Transcriptomic analysis of formic acid stress response in Saccharomyces cerevisiae.

Formic acid is a representative small molecule acid in lignocellulosic hydrolysate that can inhibit the growth of Saccharomyces cerevisiae cells during alcohol fermentation. However, the mechanism of formic acid cytotoxicity remains largely unknown. In this study, RNA-Seq technology was used to study the response of S. cerevisiae to formic acid stress at the transcriptional level. Scanning electron microscopy and Fourier transform infrared spectroscopy were conducted to observe the surface morphology of yeast cells. A total of 1504 genes were identified as being differentially expressed, with 797 upregulated and 707 downregulated genes. Transcriptomic analysis showed that most genes related to glycolysis, glycogen synthesis, protein degradation, the cell cycle, the MAPK signaling pathway, and redox regulation were significantly induced under formic acid stress and were involved in protein translation and synthesis amino acid synthesis genes were significantly suppressed. Formic acid stress can induce oxidative stress, inhibit protein biosynthesis, cause cells to undergo autophagy, and activate the intracellular metabolic pathways of energy production. The increase of glycogen and the decrease of energy consumption metabolism may be important in the adaptation of S. cerevisiae to formic acid. In addition, formic acid can also induce sexual reproduction and spore formation. This study through transcriptome analysis has preliminarily reveal the molecular response mechanism of S. cerevisiae to formic acid stress and has provided a basis for further research on methods used to improve the tolerance to cell inhibitors in lignocellulose hydrolysate.

A Risk Assessment Approach for Evaluating the Impact of Toxic Contaminants Released Indoors by Considering Various Emergency Ventilation and Evacuation Strategies.

The release of toxic airborne contaminants resulting from terrorist attacks on buildings can lead to disastrous consequences. To evaluate and reduce the effects of these emergencies, various methods and models have been developed in the past few years. Such work has provided effective tools for the building management system to do risk assessment of the contaminated areas. Although risk analysis methods to describe the contaminant dispersion scenarios made significant progress, these approaches did not generally consider the releasing scenario occurring in the ventilation system and the effect of human behavior during the developing process of an emergency event. Emergency strategies chosen by the decisionmaker are not always associated with the early-warning system, such as the sensor monitoring network and the source identification system inside the building. This study aims to provide a risk assessment model considering both the variation of contaminant concentration and occupant distribution after the release of toxic agents to obtain the exposure risk for people indoors. The contaminant dispersion is simulated using computational fluid dynamics. The evacuation process for people is modeled using Pathfinder, and the exposure risk for occupants under various emergency strategies is calculated using the efficiency factor of the contaminant source. The results of the exposure risk for 40 basic cases are discussed, and the optimal ventilation mode for these specific cases is recommended. Next, the impact of the variation of human behavior, contaminant detection time needed by sensors, and source identification time needed by inverse modeling on the exposure risk for people indoor is studied. The uncertainty and reproducibility of the numerical simulations are emphatically discussed in the Supporting Information.

[Chemical Constituents from Leaves of Acanthus ilicifolius and Their Anti-influenza Virus Activities].

OBJECTIVE: To study the chemical constituents from the leaves of Acanthus ilicifolius. METHODS: The compounds were isolated by silica and gel column chromatographic methods and identified by spectoscopic analysis. The anti-influenza virus activities of these compounds were obtained by measuring the neuraminidase activity of influenza virus. RESULTS: Five compounds were isolated and their structures were identified as blepharin(1), acteoside(2), isoverbascoside(3), daucosterol(4), and 3-O-ß-D-glucopyranosyl-stigmasterol(5). CONCLUSION: All the compounds are isolated from the leaves of Acanthus ilicifolius for the first time, and compounds 1 ~ 3 exhibit the anti-influenza virus activities.

Metabolome analysis of the response and tolerance mechanisms of Saccharomyces cerevisiae to formic acid stress.

Various inhibitors are produced during the hydrolysis of lignocellulosic biomass that can interfere with the growth of yeast cells and the production of bioethanol. Formic acid is a common weak acid inhibitor present in lignocellulosic hydrolysate that has toxic effects on yeast cells. However, the mechanism of the response of Saccharomyces cerevisiae to formic acid is not fully understood. In this study, liquid chromatography-mass spectrometry (LC-MS) was used to investigate the effects of formic acid treatment on cell metabolites of S. cerevisiae. Treatment with different concentrations of formic acid significantly inhibited the growth of yeast cells, reduced the yield of ethanol, prolonged the cell fermentation cycle, and increased the content of malondialdehyde. Principal component analysis and orthogonal partial least squares discriminant analysis showed that 55 metabolites were significantly altered in S. cerevisiae after formic acid treatment. The metabolic relevance of these compounds in the response of S. cerevisiae to formic acid stress was investigated. Formic acid can cause oxidative stress, inhibit protein synthesis, and damage DNA in S. cerevisiae, and these are possible reasons for the inhibition of S. cerevisiae cell growth. In addition, the levels of several aromatic amino acids identified in the cells of formic acid-treated yeast were increased; the biosynthesis of nucleotides was slowed, and energy consumption was reduced. These mechanisms may help to improve the tolerance of yeast cells to formic acid. The results described herein highlight our current understanding of the molecular mechanism of the response of S. cerevisiae to formic acid. The study will provide a theoretical basis for research on the tolerance mechanisms of S. cerevisiae.

