Search

The inhibitory and bactericidal activities of thyme oil against the foodborne multiple antibiotics-resistant Enterococcus faecalis biofilm were evaluated in this study. Gas chromatography-mass spectrometry revealed that more than 70% of the composition of thyme oil is thymol. Crystal violet staining assay showed that 128 and 256 mg/mL thyme oil significantly inhibited the biofilm formation of E. faecalis. The cell adherence of E. faecalis, as shown by its swimming and swarming motilities, was reduced by thyme oil. The exopolysaccharide (EPS) quantification assay showed that thyme oil inhibited the EPS synthesis in E. faecalis biofilms. The 3D-view observations through confocal laser scanning and scanning electron microscopy suggested that cell adherence and biofilm thickness were decreased in thyme oil-treated biofilms. Quantitative real-time analyses showed that the transcription of ebp and epa gene clusters, which were related to cell mobility and EPS production, was inhibited by thyme oil. Thus, thyme oil effectively inhibited the biofilm formation of E. faecalis by affecting cell adherence and EPS synthesis. Furthermore, 2,048 and 4,096 mg/mL thyme oil can effectively inactivate E. faecalis population in the mature E. faecalis biofilms by 5.75 and 7.20 log CFU/mL, respectively, after 30 min of treatment. Thus, thyme oil at different concentrations can be used as an effective antibiofilm or germicidal agent to control E. faecalis biofilms. [ABSTRACT FROM AUTHOR]

This study evaluated the antibacterial effect of the combination of e-polylysine (e-PL) and nisin against Enterococcus faecalis strains. The combination of e-PL and nisin showed synergistic antibacterial activity against three Enterococcus strains. Scanning electron microscopy and a membrane permeability assay revealed that the combined treatment with e-PL and nisin synergistically damaged the cell morphology of E. faecalis strain R612Z1 cells. Both e-PL and nisin can dissipate the transmembrane electric potential of E. faecalis R612Z1 cells, but these peptides did not affect the transmembrane pH gradient. The combination of e-PL and nisin can produce a high reactive oxygen species level in E. faecalis R612Z1 cells. The results indicated that the uptake of e-PL into cells was promoted through nisin and that the combination of e-PL and nisin could produce a high reactive oxygen species level in E. faecalis R612Z1 cells, leading to cell growth inhibition. [ABSTRACT FROM AUTHOR]

The effect of NaCl stress (0 to 8%, wt/vol) on the growth and tyramine production in two Enterococcus faecalis strains was examined during culture time. The growth of E. faecalis was inhibited by the increase in NaCl concentration, but tyramine production was unaffected. Tyramine accumulated rapidly during the logarithmic phase of the strains, and the final tyramine levels were approximately 800 gg/ml. Relative gene expression of four genes in the tyrosine decarboxylase locus, namely, tyrRS, tyrDC, tyrP, and nhaC, was evaluated at different incubation times. The results showed that NaCl stress could upregulate the expression of tyrDC and tyrP to improve the tyramine production of a single E. faecalis strain under certain conditions, and TyrS could act as a negative regulator on the genetic regulation of the tyramine cluster. [ABSTRACT FROM AUTHOR]

Tyramine production by Enterococcus faecalis R612Z1 in water-boiled salted ducks was evaluated during storage at different temperatures. The results showed that E. faecalis R612Z1 could produce tyramine in meat samples when the storage temperature was no less than 4°C. The E. faecalis R612Z1 counts of the meat samples reached 108 CFU/g on day 7 at 4°C and on day 4 at 10°C. However, the tyramine content of the meat samples stored at 10°C increased to 23.73 µg/g (on day 10), which was greater than the level in the samples stored at 4°C (7.56 µg/g). Reverse transcription quantitative PCR detection of the expression level of the tyrDC gene in E. faecalis R612Z1 in the meat samples revealed no significant changes at different storage temperatures. Thus, the changes in tyramine production of E. faecalis R612Z1 may be due to the different enzymatic activities at different storage temperatures. [ABSTRACT FROM AUTHOR]

