Characterization of the <i>Liriodendron chinense</i> Pentatricopeptide Repeat (PPR) Gene Family and Its Role in Osmotic Stress Response

The Pentatricopeptide repeat (PPR) superfamily is a large gene family in plants that regulates organelle RNA metabolism, which is important for plant growth and development. However, a genome-wide analysis of the PPR gene family and its response to abiotic stress has not been reported for the relict woody plant Liriodendron chinense. In this paper, we identified 650 PPR genes from the L. chinense genome. A phylogenetic analysis showed that the LcPPR genes could roughly be divided into the P and PLS subfamilies. We found that 598 LcPPR genes were widely distributed across 19 chromosomes. An intraspecies synteny analysis indicated that duplicated genes from segmental duplication contributed to the expansion of the LcPPR gene family in the L. chinense genome. In addition, we verified the relative expression of Lchi03277, Lchi06624, Lchi18566, and Lchi23489 in the roots, stems, and leaves and found that all four genes had the highest expression in the leaves. By simulating a drought treatment and quantitative reverse transcription PCR (qRT-PCR) analysis, we confirmed the drought-responsive transcriptional changes in four LcPPR genes, two of which responded to drought stress independent of endogenous ABA biosynthesis. Thus, our study provides a comprehensive analysis of the L. chinense PPR gene family. It contributes to research into their roles in this valuable tree species’ growth, development, and stress resistance

Flow Injection Photochemical Vapor Generation Coupled with Miniaturized Solution-Cathode Glow Discharge Atomic Emission Spectrometry for Determination and Speciation Analysis of Mercury

A novel, compact, and green method was developed for the determination and speciation analysis of mercury, based on flow injection photochemical vapor generation (PVG) coupled with miniaturized solution cathode glow discharge-atomic emission spectroscopy (SCGD-AES). The SCGD was generated between a miniature hollow titanium tube and a solution emerging from a glass capillary. Cold mercury vapor (Hg(0)) was generated by PVG and subsequently delivered to the SCGD for excitation, and finally the emission signals were recorded by a miniaturized spectrograph. The detection limits (DLs) of Hg­(II) and methylmercury (MeHg) were both determined to be 0.2 μg L^–1. Moreover, mercury speciation analysis could also be performed by using different wavelengths and powers from the UV lamp and irradiation times. Both Hg­(II) and MeHg can be converted to Hg(0) for the determination of total mercury (T-Hg) with 8 W/254 nm UV lamp and 60 s irradiation time; while only Hg­(II) can be reduced to Hg(0) and determined selectively with 4 W/365 nm UV lamp and 20 s irradiation time. Then, the concentration of MeHg can be calculated by subtracting the Hg­(II) from the T-Hg. Because of its similar sensitivity and DL at 8 W/254 nm, the simpler and less toxic Hg­(II) was used successfully as a primary standard for the quantification of T-Hg. The novel PVG-SCGD-AES system provides not only a 365-fold improvement in the DL for Hg­(II) but also a nonchromatographic method for the speciation analysis of mercury. After validating its accuracy, this method was successfully used for mercury speciation analysis of water and biological samples

A digital microfluidic diluter-based microalgal motion biosensor for marine pollution monitoring

Marine pollution and monitoring have received more and more concern in recent years. Herein, a fully automatic whole-algae biosensor was designed for low-cost and fast detection of toxic contaminants in seawater. It consists of a digital microfluidic (DMF) diluter chip, an actuation element, a detector element, and a microalgae bioreporter. A feedback-control protocol based on charging-time compensation was introduced. It ensures precise actuation of the droplet with diverse salty concentrations and contents in the marine environment. The two mixer cross-split dilution engine increases the accuracy of droplet dispensing and concentration diluting. By selecting motility of P. subcordiformis as the sensor signal, the developed biosensor showed good sensitivity and robustness for a wide range of salinity (10-37 parts per thousand), temperature (0-25 degrees C), light levels (0-325 mu mol photons m(-2) s(-1)), and cell density factor (1.0-4.0). The biosensor responses were examined in the presence of copper, lead, phenol, and nonylphenol (NP). In all cases, toxic responses (i.e. dose-related inhibition of algal motion) were detected with the detection limits of 0.65 mu mol.L-1, 1.90 mu mol.L-1, 2.85 mmol.L-1, and 5.22 mu mol.l(-1) respectively. These results were obtained in a much shorter time (2 h for our biosensor vs. 24 h-10 d for growth inhibition test) and the data are consistent with previous classical studies. We thus developed a simple, rapid, and adaptable system for marine routine monitoring and early-warning detection for lab and on-site applications

Overall and individual associations between per- and polyfluoroalkyl substances and liver function indices and the metabolic mechanism

