Effects of perspective taking on attention bias to body-related information among junior high school students with body image disturbance.

Using lexical judgment tasks, the present study explored whether perspective taking affected attention bias to body-related information among junior high school students with body image disturbance. Experiment 1 examined the junior high school students' attention bias to body schema-related words; the results showed the body image disturbance group responded significantly more quickly to negative body schema-related words than positive words, whereas the control group did not show a significant difference between positive and negative words. In Experiment 2, participants were asked to judge whether the positive or negative body schema-related words were suitable to describe themselves, when adopting their own perspective or that of another person. The results showed that reaction times to negative words were significantly shorter than to positive words when adopting a self-perspective. When taking another's perspective, there was no significant difference of reaction time between positive and negative words. This result demonstrated that perspective taking reduced attention bias to negative body schema-related information among junior high school students with body image disturbance. The present research suggests that guiding adolescents to view themselves from different perspectives can help them form a more accurate and objective body image.

Enhancing wuyiencin productivity of Streptomyces albulus (CK15) by mutagenesis breeding with atmospheric and room temperature plasma.

Streptomyces species are known for their ability to efficiently produce secondary metabolites, including various antibiotics. Wuyiencin, an antibiotic produced by Streptomyces albulus CK15, is commonly used in agriculture to control fungal diseases in crops and vegetables. In this study, we utilized atmospheric and room temperature plasma (ARTP) mutagenesis to generate mutant S. albulus strains with improved fermentation capabilities for wuyiencin production. After mutagenizing the wild-type S. albulus CK15 strain once and conducting two rounds of antimicrobial screening, three genetically stable mutants (M19, M26, and M28) were identified. These mutants showed increased wuyiencin production by 17.4%, 13.6%, and 18.5% in comparison to the CK15 strain in flask culture, respectively. The M28 mutant exhibited the highest wuyiencin activity, producing 1443.0 ± 134.6 U/mL in flask culture and 1673.8 ± 127.4 U/mL in a 5 L fermenter. These results demonstrate that ARTP is an efficient tool for microbial mutation breeding and improving wuyiencin production.

Intermittent fasting attenuates obesity-related atrial fibrillation via SIRT3-mediated insulin resistance mitigation.

OBJECTIVE: Atrial fibrillation (AF) is the most common tachyarrhythmia in urgent need of therapeutic optimization. Obesity engenders AF, and its pathogenesis is closely intertwined with insulin resistance (IR), but mechanism-based management is still underinvestigated. Intermittent fasting (IF) is a novel lifestyle intervention that mitigates IR, a potential AF driver, yet whether IF can prevent obesity-related AF remains elusive. Here, we aimed to evaluate the impacts of short-term IF on AF and to uncover the underlying mechanism. METHODS: We subjected obese mice (high-fat diet for 8-week) to IF (alternative-day fasting for another 5-week) for AF vulnerability and substrate formation assessment, and similarly treated neonatal atrial cardiomyocytes (NRCMs) and fibroblasts (NRCFs) (palmitate, 200 µM) with IF (alternative-day short-term starvation for 8-day) for mechanism investigation. RESULTS: Obese mice were prone to AF and atrial remodeling. IF reduced AF inducibility, duration, and reversed atrial remodeling including channel disturbance, left atrial dilation, cardiac hypertrophy and fibrosis in obese mice independent of weight loss. Mechanistically, IF up-regulated the SIRT3 protein level both in vivo and in vitro, and pharmacologic inhibition (3-(1H-1,2,3-Triazol-4-yl) pyridine, 50 µM) and genetic suppression of SIRT3 could attenuate the IF-mediated benefits against hypertrophy and fibrosis. Furthermore, IF activated AMPK and Akt signaling, two positive downstream targets of SIRT3, and inactivated HIF1α signaling, a negative downstream target of SIRT3 in both obese mice atria and palmitate-treated cells, while inhibition of SIRT3 reversed these effects. CONCLUSION: IF prevents obesity-related AF via SIRT3-mediated IR mitigation, thus representing a feasible lifestyle intervention to improve AF management.

