YAP-LAMB3 axis dictates cellular resistance of pancreatic ductal adenocarcinoma cells to gemcitabine.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive tumors with poor prognosis and inadequate response to treatment, such as gemcitabine (Gem), the first-line chemotherapeutic drug. Understanding the molecular determinants that control drug resistance to Gem is critical to predict potentially responsive patients and improve the benefits of Gem therapy. Emerging evidence suggests that certain developmental pathways, such as Hippo signaling, are aberrated and play important roles in Gem resistance in cancers. Although Hippo signaling has been reported to play a role in chemoresistance in cancers, it has not been clarified which specific target gene(s) functionally mediates the effect. In the present study, we found that YAP serves as a potent barrier for the cellular sensitivity of PDAC cells to Gem. We then identified and characterized laminin subunit beta 3 (LAMB3) as a bona fide target of YAP-TEAD4 to amplify YAP signaling via a feedback loop. Such a YAP-LAMB3 axis is critical to induce epithelial-mesenchymal transition and mediate Gem resistance. Taken together, we uncovered that YAP-LAMB3 axis is an important regulator of Gem, thus providing potential therapeutic targets for overcoming Gem resistance in PDAC.

Development of genic KASP SNP markers from RNA-Seq data for map-based cloning and marker-assisted selection in maize.

BACKGROUND: Maize is one of the most important field crops in the world. Most of the key agronomic traits, including yield traits and plant architecture traits, are quantitative. Fine mapping of genes/ quantitative trait loci (QTL) influencing a key trait is essential for marker-assisted selection (MAS) in maize breeding. However, the SNP markers with high density and high polymorphism are lacking, especially kompetitive allele specific PCR (KASP) SNP markers that can be used for automatic genotyping. To date, a large volume of sequencing data has been produced by the next generation sequencing technology, which provides a good pool of SNP loci for development of SNP markers. In this study, we carried out a multi-step screening method to identify kompetitive allele specific PCR (KASP) SNP markers based on the RNA-Seq data sets of 368 maize inbred lines. RESULTS: A total of 2,948,985 SNPs were identified in the high-throughput RNA-Seq data sets with the average density of 1.4 SNP/kb. Of these, 71,311 KASP SNP markers (the average density of 34 KASP SNP/Mb) were developed based on the strict criteria: unique genomic region, bi-allelic, polymorphism information content (PIC) value ≥0.4, and conserved primer sequences, and were mapped on 16,161 genes. These 16,161 genes were annotated to 52 gene ontology (GO) terms, including most of primary and secondary metabolic pathways. Subsequently, the 50 KASP SNP markers with the PIC values ranging from 0.14 to 0.5 in 368 RNA-Seq data sets and with polymorphism between the maize inbred lines 1212 and B73 in in silico analysis were selected to experimentally validate the accuracy and polymorphism of SNPs, resulted in 46 SNPs (92.00%) showed polymorphism between the maize inbred lines 1212 and B73. Moreover, these 46 polymorphic SNPs were utilized to genotype the other 20 maize inbred lines, with all 46 SNPs showing polymorphism in the 20 maize inbred lines, and the PIC value of each SNP was 0.11 to 0.50 with an average of 0.35. The results suggested that the KASP SNP markers developed in this study were accurate and polymorphic. CONCLUSIONS: These high-density polymorphic KASP SNP markers will be a valuable resource for map-based cloning of QTL/genes and marker-assisted selection in maize. Furthermore, the method used to develop SNP markers in maize can also be applied in other species.

Deciphering the activation and recognition mechanisms of Staphylococcus aureus response regulator ArlR.

