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Nanobubble water (NBW) could improve methane production from anaerobic digestion (AD) of corn straw without secondary contamination. In this study, the effect of carbon dioxide nanobubble water (CO 2 -NBW) volumes (0%, 25%, 50%, 75%, 100%) on methane production from corn straw was investigated. The results showed that addition of CO 2 -NBW could improve methane production and promote substrate degradation in AD process. The highest cumulative methane production of 132.16 mL g−1VS added was obtained in the 100% CO 2 -NBW added reactor, which was 17% higher than that in the control group. Additionally, the addition of CO 2 -NBW could mitigate the sharp decrease in pH by acting as a buffer. CO 2 -NBW could also enhance microorganism activity throughout the AD process. The electron transport system (ETS) activity was increased by 23%, while the β-glucosidase, dehydrogenase (DHA), and coenzyme F 420 activities were increased by 15%, 23%, and 11%, respectively, at optimum addition of CO 2 -NBW. Meanwhile, addition of CO 2 -NBW accelerated the production and consumption of reducing sugar and volatile fatty acids (VFAs), promoting the reduction rates of TS (Total solid) and VS (Volatile solid). [Display omitted] • Methane yield was increased by 4%–17% with CO 2 -NBW. • CO 2 -NBW addition could mitigate the sharp decrease in pH by acting as a buffer. • ETS activity was enhanced by 23% with 100% CO 2 -NBW addition. • Supplementation of CO 2 -NBW could stimulate microbial activity. • Adding CO 2 -NBW enhanced the production/consumption of reducing sugar and VFAs. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA), is a common contaminant in diverse environmental compartments and its endocrine disruptive effect on living organisms has been widely reported. Further works are still required to facilitate the research on cytotoxicity and genotoxicity. In the present study, grass carp ovary (GCO) cells were used to investigate cellular oxidative stress and genomic DNA methylation under BPA exposure. Results showed that BPA exposure for 48 h arrested cell proliferation and viability. The oxidative stress was distinctly enhanced with increased reactive oxygen species (ROS), malondialdehyde level, and oxidation of reduced glutathione (GSH) in 30 μM BPA group. Furthermore, the global 5-methylcytosine (5 mC) level was elevated and showed inverted U-shaped responses to the BPA doses. Besides, one-carbon metabolism and de novo GSH synthesis were disrupted at 30 μM BPA. Current data suggested that low dose of BPA exposure could exhibit hormesis in recycling circular biosynthesis of GSH and scavenging ROS to create a relatively reductive intracellular environment, and up-regulate transcripts of methyltransferases that increased the 5 mC level in GCO cells. While high dose of BPA distinctly induced oxidative stress, elevated de novo GSH synthesis, and then attenuated transmethylation activity and decreased 5 mC level. Current study highlighted the discrepant dose responses of BPA in fish ovary cells that facilitated the understanding of pleiotropic consequences in organisms. Image 1 • BPA exposure affected the proliferation and viability of GCO cells, accompanied by discrepant oxidative stress. • Low dose of BPA exhibited hormesis in creating a relatively reductive intracellular environment. • Global 5-methylcytosine level was enhanced and showed inverted U-shaped responses in GCO cells under BPA exposure. • Elevated de novo glutathione synthesis attenuated the one-carbon metabolism and then decreased 5-methylcytosine level. [ABSTRACT FROM AUTHOR]

Here we reported the stress responses of nutrient deprivation and extended observation of autophagy, apoptosis, and DNA methylation in zebrafish embryonic fibroblast (ZF4) cells. Our results showed that serum deprivation resulted in the changes of cell shape and adherent ability, the suppressed cell growth and viability, and the inhibited proliferation and cell cycle. Besides, the appearance of lysosome and autophagosome/autolysosome with significantly increased expression of mRNAs (ulk1a , becn1 , atg12 , sqstm1 , maplc3 , and lamp1) and proteins (Atg12, Becn1, Sqstm1, and Lamp1) indicate the autophagic activity was boosted at initial stage but relatively weakened at 48 h of serum starvation. When autophagy no longer mitigate for the stress, cell apoptosis detected by the mRNA expression of caspases, Bcl-2/Bax expression, and Annexin V/PI was gradually enhanced to execute the death plan upon prolonged starvation process. Furthermore, the methyl group metabolism was increased in accordance with autophagic activity and was suppressed by enhanced apoptotic activity. These data suggested that the recycle activity induced by autophagy could compensate the substrates and reactions of DNA transmethylation, which obviously increased 5-methylcytosine (5 mC) level in ZF4 cells. In summary, our results discovered the cellular responses under prolonged serum starvation stress and elaborated the switch from autophagy to apoptosis and corresponding correlation with 5 mC level changes in teleost fish in vitro. Image 1 • Serum deprivation changed cell morphology, viability, proliferation, and cell cycle in ZF4 cells. • Autophagic activity was boosted initially but relatively weakened later in starved ZF4 cells. • Apoptosis was gradually enhanced with early-/later-stage apoptotic cells under serum starvation. • 5-methylcytosine level was increased with altered methyl group metabolism under serum starvation. [ABSTRACT FROM AUTHOR]