Melatonin increases susceptibility to atrial fibrillation in obesity via Akt signaling impairment in response to lipid overload.

Melatonin has been proven to have antiarrhythmic potential; however, several studies have recently challenged this view. Herein, using a mouse model of obesity-induced atrial fibrillation (AF), we tentatively explored whether exogenous melatonin supplementation could increase AF susceptibility in the context of obesity. We observed that an 8-week drinking administration of melatonin (60 µg/ml in water) induced a greater susceptibility to AF in obese mice, although obesity-induced structural remodeling was alleviated. An investigation of systemic insulin sensitivity showed that melatonin treatment improved insulin sensitivity in obese mice, whereas it inhibited glucose-stimulated insulin secretion. Notably, melatonin treatment inhibited protein kinase B (Akt) signaling in the atria of obese mice and palmitate-treated neonatal rat cardiomyocytes, thereby providing an AF substrate. Melatonin increased lipid stress in obesity, as evidenced by elevated lipid accumulation and lipolysis-related gene expression, thus contributing to the impairment in atrial Akt signaling. Taken together, our results demonstrated that melatonin could increase AF susceptibility in obesity, probably due to increased lipid stress and resultant impairment of atrial Akt signaling. Our findings suggest that special precautions should be taken when administering melatonin to obese subjects.

Hydrogen sulfide protects retinal pigment epithelium cells against ferroptosis through the AMPK- and p62-dependent non-canonical NRF2-KEAP1 pathway.

Oxidative stress-induced ferroptosis of retinal pigment epithelium (RPE) cells contributes to retinal degenerative diseases. The antioxidant molecule hydrogen sulfide (H2S) regulates oxidative stress response, but its effect on the ferroptosis of RPE cells is unclear. In this study, sodium hydrosulfide (NaHS) was used as an exogenous H2S donor to intervene tert-butyl hydroperoxide (t-BHP)-induced ferroptosis of APRE-19 cells. We found that NaHS pretreatment attenuates t-BHP-induced oxidative stress and ferroptosis. Analysis of mRNA-sequencing coupled with FerrDb database identified nuclear factor erythroid-2-related factor 2 (NRF2) as a primary target for the cytoprotective role of H2S. NRF2 inhibitor ML385 reverses the effects of H2S on ferroptosis. Biochemical analysis revealed that H2S stabilizes NRF2. H2S decreases the interaction between NRF2 and KEAP1, but enhances the interaction between KEAP1 and p62. These results suggest that H2S activates the non-canonical NRF2-KEAP1 pathway. Further study demonstrated that H2S stimulates AMPK to interact and phosphorylate p62. Additionally, inhibiting AMPK or knocking down p62 blocks the effects of H2S. We speculate that targeting the non-canonical NRF2-KEAP1 pathway by H2S-based drug may benefit the treatment of retinal degenerative diseases.

Acute Hypoxia Stress-Induced Apoptosis in Gill of Japanese Flounder (Paralichthys olivaceus) by Modulating the Epas1/Bad Pathway.

The physiological responses and molecular mechanisms of apoptosis in Japanese flounder under hypoxic stress remain unclear. In the present study, we performed acute hypoxia stress on Japanese flounder (2.39 ± 0.84 mg/L) and detected gills responses in histomorphology and molecular mechanisms. The results showed that the volume of the interlamellar cell mass decreased and the gill lamellae prolonged, indicating the expansion of the respiratory surface area. Additionally, the fluorescence signal of apoptosis increased under hypoxic stress. In addition, the expression of two genes (EPAS1 and Bad) related to apoptosis increased about four-fold and two-fold, respectively, at 6 h of hypoxia. Meanwhile, the result of the dual-luciferase reporter assay showed that EPAS1 is a transcription factor, which could regulate (p < 0.05) the expression of the Bad gene, and we identified the binding site of EPAS1 was the AATGGAAAC sequence located near −766. DNA methylation assay showed that hypoxia affected the methylation status of CpG islands of EPAS1 and Bad genes. All results indicated that hypoxia could activate the EPAS1/Bad signal pathway to induce gill apoptosis of Japanese flounder. Our study provides new light on understanding the molecular mechanism of hypoxia-induced apoptosis in Japanese flounder.