Staphylococcus aureus ArlRS is a key two-component regulatory system necessary for adhesion, biofilm formation, and virulence. The response regulator ArlR consists of a C-terminal DNA-binding effector domain and an N-terminal receiver domain that is phosphorylated by ArlS, the cognate transmembrane sensor histidine kinase. We demonstrate that the receiver domain of ArlR adopts the canonical α5ß5 response regulator assembly, which dimerizes upon activation, using beryllium trifluoride as an aspartate phosphorylation mimic. Activated ArlR recognizes a 20-bp imperfect inverted repeat sequence in the ica operon, which is involved in intercellular adhesion polysaccharide production. Crystal structures of the inactive and activated forms reveal that activation induces a significant conformational change in the ß4-α4 and ß5-α5-connecting loops, in which the α4 and α5 helices constitute the homodimerization interface. Crystal structures of the DNA-binding ArlR effector domain indicate that it is able to dimerize via a non-canonical ß1-ß2 hairpin domain swapping, raising the possibility of a new mechanism for signal transduction from the receiver domain to effector domain. Taken together, the current study provides structural insights into the activation of ArlR and its recognition, adding to the diversity of response regulation mechanisms that may inspire novel antimicrobial strategies specifically targeting Staphylococcus.

Prediction of the joint action of binary mixtures based on characteristic parameter k∙ECx from concentration-response curves.

The evaluation of joint toxicity of mixtures is an important topic in toxicology. Previous studies have found that the parameter k∙ECx of concentration response curves (CRCs) can be used to assess the applicability of concentration addition model (CA). This study further assesses the predictability of k∙ECx on the joint toxicity evaluation. The toxicities of the twelve environmental pollutants, as well as those of binary mixtures with an equivalent-effect concentration ratio, to Vibrio fischeri were determined by using the microplate toxicity analysis. The toxicity evaluation of mixtures was conducted by CA and independent action model (IA). The relationship between the joint toxicity (measured by the relative model deviation ratio (rMDR)) and the k∙ECx was studied. The results shows that the k∙ECx could reflect the shape of CRCs in the whole concentration range. According to the IA and CA, 65% of the mixtures produce strong antagonistic or synergistic effect due to the significant difference of k∙ECx. The percentage of the relative difference of k∙ECx of components and the rMDRx can be fitted by an exponential function. Different types of interactions could be described using this function. It is suggested that the joint toxicity of binary mixtures can be assessed with the parameter k∙ECx, which can quickly get very important data when planning experiments, but also reduce the number of experiments.

Low Level of Vitamin D is a Risk Factor for the Occurrence of Early and Late Onset Pre-Eclampsia in Pregnant Women.

BACKGROUND: This study was aimed to investigate the relationship between 25-hydroxy vitamin D (25(OH)D) level and the occurrence of pre-eclampsia (PE) and also the risk factors of developing early and late onset PE. METHODS: A total of 370 pregnant women were included between January 2015 and December 2016 at our hospital. PE was defined as the presence of maternal blood pressure > 140/90 mmHg and 24-hour proteinuria levels > 300 mg or 2 + in a random sample of urine after the 20th week of pregnancy. Controls were pregnant women without hypertension and proteinuria. Assessment of 25(OH)D was performed at 16 - 20 weeks of gestation. Univariate and multivariate analyses were used to evaluate the association of vitamin D with PE. RESULTS: There were 201 patients with PE while 169 pregnant women were controls. Patients with PE had older maternal age (p < 0.001), earlier gestation age (p < 0.001), and higher systolic blood pressure (SBP) and diastolic blood pressure (DBP) (p < 0.001). The level of 25(OH)D in the PE group (17.26 ± 13.95 µg/L) was significantly lower than that in controls (22.15 ± 12.65 µg/L, p = 0.019). Moreover, the proportion of 25(OH)D deficiency in patients with PE was significantly higher than that of controls (27.6% vs. 0.9%, p < 0.001). Older age, high SBP, and low level of 25(OH)D were independent risk factors of both early and late onset PE during pregnancy. CONCLUSIONS: Low 25(OH)D level was more likely presented in PE patients and was an independent risk factor of both early and late onset PE.

Novel foetal echocardiographic image processing software (5D Heart) improves the display of key diagnostic elements in foetal echocardiography.

