Molecular evolutionary genetics of the cattle-adapted serovar Salmonella dublin.

An electrophoretic analysis of allelic variation at 24 enzyme loci among 170 isolates of the serovar Salmonella dublin (serotype 1,9,12[Vi]:g,p:-) identified three electrophoretic types (Du 1, Du 3, and Du 4), marking three closely related clones, one of which (Du 1) is globally distributed and was represented by 95% of the randomly selected isolates. All but 1 of 114 nonmotile isolates of serotype 1,9,12:-:- recovered from cattle and swine in the United States were genotypically Du 1. The virulence capsular polysaccharide (Vi antigen) is confined to clone Du 3, which apparently is limited in distribution to France and Great Britain. For all 29 isolates of Du 3, positive signals were detected when genomic DNA was hybridized with a probe specific for the ViaB region, which contains the structurally determinant genes for the Vi antigen; and 23 of these isolates had been serologically typed as Vi positive. In contrast, all 30 isolates of Du 1 tested with the ViaB probe were negative. These findings strongly suggest that the ViaB genes were recently acquired by S. dublin via horizontal transfer and additive recombination. The clones of S. dublin are closely similar to the globally predominant clone (En 1) of Salmonella enteritidis (serotype 1,9,12:g,m:-) in both multilocus enzyme genotype and nucleotide sequence of the fliC gene encoding phase 1 flagellin. Comparative sequencing of fliC has revealed the molecular genetic basis for expression of the p and m flagellar epitopes by which these serovars are distinguished in the Kauffmann-White serological scheme of classification.     

Catecholamines and dopamine-β-hydroxylase activity during therapeutic abortion induced by sulprostone

To evaluate the changes in circulating norepinephrine (NE), epinephrine (E) and dopamine-β-hydroxylase (DBH) caused by an intravenous infusion of a derivate of PGE₂, sulprostone, in connection with legal termination of pregnancy, serial plasma samples were analyzed for six gravidae. Plasma catecholamines were measured by a sensitive radioenzymatic method (9,10) and DBH activities by a photometric assay (11). Intravenous infusion of sulprostone, in abortifacient doses as an intravenous infusion of 3–4 μg per minute for six to eight hours produced a decrease in circulating norepinephrine. No significant alteration was found in plasma epinephrine or dopamine-β-hydroxylase activity. The finding suggests an inhibitory effect of sulprostone on the release of norepinephrine from the adrenergic terminals without inhibition of the adrenal medulla.     

Genetic Diversity and Temporal Variation in the E. COLI Population of a Human Host

Electrophoretic techniques were employed to study variation in chromosomal genes encoding enzymes and in the distribution of cryptic plasmids in the E. coli population of a human host over an 11-month period. Thirteen of the 15 enzymes studied were polymorphic, and mean genetic diversity per locus was 0.39. Among 550 clones isolated from fecal samples, protein electrophoresis revealed 53 distinct electrophoretic types (ETs). Most ETs appeared on only one or a few days and were considered transients, but two (ET-12 and ET-13) were observed many times over extended periods and represented residents. Complete turnover in the transient ETs in the population occurred in periods of from two weeks to a month. ETs appearing in one month showed no particular genetic similarity to those of the previous month. — All but 4 of the 53 ETs carried one or more "cryptic" plasmids with molecular weights ranging from 1 to 80 megadaltons. With few exceptions, the plasmid composition of each ET was unique. In the course of the 11-month sampling period, there were changes in the plasmid profiles of the resident strains ET-12 and ET-13, and also in the profile of a recurrent strain, ET-2, which was isolated on four days. Modification of the plasmid profile of ET-12 involved the sequential addition of relatively high molecular weight bands. For ET-2 and ET-13, the changes in the plasmid profiles were radical, suggesting invasions of new cell types rather than merely the addition and deletion of plasmids. — The results of this study provide three lines of evidence that recombination plays a minor role in the generation of genetic diversity in the E. coli population of a single host. (1) Several pairs of loci were in strong linkage disequilibrium; compared to a randomly generated array of genotypes, the sample of ETs contained an excess of pairs differing at one or two loci and too many pairs with highly distinctive combinations of electromorphs. (2) In most cases where pairs of ETs differed at a single locus and, therefore, could reasonably have been generated by phage- or plasmid-mobilized gene transfer, the plasmid profiles of the pair members were radically different and/or the potentially transmitted alleles were not present in other ETs in the population. (3) Although ET-12 was abundant, being represented by 252 of the 550 clones sampled, the electrophoretic type most similar to ET-12 different from it at six loci, and ET-12 carried two unique alleles. We conclude that most of the genetic diversity observed in this human host is a consequence of successive invasions of E. coli genotypes.     