Association between transoesophageal echocardiography monitoring indicators and the incidence of postoperative acute kidney injury in coronary artery bypass grafting: a study protocol for a prospective multicenter cohort study.

INTRODUCTION: Previous studies on transoesophageal echocardiography in coronary artery bypass grafting mainly focused on whether to change the surgical plan rather than improve the clinical prognosis. Currently, there are sparse studies on the relationship between transoesophageal echocardiography indicators and the prognosis of patients undergoing coronary artery bypass grafting. The primary aim of this study is to explore the association between transoesophageal echocardiography monitoring indicators the respiratory variability of inferior vena cava diameter, tricuspid annular plane systolic excursion and the incidence of acute kidney injury in coronary artery bypass grafting patients. METHODS AND ANALYSIS: We designed this prospective multicenter cohort study, which included approximately 150 adult patients (≥18 years) undergoing elective coronary artery bypass surgery. Different hospitals will be assessed to obtain information on the prevalence, risk factors, management strategies and outcomes in coronary artery bypass surgery. The cohort will be followed after the coronary artery bypass surgery period, up to 30 days after enrolment. The incidence of postoperative acute kidney injury and baseline data will be presented by descriptive statistics. We will use Freidman inspection and multivariable logistic regression to assess the association between transoesophageal echocardiography monitoring indicators and the incidence of acute kidney injury in coronary artery bypass grafting patients. ETHICS AND DISSEMINATION: The study has been approved by the ethics committee of Shandong Provincial Qianfoshan Hospital, China (approval number: YXLL-KY-2021(067)). This is an observational study that poses no risk to the patients. All participants will obtain informed consent according to the ethics committee before patient enrolment. Funding sources will have no influence on data handling, analyses or writing of the manuscript. The article is planned for submission in an international peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT05139108.

Hypoxia Affects HIF-1/LDH-A Signaling Pathway by Methylation Modification and Transcriptional Regulation in Japanese Flounder (Paralichthys olivaceus).

Japanese flounder (Paralichthys olivaceus) responsive mechanisms to hypoxia are still not fully understood. Therefore, we performed an acute hypoxic treatment (dissolved oxygen at 2.07 ± 0.08 mg/L) on Japanese flounder. It was confirmed that the hypoxic stress affected the physiological phenotype through changes in blood physiology (RBC, HGB, WBC), biochemistry (LDH, ALP, ALT, GLU, TC, TG, ALB), and hormone (cortisol) indicators. Hypoxia inducible factor-1 (HIF-1), an essential oxygen homeostasis mediator in organisms consisting of an inducible HIF-1α and a constitutive HIF-1ß, and its target gene LDH-A were deeply studied. Results showed that HIF-1α and LDH-A genes were co-expressed and significantly affected by hypoxic stress. The dual-luciferase reporter assay confirmed that transcription factor HIF-1 transcriptionally regulated the LDH-A gene, and its transcription binding sequence was GGACGTGA located at -2343~-2336. The DNA methylation status of HIF-1α and LDH-A genes were detected to understand the mechanism of environmental stress on genes. It was found that hypoxia affected the HIF-1α gene and LDH-A gene methylation levels. The study uncovered HIF-1/LDH-A signaling pathway responsive mechanisms of Japanese flounder to hypoxia in epigenetic modification and transcriptional regulation. Our study is significant to further the understanding of environmental responsive mechanisms as well as providing a reference for aquaculture.

Pharmacological inhibition of sphingolipid synthesis reduces ferroptosis by stimulating the HIF-1 pathway.