BACKGROUND: To evaluate the clinical value of foetal intelligent navigation echocardiography (5D Heart) for the display of key diagnostic elements in basic sections. METHODS: 3D volume datasets of 182 normal singleton foetuses were acquired with a four chamber view by using a volume probe. After processing the datasets by using 5D Heart, eight cardiac diagnostic planes were demonstrated, and the image qualities of the key diagnostic elements were graded by 3 doctors with different experiences in performing foetal echocardiography. RESULTS: A total of 231 volume datasets acquired from the 182 normal foetuses were used for 5D Heart analysis and display. The success rate of 8 standard diagnostic views was 88.2%, and the success rate of each diagnostic view was 55.8-99.2% and 70.7-99.0% for the random four chamber view as the initial section and for the apical four chamber view as the initial section, respectively. The success rate of each diagnostic element in the 8 diagnostic sections obtained by 5D Heart was 58.9%~ 100%. Excellent agreement was found between experienced sonographers and less-experienced sonographers (kappa> 0.769). Inter- and intra-observer agreement were substantial to near-perfect, kappa values ranging from 0.612 to 1.000 (Cohen's kappa). CONCLUSIONS: 5D Heart can significantly improve the image quality of key diagnostic elements in foetal echocardiography with low operator dependency and good reproducibility.

Spectroscopy, Thermodynamics and Molecular Docking of Fraxinellone with DNA.

Fraxinellone is an important botanical lactone compound and has been demonstrated to have insecticidal activity. To provide theoretical support to the assessment on the safety of utilizing fraxinellone as a natural insecticidal agent, the interactions between fraxinellone and armyworm DNA, salmon sperm DNA and calf thymus DNA were investigated using UV-Vis absorption spectroscopy, isothermal titration calorimetry, and molecular docking. Results showed that there were two types of combinations between fraxinellone and three kinds of DNA. Type I combination had an equilibrium constant of combination (Ka1) of about 105 and binding sites (n1) of 0.40-0.70, while type II combination had an equilibrium constant of combination (Ka2) of 103 and binding sites (n2) of 1.35-3.15. Results of molecular docking showed that there were non-classical embedding type interactions between fraxinellone and three kinds of DNA, with the reaction taking place in small groove areas of the DNA structure, resulting in relatively weak interactive forces.

NIRF-Molecular Imaging with Synovial Macrophages-Targeting Vsig4 Nanobody for Disease Monitoring in a Mouse Model of Arthritis.

Nanobody against V-set and Ig domain-containing 4 (Vsig4) on tissue macrophages, such as synovial macrophages, could visualize joint inflammation in multiple experimental arthritis models via single-photon emission computed tomography imaging. Here, we further addressed the specificity and assessed the potential for arthritis monitoring using near-infrared fluorescence (NIRF) Cy7-labeled Vsig4 nanobody (Cy7-Nb119). In vivo NIRF-imaging of collagen-induced arthritis (CIA) was performed using Cy7-Nb119. Signals obtained with Cy7-Nb119 or isotope control Cy7-NbBCII10 were compared in joints of naive mice versus CIA mice. In addition, pathological microscopy and fluorescence microscopy were used to validate the arthritis development in CIA. Cy7-Nb119 accumulated in inflamed joints of CIA mice, but not the naive mice. Development of symptoms in CIA was reflected in increased joint accumulation of Cy7-Nb119, which correlated with the conventional measurements of disease. Vsig4 is co-expressed with F4/80, indicating targeting of the increasing number of synovial macrophages associated with the severity of inflammation by the Vsig4 nanobody. NIRF imaging with Cy7-Nb119 allows specific assessment of inflammation in experimental arthritis and provides complementary information to clinical scoring for quantitative, non-invasive and economical monitoring of the pathological process. Nanobody labelled with fluorescence can also be used for ex vivo validation experiments using flow cytometry and fluorescence microscopy.

The effect of lymphadenectomy on survival and recurrence in patients with ovarian cancer: a systematic review and meta-analysis.

