Use of chromosomal integration in the establishment and expression of blaZ, a Staphylococcus aureus beta-lactamase gene, in Bacillus subtilis

With several different vectors, attempts were made to establish blaZ, a Staphylococcus aureus beta-lactamase gene, in Bacillus subtilis. Stable establishment of blaZ in B. subtilis was achieved by use of a vector that allowed the integration of a single copy of the gene into the chromosome of that host. blaZ was expressed in the heterologous host since B. subtilis strains carrying integrated blaZ produced beta-lactamase and were more resistant to ampicillin than was wild-type B. subtilis. blaZ was stably inherited in such strains, as no loss of the ability to produce beta-lactamase was observed after growth in nonselective liquid medium or on solid medium. In contrast, a blaZ-containing restriction fragment could not be established in B. subtilis with either pUB110- or pC194-based vectors. Similarly, a pC194-based shuttle vector (pGX318) containing the 5' end of blaZ (including the promoter and the coding region for the signal sequence and the first few amino acids of the mature protein) was unable to transform B. subtilis. Two derivatives of pGX318 that could be stably established in B. subtilis were isolated. The structures of these derivatives suggested that inactivation of the blaZ promoter was associated with the acquisition of the ability to be established.     

The role of insertions, deletions, and substitutions in the evolution of R6 related plasmids encoding aminoglycoside transferase ANT-(2")

Summary In 7% of gram-negative bacteria resistance to gentamicin is mainly mediated by plasmid-encoded aminoglycoside transferase ANT-(2). The genome organization of 15 aadB plasmids (42-110 kb) was analyzed by restriction and hybridization techniques. They appeared to be IncFII-like replicons but were distinct from R6 by virtue of small substitutions in the transfer region. Aminoglycoside resistance genes aadB and aadA were located on Tn21 related elements. Only one of them was able to transpose its resistance genes mer sul aadA and aadB (Tn4000), the other elements were naturally occurring defective transposons. In some of these structures deletions were identified at the termini, at sul, aadA, mer or transposition function-insertions adjacent to aadA or mer. The mode of these rearrangements and their site-specificity were considered with respect to the evolution of the Tn21 transposon family.Abbreviations aadA (genotype) AAD-(3) (phenotype): aminoglycoside 3-adenylytransferase - aadB ANT-(2): aminoglycoside 2-adenylyltransferase - aphA APH-(3)I: aminoglycoside 3-phosphotransferase - aacA AAC-(6): aminoglycoside 6-N-acetyl-transferase - aacC AAC-(3): aminoglycoside 3-N-acetyltransferase - cat CAT: chloramphenicol-acetyltransferase - Ap ampicillin - Su sulfonamides - Tc tetracycline - Sm streptomycin - Spe spectinomycin - Hg mercury - Cb carbenicillin - Dk dibekacin - Gm gentamicin - Km kanamycin - Nm neomycin - Net netilmycin - Pm paromomycin - But butirosin - Tm tobramycin - Sis sisomycin - Cm chloramphenicol - kb kilobase     

Mapping of cysteine genes on the chromosome of Pseudomonas aeruginosa PAO

Summary Three loci coding for different steps in the pathway of cysteine biosynthesis have been mapped by R68.45-mediated coconjugation analysis. The cysteine auxotrophic mutants could be subdivided into sulfite and sulfide-requiring mutants. Sulfide-requiring mutants (cysIV group) were localized at a single position between pyrF and pur-67, while sulfite-requiring mutants (cysI and cysII) mapped at two different regions. The cysI group was also localized between pyrF and pur-67, although more distal to pyrF than the cysIV group. This group included the cys-54 marker, which has been mapped previously. The second group of sulfite-requiring mutants, designated as cysII, was cotransducible with hisI and localized at the end of the PAO chromosomal map. This location was also confirmed for the marker cys-59.The marker cys-59 (which was cotransducible with his1) was cotransferred by R68.45-mediated conjugations with both the late marker pur-67 and the early marker ilv-226. As the late marker hisI was positioned at about 60–65 min (Herrmann and Günther, in press) the length of the PAO chromosome was estimated to be about 70 min.     