Ferroptosis is crucial to the pathology of many neurological diseases. Here, we found pre-treatment with myriocin, an inhibitor of de novo synthesis of sphingolipid, significantly decreased the erastin- or glutamate-induced ferroptosis of HT22 cells without requiring the recovery of intracellular glutathione. The transcriptome analysis of HT22 cells treated with or without myriocin identified the hypoxia-inducible factor 1 (HIF-1) pathway as a prime and novel drug target. Further study validated that HIF1α was required for the cytoprotective effects of myriocin. Myriocin treatment promoted the expression of HIF-1 pathway effectors including PDK1 and BNIP3 and altered the intracellular levels of glucose metabolites. Additionally, myriocin treatment stabilized HIF1α protein by decreasing its ubiquitination and proteasomal degradation. Similar effects of myriocin on HIF1α stabilization were also found in other mammalian cell lines indicating this is a common mechanism for the cytoprotective role of myriocin.

Quantum Dots with a Compact Amphiphilic Zwitterionic Coating.

Generally speaking, it is difficult to keep nanomaterials encapsulated in amphiphilic polymers like octylamine-grafted poly(acrylic acid) (OPA) compact in coating-layer, with a small hydrodynamic size. Here, we prepared stable hydrophilic quantum dots (QDs) via encapsulation in ∼3 nm-long amphiphilic and zwitterionic (AZ) molecules. After encapsulation with AZ molecules, the coated QDs are only 2.1 nm thicker in coating, instead of 5.4 nm with OPA. Meanwhile, the hydrodynamic sizes of CdSe/CdS, ZnCdSeS, ZnCdSe/ZnS, and CdSe/ZnS QDs encapsulated in AZ molecules (AZ-QDs) are less than 15 nm, and 6-7 nm smaller than those of QDs in OPA (OPA-QDs). Notably, both extracellular and intracellular nonspecific binding of AZ-QDs is approximately 100-folds lower than that of OPA-QDs.

Gluconolactone Alleviates Myocardial Ischemia/Reperfusion Injury and Arrhythmias via Activating PKCε/Extracellular Signal-Regulated Kinase Signaling.

Gluconolactone (D-glucono-1,5-lactone or GDL) is a food additive which presents in dietary products such as tofu, yogurt, cheese, bread, wine, etc. GDL has long been considered as a free radical scavenger; however, its role in cardioprotection remains elusive. In this study, using a mouse model of myocardial ischemia/reperfusion (I/R) injury and a model of hypoxia/reoxygenation (H/R) in neonatal rat cardiomyocytes (NRCM), we explored the role of GDL in I/R injury. We found that GDL (5 mg/kg, i.p.) attenuated myocardial I/R injury as evidenced by decreased infarct size, release of cardiac injury markers and apoptosis. Additionally, GDL decreased reperfusion-induced arrhythmias and oxidative stress. These effects were also observed in parallel in vitro studies. Mechanistically, we found that GDL treatment was strongly associated with activation of pro-survival extracellular signal-regulated kinase (ERK) signaling both in vivo and in vitro, and pharmacological inhibition of ERK signaling via U0126 attenuated GDL-induced cardioprotection against H/R injury in NRCM cells. To reveal how GDL regulates ERK signaling, we predicted the putative targets of GDL by Swiss Target Prediction, and protein kinase C (PKC) emerged as the most promising target for GDL. By pharmacological intervention and immunofluorescence, we found that PKCε, an important member of the PKC family, was activated after GDL treatment in heart, thereby leading to ERK activation and cardioprotection against I/R injury. Taken together, our results demonstrated that GDL acts as a potent activator of PKCε and, thus, provides cardioprotection against I/R injury via activation of ERK signaling.

Effect of toyF on wuyiencin and toyocamycin production by Streptomyces albulus CK-15.