N-Methyl-D-aspartate type glutamate receptors (NMDARs) are key mediators of synaptic activity-regulated gene transcription in neurons, both during development and in the adult brain. Developmental differences in the glutamate receptor ionotropic NMDA 2 (GluN2) subunit composition of NMDARs determines whether they activate the transcription factor cAMP-responsive element-binding protein 1 (CREB). However, whether the developmentally regulated GluN3A subunit also modulates NMDAR-induced transcription is unknown. Here, using an array of techniques, including quantitative real-time PCR, immunostaining, reporter gene assays, RNA-Seq, and two-photon glutamate uncaging with calciumimaging, we show that knocking down GluN3A in rat hippocampal neurons promotes the inducible transcription of a subset of NMDAR-sensitive genes. We found that this enhancement is mediated by the accumulation of phosphorylated p38 mitogen-activated protein kinase in the nucleus, which drives the activation of the transcription factor myocyte enhancer factor 2C (MEF2C) and promotes the transcription of a subset of synaptic activity-induced genes, including brain-derived neurotrophic factor (Bdnf) and activity-regulated cytoskeleton-associated protein (Arc). Our evidence that GluN3A regulates MEF2C-dependent transcription reveals a novel mechanism by whichNMDAR subunit composition confers specificity to the program of synaptic activityregulated gene transcription in developing neurons. [ABSTRACT FROM AUTHOR]

During mammary development, the transdifferentiation of mammary preadipocytes is one of the important sources for lactating mammary epithelial cells (MECs). However, there is limited knowledge about the mechanisms of dynamic regulation of transcriptome and genome-wide DNA methylation in the preadipocyte transdifferentiation process. Here, to gain more insight into these mechanisms, preadipocytes were isolated from adipose tissues from around the goat mammary gland (GM-preadipocytes). The GM-preadipocytes were cultured on Matrigel in conditioned media made from goat MECs to induce GM-preadipocyte-to-MEC transdifferentiation. The transdifferentiated GM-preadipocytes showed high abundance of keratin 18, which is a marker protein of MECs, and formed mammary acinar-like structures after 8 days of induction. Then, we performed transcriptome and DNA methylome profiling of the GM-preadipocytes and transdifferentiated GM-preadipocytes, respectively, and the differentially expressed genes and differentially methylated genes that play underlying roles in the process of transdifferentiation were obtained. Sub-sequently, we identified the candidate transcription factors in regulating the GM-preadipocyte-to-MEC transdifferentiation by transcription factor-binding motif enrichment analysis of differentially expressed genes and differentially methylated genes. Meanwhile, the secretory proteome of GM-preadipocytes cultured in conditioned media was also detected. By integrating the transcriptome, DNA methylome, and proteome, three candidate genes, four proteins, and several epigenetic regulatory axes were further identified, which are involved in regulation of the cell cycle, cell polarity establishment, cell adhesion, cell reprogramming, and adipocyte plasticity. These findings provide novel insights into the molecular mechanism of preadipocyte transdifferentiation and mammary development. [ABSTRACT FROM AUTHOR]

