Microcin H47 System: An Escherichia coli Small Genomic Island with Novel Features

Genomic islands are DNA regions containing variable genetic information related to secondary metabolism. Frequently, they have the ability to excise from and integrate into replicons through site-specific recombination. Thus, they are usually flanked by short direct repeats that act as attachment sites, and contain genes for an integrase and an excisionase which carry out the genetic exchange. These mobility events would be at the basis of the horizontal transfer of genomic islands among bacteria

Spironolactone Lowers Portal Hypertension by Inhibiting Liver Fibrosis, ROCK-2 Activity and Activating NO/PKG Pathway in the Bile-Duct-Ligated Rat

OBJECTIVE: Aldosterone, one of the main peptides in renin angiotensin aldosterone system (RAAS), has been suggested to mediate liver fibrosis and portal hypertension. Spironolactone, an aldosterone antagonist, has beneficial effect on hyperdynamic circulation in clinical practice. However, the mechanisms remain unclear. The present study aimed to investigate the role of spionolactone on liver cirrhosis and portal hypertension. METHODS: Liver cirrhosis was induced by bile duct ligation (BDL). Spironolactone was administered orally (20 mg/kg/d) after bile duct ligation was performed. Liver fibrosis was assessed by histology, Masson's trichrome staining, and the measurement of hydroxyproline and type I collagen content. The activation of HSC was determined by analysis of alpha smooth muscle actin (α-SMA) expression. Protein expressions and protein phosphorylation were determined by immunohistochemical staining and Western blot analysis, Messenger RNA levels by quantitative real time polymerase chain reaction (Q-PCR). Portal pressure and intrahepatic resistance were examined in vivo. RESULTS: Treatment with spironolactone significantly lowered portal pressure. This was associated with attenuation of liver fibrosis, intrahepatic resistance and inhibition of HSC activation. In BDL rat liver, spironolactone suppressed up-regulation of proinflammatory cytokines (TNFα and IL-6). Additionally, spironolactone significantly decreased ROCK-2 activity without affecting expression of RhoA and Ras. Moreover, spironolactone markedly increased the levels of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS and the activity of NO effector-protein kinase G (PKG) in the liver. CONCLUSION: Spironolactone lowers portal hypertension by improvement of liver fibrosis and inhibition of intrahepatic vasoconstriction via down-regulating ROCK-2 activity and activating NO/PKG pathway. Thus, early spironolactone therapy might be the optional therapy in cirrhosis and portal hypertension

Innovation and entrepreneurship as strategies for success among Cuban-based firms in the late years of the transatlantic slave trade

This article examines how Cuban-based firms and entrepreneurs circumvented ever- increasing risks in the illegal slave trade. The article sheds light to this question by analyzing new qualitative information of 65 Cuban-based firms against the Slavevoyages database. Our findings indicate that Cuban-based firms were entrepreneurial as they exploited the opportunities arising from the volatility of the slave trade by: (a) internalizing networks of agents which allowed the rapid diffusion of information, (b) diversifying trading goods and expanding the number of partnerships to reduce transaction costs and risk, and (c) adopting technological innovations that modified the design and use of vessels

High-Density Transcriptional Initiation Signals Underline Genomic Islands in Bacteria

Genomic islands (GIs), frequently associated with the pathogenicity of bacteria and having a substantial influence on bacterial evolution, are groups of “alien” elements which probably undergo special temporal–spatial regulation in the host genome. Are there particular hallmark transcriptional signals for these “exotic” regions? We here explore the potential transcriptional signals that underline the GIs beyond the conventional views on basic sequence composition, such as codon usage and GC property bias. It showed that there is a significant enrichment of the transcription start positions (TSPs) in the GI regions compared to the whole genome of Salmonella enterica and Escherichia coli. There was up to a four-fold increase for the 70% GIs, implying high-density TSPs profile can potentially differentiate the GI regions. Based on this feature, we developed a new sliding window method GIST, Genomic-island Identification by Signals of Transcription, to identify these regions. Subsequently, we compared the known GI-associated features of the GIs detected by GIST and by the existing method Islandviewer to those of the whole genome. Our method demonstrates high sensitivity in detecting GIs harboring genes with biased GI-like function, preferred subcellular localization, skewed GC property, shorter gene length and biased “non-optimal” codon usage. The special transcriptional signals discovered here may contribute to the coordinate expression regulation of foreign genes. Finally, by using GIST, we detected many interesting GIs in the 2011 German E. coli O104:H4 outbreak strain TY-2482, including the microcin H47 system and gene cluster ycgXEFZ-ymgABC that activates the production of biofilm matrix. The aforesaid findings highlight the power of GIST to predict GIs with distinct intrinsic features to the genome. The heterogeneity of cumulative TSPs profiles may not only be a better identity for “alien” regions, but also provide hints to the special evolutionary course and transcriptional regulation of GI regions

