The Knowledge and Practices Toward Food Safety Measures at Home in the Lebanese Community.

Hygienic measures practiced at home are highly related to the occurrence of food-borne diseases during food production, storage, and handling. Contaminated food remains a major cause of several diarrheal diseases, hospitalizations, and spikes in medical expenses. In our current study, we aimed to assess the knowledge of food safety and the food safety and hygiene practices at home among the Lebanese population. A cross-sectional study was conducted through an online questionnaire including two sections. The first section included socio-demographic characteristics of participants, whereas the second section included questions related to practices and knowledge about food safety, divided into five parts; personal hygiene practices, dry and cold storage, sanitizing and cleaning and food intoxication. A total of 1101 Lebanese above 18 years participated and provided their responses to the questionnaire. Overall, the majority of participants had fair knowledge about food safety where 96.8% of the participants answered correctly about preventing microbial growth on food. 77.9% of those participants acquired their knowledge about food safety from articles, workshops, or the internet. Moreover, females, people with children and those who cook for themselves scored significantly higher than others (68.8, 70.6, and 70%, respectively). In comparison to younger participants (67.8%), older participants (50+ and 30-49) scored higher at 69.7% and 68.9%, respectively. Higher scores were obtained for questions related to storing dried foods/meat and poultry products with percentages 91.4 and 87.8%, respectively. However, lower scores were noticed on questions related to washing raw chicken before handling and storing eggs (9.7 and 12.3%, respectively). Altogether, our results revealed the need for directed food safety awareness campaigns at the national level to educate the Lebanese community about domestic food handling practices. We believe these campaigns can significantly reduce related diseases and hospitalizations.

Social media addiction in university students in Lebanon and its effect on student performance.

Objective: This study aims to assess addiction to social media among university students and to explore the association of addiction to social media with academic performance. Methods: A random sample of 997 university students filled in a self-administered questionnaire using Google form (response rate 81%). The questionnaire adopted a validated scale (Social Media Addiction Scale, SMAS) and included questions about socio-demographics. Grade point average, absences, and passing rate were extracted for each student from the university management system. Results: Results showed that each of the three dimensions of addiction to social media (compulsive feelings, social consequences and time displacement) reduce at least one indicator of academic performance (GPA, absenteeism and passing rate). Conclusion: Results call to design and evaluate interventions that tackle different social media addiction dimensions to reduce their negative impact on academic performance.

Knowledge, attitude and practices related to COVID-19 among young Lebanese population.

BACKGROUND: As the world faces the most serious and widespread pandemic in recent history, claiming nearly 1,945,610 lives and infecting over 90 million individuals up to January 13, 2021, controlling the spread of COVID-19 is still limited to efforts done by the general population implementing rules and restrictions passed by world governments and organizations. As we wait for the approved vaccines to become widely distributed, the best approach to fighting the spread of this disease is mostly preventative depending largely on individuals' compliance. This study aimed to determine the knowledge, attitude and practices (KAP) towards COVID-19 in Lebanon. METHODS: A descriptive analysis was performed to describe the outcome measures of knowledge, attitudes and practices towards COVID-19 on a convenience sample from the Lebanese population in relation to socio-demographic characteristics and level of concern towards COVID-19. One thousand eight hundred sixty-one participants filled in an online survey (response rate: 18.5%) distributed by social media to social networks of the research team members. RESULTS: Participants were mainly young (49.4% between 18 and 24 years) and males (73.7%). Participants showed an overall appropriate knowledge of COVID-19 (67.1%) and positive attitude (around 90% were optimistic about treatment and vaccination) and had good preventive practices towards COVID-19 (around 75% washed hands and avoided public places). Knowledge and practices correlated positively with marriage, age, education, working in a healthcare field and with the level of concern about getting COVID-19. CONCLUSIONS: This study found good overall levels of KAP among the studied Lebanese population. This can help in controlling the spread of COVID-19 if individuals were forced to adhere to social distancing and appropriate preventative practices.

Antibiotic use and resistance: an unprecedented assessment of university students' knowledge, attitude and practices (KAP) in Lebanon.