Molecular basis of chromosome banding

Silver and mercury ions are known to react with the bases of nucleic acids in solution. At low cation/base ratios Ag+ has an affinity for GC pairs in DNA, whereas Hg++ is preferentially bound to AT-rich nucleic acids. We have used fluorometry to measure the effect of these cations on the fluorescence intensity of preformed complexes of acranil and DNA in solution. The results are: 1) Ag+ enhances the fluorescence intensity presumably by affecting the dye intercalated in the vicinity of GC-pairs. 2) The addition of Hg++ leads to a quenching of the fluorescence intensity of the complex at low ion/base ratios, suggesting an effect on the dye molecules bound to AT pairs. At high GC-content of the nucleic acid, slight enhancement of the fluorescence intensity occurs with Hg++. 3) With both metals there is a correlation between base content of DNA and effect on the intensity of fluorescence indicating base specificity of the dye-polymer interaction.     

Environmental predictability of taxonomic and functional community composition in high‐latitude streams

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Early Life Stress and Physical and Psychosocial Functioning in Late Adulthood

Background

Severe stress experienced in early life may have long-term effects on adult physiological and psychological health and well-being. We studied physical and psychosocial functioning in late adulthood in subjects separated temporarily from their parents in childhood during World War II.

Methods

The 1803 participants belong to the Helsinki Birth Cohort Study, born 1934–44. Of them, 267 (14.8%) had been evacuated abroad in childhood during WWII and the remaining subjects served as controls. Physical and psychosocial functioning was assessed with the Short Form 36 scale (SF-36) between 2001 and 2004. A test for trends was based on linear regression. All analyses were adjusted for age at clinical examination, social class in childhood and adulthood, smoking, alcohol intake, physical activity, body mass index, cardiovascular disease and diabetes.

Results

Physical functioning in late adulthood was lower among the separated men compared to non-separated men (b = −0.40, 95% confidence interval [95% CI]: −0.71 to −0.08). Those men separated in school age (>7 years) and who were separated for a duration over 2 years had the highest risk for lower physical functioning (b = −0.89, 95% CI: −1.58 to −0.20) and (b = −0.65, 95% CI: −1.25 to −0.05), respectively). Men separated for a duration over 2 years also had lower psychosocial functioning (b = −0.70, 95% CI: −1.35 to −0.06). These differences in physical and psychosocial functioning were not observed among women.

Conclusion

Early life stress may increase the risk for impaired physical functioning in late adulthood among men. Timing and duration of the separation influenced the physical and psychosocial functioning in late adulthood.     

Transforming growth factor-beta stimulates parathyroid hormone-related protein and osteolytic metastases via Smad and mitogen-activated protein kinase signaling pathways

Transforming growth factor (TGF)-beta promotes breast cancer metastasis to bone. To determine whether the osteolytic factor parathyroid hormone-related protein (PTHrP) is the primary mediator of the tumor response to TGF-beta, mice were inoculated with MDA-MB-231 breast cancer cells expressing a constitutively active TGF-beta type I receptor. Treatment of the mice with a PTHrP-neutralizing antibody greatly decreased osteolytic bone metastases. There were fewer osteoclasts and significantly decreased tumor area in the antibody-treated mice. TGF-beta can signal through both Smad and mitogen-activated protein (MAP) kinase pathways. Stable transfection of wild-type Smad2, Smad3, or Smad4 increased TGF-beta-stimulated PTHrP secretion, whereas dominant-negative Smad2, Smad3, or Smad4 only partially reduced TGF-beta-stimulated PTHrP secretion. When the cells were treated with a variety of protein kinases inhibitors, only specific inhibitors of the p38 MAP kinase pathway significantly reduced both basal and TGF-beta-stimulated PTHrP production. The combination of Smad dominant-negative blockade and p38 MAP kinase inhibition resulted in complete inhibition of TGF-beta-stimulated PTHrP production. Furthermore, TGF-beta treatment of MDA-MB-231 cells resulted in a rapid phosphorylation of p38 MAP kinase. Thus, the p38 MAP kinase pathway appears to be a major component of Smad-independent signaling by TGF-beta and may provide a new molecular target for anti-osteolytic therapy.