Exploring Quorum Sensing Dynamics and Biofilm Formation in the Fish Pathogen Aliivibrio salmonicida

The marine pathogen Aliivibrio salmonicida is the causative agent of cold-water vibriosis, affecting mainly farmed salmonid fish when water temperatures are below 10°C. Even though cold-water vibriosis is no longer threatening Norwegian aquaculture, the reemergence of the disease is still a possibility. Therefore, it is crucial to gain knowledge and understanding of the pathogenicity of A. salmonicida. Quorum sensing (QS) is one of the communication systems used by bacteria to regulate gene expression in a synchronized way in response to cell density by secreting and sensing extracellular signals called autoinducers (AIs). QS system controls various physiological processes, particularly virulence system and biofilm formation in many pathogenic bacteria. With the increased emergence of antibiotic-resistant in recent years, understanding and targeting QS system is expected to bring potential new breakthroughs for the prevention and treatment of Vibrio infections. The present work was initiated to increase the knowledge on the QS system and its regulation on phenotypic traits that may be important for survival and host-pathogen interaction in A. salmonicida. Alternative sigma factors such as RpoS provide the main line of responses to changes in the environment by altering gene transcription. In several vibrios, RpoS has been shown to be connected to QS system. The obtained results in this thesis, clearly indicate that an RpoS-like sigma factor, RpoQ (VSAL_II0319) is a component of the QS system and involved in regulating colony rugosity, biofilm formation, and motility in a cell density dependent manner. The transcriptomics analysis further revealed that RpoQ is involved in influencing expression of a large panel of genes including the syp operon involved in polysaccharide production. This suggests that the downregulation of biofilm development and wrinkled colony phenotype were due to RpoQ-dependent repression on polysaccharide biosynthesis genes (syp genes) at high cell density. In addition to cell density dependent control on biofilm formation and colony rugosity through QS, temperature was shown to influence the regulation of RpoQ on these phenotypes, linking this environmental factor to the development of cold-water vibriosis in seawater at low temperatures. Previous reports have shown that A. salmonicida possesses two functional autoinducer synthases, the LuxI and AinS, which are responsible for the production of eight acyl homoserine lactones (AHLs). In this thesis, the inactivation of luxI, but not ainS, led to the formation of wrinkled colonies similar to those formed by the ΔrpoQ mutant. The transcriptome analysis showed that LuxI is required for repression of syp expression, where repression of syp is likely operated through the RpoQ sigma factor. When both systems were inactivated simultaneously, strains (ΔainSluxI−) with wrinkled colonies and mushroom structured biofilm were formed. Furthermore, the exogenous addition of either LuxI, N-3-oxo-hexanoyl-L-homoserine lactone (3OC6-HSL) or AinS, N-3-hydroxy-decanoyl-L-homoserine lactone (3OHC10-HSL), to the ΔainSluxI- double mutant, inhibited biofilm development. This suggested that the downregulation of biofilm formation is operated through a common pathway when the AHL concentrations are high. The results presented in this work, add new knowledge about the nature of the QS mechanism of A. salmonicida and elucidate some aspects of the complex mechanism of biofilm formation, contributing to advancement of research in this field

Preparation, Characterization and Biological Evaluation of some Lanthanide (ΙΙΙ) ions Complexes with 3-(1-methyl-2-benzimidazolylazo)-Tyrosine

A series of lanthanide metal (???) complexes have been prepared from the new azo ligand, 3-(1-methyl-2-benzimidazolylazo)-Tyrosine (MBT). The structural feature were confirmed on the basis of their elemental analysis, metal content, molar conductance, magnetic measurement, FTIR, 1 HNMR and UV-Vis spectra studies. The isolated complexes were found to have a mole ratio (1:2) (metal:ligand) stoichiometry with the general formula [Ln(MBT)2]Cl (Ln(???) = La, Ce, Pr, Nd, Sm, Eu and Gd). The chelates were found to have octahedral structures. The FTIR spectra shows that the ligand (MBT) is coordinated to lanthanide ions as a N, N, O-tridentate anion via benzimidazole nitrogen, azo nitrogen and oxygen of hydroxyl after deprotonation. Complexes formation in solution were performed after fixing the optimum pH, molar concentration and time. Beer's low was obeyed over a range (7-9x10-5) with high molar absorptivity for all the prepared complexes solutions. Stability Constant and Gibbis free energy were also determined. The ligand (MBT) and its prepared complexes were screened invitro against two types of selected bacteria

An Investigation of the Most Common Spelling Errors in English Writing Committed by English-Major Male Students: At the University of Tabuk

