The lower convective layer (LCL) of the Atlantis II brine pool of the Red Sea is a unique environment in terms of high salinity, temperature, and high concentrations of heavy metals. Mercuric reductase enzymes functional in such extreme conditions could be considered a potential tool in the environmental detoxification of mercurial poisoning and might alleviate ecological hazards in the mining industry. Here, we constructed a mercuric reductase library from Atlantis II, from which we identified genes encoding two thermostable mercuric reductase (MerA) isoforms: one is halophilic (designated ATII-LCL) while the other is not (designated ATII-LCL-NH). The ATII-LCL MerA has a short motif composed of four aspartic acids (4D414–417) and two characteristic signature boxes that played a crucial role in its thermal stability. To further understand the mechanism behind the thermostability of the two studied enzymes, we mutated the isoform ATII-LCL-NH and found that the substitution of 2 aspartic acids (2D) at positions 415 and 416 enhanced the thermal stability, while other mutations had the opposite effect. The 2D mutant showed superior thermal tolerance, as it retained 81% of its activity after 10 min of incubation at 70°C. A three-dimensional structure prediction revealed newly formed salt bridges and H bonds in the 2D mutant compared to the parent molecule. To the best of our knowledge, this study is the first to rationally design a mercuric reductase with enhanced thermal stability, which we propose to have a strong potential in the bioremediation of mercurial poisoning.IMPORTANCEThe Red Sea is an attractive environment for bioprospecting. There are 25 brine-filled deeps in the Red Sea. The Atlantis II brine pool is the biggest and hottest of such hydrothermal ecosystems. We generated an environmental mercuric reductase library from the lowermost layer of the Atlantis II brine pool, in which we identified two variants of the mercuric reductase enzyme (MerA). One is the previously described halophilic and thermostable ATII-LCL MerA and the other is a nonhalophilic relatively less thermostable enzyme, designated ATII-LCL-NH MerA. We used the ATII-LCL-NH enzyme as a parent molecule to locate the amino acid residues involved in the noticeably higher thermotolerance of the homolog ATII-LCL MerA. Moreover, we designed a novel enzyme with superior thermal stability. This enzyme might have strong potential in the bioremediation of mercuric toxicity.

Medicinal plants are potential sources for a wide range of complex compounds with probable anticancer activity. Ephedra foeminea Forssk. (E. foeminea), a medicinal plant found in the Eastern Mediterranean, has recently been gaining popularity as a cancer remedy; there is, however, a paucity of empirical evidence supporting this claim. In this study, the effect of E. foeminea ethyl acetate, ethanol, and water crude extracts on viability, migratory ability, and the steady-state mRNA levels of genes involved in these processes was, respectively, examined using MTT assay, wound healing assay, and reverse transcriptase PCR (RT-PCR). The study concludes that all extracts significantly reduce human osteosarcoma U2OS percentage viability in a dose- and time-dependent manner, with varying potencies. The least half-maximal inhibitory concentration (IC50) was observed in the water extract after 48 h incubation (30.761±1.4 μg/mL) followed by the ethyl acetate extract after 72 h incubation (80.35±1.233 μg/mL) and finally the ethanol extract after 48 h incubation (97.499±1.188 μg/mL). Ethanol extract significantly reduced U2OS percentage wound closure. On the other hand, both ethanol and water extracts considerably reduced the steady-state mRNA expression of beta-catenin, promoting both cell proliferation and migration in osteosarcoma by regulating target genes. Additionally, E. foeminea showed no hemolytic activity. These effects suggest that E. foeminea decreases U2OS cell viability and migratory ability by modulating the expression of critical genes involved in regulating these processes and is likely cytocompatible with human erythrocytes.