OBJECTIVE: Our objective was to perform a meta-analysis examining the effectiveness of lymphadenectomy in patients with ovarian cancer. METHODS: PubMed and CENTRAL databases were searched on 15 November 2015 using the terms 'lymphadenectomy', 'ovarian cancer', 'dissection', 'para-aortic', 'pelvic' and survival. Prospective and retrospective studies comparing the outcomes of surgery with or without lymphadenectomy were included. Outcomes were 5-year overall survival, progression-free survival and recurrence rate. RESULTS: Of the 556 studies identified, 3 randomized controlled trials and 11 retrospective studies were included. Lymphadenectomy was associated with greater 5-year overall survival than no lymphadenectomy (pooled odds ratio = 1.58, 95% confidence interval: 1.41-1.77, p < 0.001). There was no difference in progression-free survival between the groups (pooled overall survival = 1.62, 95% confidence interval: 0.82-3.21, p = 0.168). Lymphadenectomy was associated with greater progression-free survival in randomized clinical trials (pooled overall survival = 1.57, 95% confidence interval: 1.11-2.21, p = 0.010), but not in retrospective studies. Lymphadenectomy was associated with a significantly lower recurrence rate (pooled overall survival = 0.51, 95% confidence interval: 0.30-0.85, p = 0.011). Lymphadenectomy was associated with greater 5-year overall survival in patients with both early and advanced stage cancer, but was associated with greater progression-free survival and lower recurrence rate only in patients with advanced stage cancer. CONCLUSION: Lymphadenectomy is associated with greater 5-year overall survival in patients with early and advanced stage ovarian cancer, but an effect on progression-free survival and recurrence rate was only found in patients with advanced stage ovarian cancer.

Molecular simulation study of hydrated Na-rectorite.

The swelling behavior of clay minerals is an important issue in industrial processes and environmental applications. Mixed-layer clay minerals containing a smectite fraction, such as rectorite, are neglected even though they could swell and exist in nature widely. The hydration of rectorite has not been well comprehended even though they are meaningful to mineralogy and industry. This study combines molecular dynamics (MD) and Monte Carlo (MC) simulations to disclose the swelling behavior of rectorite and compare with montmorillonite. From grand canonical Monte Carlo (GCMC) and MD simulations, we obtain swelling curves and swelling free-energy curves of rectorite with a relative humidity of 100%. With the comparisons of swelling free-energy minima, we find that the bilayer hydrate of Na-rectorite is more thermodynamically stable than the monolayer hydrate, which is similar to Na-montmorillonite. However, the interlayer sodium ions in rectorite show an asymmetrical distribution quite different from the symmetrical distribution in montmorillonite. Because of unequal layer charges between the smectite part and illite part of retorite, sodium ions prefer to distribute close to the illite part surface.

Occurrence of tetracycline-resistant fecal coliforms and their resistance genes in an urban river impacted by municipal wastewater treatment plant discharges.

Antibiotic resistance of fecal coliforms in an urban river poses great threats to both human health and the environment. To investigate the occurrence and distribution of antibiotic resistant bacteria in an urban river, water samples were collected from the Chanhe River in Xi'an, China. After membrane filtration of water samples, the tetracycline resistance rate of fecal coliforms and their resistance genes were detected by plating and polymerase chain reaction (PCR), respectively. We found that fecal coliforms were generally resistant to tetracycline and saw average resistance rates of 44.7%. The genes tetA and tetB were widely detected, and their positive rate was 60%-100% and 40%-90%, respectively. We found few strains containing tetC, tetK, tetQ and tetX, and we did not identify any strains containing tetG, tetM or tetO. The prevalence of tetA and tetB over other genes indicated that the main mechanism for resistance to tetracycline is by changes to the efflux pump. Our analysis of the types and proportion of tetracycline resistance genes in the Chanhe River at locations upstream and downstream of the urban center suggests that the increased number of tetracycline-resistant fecal coliforms and spatial variation of tetracycline resistance genes diversity were related to municipal wastewater treatment plant discharge.

Source identification of bacterial and viral pathogens and their survival/fading in the process of wastewater treatment, reclamation, and environmental reuse.