BACKGROUND: The emergence and spread of pathogenic bacteria that is resistant to antibiotics has become a major public health concern. The incorrect prescription, inappropriate consumption and excess use of antimicrobial drugs, specifically antibiotics, are possibly the main factors contributing to the widespread of antibiotic resistant bacteria. This study aims to evaluate the knowledge, attitude and practices (KAP) towards the use of antibiotics as well as their resistance among Lebanese university students in health and non-health related majors. METHODS: This cross-sectional study was conducted between May and June 2019 in Beirut (Lebanon) in which 750 students completed a questionnaire made up of four dimensions: Socio-demographic characteristics, 3 questions; assessment of knowledge, attitude and practices, 7, 10 and 1 question, respectively. The data was collected in spreadsheets and analysed with descriptive statistics. The difference in mean scores in each of the knowledge, attitude and practices dimensions between health and non-health related major students was analysed using t-student tests and the difference in percentages using chi-square tests. RESULTS: Almost 78% of respondents from the health related majors scored high knowledge compared to only 41% of non-health related majors (mean = 4.26; standard error = 0.05 versus mean = 3.41; standard error = 0.13, respectively). The attitude score of the health related major students (35.42%) was positive and more satisfactory compared to the non-health related students (7.32%); (mean = 9.34; standard error = 0.05 versus mean = 9.10; standard error = 0.21, respectively). However, the difference in the scores of attitudes was not statistically significant. CONCLUSIONS: Interventions to promote awareness in this area should focus more students in on non-health related majors.

First proteomic study of S-glutathionylation in cyanobacteria.

Glutathionylation, the reversible post-translational formation of a mixed disulfide between a cysteine residue and glutathione (GSH), is a crucial mechanism for signal transduction and regulation of protein function. Until now this reversible redox modification was studied mainly in eukaryotic cells. Here we report a large-scale proteomic analysis of glutathionylation in a photosynthetic prokaryote, the model cyanobacterium Synechocystis sp. PCC6803. Treatment of acellular extracts with N,N-biotinyl glutathione disulfide (BioGSSG) induced glutathionylation of numerous proteins, which were subsequently isolated by affinity chromatography on streptavidin columns and identified by nano LC-MS/MS analysis. Potential sites of glutathionylation were also determined for 125 proteins following tryptic cleavage, streptavidin-affinity purification, and mass spectrometry analysis. Taken together the two approaches allowed the identification of 383 glutathionylatable proteins that participate in a wide range of cellular processes and metabolic pathways such as carbon and nitrogen metabolisms, cell division, stress responses, and H2 production. In addition, the glutathionylation of two putative targets, namely, peroxiredoxin (Sll1621) involved in oxidative stress tolerance and 3-phosphoglycerate dehydrogenase (Sll1908) acting on amino acids metabolism, was confirmed by biochemical studies on the purified recombinant proteins. These results suggest that glutathionylation constitutes a major mechanism of global regulation of the cyanobacterial metabolism under oxidative stress conditions.

The Synechocystis PCC6803 MerA-like enzyme operates in the reduction of both mercury and uranium under the control of the glutaredoxin 1 enzyme.

In a continuing effort to analyze the selectivity/redundancy of the three glutaredoxin (Grx) enzymes of the model cyanobacterium Synechocystis PCC6803, we have characterized an enzyme system that plays a crucial role in protection against two toxic metal pollutants, mercury and uranium. The present data show that Grx1 (Slr1562 in CyanoBase) selectively interacts with the presumptive mercuric reductase protein (Slr1849). This MerA enzyme plays a crucial role in cell defense against both mercuric and uranyl ions, in catalyzing their NADPH-driven reduction. Like MerA, Grx1 operates in cell protection against both mercury and uranium. The Grx1-MerA interaction requires cysteine 86 (C86) of Grx1 and C78 of MerA, which is critical for its reductase activity. MerA can be inhibited by glutathionylation and subsequently reactivated by Grx1, likely through deglutathionylation. The two Grx1 residues C31, which belongs to the redox active site (CX(2)C), and C86, which operates in MerA interactions, are both required for reactivation of MerA. These novel findings emphasize the role of glutaredoxins in tolerance to metal stress as well as the evolutionary conservation of the glutathionylation process, so far described mostly for eukaryotes.

