The Salmonella wien virulence plasmid pZM3 carries Tn1935, a multiresistance transposon containing a composite IS1936-kanamycin resistance element

Tn1935, a 23.5-kb transposon mediating resistance to ampicillin, kanamycin, mercury, spectinomycin, and sulfonamide was isolated from pZM3, an IncFIme virulence plasmid from Salmonella wien. Tn1935 possesses the entire sequence of Tn21 and contains two additional DNA segments of 0.95 and 2.7 kb carrying the ampicillin and kanamycin resistance genes, respectively. The latter is part of a composite element since it is flanked by two IS15-like insertion sequences (IS1936) in direct orientation. IS1936 is about 800 bp long and is closely related to IS15 delta, IS26, IS46, IS140, and IS176. Functional analysis of IS1936-mediated cointegrates shows that both insertion sequences are active and able to form cointegrates at the same frequency. Resolution of the cointegrates requires the presence of the host Rec system. The presence of the composite IS1936-element within Tn1935 supports the hypothesis that multidrug resistance transposons evolved by insertion of antibiotic determinants which are themselves transposable.     

Different lipid A types in lipopolysaccharides of phototrophic and related non-phototrophic bacteria

Lipid A analyses confirm not only the present taxa of the purple nonsulfur bacteria (formerly Rhodospirillaceae), but also phylogenetical relatedness of distinct phototrophic to distinct non-phototrophic bacteria, as was suggested by cataloguing 16S rRNA. For example, lipid A with ester-bound 3-OH-10:0 and the rare amide-linked 3-oxo-14:0 is common to the phototrophic Rhodobacter capsulatus and Rhodobacter sphaeroides and also to Paracoccus denitrificans and Thiobacillus versutus. 'Lipid ADAG' (lipid A with 2,3-diamino-D-glucose (DAG)) occurs in the phototrophic Rhodopseudomonas viridis and Rhodopseudomonas palustris and also in the related non-phototrophic species, e.g., Nitrobacter winogradskyi, Pseudomonas diminuta, or Thiobacillus ferrooxidans. The phylogenetically more coherent purple sulfur bacteria (Chromatiaceae) uniformly contain D-mannose in their phosphate-free lipid A. Among the green bacteria, only the Chlorobiaceae but not the likewise chlorosome-containing Chloroflexaceae contain lipopolysaccharide. Lipid ADAG from R. viridis is a structural analogue of a biosynthetic precursor (lipid X) of enterobacterial lipid A. Lipid A synthase from Salmonella accepts not only lipid X but also the synthetic di-N-acyl-2,3-diamino-D-glucose analogue as substrate (Raetz, C.R.H., unpublished results). More and more naturally occurring lipid A's with both, 2,3-diaminoglucose and glucosamine ('mixed' lipid A, with 2,3-diaminoglucose or glucosamine dominating) are being found. Newly recognized lipid A and lipid ADAG types might offer the possibility of differentially stimulating desired biological activities in animals without also having the undesired endotoxic activities. The non-toxic lipid A from Rhodopseudomonas viridis for example is able to stimulate prostaglandin secretion in peritoneal macrophages and can be used as an antagonist to the endotoxic shock caused by Salmonella lipopolysaccharide.     

Inhibitory effect of 11-ketoandrostenedione and androstenedione on spermatogenesis in the three-spined stickleback, Gasterosteus aculeatus L.

Stickleback males were implanted with Silastic capsules filled with 11-ketoandrostenedione or androstenedione at the end of the breeding season. 11-Ketoandrostenedione prevented the natural decline in secondary sexual characters and testes weight. It also completely inhibited the commencement of spermatogenesis, which normally takes place in late summer after having been quiescent during the breeding season. Androstenedione also exerted these effects, but to a lesser degree.     

Tricyclic Imipramine Modification of the Circadian Rhythms of Hypothalamic Serotonin, its Precursors and Acid Catabolite in Individually Housed Rats

Circadian rhythms of serotonin (5HT), its precursors tryptophan (TP) and 5-hydroxy-tryptophan (5HTP) and its acid catabolite 5-hydroxy-indoleacetic acid (5HIAA), were determined in the hypothalamus of control rats and rats which had been treated continuously with subcutaneous imipramine (10 mg/kg/day) for 2 weeks.

Rats were individually housed and entrained to LD12:12. Controls showed the 5HT and TP peaks in the light and dark periods respectively, as reported in the literature, but no inverted correlation (antiphase) between SHT and 5HIAA rhythms.

Imipramine significantly modified circadian rhythm characteristics: the 5HT acrophase was advanced, that of TP and 5HIAA was delayed. Imipramine also significantly increased hypothalamic SHT and TP concentrations.     

Suitability of a rapid gas chromatographic method for total mesophilic bacteria and coliform enumeration in hamburgers

An instrumental method for the rapid determination of total mesophilic bacteria and total coliforms in hamburgers is described. The two procedures are based on the gas chromatographic determination of metabolic CO₂ in equilibrium in the head space of sealed vials containing suitable media and inoculated with aliquots of the sample under examination. Both procedures proved to be suitable for quality control of meat products, being highly sensitive, reproducible, simple and rapid. Good correlation coefficients were obtained with plate counting for microbial concentrations ranging between 10¹ and 10⁸.     

