Cross-cultural adaptation of international students in Moroccan higher education: the case study of Sub-Saharan African students at Mohammed First University

Purpose – This article intends to explore the Sub-Saharan African students' perceptions on their cross-cultural adaptation to the Moroccan society by probing into their adaptive strategies adopted in order to overcome day-to-day challenges as well as factors impeding their adaptation processes. To this end, three central research questions are advanced: (1) what are the factors that influence Sub-Saharan students' cross-cultural adaptation to the Moroccan society? (2) How do Sub-Saharan students perceive the role of host communication competence, host interpersonal relationship, ethnic proximity, host receptivity and personality type in facilitating or hindering their adaptation? And (3) how do they undergo their cross-cultural adaptation to the Moroccan society? Design/methodology/approach – The main aim of this article is to explore African Sub-Saharan students' perceptions on their adaptation to Moroccan society as well as factors affecting their adaptive experiences. Due to the complex nature of this research, opting for mixed-methods research, the combination of both qualitative and quantitative, would best serve the objective of this study. For this purpose, qualitative methods (interviews) are used to collect non-numerical data about factors that facilitate or hinder the cross-cultural adaptation of Sub-Saharan students in Morocco in the first phase, and then quantitative methods (questionnaires) are used to collect numerical data about their perceptions of their adaptation in the Moroccan society in the second phase. Findings – The results of the present study revealed that a large number of Sub-Saran African students are well adapted to the Moroccan culture, but with discrepant degrees. Their adaptation is mainly influenced by an array of intersected factors. Firstly, the participants showed that the more they were aware of the Moroccan culture and language, the more likely they would be able to function properly and effectively in different social settings. Secondly, it was found that establishing social ties with the host members was perceived as significant for easing their adaptation due to the cultural, emotional and academic support these ties provided. Thirdly, host receptivity was perceived as an important factor that facilitated the students' cross-cultural adaptation. With the case of some participants, host receptivity, however, hindered their adaptation because they were subject to different types of discriminatory and racist behaviours by some Moroccans. Lastly, intercultural personality traits displayed in flexibility, prior cross-cultural move and intercultural empathy were found to contribute to the students' overall functional fitness in the Originality/value – This is the first research to tackle the issue of Sub-Saharan African students' cultural adaptation in Morocco

GPI anchor biosynthesis in yeast: phosphoethanolamine is attached to the α1,4-linked mannose of the complete precursor glycophospholipid

Cells synthesize the GPI anchor carbohydrate core by successively adding N-acetylglucosamine, three mannoses, and phosphoethanolamine (EtN-P) onto phosphatidylinositol, thus forming the complete GPI precursor lipid which is then added to proteins. Previously, we isolated a GPI deficient yeast mutant accumulating a GPI intermediate containing only two mannoses, suggesting that it has difficulty in adding the third, α1,2-linked Man of GPI anchors. The mutant thus displays a similar phenotype as the mammalian mutant cell line S1A-b having a mutation in the PIG-B gene. The yeast mutant, herein named gpi10-1, contains a mutation in YGL142C, a yeast homolog of the human PIG-B. YGL142C predicts a highly hydrophobic integral membrane protein which by sequence is related to ALG9, a yeast gene required for adding Man in α1,2 linkage to N-glycans. Whereas gpi10-1 cells grow at a normal rate and make normal amounts of GPI proteins, the microsomes of gpi10-1 are completely unable to add the third Man in an in vitro assay. Further analysis of the GPI intermediate accumulating in gpi10 shows it to have the structure Manα1-(EtNP-)Manα1-4G1cNα1-6(acyl)Inositol-P-lipid. The presence of EtN-P on the α1,4-linked Man of GPI anchors is typical of mammalian and a few other organisms but had not been observed in yeast GPI proteins. This additional EtN-P is not only found in the abnormal GPI intermediate of gpi10-1 but is equally present on the complete GPI precursor lipid of wild type cells. Thus, GPI biosynthesis in yeast and mammals proceeds similarly and differs from the pathway described for Trypanosoma brucei in several aspect