The objective of the present study is to investigate the spelling errors committed by the Saudi English- major students (male) who are majoring English language at Department of Language and translationat the University of Tabuk, Saudi Arabia. This study adopts Cook‘s classification of errors, which categorized errors into four categories: substitution, omission, insertion, and transposition. The participants of this study included 45 male students whose first language is Arabic. The researcher used one research instrument which is the written composition essay. An analysis of errors established that errors of substitution reported (36.7%) constituting the highest proportion of errors whereas insertion spelling errors occur as the lesser frequency with a percentage mean of (14.4.%) producing13 errors. The major cause of the of learners‘ spelling errors is the wrong use of vowels and pronunciation as well as mother tongue interference. The findings of this study emphasized more focused attention to learners‘ spelling errors, as spelling teaching is an essential aspect of language learning. Keywords: Writing Spelling Error, Omission Errors, Substitution Errors, Transposition Errors, Insertion Errors

La régionalisation, nouveau mode de gouvernance du système de santé : état des lieux pour le cas du Maroc

L’impératif de l’articulation des procédés du développement humain nous mène à mettre en relief les différentes visions de la gouvernance de santé au Maroc. La régionalisation de la santé constitue une opportunité pour le pays de promouvoir le développement humain. Dans cet article, l’intérêt sera porté tout d’abord sur la notion de la régionalisation des systèmes de santé. En se focalisant sur le cas marocain, il s’agira de présenter ensuite l’évolution de ce processus ainsi qu’un bilan régional en termes de performance sanitaire. Pour conclure, le papier s’interroge sur les perspectives et les conditions nécessaires pour que ce mécanisme de gouvernance puisse être un levier de l’amélioration de la santé des populations dans les différentes régions du pays. The imperative of articulating human development processes leads us to highlight the different visions of health governance in Morocco. The regionalization of the Moroccan health system is an opportunity for the country to promote human development. In this article, interest will first be focused on the notion of regionalisation of health systems. Focusing on the Moroccan case, the evolution of this process is presented as well as a regional assessment in terms of health performance. To conclude, the paper questioned the necessary perspectives and conditions for this governance mechanism to be a lever for improving the health of populations in the different regions of the country

Potential of aqueous extracts of Allium sativum, Mentha spicata, Myrtus communis and Thymus vulgaris as antimicrobials and curing of antibiotic resistant genes in Klebsiella pneumoniae / Adel Kamal Khider and Sazan Qadir Mawlud

Eighty six clinical isolates of Klebsiella pneumoniae were isolated from various pathogenic cases from Erbil hospitals. The isolates were varied in their resistance to antibiotics, and ranged between 13-18 antibiotics out of 22. Genetic transformation between purified plasmid from K. pneumoniae and E. coli JM83 demonstrated that all tested antibiotic resistant genes were plasmid DNA born except Doxycilin resistance gene was chromosomal born. The watery extracts of Allium sativum, Mentha spicata Myrtus communis and Thymus vulgaris were proved to be most powerful against K. pneumoniae K11 and K32 isolates. A comparative evaluation of plasmids elimination from K. pneumoniae isolates by sub-MIC of plant extracts showed that these extracts could cure plasmids effectively at their respective sub-MIC concentration. Plasmid cured was observed by sub-MIC of Allium sativum and Thymus vulgaris at 350 µg ml-1 cured 2, 4 and 3 plasmids, Mentha spicata and Myrtus communis extract at 250 µg ml-1cured 2, 3 and 2, 4 plasmids from K. pneumoniae K11 and K32 isolates. Curing of plasmid DNA from K. pneumoniae isolates confirmed by determining the loss of resistance markers in cured cultures

ANALYSE MULTI FRACTALE DES ÉCHOS RADAR PAR LA MÉTHODE DES MAXIMUMS DES MODULES DE LA TRANSFORMÉE EN ONDELETTE (MMTO) 2D POUR LES SITES DE BORDEAUX (FRANCE), SÉTIF (ALGÉRIE) : APPLICATION À L'ÉLIMINATION DES ÉCHOS PARASITES

