Plasmids in Leuconostoc oenos

A new procedure was used to isolate 11 plasmids from eight Leuconostoc oenos strains. Plasmid DNA was not detected in 34 other strains of this species. Plasmid sizes ranged from 2.47 to 4.61 kilobase pairs. This is the first report of extrachromosomal elements in L. oenos.     

The oxidation product of molybdenum cofactor from milk xanthine oxidase

In extracts of acid treated molybdenum cofactor containing xanthine oxidase, fluorescence is maximally developed upon a three hours incubation. Analysis by means of reversed phase HPLC revealed the presence of several fluorescent compounds, the main one being a blue fluorescent compound with an emission maximum of 465 nm when maximal excited at 395 nm at a neutral pH. Definite proof is presented that this compound is the oxidation product of the molybdenum cofactor. The remaining fluorescent products are shown to be pterin-derivatives, yielding predominantly pterin-6-carboxylic acid upon permanganate oxidation. Purified oxidation product of molybdenum cofactor however, didn's yield a fluorescent derivative at all upon treatment with permanganate.     

Strain differences in kidney copper concentrations of male rats

The copper concentrations of the kidneys of male rats of six inbred (BN, F344, LEW, SHR, WAG/Cpb, and WAG/Rij) and one random-bred Wistar strain were determined. In inbred rats the mean concentration varied between strains and ranged from 7.10 μg/g for F 344 to 23.48 μg/g for WAG/Cpb. The calculated coefficient of genetic determination (g²) was 0.88. A remarkable discrepancy was found between the two WAG inbred strains; the WAG/Cpb had a 2.5 times higher kidney Cu concentration than the WAG/Rij. Kidney Cu concentrations of random-bred rats varied considerably; the coefficient of variation of the means was 28 and 34% in two samples taken with a 1-yr interval, respectively, indicating inhomogeneity within the population. The results indicate that the individual differences in kidney Cu concentration have a genetic basis.     

Chromosomal nodulation genes: Sym-plasmid containing Agrobacterium strains need chromosomal virulence genes (chvA and chvB) for nodulation

Summary The chromosomal genes chvA and chvB of Agrobacterium tumefaciens, which mediate attachment to plant cells, were found to be essential not only for tumour induction but also for the formation of root nodules on plants.     

Cell wall strength of Hansenula polymorpha in continuous cultures in relation to the recovery of methanol oxidase (MOX)

Summary The changes in cell wall strength of Hansenula polymorpha have been investigated in continuous cultures with respect to the recovery of methanol oxidase (MOX). Cultures grown on several substrate mixtures that enable induction of MOX have been compared with cultures grown on methanol as the sole inducer. The effects of dilution rate (D) on lysis properties have been studied. The cell wall strength was consistently influenced by growth media and D. Media containing glycerol/methanol showed the slowest lysis kinetics, with a large fraction of non-degradable cell wall material. In continuous cultures grown on a mixture of glucose and methanol both the resistance to zymolyase and the mean cell wall thickness increased at D<0.1 h^–1. The yield of MOX by zymolyase lysis is reproducible and up to 100% higher than that of the standard ultrasonic treatment. The lysis kinetics indicated that zymolyase punctures the cell wall; since the release rate of MOX is lower than that of protein, the cell contents will leak through. At D-values>0.2 h^–1, both protein and MOX release rates increase, reflecting a change in lysis mechanism due to the increased fraction of thin daughter cells. Kinetic analysis of zymolyase lysis using both physical and enzymatic methods provides information for achieving optimal recovery of MOX.Abbreviations and symbols C _MOX MOX activity [MOX units·g X^–1] - D dilution rate [h^–1] - MOX methanol oxidase - k_c decay rate constant of A 610 nm [min^–1] - k_d decay constant of MOX activity [min^–1] - k_dis dissociation rate constant [min^–1] - k_MOX release rate constant of MOX activity [min^–1] - k_p release rate constant of protein [min^–1] - R recovery efficiency of enzyme [-] - St stability of enzyme [-]     