The AbrB2 autorepressor, expressed from an atypical promoter, represses the hydrogenase operon to regulate hydrogen production in Synechocystis strain PCC6803.

We have thoroughly investigated the abrB2 gene (sll0822) encoding an AbrB-like regulator in the wild-type strain of the model cyanobacterium Synechocystis strain PCC6803. We report that abrB2 is expressed from an active but atypical promoter that possesses an extended -10 element (TGTAATAT) that compensates for the absence of a -35 box. Strengthening the biological significance of these data, we found that the occurrence of an extended -10 promoter box and the absence of a -35 element are two well-conserved features in abrB2 genes from other cyanobacteria. We also show that AbrB2 is an autorepressor that is dispensable to cell growth under standard laboratory conditions. Furthermore, we demonstrate that AbrB2 also represses the hox operon, which encodes the Ni-Fe hydrogenase of biotechnological interest, and that the hox operon is weakly expressed even though it possesses the two sequences resembling canonical -10 and -35 promoter boxes. In both the AbrB2-repressed promoters of the abrB2 gene and the hox operon, we found a repeated DNA motif [TT-(N(5))-AAC], which could be involved in AbrB2 repression. Supporting this hypothesis, we found that a TT-to-GG mutation of one of these elements increased the activity of the abrB2 promoter. We think that our abrB2-deleted mutant with increased expression of the hox operon and hydrogenase activity, together with the reporter plasmids we constructed to analyze the abrB2 gene and the hox operon, will serve as useful tools to decipher the function and the regulation of hydrogen production in Synechocystis.

SecB-like chaperone controls a toxin-antitoxin stress-responsive system in Mycobacterium tuberculosis.

A major step in the biogenesis of newly synthesized precursor proteins in bacteria is their targeting to the Sec translocon at the inner membrane. In gram-negative bacteria, the chaperone SecB binds nonnative forms of precursors and specifically transfers them to the SecA motor component of the translocase, thus facilitating their export. The major human pathogen Mycobacterium tuberculosis is an unusual gram-positive bacterium with a well-defined outer membrane and outer membrane proteins. Assistance to precursor proteins by chaperones in this bacterium remains largely unexplored. Here we show that the product of the previously uncharacterized Rv1957 gene of M. tuberculosis can substitute for SecB functions in Escherichia coli and prevent preprotein aggregation in vitro. Interestingly, in M. tuberculosis, Rv1957 is clustered with a functional stress-responsive higB-higA toxin-antitoxin (TA) locus of unknown function. Further in vivo experiments in E. coli and in Mycobacterium marinum strains that do not possess the TA-chaperone locus show that the severe toxicity of the toxin was entirely inhibited when the antitoxin and the chaperone were jointly expressed. We found that Rv1957 acts directly on the antitoxin by preventing its aggregation and protecting it from degradation. Taken together, our results show that the SecB-like chaperone Rv1957 specifically controls a stress-responsive TA system relevant for M. tuberculosis adaptive response.

Lon protease quality control of presecretory proteins in Escherichia coli and its dependence on the SecB and DnaJ (Hsp40) chaperones.

Various environmental insults result in irreversible damage to proteins and protein complexes. To cope, cells have evolved dedicated protein quality control mechanisms involving molecular chaperones and proteases. Here, we provide both genetic and biochemical evidence that the Lon protease and the SecB and DnaJ/Hsp40 chaperones are involved in the quality control of presecretory proteins in Escherichia coli. We showed that mutations in the lon gene alleviate the cold-sensitive phenotype of a secB mutant. Such suppression was not observed with either clpP or clpQ protease mutants. In comparison to the respective single mutants, the double secB lon mutant strongly accumulates aggregates of SecB substrates at physiological temperatures, suggesting that the chaperone and the protease share substrates. These observations were extended in vitro by showing that the main substrates identified in secB lon aggregates, namely proOmpF and proOmpC, are highly sensitive to specific degradation by Lon. In contrast, both substrates are significantly protected from Lon degradation by SecB. Interestingly, the chaperone DnaJ by itself protects substrates better from Lon degradation than SecB or the complete DnaK/DnaJ/GrpE chaperone machinery. In agreement with this finding, a DnaJ mutant protein that does not functionally interact in vivo with DnaK efficiently suppresses the SecB cold-sensitive phenotype, highlighting the role of DnaJ in assisting presecretory proteins. Taken together, our data suggest that when the Sec secretion pathway is compromised, a pool of presecretory proteins is transiently maintained in a translocation-competent state and, thus, protected from Lon degradation by either the SecB or DnaJ chaperones.