Streptomyces albulus CK-15 produces various secondary metabolites, including the antibiotics wuyiencin and toyocamycin, which can reportedly control a broad range of plant fungal diseases. The production of these nucleoside antibiotics in CK-15 is regulated by two biosynthesis gene clusters. To investigate the potential effect of toyocamycin biosynthesis on wuyiencin production, we herein generated S. albulus strains in which a key gene in the toyocamycin biosynthesis gene cluster, namely toyF, was either deleted or overexpressed. The toyF deletion mutant ∆toyF did not produce toyocamycin, while the production of wuyiencin increased by 23.06% in comparison with that in the wild-type (WT) strain. In addition, ΔtoyF reached the highest production level of wuyiencin 4 h faster than the WT strain (60 h vs. and 64 h). Further, toyocamycin production by the toyF overexpression strain was two-fold higher than by the WT strain, while wuyiencin production was reduced by 29.10%. qRT-PCR showed that most genes in the toyocamycin biosynthesis gene cluster were expressed at lower levels in ∆toyF as compared with those in the WT strain, while the expression levels of genes in the wuyiencin biosynthesis gene cluster were upregulated. Finally, the growth rate of ∆toyF was much faster than that of the WT strain when cultured on solid or liquid medium. Based on our findings, we report that in industrial fermentation processes, ∆toyF has the potential to increase the production of wuyiencin and reduce the timeframe of fermentation.

The mechanism of immune related signal pathway Egr2-FasL-Fas in transcription regulation and methylated modification of Paralichthys olivaceus under acute hypoxia stress.

Apoptosis genes Egr2, Fas and FasL are related to immune responses. However, the mechanism of these genes inducing apoptosis in fish are still not very clear. An acute hypoxia treatment (1.73 ± 0.06 mg/L) for 24 h was carried out on Japanese flounder (Paralichthys olivaceus). The increasingly dense apoptotic signals at 3 h, 6 h, 12 h by TUNEL in skeletal muscle indicated that hypoxia could quickly affect muscle growth and development. Furthermore, we concluded that the Egr2-FasL-Fas signal pathway, which was located at the upstream of apoptotic executor protein caspases, was related to the apoptosis by quantitative real-time PCR, protein concentration detection in ELISA and double gene in situ hybridization methods. The mechanism of the pathway was researched in transcription regulation and epigenetic modification by dual-luciferase reporter assay and bisulfite modified method, respectively. Egr2, as a transcription factor, could up-regulate the expression of FasL gene. And its binding site was mainly between -479 to -1 of FasL gene promoter. The 5th CpG dinucleotides (-514) methylation levels in FasL gene were significantly affected by hypoxia, and they were negatively correlated with its expressions. These suggested that the -514 site may be a very important site to regulate the FasL gene expression. Above results, we concluded that hypoxia activated the immune related signal pathway Egr2-FasL-Fas to induced skeletal muscle apoptosis to affect growth and development of Japanese flounder. The study revealed the mechanism of hypoxia induced apoptosis, which could provide a reference for fish immunity and aquaculture management.

DNA methylation in promoter region of immune related genes STAT3 and VEGFA and biochemical parameters change in muscle of Japanese flounder under acute hypoxia.

Acute hypoxic stress can lead to immune response in fish, but the molecular mechanism of muscle immunity in fish under acute hypoxia are still unclear. In this study, we carried out the effect of signal transducer and activator of transcription3(STAT3) and vascular endothelial growth factor A(VEGFA) on muscle immune responses of Japanese flounder (Paralichthys olivaceus) during acute hypoxic stimulation (1.65 ± 0.28mg/L O2; 3h, 6h, 12h, 24h) and reoxygenation (7.30 ± 0.40mg/L O2; R12h, R24h, R48h). In situ hybridization (ISH) showed that STAT3 and VEGFA RNA were co-located in the skeletal muscle of Japanese flounder. Japanese flounder was seriously affected by hypoxia for 3h and 6h. The expression of STAT3 and VEGFA increased significantly. The methylation levels of STAT3 5'UTR region and VEGFA promoter region were significantly lower than those in normoxia group, which was negatively correlated with the expression levels of STAT3 and VEGFA. The enzyme activities (LDH, ALT, AST, ALP) changed significantly. In addition, enzyme-linked immunosorbent assay (ELISA) detected a positive correlation between serum VEGFA concentration and muscle VEGFA mRNA. The current study have shown that Japanese flounder responded to acute hypoxic stress at multiple metabolic levels by changing DNA methylation status and activating transcription factors such as HIF-1α, Nrf2 and STAT3. It is significant for the scientific development of aquaculture through analyzing the effects of hypoxia on biological immunity.

