Two responses to MeJA induction of R2R3-MYB transcription factors regulate flavonoid accumulation in Glycyrrhiza uralensis Fisch.

Flavonoids are key components of licorice plant that directly affect its medicinal quality. Importantly, the MYB family of transcription factors serves to regulate the synthesis of flavonoids in plants. The MYB transcription factors represent one of the largest families of transcription factors in plants and play important roles in the process of plant growth and development. MYB gene expression is induced by a number of plant hormones, including the lipid-based hormone jasmonate (JA). Methyl jasmonate (MeJA) is an endogenous plant growth regulator that can induce the JA signaling pathway, which functions to regulate the synthesis of secondary metabolites, including flavonoids. In this study, MeJA was added to licorice cell suspensions, and RNA-seq analysis was performed to identify the differentially expressed genes. As a result, the MYB transcription factors GlMYB4 and GlMYB88 were demonstrated to respond significantly to MeJA induction. Subsequently, the GlMYB4 and GlMYB88 protein were shown to localize to the cell nucleus, and it was verified that GlMYB4 and GlMYB88 could positively regulate the synthesis of flavonoids in licorice cells. Overall, this research helps illustrate the molecular regulation of licorice flavonoid biosynthesis induced by MeJA.

Reaction kinetic study of nonthermal plasma continuous degradation of acetone in a closed-loop reactor.

Nonthermal plasma (NTP) degradation has been shown to be a promising method for volatile organic compounds (VOCs) removal from air. However, there have been few studies on the degradation of indoor VOCs using NTP, and even less on their reaction kinetics. In this study, NTP degradation of acetone, a representative of oxygenated VOCs, in a closed-loop reactor operating in recirculation mode was investigated. Acetone and organic by-products were characterized in real-time by proton transfer reaction time-of-flight mass spectrometry. The results showed that approximately 85.7% of the acetone degraded within 7.5 h with dielectric barrier discharge treatment at 4.3 W. Methanol, acetaldehyde, formic acid, and acetic acid were observed to be the main organic byproducts with concentrations time-dependent on the order of ppb/ppm. The concentrations of the inorganic by-products O3 and NO2 are also time-dependent and can decrease to nearly 0 after a sufficient degradation time. Based on the concentration measurement in real-time, several rate laws were used to fit the concentration variations of acetone and the organic by-products, and it was observed that they strictly followed the simple kinetic reaction rate laws: acetone followed the first-order rate law, and formic acid formation followed the one-half-order rate law, etc. This study provides a good example of characterizing NTP removal of VOCs in airtight spaces and has important theoretical and practical significance in designing a better NTP device, predicting NTP degradation reaction rate, and accelerating the practical application of NTP technology for indoor air treatment.

Real-time monitoring and quantification of organic by-products and mechanism study of acetone decomposition in a dielectric barrier discharge reactor.

Non-thermal plasma (NTP) degradation of low-concentration acetone was investigated in a cylindrical dielectric barrier discharge reactor. The effects of oxygen content and flow rate on the removal efficiency at various discharge powers were examined in real-time. The acetone removal efficiency decreases drastically and then remains stable or increases gradually as the O2 content increases from 0 to 25%, and further to 50%. The organic by-products were characterized and quantified using a real-time proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) instrument. The observed organic compounds, with concentrations about ppbv/ppmv by volume, were mainly formaldehyde, methanol, ketene, acetaldehyde, formic acid, acetone, and acetic acid. The discharge power was a critical factor affecting the concentration of the organic by-products and the selectivity toward CO2. The mechanism study based on the by-product monitor in real-time showed that acetone firstly fragments into methyl radicals, acetyl radicals, and H; then, the methyl and acetyl radicals are oxidized by O or OH radicals into acetaldehyde, methanol, and other compounds. It seems that acetaldehyde could be an intermediate in acetone decomposition. Firstly, most of the acetone molecules were decomposed into acetaldehyde molecules; then, the acetaldehyde molecules continued to be decomposed and oxidized into other compounds, such as acetic acid and formaldehyde. These investigations not only proposed a detail decomposition mechanism for acetone in dielectric barrier discharge reactor, but also provided a potential way to analyze and evaluate the practicability of NTP removal of VOCs.

Application of proton transfer reaction mass spectrometry for the assessment of toluene removal in a nonthermal plasma reactor.