A new theta-type thermosensitive replicon from Lactoccocus lactis as an integration vector for Enterococcus faecalis

We isolated a replication thermosensitive mutant of the theta-type lactococcal pUCL22 replicon. An improved version of this thermosensitive replicon was obtained by fusioning the replication repA gene with the downstream repB gene. The resulting plasmid was named pUCB3522Ts. It is highly instable at 42°C in Enterococcus faecalis. Integration into the chromosome via homologous recombination was monitored using the npr gene of E. faecalis JH2-2 as a target. A 513 bp PCR amplification product from an internal region of this npr gene was cloned into pUCB3522Ts. Integration of this construction into the JH2-2 npr gene was selected by shift temperature, from 30°C to 42°C. 85% of the analysed clones showed integration into the npr gene, demonstrating the practicality of this thermosensitive replicon as a genetic integrative tool for E. faecali

The Extracytoplasmic Function Sigma Factor SigV Plays a Key Role in the Original Model of Lysozyme Resistance and Virulence of Enterococcus faecalis

Background: Enterococcus faecalis is one of the leading agents of nosocomial infections. To cause diseases, pathogens or opportunistic bacteria have to adapt and survive to the defense systems encountered in the host. One of the most important compounds of the host innate defense response against invading microorganisms is lysozyme. It is found in a wide variety of body fluids, as well as in cells of the innate immune system. Lysozyme could act either as a muramidase and/ or as a cationic antimicrobial peptide. Like Staphylococcus aureus, E. faecalis is one of the few bacteria that are completely lysozyme resistant. Results: This study revealed that oatA (O-acetyl transferase) and dlt (D-Alanylation of lipoteicoic acids) genes contribute only partly to the lysozyme resistance of E. faecalis and that a specific transcriptional regulator, the extracytoplasmic function SigV sigma factor plays a key role in this event. Indeed, the sigV single mutant is as sensitive as the oatA/dltA double mutant, and the sigV/oatA/dltA triple mutant displays the highest level of lysozyme sensitivity suggesting synergistic effects of these genes. In S. aureus, mutation of both oatA and dlt genes abolishes completely the lysozyme resistance, whereas this is not the case in E. faecalis. Interestingly SigV does not control neither oatA nor dlt genes. Moreover, the sigV mutants clearly showed a reduced capacity to colonize host tissues, as they are significantly less recovered than the parental JH2-2 strain from organs of mice subjected to intravenous or urinary tract infections

Identification of Peptidoglycan-Associated Proteins as Vaccine Candidates for Enterococcal Infections

Infections by opportunistic bacteria have significant contributions to morbidity and mortality of hospitalized patients and also lead to high expenses in healthcare. In this setting, one of the major clinical problems is caused by Gram-positive bacteria such as enterococci and staphylococci. In this study we extract, purify, identify and characterize immunogenic surface-exposed proteins present in the vancomycin resistant enterococci (VRE) strain Enterococcus faecium E155 using three different extraction methods: trypsin shaving, biotinylation and elution at high pH. Proteomic profiling was carried out by gel-free and gel-nanoLC-MS/MS analyses. The total proteins found with each method were 390 by the trypsin shaving, 329 by the elution at high pH, and 45 using biotinylation. An exclusively extracytoplasmic localization was predicted in 39 (10%) by trypsin shaving, in 47 (15%) by elution at high pH, and 27 (63%) by biotinylation. Comparison between the three extraction methods by Venn diagram and subcellular localization predictors (CELLO v.2.5 and Gpos-mPLoc) allowed us to identify six proteins that are most likely surface-exposed: the SCP-like extracellular protein, a low affinity penicillin-binding protein 5 (PBP5),a basic membrane lipoprotein, a peptidoglycan-binding protein LysM (LysM),a D-alanyl-D-alanine carboxypeptidase (DdcP) and the peptidyl-prolyl cis-trans isomerase (PpiC). Due to their close relationship with the peptidoglycan, we chose PBP5, LysM, DdcP and PpiC to test their potential as vaccine candidates. These putative surface-exposed proteins were overexpressed in Escherichia coli and purified. Rabbit polyclonal antibodies raised against the purified proteins were able to induce specific opsonic antibodies that mediated killing of the homologous strain E. faecium E155 as well as clinical strains E. faecium E1162, Enterococcus faecalis 12030, type 2 and type 5. Passive immunization with rabbit antibodies raised against these proteins reduced significantly the colony counts of E. faecium E155 in mice, indicating the effectiveness of these surface-related proteins as promising vaccine candidates to target different enterococcal pathogens

