Prevalence of Escherichia coli and Salmonella spp. in mussels (Mytilus galloprovincialis) and serotyping of Salmonella spp. in Zenata and Mansouria regions of Morocco

Due to their immobile nature and filter-feeding habits, which enable biological particles to accumulate in their tissues, mussels are recognized as vectors of foodborne diseases. Consuming these shellfish uncooked or partly processed might result in food poisoning because of accumulated bacteria originating from the culture environment and unhygienic handling. The present study aimed to assess the presence of Salmonella and Escherichia coli as well as to biochemically and serotypically confirm Salmonella spp. in mussels (Mytilus galloprovincialis) taken from two locations in Morocco: Zenata and Mansouria. A total of 90 mussel samples were collected from October 2022 to August 2023. Two methods were employed in this study: AFNOR NF EN ISO 6579-1 (2017) for the detection of Salmonella spp., and the most probable number method (MPN) using Norm ISO/TS 16649–3 (2017) for E. coli. The number of E. coli varied between 0.2/100 g and 1.7 x 103/100 g of mussels. The percentage of Salmonella spp. detected in mussel samples was 4,4%. Further analysis revealed the identification of two distinct Salmonella serotypes, namely S. kentucky (1 isolate) and S. Typhimurium (3 isolates). This research highlights the potential risks to public health due to the presence of pathogenic bacteria in mussels from two regions of Morocco where shellfish farming and coastal tourism are significant contributors to the local economy.

Temperature-responsive size-exclusion chromatography using poly(N-isopropylacrylamide) grafted silica

Silica-based packing materials induce non-specific interactions with proteins in aqueous media because of the nature of their surface, mainly silanol groups. Therefore, the silica surface has to be modified in order to be used as stationary phase for the High Performance Size-Exclusion Chromatography (HPSEC) of proteins. For this purpose, porous silica beads were coated with hydrophilic polymer gels (dextrans of different molecular weights) carrying a calculated amount of diethyl-aminoethyl groups (DEAE). Actually, as shown by HPSEC, these dextran modified supports minimize non-specific adsorption for proteins and pullulans in aqueous solution. Then, in order to change the pore size in response to temperature, temperature responsive polymer of poly(N-isopropylacrylamide) (PIPAAm) was introduced into the surface of dextran-DEAE on porous silica beads. The structure of these supports before and after modification was alternately studied by Scanning Electronic Microscopy (SEM) and Scanning Force Microscopy (SFM). An adsorption of radiolabelled albumin was performed to complete our study. Silica modifications by dextran-DEAE and PIPAAm improve the neutrality of the support and minimize the non-specific interactions between the solid support and proteins in solution. At low temperature, the support having PIPAAm exhibits a high resolution domain in HPSEC and finally permits a better resolution of proteins and pullulans. At higher temperature, hydrophobic properties of PIPAAm produce interactions with some proteins and trigger off a slight delay of their elution time

Prediction of the Impact of Deleterious Nonsynonymous Single Nucleotide Polymorphisms on the Human RRM2B Gene: A Molecular Modeling Study

RRM2B gene encodes ribonucleoside-diphosphate reductase subunit M2 B, the p53-inducible small subunit (p53R2) of ribonucleotide reductase (RNR), an enzyme catalyzing dNTP synthesis for mitochondrial DNA. Defects in this gene may cause severe mitochondrial disease affecting mainly the nervous system. This study is aimed at examining the effect of deleterious nonsynonymous SNP (nsSNP) on the structure of the RRM2B protein, using a variety of prediction tools followed by a molecular modeling analysis. After using 13 algorithms, 19 nsSNPs were predicted deleterious. Among these variants, 18 decreased the protein stability and 16 were localized in very highly conserved regions. Protein 3D structure analysis showed that 18 variants changed amino acid interactions. These results concur with what has been found in experimental trials; 7 deleterious nsSNPs were previously reported in patients suffering from genetic disorders affecting the nervous system. Thus, our study will provide useful information to design more efficient and fast genetic tests to find RRM2B gene mutations