Aquatic photolysis of high-risk fluorinated liquid crystal monomers: Kinetics, toxicity evaluation, and mechanisms.

Despite the frequent detection of fluorinated liquid-crystal monomers (FLCMs) in the environment, the level of understanding of their fate, toxicity, and transformation remains insufficient. Herein, we investigated the degradation kinetics and mechanism of an FLCM (4-cyano-3-fluorophenyl 4-ethylbenzoate, CEB-F) under ultraviolet (UV) photolysis in aquatic environment. Our findings demonstrated that the UV photolysis of CEB-F followed first-order kinetics. Photodegradation products were identified using liquid chromatography with mass spectrometry, and detailed reaction pathways were proposed. It is postulated that through the attack of reactive oxygen species, hydroxylation, and CO/C-F bond cleavage, CEB-F gradually degraded into small molecular compounds, releasing fluorine ions. Acute immobilization tests with Daphnia magna (D. magna) revealed significant acute toxicity of CEB-F, with LC50 values ranging from 1.023 to 0.0536 µM over 24 to 96 h, emphasizing the potential high risk of FLCMs in aquatic ecosystems if inadvertently discharged. Interestingly, we found that the toxicity of CEB-F photolysis reaction solutions was effectively reduced. Through catalase and acetylcholinesterase activities analysis along with molecular docking simulation, we proposed differences in the underlying toxicity mechanisms of CEB-F and its photolysis products to D. magna. These findings highlight the potential harmful effects of FLCMs on aquatic ecosystems and enrich our understanding of the photolysis behavior of FLCMs.

Cytotoxicity and hemolysis of rare earth ions and nanoscale/bulk oxides (La, Gd, and Yb): Interaction with lipid membranes and protein corona formation.

The widespread application of rare earth elements (REEs) has raised concerns about their potential release into the environment and subsequent ingestion by humans. Therefore, it is essential to evaluate the cytotoxicity of REEs. Here, we investigated the interactions between three typical REEs (La, Gd, and Yb) ions as well as their nanometer/µm-sized oxides and red blood cells (RBCs), a plausible contact target for nanoparticles when they enter the bloodstream. Hemolysis of REEs at 50-2000 µmol L-1 was examined to simulate their cytotoxicity under medical or occupational exposure. We found that the hemolysis due to the exposure of REEs was highly dependent on their concentration, and the cytotoxicity followed the order of La3+ > Gd3+ > Yb3+. The cytotoxicity of REE ions (REIs) is higher than REE oxides (REOs), while nanometer-sized REO caused more hemolysis than that µm-sized REO. The production of reactive oxygen species (ROS), ROS quenching experiment, as well as the detection of lipid peroxidation, confirmed that REEs causes cell membrane rupture by ROS-related chemical oxidation. In addition, we found that the formation of a protein corona on REEs increased the steric repulsion between REEs and cell membranes, hence mitigating the cytotoxicity of REEs. The theoretical simulation indicated the favorable interaction of REEs with phospholipids and proteins. Therefore, our findings provide a mechanistic explanation for the cytotoxicity of REEs to RBCs once they have entered the blood circulation system of organisms.

Reference Genes Selection of Gymnosporangium yamadae during the Interaction with Apple Leaves.

Apple rust disease caused by Gymnosporangium yamadae is the one of the major threats to the development of the apple industry in China, but the pathogenic molecular mechanism of the disease remains unclear. It is imperative to screen out appropriate reference genes during the interaction between G. yamadae and apple leaves to analyze the gene expression patterns during the pathogenesis of G. yamadae. ACT, EF1, EF2, GAPDH, 40S, 60S, α-TUB, ß-TUB and UBCE3 were selected as candidate reference genes based on the transcriptomic dataset of G. yamadae. The expression levels were tested by real-time quantitative PCR during time-course infection of apple leaves and the expression stabilities were evaluated by △Ct method as well as by three software (NormFinder, geNorm and BestKeeper) and one web-based analysis software (RefFinder). The expression stability of the candidate reference genes was further validated by using the effector candidate gene Cluster-3395.48660 as the target gene in RT-qPCR. According to the results by △Ct and BestKeeper, 40S, EF2 and EF1 were the most stable reference genes, while EF1, EF2 and GAPDH were the most stable reference genes based on the NormFinder analysis result. The geNorm recommended the most stable genes EF1, EF2 and α-TUB as reference genes. Comprehensive analysis results of the RefFinder indicated EF1, EF2 and α-TUB were the most suitable genes. Based on these results, EF1, EF2 and α-TUB were considered as reference genes for analyzing the gene expression profiles of Cluster-3395.48660 in different infection stages, and the results were consistent with the transcriptome data. All the results suggest that the combination of EF1, EF2 and α-TUB proved to be acceptable reference genes during the interaction between G. yamadae and apple leaves.