Bluelight-induced,flavin-mediated transport of redox equivalents across artificial bilayer membranes

Summary This paper continues our studies of physico-chemical properties of vesicle-bound flavins. Based on previous results, an advanced model system was designed in order to study the mechanisms underlying bluelight-induced redox transport across artificial membranes. The lumen of single-shelled vesicles was charged with cytochromec, and amphiphilic flavin (AF1 3, AF1 10) was bound to the membrane. Upon bluelight irradiation redox equivalents are translocated from exogeneous 1e ^–(EDTA)-and 2e ^–(BH₃CN^–) donors across the membrane finally reducing the trapped cytochromec both under aerobic and anaerobic conditions. The mechanisms involved are explored and evidence for the involvement of various redox states of oxygen, dihydroflavin and flavosemiquinone is presented.     

Varicella-zoster viral glycoproteins analyzed with monoclonal antibodies.

Monoclonal antibodies to varicella-zoster virus were used to study viral glycoproteins by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Based on the viral glycoproteins immunoprecipitated, the five monoclonal antibodies fell into three groups. Two antibodies, 4B7 and 8G9 (group 1), immunoprecipitated a single glycoprotein of molecular weight (MW) 118,000 (118K glycoprotein) and had high neutralizing activity in the absence of complement. One antibody, 3C7 (group 2), which lacked neutralizing activity, immunoprecipitated two glycoproteins of MWs 120,000 and 118,000 and a glycoprotein giving a diffuse band in the region of 64,000 to 65,000. Pulse-chase experiments and experiments with monensin as an inhibitor of glycosylation suggested that the 120K polypeptide was derived by glycosylation of the 118K polypeptide and that a 43K antigen was processed into the 64 to 65K glycoprotein. Two antibodies, 3G8 and 4E6 (group 3), both had neutralizing activity only in the presence of complement, and both immunoprecipitated at least five polypeptides, with MWs ranging from 50,000 to 90,000. Antibody 3G8 was isotype immunoglobulin G2b (IgG2b), and its immunoprecipitating activity was stronger than that of 4E6, which was isotype IgG1. Pulse-chase experiments with antibody 3G8 showed that lower-MW glycopeptides chased into three polypeptides of MWs 90,000, 80,000, and 60,000 by 24 h. Immunoprecipitation experiments with antibody 3G8 on infected cells treated with glycosylation inhibitors 2-deoxyglucose, monensin, and tunicamycin, suggested that a prominent, early-appearing 70K polypeptide may have been processed into the glycoproteins of higher MWs and that the 60K polypeptide may have been derived by glycosylation of polypeptides of lower MWs.     

Capacity of different cell types to stimulate cytotoxic T lymphocyte precursor cells in the presence of interleukin 2

Plastic-adherent cells enriched for dendritic cells (AC) were found to be among the most potent stimulator cells for the activation of cytotoxic T lymphocytes (CTL) in vitro in the presence of interleukin 2 (IL 2) and a constant second set of allogeneic stimulator cells. Concanavalin A-activated nylon wool-nonadherent spleen cells ( CNWT ), concanavalin A-activated unfractionated spleen cells ( Cspl ), and some variants of the ESb T lymphoma line were equally effective as stimulator cells, however, and provoked a substantial cytotoxic response at concentrations of 10(4) cells per culture or less. In contrast, nonactivated nylon wool-nonadherent spleen cells ( NWT ) or unfractionated spleen cells (Spl) and cells of the P815 mastocytoma, the Meth A fibrosarcoma, and the T cell lymphomas Ly 5178 Eb and ESb did not stimulate cytotoxic responses at these cell concentrations. The strong stimulatory potential of the Cspl preparation was reduced by treatment with anti-Thy-1 antibody plus complement, whereas the stimulatory activity of the AC preparation was resistant to this treatment. All cell types tested expressed class I major histocompatibility antigens. Nonactivated NWT cells, in contrast to the CNWT preparation, showed no detectable staining with anti-I-E or anti-I-A antibodies and also a slightly weaker staining with class I antisera. Experiments with the tumor cell lines revealed, however, that there was no strict correlation between stimulatory potential and density of class I alloantigens or the expression of I-E determinants. Experiments on primary cytotoxic responses in vivo gave similar results. Experiments in cultures with a single set of stimulator cells and I region-compatible responder cells indicated that AC and Cspl or CNWT also have a markedly stronger capacity than NWT to induce IL 2-dependent DNA synthesis.     

