells; and (c) the ATP-dependent proteolytic activity of both systems was inhibited substantially by certain chemical agents (orthovanadate, N-ethylmaleimide, o-phenanthroline, and phenylmethylsulfonyl fluoride) but only slightly, if at all, by others (epsilon-aminocaproic acid and leupeptin). When excess human erythrocyte ubiquitin was added to the beta-thalassemic cell-free systems, a stimulation in ATP-dependent proteolysis of 3H-alpha chains ranging from 30 to 58% was observed. Conversely, addition of from 1.25 to 2.50 mg/ml affinity-purified rabbit antiubiquitin inhibited almost all (greater than 90%) of the ATP-dependent 3H-alpha chain proteolysis; in control experiments, antiubiquitin neutralized with excess ubiquitin inhibited only 13 to 30% of the total (including ubiquitin-stimulated) ATP-dependent proteolysis.(ABSTRACT TRUNCATED AT 400 WORDS)