Occurrence of Bacterial Pathogens and Human Noroviruses in Shellfish-Harvesting Areas and Their Catchments in France

During a 2-year study, the presence of human pathogenic bacteria and noroviruses was investigated in shellfish, seawater and/or surface sediments collected from three French coastal shellfish-harvesting areas as well as in freshwaters from the corresponding upstream catchments. Bacteria isolated from these samples were further analyzed. Escherichia coli isolates classified into the phylogenetic groups B2, or D and enterococci from Enterococcus faecalis and E. faecium species were tested for the presence of virulence genes and for antimicrobial susceptibility. Salmonella members were serotyped and the most abundant serovars (Typhimurium and its monophasic variants and Mbandaka) were genetically characterized by high discriminative subtyping methods. Campylobacter and Vibrio were identified at the species level, and haemolysin-producing Vibrio parahaemolyticus were searched by tdh- and trh- gene detection. Main results showed a low prevalence of Salmonella in shellfish samples where only members of S. Mbandaka were found. Campylobacter were more frequently isolated than Salmonella and a different distribution of Campylobacter species was observed in shellfish compared to rivers, strongly suggesting possible additional inputs of bacteria. Statistical associations between enteric bacteria, human noroviruses (HuNoVs) and concentration of fecal indicator bacteria revealed that the presence of Salmonella was correlated with that of Campylobacter jejuni and/or C. coli as well as to E. coli concentration. A positive correlation was also found between the presence of C. lari and the detection of HuNoVs. This study highlights the importance of simultaneous detection and characterization of enteric and marine pathogenic bacteria and human noroviruses not only in shellfish but also in catchment waters for a hazard assessment associated with microbial contamination of shellfish