Pathogenic safety is drawing wide concern in water reclamation and reuse. In order to elucidate survive/fade of pathogens during the processes of wastewater treatment and reclamation, general indicators (fecal coliform and Escherichia coli), pathogenic bacteria (Salmonella and Shigella) and viruses (enterovirus, rotavirus and norovirus) were investigated in an A(2)O-MBR system. Attention was paid to their strengths from different sources, at various stages of the treatment, and in the product water. According to findings, black water was the main source for pathogens-at least 1-2-log higher in concentration than those from other sources. The preliminary treatment of wastewater by fine screens could bring about 0.2-0.4-log removal for almost all pathogens. The biological treatment units achieved almost identical removal (1.3-1.7-log) for bacteria and viruses. However, subsequent treatment in the membrane bioreactor showed varied removal for fecal coliform (4.7-log), E. coli (2.6-log) and the other pathogens (0.7-1.0-log), indicating that a high reduction of indicator bacteria may not imply equivalent removal of bacterial and viral pathogens. Chlorination was proved to be effective for eliminating all pathogens. In the artificial lake where the product water was stored, fecal coliform was not detected during the study period, but E. coli and pathogens were frequently detected, indicating that these bacterial and viral pathogens may be originating from non-fecal sources. On sunny summer days, the lake water could be bacteria-free due to sunlight radiation, but viruses were still detectable. Therefore, secondary disinfection may have to be adopted when the reclaimed water stored in such an open reservoir is supplied for strict reuse purposes.

Unacclimated activated sludge improved nitrate reduction and N2 selectivity in iron filling/biochar systems.

Iron (Fe)-based denitrification is a proven technology for removing nitrate from water, yet challenges such as limited pH preference range and low N2 selectivity (reduction of nitrate to N2) persist. Adding biochar (BC) can improve the pH preference range but not N2 selectivity. This study aimed to improve nitrate reduction and N2 selectivity in iron filling/biochar (Fe/BC) systems with a simplified approach by coupling unacclimated microbes (M) in the system. Factors such as initial pH, Fe/BC ratio, and Fe/BC dosage on nitrate removal efficiency and N2 selectivity were evaluated. Results show that the introduction of microbes significantly enhanced nitrate removal and N2 selectivity, achieving 100 % nitrate removal and 79 % N2 selectivity. The Fe/BC/M system exhibited efficient nitrate reduction at pH of 2-10. Moreover, the Fe/BC/M system demonstrated an improved electrochemical active surface area (ECSA), lower electron transfer resistance and lower corrosion potential, leading to enhanced nitrate reduction. The high i0 value in Fe/BC/M system means more Hads could be generated, thus improving the N2 selectivity. This study provides valuable insights into a novel approach for effective nitrate removal, offering a potential solution to the environmental challenges posed by excessive nitrate in wastewater, surface water and ground water.

Mitochondrial­associated endoplasmic reticulum membrane interference in ovarian cancer (Review).

The mitochondria­associated endoplasmic reticulum (ER) membrane (MAM), serving as a vital link between the mitochondria and ER, holds a pivotal role in maintaining the physiological function of these two organelles. Its specific functions encompass the participation in the biosynthesis and functional regulation of the mitochondria, calcium ion transport, lipid metabolism, oxidative stress and autophagy among numerous other facets. Scientific exploration has revealed that MAMs hold potential as effective therapeutic targets influencing the mitochondria and ER within the context of cancer therapy. The present review focused on elucidating the related pathways of mitochondrial autophagy and ER stress and their practical application in ovarian cancer, aiming to identify commonalities existing between MAMs and these pathways, thereby extending to related applications of MAMs in ovarian cancer treatment. This endeavor aimed at exploring new potential for MAMs in clinically managing ovarian cancer.

The Functional Study of Response Regulator ArlR Mutants in Staphylococcus Aureus.