Coronavirus disease 2019 has posed an enormous global health and economic burden. To date, 324 million confirmed cases and over 5.5 million deaths have been reported. Several studies have reported comorbidities and coinfections associated with complicated and serious COVID-19 infections. Data from retrospective, prospective, case series, and case reports from various geographical locations were assessed, which included ~ 2300 COVID-19 patients with varying comorbidities and coinfection. We report that Enterobacterales with Staphylococcus aureus was the most while Mycoplasma pneumoniae was the least prevalent coinfection in COVID-19 patients with a comorbidity. In this order, hypertension, diabetes, cardiovascular disease, and pulmonary disease were the prevalent comorbidities observed in COVID-19 patients. There was a statistically significant difference in the prevalent comorbidities observed in patients coinfected with Staphylococcus aureus and COVID-19 and a statistically non-significant difference in the prevalent comorbidities in patients coinfected with Mycoplasma pneumoniae and COVID-19 as compared to similar infections in non-COVID-19 coinfection. We report a significant difference in the prevalent comorbidities recorded in COVID-19 patients with varying coinfections and varying geographic study regions. Our study provides informative data on the prevalence of comorbidities and coinfections in COVID-19 patients to aid in evidence-based patient management and care.

The hypersaline Kebrit Deep brine pool in the Red Sea is characterized by high levels of toxic heavy metals. Here, we describe two structurally related mercuric reductases (MerAs) from this site which were expressed inEscherichia coli. Sequence similarities suggest that both genes are derived from proteobacteria, most likely theBetaproteobacteriaorGammaproteobacteria. We show that one of the enzymes (K35NH) is strongly inhibited by NaCl, while the other (K09H) is activated in a NaCl-dependent manner. We infer from this difference that the two forms might support the detoxification of mercury in bacterial microorganisms that employ the compatible solutes and salt-in strategies, respectively. Three-dimensional structure modeling shows that all amino acid substitutions unique to each type are located outside the domain responsible for formation of the active MerA homodimer, and the vast majority of these are found on the surface of the molecule. Moreover, K09H exhibits the predominance of acidic over hydrophobic side chains that is typical of halophilic salt-dependent proteins. These findings enhance our understanding of how selection pressures imposed by two environmental stressors have endowed MerA enzymes with catalytic properties that can potentially function in microorganisms that utilize distinct mechanisms for osmotic balance in hypersaline environments.IMPORTANCEAnalysis of two structurally homologous but catalytically distinct mercuric reductases from the Kebrit Deep brine in the Red Sea sheds light on the adaptations that enable microorganisms to cope simultaneously with extreme salinity and toxic mercury compounds. One is strongly inhibited by high NaCl concentrations, while the other exhibits NaCl-dependent activation. Their different activity profiles imply that they may derive from bacterial microorganisms that utilize compatible solutes and salt-in strategies, respectively, to maintain osmotic balance. Three-dimensional modeling reveals that regions not involved in formation of the active homodimer are conserved between the two. However, in the NaCl-dependent form, distinct amino acid substitutions are found in areas that are critical for stability in high salt. The work provides insights into how two environmental stressors have shaped the structure of orthologous enzymes through selection and adaptation, enabling them to retain their catalytic function in what may be very different cellular contexts.

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that reside in multiple tissues are capable of self-renewal and differentiation into various cell types. These properties make them promising candidates for regenerative therapies. MSC identification is critical in yielding pure populations for successful therapeutic applications; however, the criteria for MSC identification proposed by the International Society for Cellular Therapy (ISCT) are inconsistent across different tissue sources. This study aimed to identify potential markers to be used together with the ISCT criteria to provide a more accurate means of MSC identification. Thus, we carried out a computational comparative analysis of the gene expression in human and mouse MSCs derived from multiple tissues to identify the differentially expressed genes that are shared between the two species. We show that six members of the proteasome degradation system are similarly expressed across MSCs derived from bone marrow, adipose tissue, amnion, and umbilical cord. Additionally, with the help of predictive models, we found that the expression profile of these genes correctly validated the identity of the MSCs across all the tissue sources tested. Moreover, using genetic interaction networks, we showed a possible link between these genes and antioxidant enzymes in the MSC antioxidant defense system, thereby pointing to their potential role in prolonging the life span of MSCs. According to our findings, members of the proteasome degradation system may serve as stemness-related markers.