Proton transfer reaction mass spectrometry (PTR-MS) is a mature technique for the real-time measurement and monitoring of volatile organic compounds in the atmosphere. In this paper, a modified quantification method for PTR-MS was used to assess the performance of nonthermal plasma (NTP) reactor for the removal of toluene which was widely used in industrial production processes. Toluene and 11 corresponding organic by-products were tentatively identified and quantified by a proton transfer reaction time-of-flight mass spectrometer. The degradation dynamics of toluene and the formation of organic by-products were monitored in real-time (resolution = 1 second) under "plasma off" and "plasma on" conditions. We conclude that initial concentration and gas flow rate were the key parameters in the health risk assessment of NTP for the removal of toluene. The toluene removal efficiency and CO2 selectivity decreased with increasing upstream toluene concentration or gas flow rate, whereas the health risk influence index increased with increasing upstream toluene concentration or gas flow rate. The highest removal efficiency of toluene (100%), CO2 selectivity (53.2%), and the best health risk influence index for organic by-products (0.11) were achieved when the toluene concentration was kept at 105 ppmv and flow rate at 0.4 L/minute. The results demonstrate that PTR-MS is a promising tool to improve the practical applications of volatile organic compound removal by NTP because it can be used to optimize the NTP working conditions by providing a precise, fast, and clear health risk assessment for organic by-products based on their real-time analysis.

Oil mixing behavior after an oil spill: identification conflicts of different fingerprints.

Clearing up whether spilled oil is mixed or not can strengthen the accuracy of oil spill identification. In the present study, the biomarkers in spilled oil samples were detected. The weathering modes of different types of diagnostic ratio and carbon isotope values of individual n-alkanes were also analyzed. The results showed that the diagnostic ratios of steroids, terpenes and aromatics, and weathering characteristics of carbon isotope composition (δ13C) of individual n-alkanes supported the idea that Dalian oil spill emerged from a single oil source. Furthermore, commonly used diagnostic ratios of n-alkanes indicated that the Dalian oil spill had undergone the oil mixing process. The different identifying outcomes indicate that some kinds of n-alkane-rich substance (such as oil dispersants) were mixed in the Dalian spilled oil and interfered with the routine diagnosis ratios of n-alkanes.

On-line quantification and human health risk assessment of organic by-products from the removal of toluene in air using non-thermal plasma.

Harmful organic by-products, produced during the removal of volatile organic compounds (VOCs) from the air by treatment with non-thermal plasma (NTP), hinder the practical applications of NTP. An on-line quantification and risk assessment method for the organic by-products produced by the NTP removal of toluene from the air has been developed. Formaldehyde, methanol, ketene, acetaldehyde, formic acid, acetone, acetic acid, benzene, benzaldehyde, and benzoic acid were determined to be the main organic by-products by proton transfer reaction mass spectrometry (PTR-MS), a powerful technique for real-time and on-line measurements of trace levels of VOCs, and a health-related index (HRI) was introduced to assess the health risk of these organic by-products. The discharge power (P) is a key factor affecting the formation of the organic by-products and their HRI values. Higher P leads to a higher removal efficiency (η) and lower HRI. However, higher P also means higher cost and greater production of discharge by-products, such as NOx and O3, which are also very dangerous to the environment and human health. In practical applications P, HRI, and η must be balanced, and sometimes the risks posed by the organic by-products are even greater than those of the removed compounds. Our mechanistic study reveals that acetone is a crucial intermediate for the removal of toluene by NTP, and we found that toluene molecules first fragment into acetone molecules, followed by other by-products. These observations will guide the study of the mechanism of aromatic molecule dissociation in plasma.

Penicitroamide, an Antimicrobial Metabolite with High Carbonylization from the Endophytic Fungus Penicillium sp. (NO. 24).

Penicitroamide (1), a new metabolite with a new framework, was isolated from the ethyl acetate extract of the PDB (Potato Dextrose Broth) medium of Penicillium sp. (NO. 24). The endophytic fungus Penicillium sp. (NO. 24) was obtained from the healthy leaves of Tapiscia sinensis Oliv. The structure of penicitroamide (1) features a bicyclo[3.2.1]octane core unit with a high degree of carbonylization (four carbonyl groups and one enol group). The chemical structure of penicitroamide (1) was elucidated by analysis of 1D-, 2D-NMR and MS data. In bioassays, penicitroamide (1) displayed antibacterial potency against two plant pathogens, Erwinia carotovora subsp. Carotovora (Jones) Bersey, et al. and Sclerotium rolfsii Sacc. with MIC50 at 45 and 50 µg/mL. Compound 1 also showed 60% lethality against brine shrimp at 10 µg/mL. Penicitroamide (1) exhibited no significant activity against A549, Caski, HepG2 and MCF-7 cells with IC50 > 50 µg/mL. Finally, the possible biosynthetic pathway of penicitroamide (1) was discussed.

Cytotoxic tremulanes and 5,6-secotremulanes, four new sesquiterpenoids from a plant-associated fungus X1-2.

Two new tremulanes and two new 5,6-secotremulanes, davotremulanes A-D 1-4, along with four known compounds 5-8, were isolated from the culture extract of X1-2, an unidentified plant-associated fungus, which was isolated from the endangered plant, Davidia involucrate Baill. in Shennongjia District. The structures of new compounds 1-4 were established on the basis of extensive spectroscopic analysis. Compounds 1-8 were evaluated for cytotoxic activity to four cancer cell lines, and compounds 1, 2 and 5 displayed selectively moderate activities to A549 cell line with IC50 at 15.3, 25.2, 35.2 µg/mL.