Analisis de la mutacion mdr1-1�¢ del gen MDR1 en el perro Cimarron Uruguayo

Objective. The aim of this paper is to analyze the frequency of the mdr1-1D mutation of the MDR1 gene in a dog sample of the Uruguayan Cimarron breed with the objective of increasing the knowledge of this breed�s genome. Materials and methods. Thirty-six animals of this breed were analyzed. The MDR1 gene region, which includes the location where the mutation would be present, was amplified by PCR. Results. The mutation was not detected in any of the analyzed Uruguayan Cimarron. Conclusions. The lack of described ivermectin intoxication cases in veterinary clinic in this breed is explained by the lack of the mutation object of this study. The sequence studied in Cimarron dogs is kept compared to other breeds, except Collies and related breeds (Border Collie, Bearded Collie, Old English sheepdog).Objetivo. El propósito de este trabajo fue analizar la frecuencia de la mutación mdr1-1D del gen MDR1 en una muestra de perros de raza Cimarrón Uruguayo con el fin de profundizar en el conocimiento del genoma del animal. Materiales y métodos. Se analizaron treinta y seis animales de la raza mencionada. La región del gen MDR1 que incluiría la mutación se amplificó por PCR. Resultados. En los perros cimarrones analizados no se detectó la mutación mencionada. Conclusiones. La ausencia de la mutación estudiada explicaría el hecho de que no se hayan descrito casos de intoxicación por ivermectina en esta raza. La secuencia en el perro Cimarrón es conservada respecto de otras razas caninas, excepto Collie y sus derivadas

Experimental and modelling study of the interaction of bentonite with alkaline water

Compacted bentonite is planned to be used as buffer and backfill materials for the containment of radioactive waste in underground repositories. The performance of these barriers depends on the swelling capacity of bentonite upon hydration. Prolonged interaction between bentonite and alkaline fluids from neighbouring concrete structures can impair the swelling capacity due to profound changes in the chemical composition of bentonite. The coupled hydro-chemo-mechanical behaviour of bentonite under such conditions is at present not well understood. This paper presents for the first time a combined experimental and modelling study that addresses this coupled behaviour with the aim of understanding the key mechanisms leading to swelling pressure loss. Two experiments are presented in which compacted Wyoming bentonite was saturated with either clay or cementitious water, leading to different initial swelling capacities. The samples were subsequently subject to a flow of a KOH-rich cementitious water leading to a slow but sustained decrease in swelling pressure in both tests. The main novelty is the application of a recently developed hydro-chemo-mechanical model for bentonite for interpretation of the experiments. The model accounts for the impact of montmorillonite dissolution, cation exchange reactions, and changes in salinity on the swelling capacity of bentonite. The model results show a relatively good agreement with experimental measurements and suggest that the decrease in swelling capacity of bentonite is driven primarily by an increase in potassium fraction in the interlayer water and by montmorillonite dissolution

Inter-Laboratory Evaluation Of A Duplex RT-PCR Method Using Crude Extracts For The Simultaneous Detection Of Prune Dwarf Virus And Prunus Necrotic Ringspot Virus

The operational capacity of a duplex RT-PCR method for simultaneous detection of Prune dwarf virus (PDV) and Prunus necrotic ringspot virus (PNRSV) has been established by nine European laboratories. A total of 576 samples from Prunus trees with known sanitary status, corresponding to 32 samples in two repetitions for each laboratory, were analysed. The level of sensitivity achieved by the method was 98.3% for PDV and 90.4% for PNRSV. The specificity was 87.4% for PDV and 94.3% for PNRSV. The unilateral 95% confidence intervals were calculated for all these values. Cohen's Kappa coefficient of repeatability and reproducibility of the technique indicated a strong agreement between data. Likelihood ratios were 7.50 (positive) and 0.02 (negative) for PDV. For PNRSV, the positive likelihood ratio was 15.00 while the negative likelihood ratio was 0.11. In addition, post-test probabilities of infection were calculated to manage the risk associated with the routine use of this method. This allows an accurate test result interpretation to facilitate the integration of this new technique into a certification scheme