Jolkinolide B inhibits proliferation or migration and promotes apoptosis of MCF-7 or BT-474 breast cancer cells by downregulating the PI3K-Akt pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: The diterpenoids extracted from Euphorbia kansui S.L. Liou ex S.B.Ho, Euphorbia fischeriana Steud. have good antitumor effects. Jolkinolide B has anti-breast cancer effect, but it is unclear whether it has different therapeutic effects between luminal A subtype and luminal B subtype breast cancer. AIM OF THE STUDY: This study investigated the Jolkinolide B has different therapeutic, important targets and pathways effects between luminal A subtype and luminal B subtype breast cancer. MATERIALS AND METHODS: We used bioinformatics to predict the biological process and molecular mechanism of Jolkinolide B in treating two types of breast cancer. Then, in vitro, cultured MCF-7 cells and BT-474 cells were divided into control group, PI3K inhibitor + control group, Jolkinolide B group and PI3K inhibitor + Jolkinolide B group. The CCK-8 assay, Flow cytometric analysis and Transwell cell migration assay was used to detect the cell proliferation, apoptosis, and migration in each group, respectively. ELISA was used to measure the content of Akt and phosphorylated Akt (p-Akt) in cell lysis buffer. RESULTS: Compared to luminal A breast cancer, Jolkinolide B had more targets, proliferation, migration processes and KEGG pathways when treating luminal B subtype breast cancer. Jolkinolide B significantly prolonged the survival time of luminal B subtype breast cancer patients. Compared to the control group, the cell proliferation absorbance value (A value) and migration number of the two kinds of breast cancer cells in the Jolkinolide B group were decreased (P < 0.01, n = 6), and the number of apoptotic cells was increased (P < 0.01, n = 6). Compared to the Jolkinolide B group, the A value and migration number of the two types of breast cancer cells were significantly decreased in the PI3K inhibitor + Jolkinolide B group (P < 0.01, n = 6), and the number of apoptotic cells was significantly increased (P < 0.01, n = 6). In addition, compared to MCF-7 cells, the A value and migration number of BT-474 cells stimulated with Jolkinolide B were significantly decreased (P < 0.01, n = 6), and the number of apoptotic cells was significantly increased (P < 0.01, n = 6). Akt and p-Akt protein levels in the two breast cancer cell lines in the Jolkinolide B group were all decreased (P < 0.01, n = 6), especially in BT-474 cells stimulated by Jolkinolide B. CONCLUSION: Jolkinolide B regulates the luminal A and luminal B subtypes of breast cancer through PI3K-Akt, EGFR and other pathways. Jolkinolide B has more significant therapeutic effect on luminal B subtype breast cancer. In vitro, experiments verified that Jolkinolide B significantly inhibited the proliferation and migration activity of BT-474 breast cancer cells by downregulating the PI3K-Akt pathway.

Enhancing Fatty Acids Oxidation via L-Carnitine Attenuates Obesity-Related Atrial Fibrillation and Structural Remodeling by Activating AMPK Signaling and Alleviating Cardiac Lipotoxicity.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical setting. Its pathogenesis was associated with metabolic disorder, especially defective fatty acids oxidation (FAO). However, whether promoting FAO could prevent AF occurrence and development remains elusive. In this study, we established a mouse model of obesity-related AF through high-fat diet (HFD) feeding, and used l-carnitine (LCA, 150 mg/kg⋅BW/d), an endogenous cofactor of carnitine palmitoyl-transferase-1B (CPT1B; the rate-limiting enzyme of FAO) to investigate whether FAO promotion can attenuate the AF susceptibility in obesity. All mice underwent electrophysiological assessment for atrial vulnerability, and echocardiography, histology and molecular evaluation for AF substrates and underlying mechanisms, which were further validated by pharmacological experiments in vitro. HFD-induced obese mice increased AF vulnerability and exhibited apparent atrial structural remodeling, including left atrial dilation, cardiomyocyte hypertrophy, connexin-43 remodeling and fibrosis. Pathologically, HFD apparently leads to defective cardiac FAO and subsequent lipotoxicity, thereby evoking a set of pathological reactions including oxidative stress, DNA damage, inflammation, and insulin resistance. Enhancing FAO via LCA attenuated lipotoxicity and lipotoxicity-induced pathological changes in the atria of obese mice, resulting in restored structural remodeling and ameliorated AF susceptibility. Mechanistically, LCA activated AMPK/PGC1α signaling both in vivo and in vitro, and pharmacological inhibition of AMPK via Compound C attenuated LCA-induced cardio-protection in palmitate-treated primary atrial cardiomyocytes. Taken together, our results demonstrated that FAO promotion via LCA attenuated obesity-mediated AF and structural remodeling by activating AMPK signaling and alleviating atrial lipotoxicity. Thus, enhancing FAO may be a potential therapeutic target for AF.