Relationship among several key cell cycle events in the developmental cyanobacterium Anabaena sp. strain PCC 7120.

When grown in the absence of a source of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops, within 24 h, a differentiated cell type called a heterocyst that is specifically involved in the fixation of N(2). Cell division is required for heterocyst development, suggesting that the cell cycle could control this developmental process. In this study, we investigated several key events of the cell cycle, such as cell growth, DNA synthesis, and cell division, and explored their relationships to heterocyst development. The results of analyses by flow cytometry indicated that the DNA content increased as the cell size expanded during cell growth. The DNA content of heterocysts corresponded to the subpopulation of vegetative cells that had a big cell size, presumably those at the late stages of cell growth. Consistent with these results, most proheterocysts exhibited two nucleoids, which were resolved into a single nucleoid in most mature heterocysts. The ring structure of FtsZ, a protein required for the initiation of bacterial cell division, was present predominantly in big cells and rarely in small cells. When cell division was inhibited and consequently cells became elongated, little change in DNA content was found by measurement using flow cytometry, suggesting that inhibition of cell division may block further synthesis of DNA. The overexpression of minC, which encodes an inhibitor of FtsZ polymerization, led to the inhibition of cell division, but cells expanded in spherical form to become giant cells; structures with several cells attached together in the form of a cloverleaf could be seen frequently. These results may indicate that the relative amounts of FtsZ and MinC affect not only cell division but also the placement of the cell division planes and the cell morphology. MinC overexpression blocked heterocyst differentiation, consistent with the requirement of cell division in the control of heterocyst development.

Inhibition of cell division suppresses heterocyst development in Anabaena sp. strain PCC 7120.

When the filamentous cyanobacterium Anabaena PCC 7120 is exposed to combined nitrogen starvation, 5 to 10% of the cells along each filament at semiregular intervals differentiate into heterocysts specialized in nitrogen fixation. Heterocysts are terminally differentiated cells in which the major cell division protein FtsZ is undetectable. In this report, we provide molecular evidence indicating that cell division is necessary for heterocyst development. FtsZ, which is translationally fused to the green fluorescent protein (GFP) as a reporter, is found to form a ring structure at the mid-cell position. SulA from Escherichia coli inhibits the GTPase activity of FtsZ in vitro and prevents the formation of FtsZ rings when expressed in Anabaena PCC 7120. The expression of sulA arrests cell division and suppresses heterocyst differentiation completely. The antibiotic aztreonam, which is targeted to the FtsI protein necessary for septum formation, has similar effects on both cell division and heterocyst differentiation, although in this case, the FtsZ ring is still formed. Therefore, heterocyst differentiation is coupled to cell division but independent of the formation of the FtsZ ring. Consistently, once the inhibitory pressure of cell division is removed, cell division should take place first before heterocyst differentiation resumes at a normal frequency. The arrest of cell division does not affect the accumulation of 2-oxoglutarate, which triggers heterocyst differentiation. Consistently, a nonmetabolizable analogue of 2-oxoglutarate does not rescue the failure of heterocyst differentiation when cell division is blocked. These results suggest that the control of heterocyst differentiation by cell division is independent of the 2-oxoglutarate signal.

Heterocyst differentiation and pattern formation in cyanobacteria: a chorus of signals.

