Biochemical Analysis Leads to Improved Orthogonal Bioluminescent Tools

Engineered luciferase-luciferin pairs have expanded the number of cellular targets that can be visualized in tandem. While light production relies on selective processing of synthetic luciferins by mutant luciferases, little is known about the origin of selectivity. The development of new and improved pairs requires a better understanding of the structure−function relationship of bioluminescent probes. In this work, we report a biochemical approach to assessing and optimizing two popular bioluminescent pairs: Cashew/d -luc and Pecan/4′-BrLuc. Single mutants derived from Cashew and Pecan revealed key residues for selectivity and thermal stability. Stability was further improved through a rational addition of beneficial residues. In addition to providing increased stability, the known stabilizing mutations surprisingly also improved selectivity. The resultant improved pair of luciferases are >100-fold selective for their respective substrates and highly thermally stable. Collectively, this work highlights the importance of mechanistic insight for improving bioluminescent pairs and provides significantly improved Cashew and Pecan enzymes which should be immediately suitable for multicomponent imaging applications.     

Analysis of volatile compounds and antioxidant activity in rice extracts (Oryza sativa L.) extracted by various conditions

This study focused on the analysis of the volatiles present in rice extracts (Oryza sativa L.) produced under various extraction conditions (i.e. the range of temperature was 50, 60 and 70 °C, and particle size was whole, 355, and 710 μm) The main volatiles identified were ethyl palmitate, benzenemethanol, nonanal, hexanal and 3-methyl-1-butanol. The highest levels of flavour compounds extracted from rice cultivated in Icheon and Cheorwon were recorded at an extraction temperature of 70 and 60 °C, respectively, and at a rice particle size of 355 μm. Non-volatile rice extracts were tested for antioxidant activity using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The antioxidant activity of Icheon rice extracts at a concentration of 2000 ppm was found to be 84.33 and 84.39% in the DPPH and ABTS assays, respectively.     

DHkmeans-ℓdiversity: distributed hierarchical K-means for satisfaction of the ℓ-diversity privacy model using Apache Spark

The Journal of Supercomputing - One of the main steps in the data lifecycle is to publish it for data analysts to discover hidden patterns. But, data publishing may lead to unwanted disclosure of...     

Flash sintering of cationic conductive ceramics: A way to build multilayer systems

Flash Sintering (FS), that allows densifying ceramics at low furnace temperature in a few seconds, requires a reversible electrochemical reaction to enable the current flow through the electrode / material interface. For Li⁺ pure ionic conductors such as Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP), the best material to ensure this fast charge transfer reaction is a mixed Li⁺/e⁻ conductor, eg, LiCoO₂ (LCO). This paper demonstrates the feasibility of FS on LCO between two Pt electrodes and on multi-layers systems using LCO or LATP+LCO composite as electrodes. It is shown that a composite electrode both allows the flash event to occur and prevents the delamination possibly observed with pure LCO by lowering interfacial stresses.     

RGDS-Modified Superporous Poly(2-Hydroxyethyl Methacrylate)-Based Scaffolds as 3D In Vitro Leukemia Model

Superporous poly(2-hydroxyethyl methacrylate-co-2-aminoethyl methacrylate) (P(HEMA-AEMA)) hydrogel scaffolds are designed for in vitro 3D culturing of leukemic B cells. Hydrogel porosity, which influences cell functions and growth, is introduced by adding ammonium oxalate needle-like crystals in the polymerization mixture. To improve cell vitality, cell-adhesive Arg-Gly-Asp-Ser (RGDS) peptide is immobilized on the N-(γ-maleimidobutyryloxy)succinimide-activated P(HEMA-AEMA) hydrogels via reaction of SH with maleimide groups. This modification is especially suitable for the survival of primary chronic lymphocytic leukemia cells (B-CLLs) in 3D cell culture. No other tested stimuli (interleukin-4, CD40 ligand, or shaking) can further improve B-CLL survival or metabolic activity. Both unmodified and RGDS-modified P(HEMA-AEMA) scaffolds serve as a long-term (70 days) 3D culture platforms for HS-5 and M2-10B4 bone marrow stromal cell lines and MEC-1 and HG-3 B-CLL cell lines, although the adherent cells retain their physiological morphologies, preferably on RGDS-modified hydrogels. Moreover, the porosity of hydrogels allows direct cell lysis, followed by efficient DNA isolation from the 3D-cultured cells. P(HEMA-AEMA)-RGDS thus serves as a suitable 3D in vitro leukemia model that enables molecular and metabolic assays and allows imaging of cell morphology, interactions, and migration by confocal microscopy. Such applications can prospectively assist in testing of drugs to treat this frequently recurring or refractory cancer.     

Development of enhanced selective media for detection of Vibrio parahaemolyticus in oysters

This study was undertaken to develop enhanced selective media for detection of Vibrio parahaemolyticus in oysters. Primarily, tryptic soy agar (TSA) was supplemented with 4.5–5% NaCl, 0.1–0.5% oxgall, and/or 1–2% sodium citrate, and adjusted to pH 8–9. A total of 21 Vibrio spp., 24 indicators, and 26 food-borne isolates were streaked on the modified media, followed by 24 h of incubation at 37 °C. While all the indicators and isolates failed to grow on TSA containing 5% NaCl, 0.5% oxgall, and 2% sodium citrate (TSA_OSS1; pH 9), V. parahaemolyticus was culturable on this selective medium. Particularly, the ability of TSA_OSS1 to quantify V. parahaemolyticus in oysters was superior to thiosulphate citrate bile salts sucrose (TCBS) agar. V. parahaemolyticus distinctly produced its white-yellowish, round, and edge-pointed colony on TSA_OSS1. TSAO_SS1 with high selectivity potentials over TCBS may be a promising alternative for detection of V. parahaemolyticus in seafoods or natural reservoirs. Supplementary InformationThe online version contains supplementary material available at (10.1007/s10068-021-00877-0)     

Evaluation of microbiological quality and safety of fresh-cut fruit products at retail levels in Korea

Food Science and Biotechnology - The risk of foodborne illnesses caused by pathogens could be increased in fresh-cut fruit products owing to contamination during processing. Therefore, this study...     

Pyrazinium Salts as Efficient Organocatalysts of Mild Oxidations with Hydrogen Peroxide

A series of 3‐substituted pyrazinium tetrafluoroborates was prepared as simple analogues of flavinium salts which are efficient organocatalysts for oxidations with hydrogen peroxide. It was shown that pyrazinium derivatives with an electron‐withdrawing substituent catalyze mild oxidations of sulfides to sulfoxides and Baeyer–Villiger oxidations in a similar way to flavinium catalysts. The most reactive catalyst, 3‐cyanopyrazinium tetrafluoroborate, was efficiently employed in preparative sulfoxidations of aromatic and aliphatic sulfides as well as in Baeyer–Villiger oxidations of cyclobutanones. A proposed mechanism for the catalysis is based on the formation of pyrazine hydroperoxide which is the agent oxidizing the substrate.