Role of mprF1 and mprF2 in the Pathogenicity of Enterococcus faecalis

Aujourd hui, Enterococcus faecalis est considéré comme l un des plus importants agents pathogènes causant des maladies nosocomiales. En raison de sa résistance innée et acquise aux antibiotiques, l identification de nouvelles cibles pour le traitement de cette bactérie est une grande priorité. Le facteur Multiple Peptide Résistance (MprF), qui a été décrit en premier chez Staphylococcus aureus, modifie le phosphatidylglycérol avec de la lysine et réduit ainsi la charge négative de l enveloppe cellulaire. Ceci a comme conséquence d augmenter la résistance aux peptides antimicrobiens cationiques (PAC). Deux gènes paralogues putatifs (mprF1 et mprF2) ont été identifiés chez E. faecalis par recherche BLAST en utilisant le gène décrit chez S. aureus. Une caractérisation de ces deux gènes d E. faecalis ainsi que des mécanismes conduisant à une résistance aux PAC, pourrait aider à développer des nouvelles stratégies thérapeutiques contre ce pathogène. Deux mutants de délétion et un double mutant ont été construits par recombinaison homologue chez E. faecalis. L analyse des phospholipides des membranes cytoplasmiques des deux mutants mprF1 et mprF2 par chromatographie sur couche mince a montré que seule l inactivation de mprF2 inhibe la synthèse de trois amino-phosphatidlyglycérol distincts (comme la Lysine-PG, l Alanine-PG et l Arginine-PG). De plus, le mutant mprF2 est également plus sensible aux PAC que la souche sauvage. La capacité de formation d un biofilm est généralement considérée comme un facteur important de virulence, ce qui est également le cas pour les entérocoques. Le mutant mprF2 montre une capacité accrue dans ce phénomène. Ceci semble être du à une augmentation de la concentration d ADN extracellulaire dans le biofilm formé par ce mutant. Curieusement, cette augmentation est indépendante d une autolyse. Le mutant mprF2 est également plus résistant à l opsonophagocytose. Cependant, le gène mprF2 ne joue aucun rôle dans les bactériémies de souris et les endocardites de rats.En revanche, aucun phénotype n a été trouvé pour un mutant mprF1 jusqu à présent. Cette mutation ne modifie ni la synthèse de l aminoacyl-PG en condition de laboratoire ni la résistance aux PAC et à l opsonophagocytose. Par conséquent, il semble que mprF2 soit le seul gène mprF fonctionnel chez E. faecalis. Néanmoins, contrairement à d autres bactéries, mprF2 ne semble pas être un facteur de virulence majeur pour cette espèce.Enterococcus faecalis is regarded nowadays as one of the most important nosocomial pathogens. Due to its innate and acquired resistance to antibiotics, identification of new targets for antimicrobial treatment of E. faecalis is a high priority. The multiple peptides resistance factor (MprF), which was first described in Staphylococcus aureus, modifies phosphatidylglycerol with lysine and reduces the negative charge of the membrane, thus increasing resistance to cationic antimicrobial peptides (CAMPs). Two putative mprF paralogs (mprF1 and mprF2) were identified in E. faecalis by Blast search using the well-described S. aureus gene as a lead. A better understanding of these two genes and mechanisms leads to enterococcal resistance to CAMPs might help designing therapeutic strategies against this bacteria. Two single deletion mutants and double mutant in E. faecalis were created by homologues recombination. Analysis of cell membrane phospholipids from both mutants by thin-layer chromatography showed that inactivation of mprF2 abolished the synthesis of three distinct amino-phosphatidylglycerol (mostly likely Lysin-PG, Alanine-PG and Argine-PG). The CAMPs testing assay demonstrated that the deletion mutant of mprF2 was more susceptible to CAMPs than the wild type. Biofilm formation is usually regarded as a virulence factor which provides an important way for enterococci to cause infections. Inactivation of mprF2 led to increase the biofilm formation which we showed that it was due to the accumulation of eDNA in the biofilm, but the release of eDNA is independent from autolysis. The mprF2 mutant was resistance to killing by opsonophagocytosis more than wild type. However, the mprF2 gene plays no role in bacteremia in mice and rat endocarditis. Our results showed that non polar effect mprF1 mutant does not affect in the synthesis of aminoacyl-PG in the laboratory condition. It also has no effect on susceptible to CAMPs, opsonic killing and autolysis. Therefore, it seems that mprF2 is the only functional mprF gene in E. faecalis in the laboratory condition. Unlike mprF found in other bacteria, mprF does not seem to be a major virulence factor in enterococci.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Large-Scale Screening of a Targeted Enterococcus faecalis Mutant Library Identifies Envelope Fitness Factors

Spread of antibiotic resistance among bacteria responsible for nosocomial and community-acquired infections urges for novel therapeutic or prophylactic targets and for innovative pathogen-specific antibacterial compounds. Major challenges are posed by opportunistic pathogens belonging to the low GC% Gram-positive bacteria. Among those, Enterococcus faecalis is a leading cause of hospital-acquired infections associated with life-threatening issues and increased hospital costs. To better understand the molecular properties of enterococci that may be required for virulence, and that may explain the emergence of these bacteria in nosocomial infections, we performed the first large-scale functional analysis of E. faecalis V583, the first vancomycin-resistant isolate from a human bloodstream infection. E. faecalis V583 is within the high-risk clonal complex 2 group, which comprises mostly isolates derived from hospital infections worldwide. We conducted broad-range screenings of candidate genes likely involved in host adaptation (e.g., colonization and/or virulence). For this purpose, a library was constructed of targeted insertion mutations in 177 genes encoding putative surface or stress-response factors. Individual mutants were subsequently tested for their i) resistance to oxidative stress, ii) antibiotic resistance, iii) resistance to opsonophagocytosis, iv) adherence to the human colon carcinoma Caco-2 epithelial cells and v) virulence in a surrogate insect model. Our results identified a number of factors that are involved in the interaction between enterococci and their host environments. Their predicted functions highlight the importance of cell envelope glycopolymers in E. faecalis host adaptation. This study provides a valuable genetic database for understanding the steps leading E. faecalis to opportunistic virulence