Heterocyst differentiation in filamentous cyanobacteria provides an excellent prokaryotic model for studying multicellular behaviour and pattern formation. In Anabaena sp. strain PCC 7120, for example, 5-10% of the cells along each filament are induced, when deprived of combined nitrogen, to differentiate into heterocysts. Heterocysts are specialized in the fixation of N(2) under oxic conditions and are semi-regularly spaced among vegetative cells. This developmental programme leads to spatial separation of oxygen-sensitive nitrogen fixation (by heterocysts) and oxygen-producing photosynthesis (by vegetative cells). The interdependence between these two cell types ensures filament growth under conditions of combined-nitrogen limitation. Multiple signals have recently been identified as necessary for the initiation of heterocyst differentiation, the formation of the heterocyst pattern and pattern maintenance. The Krebs cycle metabolite 2-oxoglutarate (2-OG) serves as a signal of nitrogen deprivation. Accumulation of a non-metabolizable analogue of 2-OG triggers the complex developmental process of heterocyst differentiation. Once heterocyst development has been initiated, interactions among the various components involved in heterocyst differentiation determine the developmental fate of each cell. The free calcium concentration is crucial to heterocyst differentiation. Lateral diffusion of the PatS peptide or a derivative of it from a developing cell may inhibit the differentiation of neighbouring cells. HetR, a protease showing DNA-binding activity, is crucial to heterocyst differentiation and appears to be the central processor of various early signals involved in the developmental process. How the various signalling pathways are integrated and used to control heterocyst differentiation processes is a challenging question that still remains to be elucidated.

Expression of split dnaE genes and trans-splicing of DnaE intein in the developmental cyanobacterium Anabaena sp. PCC 7120.

Protein intein is widespread in a variety of organisms. Several intein elements are also present in cyanobacteria, and some of them have been studied biochemically in vitro. However, no evidence is available for intein removal in vivo in cyanobacteria. In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, the DNA replication factor DnaE is encoded by two split open reading frames (ORFs) far apart from each other on the chromosome, and each of them could contain a split intein element. This organism can undergo a developmental process leading to the formation of nitrogen-fixing cells, or heterocysts. Heterocysts are terminally differentiated cells with arrest of cell cycle. Since DnaE is an important cell cycle element involved in DNA replication, we would like to provide in vivo evidence for DnaE intein removal in cyanobacteria and determine whether mature DnaE protein is still present in heterocysts. In this study, we showed that the products of these two ORFs were joined together to form a complete DnaE protein through the process of protein trans-splicing. More interestingly, protein trans-splicing could be detected in vivo for the first time in cyanobacteria, which allowed us to compare the formation of mature DnaE protein in heterocysts and vegetative cells, and show that mature DnaE protein could be formed in both cell types. Transcriptional fusion between the promoter regions of the two split ORFs and gfp reporter also demonstrate that both ORFs are transcribed in vegetative cells and heterocysts, without strong variation during the process of heterocyst differentiation. Although heterocysts are terminally differentiated and may not replicate its chromosome, the expression and maturation of DnaE in these cells may underlie the need for DNA replication machinery in processes such as DNA recombination and repair.

Protein phosphorylation on Ser, Thr and Tyr residues in cyanobacteria.

Cyanobacteria belong to an extremely diverse group of gram-negative prokaryotes. They are all able to perform oxygen-evolving photosynthesis, but differ in morphology, ecological habitats, and physiology. This diversity is also reflected in the complexity of regulatory proteins involved in protein phosphorylation on Ser, Thr and Tyr residues. For those strains whose genomes are completely sequenced, for example, the number of genes identified so far that encode Ser/Thr and Tyr kinases range from none to 52. Genetic, molecular as well as functional genomic analyses demonstrate that Ser/Thr and Tyr kinases and phosphatases are involved in the regulation of a variety of activities according to changes in growth conditions or cell metabolism, such as cell motility, carbon and nitrogen metabolism, photosynthesis and stress response. The major challenge in the near future is to integrate these components into signaling pathways and identify their targets. Some of the Ser/Thr and Tyr kinases and phosphatases are expected to interact with classical two-component signaling pathways.