Dibutyl phthalate (DBP) is commonly applied plasticizer in plastic products such as face masks, easily leaches or migrates into environment and its widespread contamination posed profound health risks. Further concerns rise regarding to the toxicity of DBP at subcellular level, while little is known about the ranging effects on mitochondrial susceptibility. Present study investigated the mitochondrial impairments with implicated cell death upon DBP exposure on zebrafish cells. Elevated mitochondrial oxidative stress reduced its membrane potential and count, enhanced fragmentation, and impaired ultrastructure that showed smaller size and cristae rupture. Afterwards, the critical function of ATP synthesis was damaged and the stabilized binding capacity between DBP with mitochondrial respiratory complexes was simulated by the molecular docking. And the top pathways enrichment of mitochondrion and metabolism by transcriptome analyses verified the mitochondrial dysfunction that indicated the human diseases risks. The mitochondrial DNA (mtDNA) replication and transcription with DNA methylation modifications were also disrupted, reflecting the genotoxicity on mtDNA. Moreover, the activated autophagy and apoptosis underlying mitochondrial susceptibility integrated into cellular homeostasis changes. These findings provide the first systemic evidence broadening and illustrating the mitochondrial toxicity of DBP exposure on zebrafish model that raise concern on phthalates contamination and ecotoxicological evaluation. [Display omitted] • DBP exposure elevated oxidative stress, impaired mitochondrial function and ultrastructure. • DBP showed stabilized binding capacity with the mitochondrial respiratory complexes. • DBP induced mtDNA instability including hypermethylation, depressed replication and transcription. • Mitochondrial susceptibility indicated the risks of neurodegenerative disorders. [ABSTRACT FROM AUTHOR]

Abstract In this study, characteristics of dissolved organic matter (DOM) and bacterial community structure in rice washing drainage (RWD)-based groundwater denitrification systems inoculated with and without seeding sludge were investigated. Complete nitrate removal was achieved with a maximum denitrification rate of 64.1 mg NO 3 −-N·(gVSS·h)−1. Analysis of three-dimension fluorescence excitation-emission matrix (FEEM) identified three main compositions of DOM associated with tryptophan protein-like, aromatic protein-like, and polycarboxylate humic acid-like substances in the inoculated system, while one composition associated with tryptophan protein-like substance in the un-inoculated system. Illumina sequencing analysis revealed a distinguished bacterial community structure in two systems over time. Notably, the microbial diversity was significant lower in the un-inoculated system than that in the system inoculated with seeding sludge. The predominant phyla shifted from Proteobacteria (49.2%), Bacteroidetes (20.5%) and Chloroflexi (14.8%) in the seeding sludge to Bacteroidetes (56.3%) and Proteobacteria (37.7%) after the RWD addition in the inoculated system. With RWD as sole microbe source, temporal changes in the bacterial structure from Proteobacteria (99.4%) and Bacteroidetes (5.3%) to Proteobacteria (88.8%) and Bacteroidetes (10.3%) were observed in the un-inoculated system. Specific comparison down to the genus level showed the dominant denitrifying bacteria of Thiobacillus , Anaerolineaceae and Methylophilaceae in the seeding sludge. Ideonella , Cloacibacterium and Enterobacter were dominant after the RWD addition in the inoculated system, while Stenotrophomonas and Enterobacter were dominant genera when RWD as sole bacteria source in the un-inoculated system. This finding indicates that both RWD addition and inoculation had strong impacts on bacterial community structure. Highlights • Denitrification rate reached 64.1 mg NO 3 −-N·(gVSS·h)−1 in RWD-based system. • FEEM results indicate sludge inoculation increased DOM generation. • Tryptophan protein, aromatic protein and humic acid-like substances were main DOMs. • Minimization of DOM was achieved with RWD as sole carbon and microbe source. • Microbial community in both inoculated and un-inoculated systems was unveiled by Illumina sequencing. [ABSTRACT FROM AUTHOR]