Toxic effect and mechanism of ß-cypermethrin and its chiral isomers on HTR-8/SVneo cells.

Beta-cypermethrin (ß-CYP) consists of four chiral isomers, acting as an environmental estrogen and causing reproductive toxicity, neurotoxicity, and dysfunctions in multiple organ systems. This study investigated the toxic effects of ß-CYP, its isomers, metabolite 3-phenoxybenzoic acid (3-PBA), and 17ß-estradiol (E2) on HTR-8/SVneo cells. We focused on the toxic mechanisms of ß-CYP and its specific isomers. Our results showed that ß-CYP and its isomers inhibit HTR-8/SVneo cell proliferation similarly to E2, with 100 µM 1S-trans-αR displaying significant toxicity after 48 h. Notably, 1S-trans-αR, 1R-trans-αS, and ß-CYP were more potent in inducing apoptosis and cell cycle arrest than 1R-cis-αS and 1S-cis-αR at 48 h. AO/EB staining and flow cytometry indicated dose-dependent apoptosis in HTR-8/SVneo cells, particularly at 100 µM 1R-trans-αS. Scratch assays revealed that ß-CYP and its isomers variably reduced cell migration. Receptor inhibition assays demonstrated that post-ICI 182780 treatment, which inhibits estrogen receptor α (ERα) or estrogen receptor ß (ERß), ß-CYP, its isomers, and E2 reduced HTR-8/SVneo cell viability, whereas milrinone, a phosphodiesterase 3 A (PDE3A) inhibitor, increased viability. Molecular docking studies indicated a higher affinity of ß-CYP, its isomers, and E2 for PDE3A than for ERα or ERß. Consequently, ß-CYP, its isomers, and E2 consistently led to decreased cell viability. Transcriptomics and RT-qPCR analyses showed differential expression in treated cells: up-regulation of Il24 and Ptgs2, and down-regulation of Myo7a and Pdgfrb, suggesting the PI3K-AKT signaling pathway as a potential route for toxicity. This study aims to provide a comprehensive evaluation of the cytotoxicity of chiral pesticides and their mechanisms.

Nitrogen addition regulates the effects of variation in precipitation patterns on plant biomass formation and allocation in a Leymus chinensis grassland of northeast China.

Global warming is predicted to change precipitation amount and reduce precipitation frequency, which may alter grassland primary productivity and biomass allocation, especially when interact with other global change factors, such as nitrogen deposition. The interactive effects of changes in precipitation amount and nitrogen addition on productivity and biomass allocation are extensively studied; however, how these effects may be regulated by the predicted reduction in precipitation frequency remain largely unknown. Using a mesocosm experiment, we investigated responses of primary productivity and biomass allocation to the manipulated changes in precipitation amount (PA: 150 mm, 300 mm, 450 mm), precipitation frequency (PF: medium and low), and nitrogen addition (NA: 0 and 10 g N m-2 yr-1) in a Leymus chinensis grassland. We detected significant effects of the PA, PF and NA treatments on both aboveground biomass (AGB) and belowground biomass (BGB); but the interactive effects were only significant between the PA and NA on AGB. Both AGB and BGB increased with an increment in precipitation amount and nitrogen addition; the reduction in PF decreased AGB, but increased BGB. The reduced PF treatment induced an enhancement in the variation of soil moisture, which subsequently affected photosynthesis and biomass formation. Overall, there were mismatches in the above- and belowground biomass responses to changes in precipitation regime. Our results suggest the predicted changes in precipitation regime, including precipitation amount and frequency, is likely to alter primary productivity and biomass allocation, especially when interact with nitrogen deposition. Therefore, predicting the influence of global changes on grassland structure and functions requires the consideration of interactions among multiple global change factors.

Identification of microRNAs in Silver Carp (Hypophthalmichthys molitrix) Response to Hypoxia Stress.

Hypoxia is one of the serious stresses in fish culture, which can lead to physical and morphological changes, and cause injury and even death to fish. Silver carp (Hypophthalmichthys molitrix) is an important economic fish and widely distributed in China. MicroRNA is a kind of endogenous non-coding single-stranded small RNA, which is involved in cell development, and immune response and gene expression regulation. In this study, silver carp were kept in the closed containers for hypoxia treatment by spontaneous oxygen consumption. The samples of heart, brain, liver and gill were collected, and the total RNAs extracted separately from the four tissues were mixed in equal amounts according to the concentration. Afterwards, the RNA pool was constructed for high-throughput sequencing, and based on the small RNA sequencing, the differentially expressed microRNAs were identified. Furthermore, their target gene prediction and enrichment analyses were carried out. The results showed that a total of 229 known miRNAs and 391 putative novel miRNAs were identified, which provided valuable resources for further study on the regulatory mechanism of miRNAs in silver carp under hypoxia stress. The authors verified 16 differentially expressed miRNAs by qRT-PCR, and the results were consistent with small RNA sequencing (sRNA-seq). The predicted target genes number of differentially expressed miRNAs was 25,146. GO and KEGG functional enrichment analysis showed that these target genes were mainly involved in the adaption of hypoxia stress in silver carp through biological regulation, catalytic activity and apoptosis. This study provides references for further study of interaction between miRNAs and target genes, and the basic data for the response mechanism under hypoxia stress in silver carp.

Facile synthesis of a bismuth nanostructure with enhanced selectivity for electrochemical conversion of CO2 to formate.

Electrochemically converting carbon dioxide (CO2) to formate offers a promising approach for energy conversion and storage. Bismuth is believed to be one of the promising candidates for CO2 electroreduction, but the poor selectivity and complexity of synthesis limit its real application on a large scale. In this work, a facile one-step-reduction method was developed to prepare a bismuth nanostructure in aqueous solution. Owing to its enhanced reactive sites and exposed crystal plane, the prepared Bi nanostructure exhibits excellent performance for CO2 electroreduction, which reaches the maximum faradaic efficiency for formate as high as 92% at a potential of -0.9 V versus a reversible hydrogen electrode. Additionally, the large current density and remarkable durability also reveal its high intrinsic CO2 electroreduction activity. The density functional theory calculation confirms that the formation of intermediate *OCHO that finally converts to formate is thermodynamically favorable on Bi high-index planes. We anticipate that such a facile synthesis strategy and excellent electrocatalytic performance of the Bi nanostructure will be easy to scale up, realizing its industrialization applications in CO2 electrochemical conversion.