Serendipita indica alleviates drought stress responses in walnut (Juglans regia L.) seedlings by stimulating osmotic adjustment and antioxidant defense system.

Juglans regia L. is a good host for Serendipita indica. Under drought condition, seedlings colonized with S. indica showed higher values in plant height, total fresh biomass, root/shoot ratio, relative growth rate, leaf relative water content and chlorophyll content, gas exchange parameters, maximal photochemical efficiency, photochemical quenching, and effective photosystem II quantum yield than the uncolonized seedlings. It suggested beneficial effects of S. indica on host plants' growth and physiological parameters in response to drought. In comparison with the uncolonized seedlings, S. indica-colonized seedlings showed lower levels in hydrogen peroxide, superoxide anion, malondialdehyde, and relative electrical conductivity under drought condition, suggesting the ability of S. indica to prevent or retard the accumulation of reactive oxygen species and to diminish the oxidative injure. Furthermore, walnut seedlings responded to drought by actively accumulating osmotic regulation substances including soluble protein, soluble sugar, and proline. Root colonization with S. indica was more conductive to the accumulation. Moreover, in response to drought stress, walnut seedlings, regardless of colonization, increased activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione reductase, levels of ascorbate and glutathione, and ratios of reduced ascorbate/dehydroascorbic acid and reduced glutathione/oxidized glutathione in leaves and roots. S. indica colonization induced much more increase in the abovementioned indicators as compared to the uncolonized seedlings. Overall, S. indica colonization alleviated the detrimental effects of drought stress by altering root system, enhancing osmotic adjustment, and repressing the accumulation of reactive oxygen species via stimulating antioxidant system including enzymatic and nonenzymatic components. KEY POINTS: • S. indica stimulated root growth of walnut seedlings under drought condition. • S. indica accelerated osmotic adjustment under drought condition. • S. indica activated antioxidant defense mechanism under drought condition.

Combined impact of TiO2 nanoparticles and antibiotics on the activity and bacterial community of partial nitrification system.

The effects of TiO2 nanoparticles (nano-TiO2) together with antibiotics leaking into wastewater treatment plants (WWTPs), especially the partial nitrification (PN) process remain unclear. To evaluate the combined impact and mechanisms of nano-TiO2 and antibiotics on PN systems, batch experiments were carried out with six bench-scale sequencing batch reactors. Nano-TiO2 at a low level had minimal effects on the PN system. In combination with tetracycline and erythromycin, the acute impact of antibiotics was enhanced. Both steps of nitrification were retarded due to the decrease of bacterial activity and abundance, while nitrite-oxidizing bacteria were more sensitive to the inhibition than ammonia-oxidizing bacteria. Proteobacteria at the phylum level and Nitrosospira at the genus level remained predominant under single and combined impacts. The flow cytometry analysis showed that nano-TiO2 enhanced the toxicity of antibiotics through increasing cell permeability. Our results can help clarify the risks of nano-TiO2 combined with antibiotics to PN systems and explaining the behavior of nanoparticles in WWTPs.

