Correction: Enantiomeric NMR discrimination of carboxylic acids using actinomycin D as a chiral solvating agent.

Correction for 'Enantiomeric NMR discrimination of carboxylic acids using actinomycin D as a chiral solvating agent' by Liwen Bai, et al., Org. Biomol. Chem., 2019, 17, 1466-1470.

Enantiomeric NMR discrimination of carboxylic acids using actinomycin D as a chiral solvating agent.

Actinomycin D (Act-D) is a biologically important polypeptide antibiotic clinically used to treat several malignant tumors. Herein, we extended its hitherto-unexplored application as an applicable chiral solvating agent (CSA) for the rapid enantiomeric determination of different chiral carboxylic acids in deuterated chloroform by 1H NMR spectroscopy. Notable enantiodiscrimination with well-splitting α-H or α-CH3 resonance signals of the enantiomers of carboxylic acids were achieved without significant interference from Act-D. To check its applicability for the determination of enantiomeric excess (ee) values, various mandelic acid (MA) samples were determined and compared with the observed ones, resulting in an excellent linear relationship. To our knowledge, this is the first example of using a natural antibiotic compound as a CSA to achieve chiral recognition for carboxylic acids.

A Self-Assembled Oligopeptide as a Versatile NMR Alignment Medium for the Measurement of Residual Dipolar Couplings in Methanol.

Residual dipolar coupling (RDC) is a powerful structural parameter for the determination of the constitution, conformation, and configuration of organic molecules. Herein, we report the first liquid crystal-based orienting medium that is compatible with MeOH, thus enabling RDC acquisitions of a wide range of intermediate to polar organic molecules. The liquid crystals were produced from self-assembled oligopeptide nanotubes (AAKLVFF), which are stable at very low concentrations. The presented alignment medium is highly homogeneous, and the size of RDCs can be scaled with the concentration of the peptide. To assess the accuracy of the RDC measurement by employing this new medium, seven bioactive natural products from different classes were chosen and analyzed. The straightforward preparation of the anisotropic alignment sample will offer a versatile and robust protocol for the routine RDC measurement of natural products.

Establishment and characterization of fin cell lines from diploid, triploid, and tetraploid oriental weatherfish (Misgurnus anguillicaudatus).

Continuous fin cell lines from diploid, triploid, and tetraploid oriental weatherfish, Misgurnus anguillicaudatus, were established and characterized. The cell lines, designated DIMF, TRMF, and TEMF, respectively, were subcultured more than 80 times since initiation in October 2012 and were preserved at the China Center for Type Culture Collection as sample numbers C2013109, C2013110, C2013111, respectively. The cell lines consist predominantly of fibroblast-like cells. At the 50th passage, the population doubling times were 48.43 h (DIMF), 36.01 h (TRMF), and 41.45 h (TEMF). Cell survival rate of these three kinds of cells was 80.88 ± 1.38, 84.48 ± 1.13, and 81.57 ± 1.28 %, respectively, when recovered after storage in liquid nitrogen for 60 days at the 40th passage. The chromosome numbers measured from 100 metaphase plates at the 50th passage were 2n = 50 (68 %), 3n = 75 (59 %), and 4n = 100 (54 %) for DIMF, TRMF, and TEMF cells, respectively. At the 60th passage, the chromosome numbers for DIMF and TRMF cells were still 50 (52 %) and 75 (70 %), but the chromosome number for TEMF cells ranged from 88 to 100; a chromosome number of 96 accounted for 26 % of the cells, and the karyotype analysis showed 4n = 96, 16 m + 8sm + 72t, NF = 120; thus, compared with cells at the 50th passage, a group of metacentric chromosomes was missing. Microsatellite marker analysis was conducted using DIMF, TRMF, and TEMF cells and muscle tissue of oriental weatherfish, which confirmed that the three cell lines established in this study were from oriental weatherfish. The cell lines were exposed to two fish viruses to determine their susceptibility to infection; they were susceptible to spring viremia of carp virus but not to piscine nodavirus. Establishment of fin cell lines from different ploidy oriental weatherfish increases the existing number of fish cell lines available for research, and it provides a model for investigating the mechanisms of growth and genetics in polyploid fish.

Nucleoside modification-based flexizymes with versatile activity for tRNA aminoacylation.

Extensive research has focused on genetic code reprogramming using flexizymes (Fxs), ribozymes enabling diverse tRNA acylation. Here we describe a nucleoside-modification strategy for the preparation of flexizyme variants derived from 2'-OMe, 2'-F, and 2'-MOE modifications with unique and versatile activities, enabling the charging of tRNAs with a broad range of substrates. This innovative strategy holds promise for synthetic biology applications, offering a robust pathway to expand the genetic code for diverse substrate incorporation.