Multi-objective optimization for sensor placement against suddenly released contaminant in air duct system.

When a chemical or biological agent is suddenly released into a ventilation system, its dispersion needs to be promptly and accurately detected. In this work, an optimization method for sensors layout in air ductwork was presented. Three optimal objectives were defined, i.e. the minimum detection time, minimum contaminant exposure, and minimum probability of undetected pollution events. Genetic algorithm (GA) method was used to obtain the non-dominated solutions of multiobjectives optimization problem and the global optimal solution was selected among all of the non-dominated solutions by ordering solutions method. Since the biochemical attack occurred in a ventilation system was a random process, two releasing scenarios were proposed, i.e. the uniform and the air volume-based probability distribution. It was found that such a probability distribution affected the results of optimal sensors layout and also resulted in different detect time and different probability of undetected events. It was discussed how the objective functions are being compatible and competitive with each other, and how sensor quantity affect the optimal results and computational load. The impact of changes on other parameters was given, i.e. the deposition coefficient, the air volume distribution and the manual releasing. This work presents an angle of air ductwork design for indoor environment protection and expects to help in realizing the optimized sensor system design for sudden contaminant releasing within ventilation systems.

Simultaneous determination of the major isosteroidal alkaloids and their glucosides in the bulbs of Fritillaria by high performance liquid chromatography coupled with evaporative light scattering detection.

AIM: To establish an HPLC-ELSD method for the simultaneous determination of five major bioactive isosteroidal alkaloids and gluco-alkaloids in the bulbs of Fritillaria namely peimissine, imperialine, sinpeinine A, imperialine-3 beta-glucoside and yibeinoside A. METHODS: A Nova-Pak C18 column (150 mm x 3.9 mm ID) was used. The chromatography was carried out with a linear gradient programming. The mobile phase was acetonitrile-water (containing 0.1% diethylamine) and the flow rate was 1.0 mL.min-1. RESULTS: The linear range of peimissine was 13.1-288.2 mg.L-1 (r2 = 0.9975), imperialine-3 beta-glucoside 7.7-169.4 mg.L-1 (r2 = 0.9993), yibeinoside A 7.3-160.6 mg.L-1 (r2 = 0.9997), imperialine 16.5-363.0 mg.L-1 (r2 = 0.9992), sinpeinine A 8.7-191.4 mg.L-1 (r2 = 0.9942). CONCLUSION: The method is accurate with overall intra- and inter-day variation less than 5% and recovery more than 95%. The method was successfully applied to analyze five major bioactive alkaloids and gluco-alkaloids in three Fritillaria bulbs.

Development of solvent micro-extraction combined with derivatization.

Solvent microextraction (SME), such as single-drop microextraction (SDME), hollow-fiber liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME), has been explored for its ability to cover a wide range of analytes. Microextraction, combined microextraction with derivatization can greatly improve separation, detectability and compound identification, expand its scope of application, and improve the effect of analysis. In this view, the article not only highlights the development of the microextraction technology such as SDBE, HF-LPME and DLLME, but also improves the key strategies of microextraction coupled to derivatization in analytical chemistry. In order to encourage further development of microextraction-derivatization, its coupling with different analytical techniques such as GC or GC-MS, HPLC, and the other technique has also been discussed.

Chemical characteristics of Salvia miltiorrhiza (Danshen) collected from different locations in China.

The chemical characteristics of Salvia miltiorrhiza , also called "danshen" in China, were investigated on the basis of the simultaneous quantitative determination of 13 hydrophilic and lipophilic compounds, namely, protocatechuic acid, protocatechuic aldehyde, caffeic acid, ferulic acid, isoferulic acid, rosmarinic acid, salvianolic acid B, salvianolic acid A, dihydrotanshinone I, przewalskin, cryptotanshinone, tanshinone I, and tanshinone IIA, in 74 samples collected from different locations using ultraperformance liquid chromatography (UPLC). Hierarchical clustering analysis based on 13 investigated compounds and the similarity of the entire chromatographic pattern showed that S. miltiorrhiza was significantly different from Salvia przewalskii , an adulterant of danshen. The chemical characteristics of S. miltiorrhiza collected from different locations in China were revealed, and salvianolic acid B, rosmarinic acid, cryptotanshinone, and tanshinones I and IIA were optimized as markers for the evaluation, which is helpful in the quality control of S. miltiorrhiza.

The extraction of imperialine and imperialine-3 beta-glucoside from Fritillaria pallidiflora Schrenk and quantitative determination by HPLC-evaporative light scattering detection.

The extraction procedure and quantitative determination by HPLC-evaporative light scattering detection (ELSD) of the main bioactive components, namely, imperialine (1) and imperialine-3 beta-glucoside (2), of bulbs of Fritillaria pallidiflora Schrenk have been investigated. The most efficient method for the simultaneous extraction of 1 and 2 involved pre-treatment of the bulb powder with ammonia, followed by reflux with dichloromethane:methanol at 90 degrees C for 4 h. Simultaneous determination of non-chromophoric 1 and 2 by HPLC-ELSD employed a Kromasil C18 column eluted with acetonitrile:water:diethylamine. The assay was accurate and reproducible with an overall variation lower than 4% and a sample recovery higher than 98%. The methods described have been successfully used to evaluate the quality of three batches of the crude traditional Chinese medicinal herb derived from the bulbs of F. pallidiflora.