Immune correlates of NF-κB and TNFα promoter DNA methylation in Japanese flounder (Paralichthys olivaceus) muscle and immune parameters change response to vibrio anguillarum infection.

Vibrio anguillarum infection can activate NF-κB/TNFα pathway in the immune organs of fish. Fish muscle is also an important immune organ, but the research on its immune function is few. Our aim was to study regulating mechanism of NF-κB and TNFα gene expressions in the muscle of Japanese flounder (Paralichthys olivaceus) which was under Vibrio anguillarum infection (0, 24, 48, 72 and 96 h). The results showed that the expressions of NF-κB and TNFα increased significantly at 48 h, and there was a significant positive correlation between them. In situ hybridization confirmed the co-existence of NF-κB and TNFα genes in Japanese flounder muscle. Interestingly, the expression of the TNFα gene was regulated by the DNA methylation and its methylation level was negatively correlated with the expression. The lowest methylation level of TNFα occurred at 48 h under Vibrio anguillarum infection (P < 0.05). And more, when the fragment (-2122 âˆ¼ -730) was deleted on TNFα gene promoter, double luciferase activity was the highest, indicating that fragment (-730-0) was the transcription factor binding region. The site (-78 ~ -69) on the fragment (-730-0) binding NF-κB was mutated, and double luciferase activity decreased significantly. The results confirmed that the site (-78 ~ -69) was indeed an important binding site for NF-κB. In addition, the activity of TNFα in the serum of Japanese flounder changed with the prolongation of vibrio anguillarum infection, and the concentration of other immune factors such as ALP, ALT, AST and LDH also changed in the muscle under vibrio anguillarum infection. They all showed a trend of first increasing and then decreasing. Above studies implied that Japanese flounder responded to Vibrio anguillarum infection at the immune level with the change of its methylation status and the activation of transcription factor. By studying the mechanism of immune pathways, understanding the response to immune stress is great significant to the research of fish breeding for disease resistance.

Acute hypoxia effects on Keap1/Nrf2 (Mafs)-GST pathway related oxidative metabolism in muscle of Japanese flounder (Paralichthys olivaceus).

Acute hypoxia can aggravate the oxidation metabolism of fish muscle tissue. However, the molecular mechanism of oxidative metabolism in fish muscle under acute hypoxia is not very clear. We carried out effects of a typical oxidative metabolism pathway Keap1/Nrf2 (MafG)-GST on muscle oxidative metabolism of Japanese flounder (Paralichthys olivaceus) during acute hypoxia stimulation (1.65 ± 0.05 mg/L; 1 h, 3 h, 6 h, 12 h, 24 h) and reoxygenation (7.30 ± 0.08 mg/L; R12 h, R24 h, R48 h). The mRNAs of Nrf2 and GST in skeletal muscle were found co-existent, and their expressions were significant increase in 3 h and 6 h. The methylation level of CpG island1 in Nrf2 promoter, whose minimum value appeared at 3 h hypoxia treatment group, was affected by acute hypoxia, and it was negatively correlated with Nrf2 expression. The result suggests that environmental factors may regulate gene expression by epigenetic modification. Dual-luciferase reporter assay showed that GST gene was activated by transcription factor Nrf2, whose transcriptional activation binding region in GST promoter was antioxidant response element located near -980 and -852 sites, and Keap1 and MafG were Nrf2 antagonistic and synergistic factor, respectively. Furthermore, the GST activity changed with hypoxia and reoxygenation treatment in muscle, where other oxidative stress factor (MDA), antioxidant factors (T-AOC, GSH) and antioxidant enzyme activities (GST, SOD, CAT) were also changed. The results of MDA and T-AOC being further different between its hypoxia and normoxia groups (P < 0.05) at 6 h demonstrated that hypoxia stimulation lasting for 6 h would deeply affect Japanese flounder. The study illustrated that Japanese flounder responded to acute hypoxia in multiple metabolic levels by changing methylation status and transcription factor activation. It is significant to understand oxidative metabolic mechanism, analyze organism stress response and promote the scientific development of aquaculture.