To investigate the effects of luteolin (LUT) on the growth, antioxidant capacity, non−specific immunity and intestinal microbiota of red swamp crayfish (Procambarus clarkii), 300 individual crayfish (4.17 ± 0.50 g average body weight and 50.19 ± 1.40 mm average body length) were randomly divided into five groups and fed with LUT doses of 0 mg/kg (CG), 50 mg/kg (LG50), 100 mg/kg (LG100), 300 mg/kg (LG300), and 500 mg/kg (LG500) for 8 weeks, respectively. Firstly, the results demonstrated that the survival and growth performance were significantly improved in all LUT added groups compared to the control (CG group), with no significant differences in hepatosomatic index, feed coefficient and muscle components, and the crayfish in LG100 group showed the maximal survival rate (SR) and specific growth rate (SGR) (P < 0.05). Secondly, histological observations displayed that the hepatopancreas and intestine tissues were not impacted in the LUT−supplemented groups, and the length of intestinal folds was significantly increased in LG100 and LG300 groups. Thirdly, LG50, LG100, and LG300 groups produced significantly increased hepatopancreatic antioxidant enzyme activities and hemolymph immune indicators compared with the control. In all experimental groups, malondialdehyde (MDA) contents were significantly reduced, as were aspartate aminotransferase and alanine aminotransferase activities. Lastly, dietary LUT specifically improved the structure and optimized the function of the gut microbiota. Compared to the control, the LG100 group displayed a significant increase in the index of Chao1 and Observed species, an increase in the relative abundance of Proteobacteria and Actinobacteria, a decrease in the ratio of Bacteroidetes to Firmicutes, and an increase in the abundance of Thermomonas , Turicibacter , Bdellovibrio and Enterococcus. PICRUSt analysis demonstrated a significant improvement in the KEGG pathway associated with isoflavone biosynthesis in the LG group. In conclusion, the present study confirms that dietary supplementation with 50−300 mg/kg LUT favors growth, non−specific immunity and antioxidant function in P. clarkii , with optimal additions ranging from 102−165 mg/kg. Furthermore, it optimized gut microbiota function, suggesting that LUT can be used as a potential feed additive for P. clarkii. These findings provide new insights for crayfish's healthy culture. • The optimal level of LUT addition to P. clarkii diet was 102−165 mg/kg. • Dietary addition of LUT improved the survival and growth performance of P. clarkii. • Dietary addition of LUT enhanced the antioxidant and immune capacity of P. clarkii. • Dietary addition of LUT improved intestinal microbiota structure of P. clarkii. [ABSTRACT FROM AUTHOR]

The red swamp crayfish (Procambarus clarkii) is an important farming species in China and there is a high degree of overlap between the main crayfish production areas and areas contaminated with the heavy metal lead (Pb), thus putting crayfish farming at potential risk of Pb contamination. To assess the toxic effects of Pb on crayfish, in this study they were exposed to different concentrations of Pb (0, 0.1, 1, 10, 50 mg/L) for 72 h, and 0.1 mg/L represents the level of Pb in the contaminated water. Histomorphology and activities of antioxidant or immune-related enzymes suggest that the damage of Pb to the hepatopancreas and intestine was dose- and time-dependent, with the intestine being more sensitive to Pb than the hepatopancreas. Notably, after a short period (24 h) of stress at low concentrations (0.1 mg/L) of Pb, the malondialdehyde (MDA) content and antioxidant enzymes such as catalase (CAT) and glutathione peroxidase (GSH-Px) in the intestine of crayfish showed significant changes, indicating that low concentrations of Pb were also highly detrimental to crayfish. High-throughput sequencing of the intestinal microbial community indicated that Pb exposure led to a disturbance in the relative abundance of intestinal bacteria, increasing the abundance of pathogenic bacteria (Bosea, Cloacibacterium, Legionella spp.) and decreasing the abundance of potentially beneficial bacteria (Chitinibacter, Chitinilyticum, Paracoccus, Microbacterium, Demequina , and Acinetobacter spp.). In conclusion, Pb damages the hepatopancreas and intestinal barrier of crayfish, leading to the destruction of their anti-stress ability and immune response, and at the same time disrupts the homeostasis of intestinal microbes, resulting in adverse effects on the gut. This study contributed to the assessment of the ecotoxicity of the heavy metal Pb to the crustacean aquatic animals. [ABSTRACT FROM AUTHOR]