Per- and polyfluoroalkyl substances (PFAS) can disrupt liver homeostasis. Studies have shown that a single exposure to PFAS may provoke abnormal liver function; however, few studies have investigated the overall effect of PFAS mixtures. We aimed to investigate associations between exposure to PFAS mixtures and liver function indices and explore the relevant mechanisms. This study included 278 adult males from Guangzhou, China. Serum metabolite profiles were analyzed using untargeted metabolomics. We applied weighted quantile sum (WQS) regression as well as Bayesian kernel machine regression (BKMR) to analyze the association of nine PFAS mixtures with 14 liver function indices. PFAS mixtures were positively associated with apolipoprotein B (APOB) and gamma-glutamyltransferase (GGT) and negatively associated with direct bilirubin (DBIL) and total bilirubin (TBIL) in both the WQS and BKMR analyses. In addition, Spearman’s correlation test showed individual PFAS correlated with APOB, GGT, TBIL, and DBIL, while there’s little correlation between individual PFAS and other liver function indices. In linear regression analysis, PFHxS, PFOS, PFHpS, PFNA, PFDA, and PFUdA were associated with APOB; PFOA, PFDA, PFOS, PFNA, and PFUdA were associated with GGT. Subsequently, a metabolome-wide association study and mediation analysis were combined to explore metabolites that mediate these associations. The mechanisms linking PFAS to APOB and GGT are mainly related with amino acid and glycerophospholipid metabolism. High-dimensional mediation analysis showed that glycerophospholipids are the main markers of the association between PFAS and APOB, and that (R)-dihydromaleimide, Ile Leu, (R)-(+)-2-pyrrolidone-5-carboxylic acid, and L-glutamate are the main markers of the association between PFAS and GGT. In summary, overall associations between PFAS and specific indices of liver function were found using two statistical methods; the metabolic pathways and markers identified here may serve to prompt more detailed study in animal-based systems, as well as a similar detailed analysis in other populations

Microfluidic chemostatic bioreactor for high-throughput screening and sustainable co-harvesting of biomass and biodiesel in microalgae

As a renewable and sustainable source for energy, environment, and biomedical applications, microalgae and microalgal biodiesel have attracted great attention. However, their applications are confined due to the cost-efficiency of microalgal mass production. One-step strategy and continuous culturing systems could be solutions. However, current studies for optimization throughout microalgae-based biofuel production pipelines are generally derived from the batch culture process. Better tools are needed to study algal growth kinetics in continuous systems. A microfluidic chemostatic bioreactor was presented here, providing low-bioadhesive cultivations for algae in a cooperative environment of gas, nutrition, and temperature (GNT) involved with high throughput. The chip was used to mimic the continuous culture environment of bioreactors. It allowed simultaneously studying of 8 × 8 different chemostatic conditions on algal growth and oil production in parallel on a 7 × 7 cm2 footprint. On-chip experiments of batch and continuous cultures of Chlorella. sp. were performed to study growth and lipid accumulation under different nitrogen concentrations. The results demonstrated that microalgal cultures can be regulated to grow and accumulate lipids concurrently, thus enhancing lipid productivity in one step. The developed on-chip culturing condition screening, which was more suitable for continuous bioreactor, was achieved at a half shorter time, 64-times higher throughput, and less reagent consumption. It could be used to establish chemostat cultures in continuous bioreactors which can dramatically accelerate the development of renewable and sustainable algal for CO2 fixation and biosynthesis and related systems for advanced sustainable energy, food, pharmacy, and agriculture with enormous social and ecological benefits

Ambient ozone and mortality from respiratory diseases: A nationwide analysis in China

Background: Although the health impacts of ambient ozone (O3) have been widely assessed, studies simultaneously investigating the acute and chronic effects of O3 on mortality from respiratory diseases (RESP) are scarce. Methods: We extracted personal information of all recorded deaths from RESP throughout 2013–2018 in six provinces in China. The daily, seasonal, and annual mean air pollutant concentrations at the township/subdistrict level were estimated by a random forest model. The acute association between the maximum daily average 8h ozone (MDA8 O3) and RESP mortality was examined by a time-stratified case-crossover study design, and the chronic association was estimated by a difference-in-differences (DID) analysis approach. We also calculated the attributable fraction (AF) of RESP mortality attributable to MDA8 O3. Results: There were 1,034,226 RESP deaths included in this study. The excess risks (ERs) of overall RESP mortality for each 10 μg/m3 increase in short-term (lag03 days) and long-term (one-year average) exposure to MDA8 O3 were 0.38 % (95%CI: 0.26 %, 0.50 %) and 4.37 % (3.91 %, 4.84 %), respectively. The AFs of overall RESP mortality ascribed to short- and long-term MDA8 O3 exposures were 3.00 % (2.03 %, 3.95 %) and 29.45 % (26.86 %, 31.95 %), respectively. The average annual number of RESP deaths attributable to short-term MDA8 O3 exposure was 30,790 and 302,254 were attributable to long-term MDA8 O3 exposure across China during 2013–2018. Conclusion: Both short- and long-term exposure to ambient MDA8 O3 were positively associated with RESP mortality, and long-term exposure to MDA8 O3 may lead to a greater RESP mortality burden than short-term exposure to MDA8 O3