Staphylococcus aureus is a major cause of hospital-associated infections worldwide. The organism's ability to form biofilms has led to resistance against current treatment options such as beta-lactams, glycopeptides, and daptomycin. The ArlRS two-component system is a crucial regulatory system necessary for S. aureus autolysis, biofilm formation, capsule synthesis, and virulence. This study aims to investigate the role of the arlR deletion mutant in the detection and activation of S. aureus. We created an arlR deleted mutant and complementary strains and characterized their impact on the strains using partial growth measurement. The quantitative real-time PCR was performed to determine the expression of icaA, and the microscopic images of adherent cells were captured at the optical density of 600 to determine the primary bacterial adhesion. The biofilm formation assay was utilized to investigate the number of adherent cells using crystal violet staining. Eventually, the Triton X-100 autolysis assay was used to determine the influence of arlR on the cell autolytic activities. Our findings indicate that the deletion of arlR reduced the transcriptional expression of icaA but not icaR in the ica operon, leading to decrease in polysaccharide intercellular adhesin (PIA) synthesis. Compared to the wild-type and the complementary mutants, the arlR mutant exhibited decreased in biofilm production but increased autolysis. It concluded that the S. aureus response regulatory ArlR influences biofilm formation, agglutination, and autolysis. This work has significantly expanded our knowledge of the ArlRS two-component regulatory system and could aid in the development of novel antimicrobial strategies against S. aureus.

Menstrual blood-derived mesenchymal stem cells combined with collagen I gel as a regenerative therapeutic strategy for degenerated disc after discectomy in rats.

BACKGROUND: Annulus fibrosis (AF) defects have been identified as the primary cause of disc herniation relapse and subsequent disc degeneration following discectomy. Stem cell-based tissue engineering offers a promising approach for structural repair. Menstrual blood-derived mesenchymal stem cells (MenSCs), a type of adult stem cell, have gained attention as an appealing source for clinical applications due to their potential for structure regeneration, with ease of acquisition and regardless of ethical issues. METHODS: The differential potential of MenSCs cocultured with AF cells was examined by the expression of collagen I, SCX, and CD146 using immunofluorescence. Western blot and ELISA were used to examine the expression of TGF-ß and IGF-I in coculture system. An AF defect animal model was established in tail disc of Sprague-Dawley rats (males, 8 weeks old). An injectable gel containing MenSCs (about 1*106/ml) was fabricated and transplanted into the AF defects immediately after the animal model establishment, to evaluate its repairment properties. Disc degeneration was assessed via magnetic resonance (MR) imaging and histological staining. Immunohistochemical analysis was performed to assess the expression of aggrecan, MMP13, TGF-ß and IGF-I in discs with different treatments. Apoptosis in the discs was evaluated using TUNEL, caspase3, and caspase 8 immunofluorescence staining. RESULTS: Coculturing MenSCs with AF cells demonstrated ability to express collagen I and biomarkers of AF cells. Moreover, the coculture system presented upregulation of the growth factors TGF-ß and IGF-I. After 12 weeks, discs treated with MenSCs gel exhibited significantly lower Pffirrmann scores (2.29 ± 0.18), compared to discs treated with MenSCs (3.43 ± 0.37, p < 0.05) or gel (3.71 ± 0.29, p < 0.01) alone. There is significant higher MR index in disc treated with MenSCs gel than that treated with MenSCs (0.51 ± 0.05 vs. 0.24 ± 0.04, p < 0.01) or gel (0.51 ± 0.05 vs. 0.26 ± 0.06, p < 0.01) alone. Additionally, MenSCs gel demonstrated preservation of the structure of degenerated discs, as indicated by histological scoring (5.43 ± 0.43 vs. 9.71 ± 1.04 in MenSCs group and 10.86 ± 0.63 in gel group, both p < 0.01), increased aggrecan expression, and decreased MMP13 expression in vivo. Furthermore, the percentage of TUNEL and caspase 3-positive cells in the disc treated with MenSCs Gel was significantly lower than those treated with gel alone and MenSCs alone. The expression of TGF-ß and IGF-I was higher in discs treated with MenSCs gel or MenSCs alone than in those treated with gel alone. CONCLUSION: MenSCs embedded in collagen I gel has the potential to preserve the disc structure and prevent disc degeneration after discectomy, which was probably attributed to the paracrine of growth factors of MenSCs.

A study of long-term toxicity of multiple mixtures with hormetic effects by the characteristic parameter σ2(k∙ECx) and stepwise method.