ATP-binding cassette transporter A1 (ABCA1), which promotes cholesterol efflux from cells and inhibits inflammatory responses, is highly expressed in the kidney. Research has shown that exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, promotes ABCA1 expression in multiple tissues and organs; however, the mechanisms underlying exendin-4 induction of ABCA1 expression in glomerular endothelial cells are not fully understood. In this study we investigated the effect of exendin-4 on ABCA1 in glomerular endothelial cells of diabetic kidney disease (DKD) and the possible mechanism. We observed a marked increase in glomerular lipid deposits in tissues of patients with DKD and diabetic apolipoprotein E knock-out (apoE-/-) mice by Oil Red O staining and biochemical analysis of cholesterol. We found significantly decreased ABCA1 expression in glomerular endothelial cells of diabetic apoE-/- mice and increased renal lipid, cholesterol, and inflammatory cytokine levels. Exendin-4 decreased renal cholesterol accumulation and inflammation and increased cholesterol efflux by up-regulating ABCA1. In human glomerular endothelial cells, GLP-1R-mediated signaling pathways (e.g. Ca2+/ calmodulin-dependent protein kinase, cAMP/PKA, PI3K/AKT, and ERK1/2) were involved in cholesterol efflux and inflammatory responses by regulating ABCA1 expression. We propose that exendin-4 increases ABCA1 expression in glomerular endothelial cells, which plays an important role in alleviating renal lipid accumulation, inflammation, and proteinuria in mice with type 2 diabetes. [ABSTRACT FROM AUTHOR]

Interleukin-17 (IL-17)-secreting T helper 17 cells were recently identified as a CD4+ T helper subset and implicated in various inflammatory and autoimmune diseases. The issues of whether and by what mechanism hyperlipidemic stress induces IL-17A to activate aortic endothelial cells (ECs) and enhance monocyte adhesion remained largely unknown. Using biochemical, immunological, microarray, experimental data mining analysis, and pathological approaches focused on primary human and mouse aortic ECs (HAECs and MAECs) and our newly generated apolipoprotein E (ApoE)-/-/IL-17A-/- mice, we report the following new findings. 1) The hyperlipidemia stimulus oxidized low density lipoprotein up-regulated IL-17 receptor(s) in HAECs and MAECs. 2) IL-17A activated HAECs and increased human monocyte adhesion in vitro. 3) A deficiency of IL-17A reduced leukocyte adhesion to endothelium in vivo. 3) IL-17A activated HAECs and MAECs via up-regulation of proinflammatory cytokines IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), chemokine CXC motif ligand 1 (CXCL1), and CXCL2. 4) IL-17A activated ECs specifically via the p38 mitogen-activated protein kinases (MAPK) pathway; the inhibition of p38MAPKin ECs attenuated IL-17Amediated activation by ameliorating the expression of the aforementioned proinflammatory cytokines, chemokines, and EC adhesion molecules including intercellular adhesion molecule 1. Taken together, our results demonstrate for the first time that IL-17A activates aortic ECs specifically via p38 MAPK pathway. [ABSTRACT FROM AUTHOR]

Gastrointestinal probiotics are important members of intestinal microflora in both healthy animals and human beings, and these bacteria may reduce the risk of infection caused by certain opportunistic pathogens through exclusive inhibition, competition, and displacement. The lp_1643 protein on the cell surface of Lactobacillus plantarum WCFSI was assumed to possess a mucus-binding capability. This study aimed to determine if purified His-N2 protein exclusively inhibits pathogen adhesion to porcine mucus. The interaction of the His-N2 protein with porcine mucus was determined by indirect enzyme-linked immunosorbent assay (ELISA), and the adhesion was assessed by a traditional plating method to count the bacteria adhered to the porcine mucus. Indirect ELISA showed that His-N2 protein adhered to porcine mucus, and its interacting molecules existed. The His-N2 protein effectively inhibited the adhesion of Escherichia coli DH5α, Listeria monocytogenes CMCC54004, Salmonella Typhimurium ATCC 14028, and Shigella flexneri CMCC(B)51572 to porcine mucus. Results showed that inhibition of pathogen adhesion to porcine mucus depended on dose and strain. The adhesion of L. monocytogenes CMCC54004, Salmonella Typhimurium ATCC 14028, and S. flexneri CMCC(B)51572 was reduced by 95.7, 97.0, and 95.7%, respectively, by pre-adding 100 µl of 3.92 mg/ml of His-N2 protein, whereas that of E. coli DH5α was only 50.4%. The inhibition of adhesion of some pathogens by His-N2 was different at pH 6.6 and 7.5. The inhibition of E. coli DH5α, L. monocytogenes CMCC54004, and Salmonella Typhimurium ATCC 14028 at pH 6.6 was significantly higher than that at pH 7.5, whereas no statistically significant difference was observed in S. flexneri CMCC(B)51572. These results suggest that various types of inhibition mechanisms of His-N2 were involved in different pathogens. [ABSTRACT FROM AUTHOR]