Etude des facteurs sigma de fonction extracytoplasmique (ECF) et leur lien avec la résistance au lysozyme et la virulence chez Enterococcus faecalis ([thèse soutenue sur un ensemble de travaux])

Enterococcus faecalis est une bactérie lactique commensale de la flore gastro-intestinale des hommes et des animaux. Au cours de ces deux dernières décennies, elle a émergé comme une cause majeure d infections nosocomiales. Pour provoquer une infection, cette bactérie doit être capable de contourner les défenses de l hôte. Un des composés les plus importants et les plus répandus de l'arsenal anti infectieux des vertébrés est le lysozyme. Une méthode commune d'adaptation au stress chez les bactéries repose sur l utilisation de facteurs sigma alternatifs par l ARN polymérase. Parmi eux, les facteurs sigma de fonction extracytoplasmique (ECF) constituent un groupe distinct, dédié à la réponse aux stress environnementaux et éventuellement au processus infectieux. Dans ce travail, nous avons entrepris de caractériser les facteurs sigma ECF SigV, SigX et SigG d E. faecalis, ainsi que les causes de sa forte résistance au lysozyme. Nous avons mis en évidence que ce germe possède un mécanisme original de résistance au lysozyme où SigV joue un rôle majeur. De plus, SigV est également impliqué de façon importante dans la virulence d E. faecalis, établissant ainsi un lien direct avec la résistance au lysozyme. En absence d'un régulateur de la réponse générale au stress chez E. faecalis, il apparaît que SigV peut remplir ce rôle, du moins en partie. Les facteurs SigX et SigG contribuent modérément à la réponse aux stress et à la virulence d E. faecalis. Ils sont respectivement impliqués dans la résistance au pH acide et au choc thermique.The lactic acid bacterium Enterococcus faecalis is a commensal member of human and animal flora of the gastro-intestinal tract. Over the past two decades, E. faecalis has emerged as an opportunistic pathogen and one of the leading causes of nosocomial infections. In fact, problems occur when this organism gains access to sites it does not normally colonize. To cause diseases, opportunistic bacteria have to adapt and survive to the defence systems encountered within the host. One of the most important and widespread compounds of the host innate defence response against invading microorganisms is the lysozyme. A common method of adaptation to stress in bacteria is to switch the sigma factor used by the core RNA polymerase. The extracytoplasmic function (ECF) sigma factors constitute a distinct group of alternative sigma factors, which regulate gene expression in response to environnemental stress and pathogenesis. This study aimed to characterize the ECF sigma factors SigV, SigX and SigG of E. faecalis. It is assumed that E. faecalis is one of the few bacteria that are completely lysozyme resistant. In our work, we investigated the causes of this abnormal lysozyme resistance. Evidence was found that E. faecalis displays an original model of lysozyme resistance mechanism in which SigV plays a key role. SigV is also importantly involved in virulence of E. faecalis. Thereby, in absence of a general stress response regulator in the genome sequence of E. faecalis, it appears that SigV can fulfil this role at least in part. This work revealed also the involvement of SigX and SigG, respectively in acid pH and heat shock treatments, and both contribute moderately to the virulence.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Étude de la résistance au lysozyme chez Enterococcus faecalis

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF