Comparative evaluation of three Lactobacilli with strain-specific activities for rats when supplied in drinking water

To test the in vivo benefits of three lactobacilli and to compare their different efficacies based on strain-specific activities by using rats as an experimental model, a growth-promotion and a challenge trial were conducted. The three strains, Lactobacillus salivarius G1-1, Lactobacillus reuteri G22-2, and Lactobacillus reuteri G8-5 shared antimicrobial, bile-salt-hydrolase and amylolytic activities in vitro, respectively. In the 17 day growth-promotion trial, 48 rats were allotted to four treatments with 12 replicates per treatment: a control group, which received saline, as well as three experimental groups, which received 10⁸ cells/ml of one of the three lactobacilli in saline suspension. The results showed that compared with the control group, L. reuteri G8-5 significantly improved feed efficiency and decreased fecal pH values on days 8 and 17, concomitant with reduced faecal coliform counts on d 17 (p < 0.05). All treatments with lactobacilli caused an increase in the moisture content of the faeces and a decrease in the serum total cholesterol and blood urea nitrogen levels. High-density lipoprotein cholesterol was only elevated for rats which received L. reuteri G22-2. In the Salmonella-challenge trial, 40 rats were allotted to five treatments (8 replicates per treatment) which consisted of a positive control (infected, no Lactobacillus pretreatment), a negative control (uninfected, no Lactobacillus pretreatment) and three Lactobacillus-pretreated groups (10⁹ cells/ml in saline). The results showed that rats in all Lactobacillus pretreated groups were protected from infection with significantly higher weight gain, feed intake and feed efficiency compared with positive control rats (p < 0.05). Rats treated with L. salivarius G1-1 and L. reuteri G22-2 tended to exhibit higher weight gains than those pretreated with L. reuteri G8-5. Significantly lower Salmonella shedding in faeces, Salmonella numbers in the spleen and the relative weight of the spleen were observed in the Lactobacillus groups (p < 0.05). Based on the overall results, it can be concluded that not all strains within the same lactobacilli species show similar effects and that some of the beneficial functionalities to animals were strain-specific. Therefore strains for practical application need to be carefully selected based on their strain-specific characters.     

Prolonging the female reproductive lifespan and improving egg quality with dietary omega‐3 fatty acids

Women approaching advanced maternal age have extremely poor outcomes with both natural and assisted fertility. Moreover, the incidence of chromosomal abnormalities and birth defects increases with age. As of yet, there is no effective and practical strategy for delaying ovarian aging or improving oocyte quality. We demonstrate that the lifelong consumption of a diet rich in omega‐3 fatty acids prolongs murine reproductive function into advanced maternal age, while a diet rich in omega‐6 fatty acids is associated with very poor reproductive success at advanced maternal age. Furthermore, even short‐term dietary treatment with a diet rich in omega‐3 fatty acids initiated at the time of the normal age‐related rapid decline in murine reproductive function is associated with improved oocyte quality, while short‐term dietary treatment with omega‐6 fatty acids results in very poor oocyte quality. Thus, omega‐3 fatty acids may provide an effective and practical avenue for delaying ovarian aging and improving oocyte quality at advanced maternal age.     

Negative Affect Mediates Effects of Psychological Stress on Disordered Eating in Young Chinese Women

Background

The bi-relationships between psychological stress, negative affect and disordered eating has been well studied in western culture, while tri-relationship among them, i.e. how some of those factors influence these bi-relationships, has rarely been studied. However, there has been little related study in the different Chinese culture. This study was conducted to investigate the bi-relationships and tri-relationship between psychological stress, negative affect, and disordered eating attitudes and behaviors in young Chinese women.

Methodology

A total of 245 young Chinese policewomen employed to carry out health and safety checks at the 2010 Shanghai World Expo were recruited in this study. The Chinese version of the Perceived Stress Scale (PSS-10), Beck Depression Inventory Revised (BDI-II), Beck Anxiety Inventory (BAI), and Eating Attitude Test (EAT-26) were administered to all participants.