Genetic and blood coagulation characterization of “Swedish” families with von Willebrand's disease types I and III: New aspects of heredity

Summary Twenty-five patients with von Willebrand's disease (vWD) type III were analysed with regard to blood coagulation variables and possible deletions. Nine of the probands and their families were further investigated with DNA linkage analyses. Different patterns of heredity can be suggested in our families with vWD type III, on the basis of blood coagulation analyses. The findings suggest homozygosity in five families and the possibility of compound heterozygosity or a new mutation in the proband in three families. The linkage analyses confirm the results of the coagulation analyses. The segregation of the von Willebrand factor (vWF) gene can be followed in the families, and carrier diagnosis can be made in several of the probands' relatives. The possibility of large deletions in the vWF gene of the probands and their parents was investigated with probes representing the whole vWF cDNA. No deletions were found.This study was approved by the Ethics Committee of the Karolinska Hospital (No. 84:1)     

Variants of the anti-Müllerian hormone gene in a compound heterozygote with the persistent Müllerian duct syndrome and his family

Summary The human genome contains a large number of interspersed simple repeat sequences that are variable in length and can therefore serve as highly informative, polymorphic markers. Typing procedures include conventional multilocus and single locus probing, and polymerase chain reaction aided analysis. We have identified simple sequences in a cosmid clone stemming from the human Y chromosome and consisting of (gata)_n repeats. We have compared these with two equivalent simple repeat loci from chromosome 12. After amplifying the tandemly repeated motifs, we detected between four and eight different alleles at each of the three loci. Codominant inheritance of the alleles was established in family studies and the informativity of the simple repeat loci was determined by typing unrelated individuals. The polymorphisms are suitable for application in linkage studies, practical forensic case work, deficiency cases in paternity determination, and for studying ethnological questions. The mutational mechanisms that bring about changes in simple repeats located both on the autosomes and on the sex chromosomes, are discussed.Professor Dr. Otto Prokop (Humboldt-Universität Berlin) on the occasion of his 70th birthday     

Occurrence of a capsule in Aeromonas salmonicida

Aeromonas salmonicida grown in a medium with excess glucose as carbon source produces both capsular and exocellular polysaccharides. The capsular polysaccharide is composed of glucose, mannose, rhamnose, N-acetylmannosamine and mannuronic acid in the molar ratios of approximately 5:3:0.75:2:1. The extracellular polysaccharide is similarly constituted, but in the molar ratios of approximately 4.75:10.5:1.5:2:1. The capsular and exocellular polysaccharides did not cross-react with monoclonal antibodies against the A-layer or the O-antigen lipopolysaccharide.     

Biologic markers in ethylene oxide-exposed workers and controls

Ethylene oxide (EtO) is an alkylating agent and a model direct-acting mutagen and carcinogen. This study has evaluated a panel of biologic markers including EtO-hemoglobin adducts (EtO-Hb), sister-chromatid exchanges (SCEs), micronuclei, chromosomal aberrations (CAs), DNA single-strand breaks (SSB) and an index of DNA repair (ratio of UDS to NA-AAF-DNA binding) in the peripheral blood cells of 34 workers at a sterilization unit of a large university hospital and 23 controls working in the university library. Comprehensive environmental histories were obtained on each subject including detailed occupational and smoking histories. Industrial hygiene data obtained prior to the study and personal monitoring during the 8 years preceding the study showed that workers were subject to low-level exposure near or below the current Occupational Safety and Health Administration (OSHA) standard of 1 ppm (TWA). Personal monitoring data obtained during 2 weeks prior to blood sampling were uniformly less than 0.3 ppm (TWA). After adjusting for smoking, EtO workplace exposure was significantly (p less than 0.001) associated with EtO-Hb (a carcinogen-protein adduct) and 2 measures of SCEs [the average number of SCEs/cell (SCE50) and the number of high frequency cells (SCEHFC)]. There was an apparent suppression of DNA repair capacity in EtO-exposed individuals as measured by the DNA repair index; i.e., the ratio of unscheduled DNA synthesis (UDS) and NA-AAF-DNA binding (p less than 0.01). No association of DNA repair index with smoking was found. Another important finding of this study is the highly significant correlation between EtO-Hb adduct levels and SCEHFC (p less than 0.01) and SCEs (p less than 0.02) which provides evidence of a direct link between a marker of biologically effective dose and markers of genotoxic response. In contrast, micronuclei, CAs and SSBs were not significantly elevated in the workers. The activity of the u-isoenzyme of glutathione-S-transferase (GT) was measured as a possible genetic marker of susceptibility and a modulator of biomarker formation. However, possibly because of confounding by age, no significant relationships were found between GT and any of the exposure-related markers by ANOVA or among other independent variables by regression. This study demonstrates significant effects of low-level EtO exposure, independent of smoking history, near or below 1 ppm on multiple biomarkers and suggests that the current OSHA standard may not be adequately protective. Previously described effects of smoking on EtO-Hb adducts, SCEs and SCEHFC were also seen in this study.(ABSTRACT TRUNCATED AT 400 WORDS)