International audienceIn this work, the 2D-WTMM multifractal approach was applied to analysis the radar echoes, and to identify the unwanted echoes coming from terrestrial surface. With this intention, we considered radar images taken from two areas where different climates and relief prevail. We showed that almost Anaprops are characterized by a monofractal spectrum contrary to the echoes of precipitations which present a multifractal character. Moreover, we showed that the Holder coefficient and the combination of the spectrum mode and density of skeleton per pixel present robust factors to discriminate between the two types of echoes. Indeed, the unwanted echoes are practically eliminated at 98 per cent whereas the echoes of precipitation are almost preserved at 98,2 per cent. Also, we showed that the error between the measured intensity on the ground and the estimated intensity after treatment of the unwanted echoes does not exceed 5% for the Sétif site. Because the computation time is three minutes, the radar images can be processed in real-time.Dans le présent travail, l'approche MMTO-2d est appliquée pour l'analyse multi fractale des échos radar et l'identification des échos parasites en provenance de la surface terrestre. Pour ce faire, nous avons considéré des images radar prises dans deux régions où prévalent des climats et des reliefs différents. Il s'agit des sites de Sétif (Algérie) et Bordeaux (France). Nous avons montré que la plupart des Anaprops sont caractérisés par un spectre monofractal contrairement aux échos de précipitations qui présentent un caractère multi fractal. En outre, nous avons montré que le coefficient d'Holder ou la combinaison mode du spectre et densité de squelette par pixel se présentent comme des facteurs robustes de discrimination entre les deux types d'échos. En effet, les échos parasites sont pratiquement éliminés à 98% alors que les échos de précipitation sont quasiment conservés à 98,2%. Aussi, nous avons montré que l'erreur entre l'intensité mesurée au sol et estimée après traitement des échos parasites ne dépasse pas 5% pour le site de Sétif. Etant donné que le temps de traitement est égal à trois minutes, les images radar peuvent être traitées en temps réel

Mapping Groundwater Levels in Erbil Basin

In the Erbil Basin, which is located in Kurdistan Region at northern part of Iraq, several production wells have been selected for monthly monitoring of groundwater levels. The continuous depletion of groundwater levels has been recorded due to uncontrolled exploitation from both legal and illegal wells that poses a major problem in selected Basin, which is classified as arid and semi-arid regions. Accurate prediction of groundwater depth and elevation maps is crucial for the development of effective groundwater management strategies in the aquifer system of the area. Depth to groundwater measures for each of the 55 wells that distributed across the North, Central, and South sub-basins of Erbil, also mapped and compared with wells data that are recorded periodically by the Directorate of Erbil Groundwater. The methodology of this study is involved mapping groundwater tables for the measured wells in (2022) with surveying wells coordinates as field observations, and compare with data of groundwater tables in (2004) that archived by groundwater directorate. This study employs high-accuracy surveying techniques for the selected wells and utilizes geographic information systems (GIS) as a successful tool for mapping groundwater levels using both Kriging and IDW interpolation methods. The results are indicated successfully that groundwater tables have sudden drawdown during these (18) years, the main reasons behind that is drilling numerous wells without planning and lack of management of the wells system in the study area. Meanwhile, Erbil basin required better planning and management of groundwater resources. The study concludes that there is lack in groundwater management need to keep the sustainability of this vital resources, and observing monthly groundwater levels need to be connected with high accuracy sensor inside observation wells not manually measuring groundwater levels by damaged sounders. Unfortunately, there is no observation wells inside Erbil basin, the recorded data are within production wells that cannot represent as actual levels of the groundwater. The main objective of this study is to present the actual problems in the study area by create the maps of the groundwater table for the selected basin and to be used as a basic plan in developing strategies for effective management and planning of Erbil groundwater resources. And also employed to protect aquifer storage and prevent depletion of groundwater resources

Dynamic Response of Historical Masonry Minaret under Seismic Excitation

In order to study the dynamic response of historical masonry structures, a scaled down brick masonry model constructed in civil engineering department at Baghdad University to simulate a part of a real case study, which is Alkifil historic minaret. Most of the previous researches about masonry structures try to understand the behavior of the masonry under seismic loading by experimental and numerical methods. In this paper, the masonry units (bricks) simulated in scale (S= 1/6) with the exact shape of the prototype bricks. Cementitious tile adhesive was selected to be the mortar for the modeling. The height of the model designed to be 1.5 m with a 0.5 m diameter. Detailed construction steps were presented in this paper. Experts built the model with high accuracy. A shaking table and other dynamic testing facilities were used at the University of Baghdad. The model was tested using the time-compressed El Centro 1940 NS earthquake at different amplitudes. The first ground motion of (PGA= 0.05g) which considered as weak ground motion was used to check the adequacy of the conventional behavior of the masonry model and the limit of the elastic behavior of the model during weak earthquakes. Moderate ground motion (PGA=0.15g) was performed to investigate the response of the model with minor to moderate damages. The severe ground motions were not appropriate to use in such circumstances because of the possibility to overturn the model. The experimental results showed very adequacy of the model to withstand the weak and moderate earth motion with no observed cracks