First-Principles Study on the Structural and Electronic Properties of Monolayer MoS2 with S-Vacancy under Uniaxial Tensile Strain.

Monolayer molybdenum disulfide (MoS2) has obtained much attention recently and is expected to be widely used in flexible electronic devices. Due to inevitable bending in flexible electronic devices, the structural and electronic properties would be influenced by tensile strains. Based on the density functional theory (DFT), the structural and electronic properties of monolayer MoS2 with a sulfur (S)-vacancy is investigated by using first-principles calculations under uniaxial tensile strain loading. According to the calculations of vacancy formation energy, two types of S-vacancies, including one-sulfur and two-sulfur vacancies, are discussed in this paper. Structural analysis results indicate that the existence of S-vacancies will lead to a slightly inward relaxation of the structure, which is also verified by exploring the change of charge density of the Mo layer and the decrease of Young's modulus, as well as the ultimate strength of monolayer MoS2. Through uniaxial tensile strain loading, the simulation results show that the band gap of monolayer MoS2 decreases with increased strain despite the sulfur vacancy type and the uniaxial tensile orientation. Based on the electronic analysis, the band gap change can be attributed to the π bond-like interaction between the interlayers, which is very sensitive to the tensile strain. In addition, the strain-induced density of states (DOS) of the Mo-d orbital and the S-p orbital are analyzed to explain the strain effect on the band gap.

The Electronic Properties of O-Doped Pure and Sulfur Vacancy-Defect Monolayer WS2: A First-Principles Study.

Based on the density functional theory (DFT), the electronic properties of O-doped pure and sulfur vacancy-defect monolayer WS2 are investigated by using the first-principles method. For the O-doped pure monolayer WS2, four sizes (2 × 2 × 1, 3 × 3 × 1, 4 × 4 × 1 and 5 × 5 × 1) of supercell are discussed to probe the effects of O doping concentration on the electronic structure. For the 2 × 2 × 1 supercell with 12.5% O doping concentration, the band gap of O-doped pure WS2 is reduced by 8.9% displaying an indirect band gap. The band gaps in 3 × 3 × 1 and 4 × 4 × 1 supercells are both opened to some extent, respectively, for 5.55% and 3.13% O doping concentrations, while the band gap in 5 × 5 × 1 supercell with 2.0% O doping concentration is quite close to that of the pure monolayer WS2. Then, two typical point defects, including sulfur single-vacancy (VS) and sulfur divacancy (V2S), are introduced to probe the influences of O doping on the electronic properties of WS2 monolayers. The observations from DFT calculations show that O doping can broaden the band gap of monolayer WS2 with VS defect to a certain degree, but weaken the band gap of monolayer WS2 with V2S defect. Doping O element into either pure or sulfur vacancy-defect monolayer WS2 cannot change their band gaps significantly, however, it still can be regarded as a potential method to slightly tune the electronic properties of monolayer WS2.

Toxic effects of glyphosate on diploid and triploid fin cell lines from Misgurnus anguillicaudatus.

We examined the toxic effects of glyphosate on diploid (DIMF) and triploid (TRMF) fin cell lines from the Oriental Weather Loach Misgurnus anguillicaudatus. The LC50 values of glyphosate estimated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay were 315.34 and 371.77 mg/L for DIMF and TRMF, respectively. Superoxide dismutase (SOD) and glutathione-S-transferase (GST) activities in DIMF and TRMF cells gradually increased and then decreased with increasing glyphosate concentrations, reaching a maximum at 240 mg/L glyphosate. In contrast, acetylcholinesterase (AChE) activities in DIMF and TRMF decreased with increasing concentrations of glyphosate in a concentration-dependent manner. SOD and AChE activities were generally significantly higher in TRMF compared with DIMF cells (P < 0.05). The rates of micronucleus and abnormal nuclei were significantly higher in DIMF and TRMF groups treated with 80-560 mg/L glyphosate compared with the control groups (P < 0.01). The highest micronuclei rates in both DIMF and TRMF cells (both 4.30‰) occurred at 400 mg/L glyphosate. There were no differences in the rates of micronuclei and abnormal nuclei between DIMF and TRMF cells at any glyphosate concentration. Cell damage, including chromatin condensation, nucleus distortion, and broken and reduced endoplasmic reticulum, mitochondria, and ribosomes, were found in both cells treated with the LC50 concentration of glyphosate. Moreover, vacuolization and apoptotic bodies occurred in glyphosate-exposed DIMF and TRMF cells, indicating apoptosis. These results indicate that glyphosate in the range of tested concentrations represent a potential risk to loach through inhibiting proliferation of diploid and triploid cell lines and induces micronuclei and apoptosis.