Thermodynamic and kinetic characterization of PccH, a key protein in microbial electrosynthesis processes in Geobacter sulfurreducens.

The monoheme c-type cytochrome PccH from Geobacter sulfurreducens, involved in the pathway of current-consumption in biofilms, was electrochemically characterized in detail. Cyclic voltammetry was used to determine the kinetics and thermodynamics properties of PccH redox behavior. Entropy, enthalpy and Gibbs free energy changes associated with the redox center transition between the ferric and the ferrous state were determined, indicating an enhanced solvent exposure. The midpoint redox potential is considerably low for a monoheme c-type cytochrome and the heterogeneous electron transfer constant rate reflects a high efficiency of electron transfer process in PccH. The midpoint redox potential dependence on the pH (redox-Bohr effect) was investigated, over the range of 2.5 to 9.1, and is described by the protonation/deprotonation events of two distinct centers in the vicinity of the heme group with pKa values of 2.7 (pKox1); 4.1 (pKred1) and 5.9 (pKox2); 6.4 (pKred2). Based on the inspection of PccH structure, these centers were assigned to heme propionic acids P13 and P17, respectively. The observed redox-Bohr effect indicates that PccH is able to thermodynamically couple electron and proton transfer in the G. sulfurreducens physiological pH range.

A comparative genomics study of the microbiome and freshwater resistome in Southern Pantanal.

This study explores the resistome and bacterial diversity of two small lakes in the Southern Pantanal, one in Aquidauana sub-region, close to a farm, and one in Abobral sub-region, an environmentally preserved area. Shotgun metagenomic sequencing data from water column samples collected near and far from the floating macrophyte Eichhornia crassipes were used. The Abobral small lake exhibited the highest diversity and abundance of antibiotic resistance genes (ARGs), antibiotic resistance classes (ARGCs), phylum, and genus. RPOB2 and its resistance class, multidrug resistance, were the most abundant ARG and ARGC, respectively. Pseudomonadota was the dominant phylum across all sites, and Streptomyces was the most abundant genus considering all sites.

Cytotoxicity of Methotrexate Conjugated to Glycerol Phosphate Modified Superparamagnetic Iron Oxide Nanoparticles.

A systematic study was carried out to evaluate the uptake and cytotoxicity of methotrexate (MTX) conjugated to superparamagnetic iron oxide nanoparticles (SPIONs) modified with glycerol phosphate (Glyc) and phosphorylethanolamine (PEA), using MCF-7 cancer cell line as model. The ligand shell composition was controlled in such a way to get SPIONs with nine different surface functionalization and up to three co-conjugated ligands but the very iron oxide core, in order to test and compare uptake and cytotoxicity, and verify possible additive effects. Folic acid (FA), the non-toxic analogue of MTX, was also explored as ligand for SPIONs. Glyc was shown to enhance dramatically the cellular uptake despite the high negative zeta potentials, whereas PEA, FA and MTX was found to have a much lower effect on the cellular uptake. Also, a significant ten times lowering of IC50 was observed for the co-conjugated MTX in the SPION-Glyc/PEA/MTX as compared to the free drug, whereas the analogue SPION-Glyc/PEA/FA nanoparticles exhibited no significant cytotoxicity. In short, the conjugation of MTX to SPIONs enhanced dramatically its cytotoxicity and decreased the IC50 value against MCF-7 tumor cells as compared to the free drug, probably due to the enhanced uptake of SPIONs as a result of their surface modification with Glyc/PEA, demonstrating that SPION-Glyc/PEA is a good nanocarrier for co-conjugated methotrexate.

Differential expression of angiogenesis-related miRNAs and VEGFA in cirrhosis and hepatocellular carcinoma.

INTRODUCTION: Liver cirrhosis (LC) is a heterogeneous liver disease, the last stage of liver fibrosis, and the major risk factor for hepatocellular carcinoma (HCC). Our study aimed to evaluate the expression of microRNAs and the endothelial vascular growth factor (VEGFA) gene in LC and HCC. MATERIAL AND METHODS: The sample group consisted of 46 tissue samples: 21 of LC, 15 of HCC, and 10 of non-tumoural and non-cirrhotic liver tissue (control group). MiRNAs were chosen based on a mirDIP prediction database as regulators of the VEGFA gene. Gene expression of VEGF and miRNAs was quantified by real-time quantitative polymerase chain reaction. VEGFA protein expression was evaluated by ELISA. RESULTS: VEGFA gene expression was significantly overexpressed in LC compared to the control group (p < 0.0001). Hsa-miR-206 (p = 0.0313) and hsa-miR-637 (p = 0.0156) were down-expressed in LC. In HCC, hsa-miR-15b (p = 0.0010), hsa-miR-125b (p = 0.0010), hsa-miR-423-3p (p = 0.0010), hsa-miR-424 (p = 0.0313), hsa-miR-494 (p < 0.0001), hsa-miR-497 (p < 0.0001), hsa-miR-612 (p = 0.0078), hsa-miR-637 (p < 0.0001), and hsa-miR-1255b (p = 0.0156) presented down-expression. CONCLUSIONS: Overexpression of VEGFA in LC suggests impairment of angiogenesis in this tissue. The differential expression of microRNAs in LC and HCC observed in our study can lead to the evaluation of possible biomarkers for these diseases.