Evidence that pH induced activation of the rat hepatic glucocorticoid-receptor complex is irreversible

The possible reversibility of pH induced activation of the glucocorticoid-receptor complex was studied. Generally, this was accomplished by activating rat liver cytosol at pH 8.5 (15 degrees C, 30 min), and then returning it to pH 6.5 for a second incubation (15 degrees C, 30 min). Activation was quantitated by measuring the binding of [3H]triamcinolone acetonide [( 3H]TA)-receptor complexes to DNA-cellulose. When cytosol was incubated at pH 6.5, only 4.1% of the [3H]TA-receptor complexes bound to DNA-cellulose. However, 39.2% of the complexes bound when the cytosol was pH activated. When pH activation was followed by a second incubation at pH 6.5, 47.0% of the steroid-receptor complexes bound. Thus, according to the DNA-cellulose binding assay, pH induced activation was irreversible. In order to visualize both activated and unactivated [3H]TA-receptor complexes during this process, diethylaminoethyl (DEAE)-cellulose chromatography was performed. When cytosol was incubated at pH 6.5, only 19.6% of the [3H]TA-receptor complexes were eluted in the activated form from DEAE-cellulose. However, 67.5% of the complexes were eluted in the activated form when cytosol was pH activated. When pH activation was followed by a second incubation at pH 6.5, 74.9% of the steroid-receptor complexes were eluted in the activated form. Thus, DEAE-cellulose chromatography also showed that pH induced activation was irreversible. This is the first known report that the combination of DNA-cellulose binding and DEAE-cellulose chromatography have been used to study pH induced activation of the glucocorticoid-receptor complex. By these criteria, we conclude that in vitro pH induced activation is irreversible.     

pH dependence of the in situ formation of an organicN-chloramine water disinfectant

Summary Staphylococcus aureus was used to assess the bactericidal efficacy of aqueous solutions of the organicN-chloramine compound 3-chloro-4,4-dimethyl-2-oxazolidinone (agent I) formed in situ. The rate of in situ formation, accomplished by reacting free chlorine with the amine precursor, was a function of pH. When the reagents were combined under acidic conditions (pH5.5) and allowed to react for 22 h, sufficient residual free chlorine was present to inactivate the bacteria in less than 5 min. When combined under less acidic conditions (pH6.0), comparable bacterial inactivation required 30–60 min due to the extensive reaction of the free chlorine to form agent I. The kill rates present under less acidic and neutral conditions are equivalent to those for pre-formed agent I. In water disinfection applications for pH6.0, in situ formation of agent I would provide a combination of rapid initial and slower long-term disinfection.     

Effect of age and training on aerobic capacity and body composition of master athletes

Maximum oxygen uptake (VO2max) and body composition have been shown to deteriorate with age. How much of the decline is attributable to aging and how much is affected by reduced physical activity is not known. The purpose of this investigation was to determine the aerobic capacity and body composition of 24 master track athletes and to evaluate the relationship to age and maintenance of training over a 10-yr period. The subjects (50-82 yr of age) were retested after a 10.1-yr follow-up (T2). All continued their aerobic training, but only 11 were still highly competitive (COMP) and continued to train at the same intensity. The other 13 athletes studied became noncompetitive (post-COMP) and reduced their training intensity. The results showed the COMP group to maintain its VO2max and maximum O2 pulse while the post-COMP group showed a significant decline (54.2-53.3 vs. 52.5-45.9 ml X kg-1 X min-1; 20.7-20.8 vs. 22.4-20.0 ml/beat from test one (T1) to T2 for the COMP vs. post-COMP groups, respectively). Maximum heart rate declined 7 beats/min for both groups. Body composition showed no difference between groups from T1 to T2. For both groups body weight declined slightly (70.0-68.9 kg), percent fat increased significantly (13.1-15.1%), and fat-free weight decreased significantly (61.0-59.0 kg). Thus, when training was maintained, aerobic capacity remained unchanged over the follow-up period. Body composition changed for both groups and may have been related to aging and/or the type of training performed.     

Characterization of an amidated form of pancreatic polypeptide from the daddy sculpin (Cottus scorpius)

The primary structure of pancreatic polypeptide from the teleostean fish, Cottus scorpius (daddy sculpin) was established as: YPPQPESPGGNASPEDWAKYHAAVRHYVNLITRQRYNH2 The presence of a COOH-terminally alpha-amidated amino acid was established using an HPLC method of general applicability. Although the peptide shows strong homology towards anglerfish pancreatic polypeptide (86%), homology towards porcine peptide YY (PYY) (61%) and porcine neuropeptide Y (NPY) (61%) was greater than towards porcine pancreatic polypeptide (PP) (47%). This result supports suggestions that the gene duplication events which led to PP, NPY and PYY formation took place after the time of divergence of fish and mammals.