The polysaccharide carrageenan is used as a natural precursor to prepare micro-mesoporous carbon spheres. The carbon spheres were synthesized by hydrothermal carbonization of carrageenan, and subsequent chemical activation by KOH at different temperatures. The obtained micro-mesoporous carbon spheres have high surface area (up to 2502 m² g-1) and large pore volume (up to 1.43 cm³ g-1). Moreover, the micro- and mesoporosity can be finely tuned be modifying the activation temperatures in the range of 700-900 °C. The carbon spheres activated at 900 °C present high specific capacitance of 230 F g-1 at a current density of 1 A g-1 and good ion transport kinetics. The good capacitive performance can be ascribed to the high specific surface area, well-controlled micro- and mesoporosity and narrow pore size distribution. [ABSTRACT FROM AUTHOR]

This paper studies the behavior and capacity of stainless steel lipped C-section stub columns under axial compression. A total of 10 tests were conducted on stub columns to investigate the failure mechanism and mode, the load–displacement curves, the section strain variation and the capacity. A comparison of the test results with code predictions indicates that the design strengths are lower than the experimental strengths and that the deviation between the test and predicted results decreases as the section plate slenderness coefficient increases. A finite element model is built to conduct parametric studies on the influential factors of member strength. Finally, based on the finite element analysis of 98 stub column specimens, a direct strength equation for stainless steel lipped C-section stub columns is proposed. [ABSTRACT FROM AUTHOR]

Rosin was once widely used for removal of duck feathers in China and is still being used secretly in some poultry processing enterprises. Abietic acid (AA) and dehydroabietic acid (DHAA) are the major compounds of rosin. In the present study, 90 duck samples were collected for investigation of AA and DHAA residues. Abietic acid and DHAA were simultaneously detected in 13 out 40 raw ducks, 8 out of 26 water-boiled salted ducks, and 7 out of 24 roasted ducks, respectively. In positive samples, averages of AA were significantly higher than those of DHAA in positive samples of the 3 types of ducks (P < 0.05). Averages of AA and DHAA in positive raw ducks were significantly higher than those in positive roasted ducks (P < 0.05). The results indicated that almost one-third of raw ducks were defeathered by means of rosin-containing defeathering agent, and cooking processes could reduce the A A and DHAA residues to some extent, but could not eliminate them completely. [ABSTRACT FROM AUTHOR]

As an interesting energy-absorbing structure, auxetic reentrant honeycomb has attracted much attention in recent decades. Furthermore, due to the adjustable design in the configuration of the graded auxetic reentrant honeycomb (GARH), its mechanical performances were of greater designability and controllability. In this manuscript, compressive properties of the positive gradient auxetic honeycomb (PGAH) and negative gradient auxetic honeycomb (NGAH) were both investigated under different compression velocities. Meanwhile, the negative Poisson's ratio effects on the deformation behaviours and crushing stresses of the PGAH and NGAH were systematically studied. It was found that a new shrinkage deformation mechanism existed in the NGAH, which was different from the dynamic compressive properties of the PGAH and homogeneous auxetic honeycomb in the existing studies. Besides, the energy dissipation characteristics of both the PGAH and NGAH were also investigated. The results showed that, when under the medium and high compression velocities, the energy dissipation of the NGAH were 12.1 times and 7.41 times of those in the PGAH, respectively. It could be indicated that the NGAH was an ideal energy-absorbing structure. [ABSTRACT FROM AUTHOR]