A previous study found that the characteristic parameter σ2(k∙ECx) (the concentration ECx and slope k of the concentrationresponse curve (CRC) at the effect x %) can predict the acute combined toxicity of multiple mixtures with S-shaped CRCs. In this paper, the competence of σ2(k∙ECx) to predict the long-term toxicity of multiple mixtures with J-shaped CRCs was explored using the Aliivibrio fischeri as the test organism. The combined toxicity was evaluated by the independent action (IA) model and the effect ratio (ERx) model. The stepwise method was used to divide J-shaped CRC into ML and MR (SL and SR). The results showed that the σ2(k∙ECx) and ERx of each segment was in good agreement with the exponential function. A new type of mixture was added to the original type A and type B, whose rules of interaction were opposite to those of type B (named opposite B, OB). This paper improves the understanding and analysis of the J-shaped CRCs in environmental risk assessment.

Joint action of binary mixtures based on parameter k·ECx from concentration-response curves in long-term toxicity assay.

A previous acute toxicity study of binary mixtures showed that the combined toxicity can be predicted with the parameter k∙ECx. To systematically investigate the ability of k∙ECx to predict the chronic combined toxicity of binary mixtures, the toxicity of six contaminants and five binary mixtures was determined by long-term microplate toxicity analysis (L-MTA) using Aliivibrio fischeri as the test organism. The independent action model (IA) and the relative model deviation ratio (rMDR) were employed to determine the relationship between the Δ(k∙ECx)% and rMDRx. The results showed that these two factors conformed to the exponential function in long-term toxicity. Owing to the time-dependence of toxicity, the mixture type of chronic toxicity changes to the relative type of acute toxicity. If the acute toxicity of binary mixtures changes their mode of joint action throughout the concentration range, the chronic toxicity will also change their mode of joint action, and vice versa. This study clarified the change rules of the joint action of binary mixtures in acute and chronic toxicity which can promote research on chronic toxicity of binary mixtures.

Study of the joint action of multi-component mixtures based on parameter σ2(k∙ECx) characterizing the shape difference of concentration-response curves.

A previous study has revealed that the parameter k∙ECx, characterizing the shape of concentration-response curves (CRCs), could predict the combined toxicity of binary mixtures. This study further explored the predictability of multi-component mixtures. Eleven component mixtures were designed using the uniform design ray, and the acute toxicity of the eleven environmental pollutants and their mixtures to Vibrio fischeri was determined using microplate toxicity analysis. We used independent action (IA) and the effect residual ratio (ERRx) models to evaluate the combined toxicity of multi-component mixtures and ascertain the functional relationship between σ2(k∙ECx), a parameter characterizing the CRC morphological difference of multi-component mixtures, and combined toxicity. The variance σ2(k∙ECx) of each component characteristic parameter of multi-component mixtures gradually increased in the concentration range, and the relationship between σ2(k∙ECx) and ERRx was consistent with the exponential function. The literature verification showed that this rule is generally applicable to the acute toxicity of multi-component mixtures to luminescent bacteria. The exponential function showed the variation rule of the joint action of multi-component mixtures. In the present study, the joint toxicity of multi-component mixtures can be predicted from single toxicity and small amount of multiple toxicity, circumventing complex multi-component toxicity experiments.

Enhancements of short-chain fatty acids production via anaerobic fermentation of waste activated sludge by the combined use of persulfate and micron-sized magnetite.

The combination of persulfate (PDS) with micron-sized magnetite (Fe3O4) was introduced into the process of anaerobic fermentation (AF) to scrutinize the short chain fatty acid (SCFA) production from waste activated sludge for the first time. The synergetic effect of PDS and Fe3O4 results in the promotion of intracellular and extracellular substance liberation, augment in key hydrolases activities, and enrichment of hydrolytic and acidifying microbial population. Meanwhile, carbohydrate, amino acid, and energy metabolism as well as enzymes, are considerably accelerated. Consequently, the maximum SCFAs yield is significantly enhanced to 391.25 mg COD/L on day 8 of AF with the addition of 0.3 g Fe3O4/g SS and 0.5 g PDS/g SS, which was 2.39-folds than that of the control. The relative abundance of Actinobacteria were highly enriched and reached to 35.76% at the class level. This work affords an effective avenue to evidently boost the production of SCFAs from WAS via AF.