Enzymatic decontamination of paraoxon-ethyl limits long-term effects in planarians

Thermodynamic Insights into Phosphonate Binding in Metal-Azolate Frameworks

Organophosphorus chemicals, including chemical warfare agents (CWAs) and insecticides, are acutely toxic materials that warrant capture and degradation. Metal-organic frameworks (MOFs) have emerged as a class of tunable, porous, crystalline materials capable of hydrolytically cleaving, and thus detoxifying, several organophosphorus nerve agents and their simulants. One such MOF is M-MFU-4l (M = metal), a bioinspired azolate framework whose metal node is composed of a variety of divalent first-row transition metals. While Cu-MFU-4l and Zn-MFU-4l are shown to rapidly degrade CWA simulants, Ni-MFU-4l and Co-MFU-4l display drastically lower activities. The lack of reactivity was hypothesized to arise from the strong binding of the phosphate product to the node, which deactivates the catalyst by preventing turnover. No such study has provided detailed insight into this mechanism. Here, we leverage isothermal titration calorimetry (ITC) to monitor the binding of an organophosphorus compound with the M-MFU-4l series to construct a complete thermodynamic profile (Ka, ΔH, ΔS, ΔG) of this interaction. This study further establishes ITC as a viable technique to probe small differences in thermodynamics that result in stark differences in material properties, which may allow for better design of first-row transition metal MOF catalysts for organophosphorus hydrolysis.

Quantitative Measurements of Pharmacological and Toxicological Activity of Molecules

Toxicity and pharmacological activity scales of molecules, in particular toxicants, xenobiotics, drugs, nutraceuticals, etc., are described by multiples indicators, and the most popular is the median lethal dose (LD50). At the molecular level, reversible inhibition or binding constants provide unique information on the potential activity of molecules. The important problem concerning the meaningfulness of IC50 for irreversible ligands/inhibitors is emphasized. Definitions and principles for determination of these quantitative parameters are briefly introduced in this article. Special attention is devoted to the relationships between these indicators. Finally, different approaches making it possible to link pharmacological and toxicological properties of molecules in terms of molecular interactions (or chemical reactions) with their biological targets are briefly examined. Experimental trends for future high-throughput screening of active molecules are pointed out.

Temporal dynamics for areal unit-based co-occurrence COVID-19 trajectories

The dynamic mechanism of the COVID-19 pandemic has been studied for disease prevention and health protection through areal unit-based log-linear Poisson processes to understand the outbreak of the virus with confirmed daily empirical cases. The predictor of the evolution is structured as a function of a short-term dependence and a long-term trend to identify the pattern of exponential growth in the main epicenters of the virus. The study provides insight into the possible pandemic path of each areal unit and a guide to drive policymaking on preventive measures that can be applied or relaxed to mitigate the spread of the virus. It is significant that knowing the trend of the virus is very helpful for institutions and organizations in terms of instituting resources and measures to help provide a safe working environment and support for all workers/staff/students.

Disrupting quorum sensing alters social interactions in Chromobacterium violaceum

Quorum sensing (QS) is a communication system used by bacteria to coordinate a wide panel of biological functions in a cell density-dependent manner. The Gram-negative Chromobacterium violaceum has previously been shown to use an acyl-homoserine lactone (AHL)-based QS to regulate various behaviors, including the production of proteases, hydrogen cyanide, or antimicrobial compounds such as violacein. By using combined metabolomic and proteomic approaches, we demonstrated that QS modulates the production of antimicrobial and toxic compounds in C. violaceum ATCC 12472. We provided the first evidence of anisomycin antibiotic production by this strain as well as evidence of its regulation by QS and identified new AHLs produced by C. violaceum ATCC 12472. Furthermore, we demonstrated that targeting AHLs with lactonase leads to major QS disruption yielding significant molecular and phenotypic changes. These modifications resulted in drastic changes in social interactions between C. violaceum and a Gram-positive bacterium (Bacillus cereus), a yeast (Saccharomyces cerevisiae), immune cells (murine macrophages), and an animal model (planarian Schmidtea mediterranea). These results underscored that AHL-based QS plays a key role in the capacity of C. violaceum to interact with micro- and macroorganisms and that quorum quenching can affect microbial population dynamics beyond AHL-producing bacteria and Gram-negative bacteria.