The N-terminal sequence of ribosomal protein L10 from the archaebacterium Halobacterium marismortui and its relationship to eubacterial protein L6 and other ribosomal proteins

The amino-terminal sequence of ribosomal protein L10 from Halobacterium marismortui has been determined up to residue 54, using both a liquid- and a gas-phase sequenator. The two sequences are in good agreement. The protein is clearly homologous to protein HcuL10 from the related strain Halobacterium cutirubrum. Furthermore, a weaker but distinct homology to ribosomal protein L6 from Escherichia coli and Bacillus stearothermophilus can be detected. In addition to 7 identical amino acids in the first 36 residues in all four sequences a number of conservative replacements occurs, of mainly hydrophobic amino acids. In this common region the pattern of conserved amino acids suggests the presence of a beta-alpha fold as it occurs in ribosomal proteins L12 and L30. Furthermore, several potential cases of homology to other ribosomal components of the three ur-kingdoms have been found.     

Subcellular localization of the 84,000 dalton heat-shock protein in mouse neuroblastoma cells: evidence for a cytoplasmic and nuclear location

Using affinity-purified antibodies, the 84,000 dalton heat-shock protein (hsp) has been localized in mouse N2A neuroblastoma cells by immunocytochemical techniques. Immunofluorescence microscopy showed that hsp84 was present both in the cytoplasm and in the nucleus. The nucleoli were found to be unlabelled. Immunogold labelling on ultrathin cryosections revealed that hsp84 was evenly distributed throughout the entire cytoplasm. No preferential association of hsp84 with the plasma membrane or with membranes from organelles was observed. In the nucleus the hsp84 was present in both the euchromatin and heterochromatin. In the nucleolus only the fibrillar part was labelled and virtually no gold particles were observed in the granular part. A long-term hyperthermic treatment of 3 h at 42.5 degrees C was found to induce an accumulation of hsp84 inside the nucleus. No alterations in hsp84 distribution were observed during a treatment of the cells with 75 microM sodium arsenite for 3 h. Drastic alterations were observed in the nucleoli after both stress treatments. The granular part had totally disappeared and only remnants of the fibrillar part which contained hsp84, were found. Besides the nuclear accumulations of hsp84 during heat shock, no additional changes in the hsp84 location in stressed cells were observed. During a recovery from the heat shock by replacing the cells at 37 degrees C, a decrease in the nuclear location of hsp84 was observed, indicating the reversibility of this process. The significance of these results for the role of hsp84 in normal and in stressed cells is discussed.     

Functional reconstitution of influenza virus envelopes.

We have examined several procedures for the reconstitution of influenza virus envelopes, based on detergent removal from solubilized viral membranes. With octylglucoside, no functionally active virosomes are formed, irrespective of the rate of detergent removal: in the final preparation the viral spike proteins appear predominantly as rosettes. Protein incorporation in reconstituted vesicles is improved when a method based on reverse-phase evaporation of octylglucoside-solubilized viral membranes in an ether/water system is employed. However, the resulting vesicles do not fuse with biological membranes, but exhibit only a non-physiological fusion reaction with negatively charged liposomes. Functional reconstitution of viral envelopes is achieved after solubilization with octaethyleneglycol mono(n-dodecyl)ether (C12E8), and subsequent detergent removal with Bio-Beads SM-2. The spike protein molecules are quantitatively incorporated in a single population of virosomes of uniform buoyant density and appear on both sides of the membrane. The virosomes display hemagglutination activity and a strictly pH-dependent hemolytic activity. The virosomes fuse with erythrocyte ghosts, as revealed by a fluorescence resonance energy transfer assay. The rate and the pH dependence of fusion are essentially the same as those of the intact virus. The virosomes also fuse with cultured cells, either at the level of the endosomal membrane or directly with the cellular plasma membrane upon a brief exposure to low pH.