Principal Findings

The total scores of PSS-10, BDI-II and BAI were all highly correlated with that of EAT-26. The PSS-10 score significantly correlated with both BDI-II and BAI scores. There was no statistically significant direct effect from perceived stress to disordered eating (–0.012, 95%CI: –.038∼0.006, p = 0.357), however, the indirect effects from PSS-10 via affect factors were statistically significant, e.g. the estimated mediation effects from PSS to EAT-26 via depression and anxiety were 0.036 (95%CI: 0.022∼0.044, p<0.001) and 0.015 (95%CI: 0.005∼0.023, p<0.01), respectively.

Conclusions

Perceived stress and negative affects of depression and anxiety were demonstrated to be strongly associated with disordered eating. Negative affect mediated the relationship between perceived stress and disordered eating. The findings suggest that effective interventions and preventative programmes for disordered eating should pay more attention to depression and anxiety among the young Chinese female population.     

The N-Terminal HSDCIF Motif Is Required for Cell Surface Trafficking and Dimerization of Family B G Protein Coupled Receptor PAC1

PAC1 is PACAP (pituitary adenylate cyclase-activating polypeptide) preferring receptor belonging to class B G protein coupled receptor (GPCR) mediating the most effects of PACAP. The important role of G protein coupled receptor homo/heteromerization in receptor folding, maturation, trafficking, and cell surface expression has become increasingly evident. The bimolecular fluorescence complementation (BiFC) and bioluminescence resonance energy transfer (BRET) assay were used in this research to confirm the dimerization of PAC1 for the first time. The structure-activity relationship focused on the N-terminal HSDCIF motif, which locates behind the signal sequence and has high homology with PACAP (1–6), was assayed using a receptor mutant with the deletion of the HSDCIF motif. The fluorescence confocal microscope observation showed that the deletion of the HSDCIF motif impaired the cell delivery of PAC1. The results of BiFC, BRET and westernblot indicated that the deletion of HSDCIF motif and the replacement of the Cys residue with Ala in HSDCIF motif resulted in the disruption of receptor dimerization. And the exogenous chemically synthesized oligopeptide HSDCIF (100 nmol/L) not only down-regulated the dimerization of PAC1, induced the internalization of PAC1, but also inhibited the proliferation of CHO cells expressing PAC1 stably and decreased the activity of PACAP on the cell viability. All these data suggested that the N-terminal HSDCIF motif played key role in the trafficking and the dimerization of PAC1, and the exogenous oligopeptide HSDCIF had effects on the cell signaling, trafficking and the dimerization of PAC1.     

Rewiring central carbon metabolism for tyrosol and salidroside production in Saccharomyces cerevisiae

Metabolic engineering of Saccharomyces cerevisiae for high-level production of aromatic chemicals has received increasing attention in recent years. Tyrosol production from glucose by S. cerevisiae is considered an environmentally sustainable and safe approach. However, the production of tyrosol and salidroside by engineered S. cerevisiae has been reported to be lower than 2 g/L to date. In this study, S. cerevisiae was engineered with a push-pull-restrain strategy to efficiently produce tyrosol and salidroside from glucose. The biosynthetic pathways of ethanol, phenylalanine, and tryptophan were restrained by disrupting PDC1, PHA2, and TRP3. Subsequently, tyrosol biosynthesis was enhanced with a metabolic pull strategy of introducing PcAAS and EcTyrA^M53I/A354V. Moreover, a metabolic push strategy was implemented with the heterologous expression of phosphoketolase (Xfpk), and then erythrose 4-phosphate was synthesized simultaneously by two pathways, the Xfpk-based pathway and the pentose phosphate pathway, in S. cerevisiae. Furthermore, the heterologous expression of Xfpk alone in S. cerevisiae efficiently improved tyrosol production compared with the coexpression of Xfpk and phosphotransacetylase. Finally, the tyrosol yield increased by approximately 135-folds, compared with that of parent strain. The total amount of tyrosol and salidroside with glucose fed-batch fermentation was over 10 g/L and reached levels suitable for large-scale production.     

Transcriptional regulation of ATP-binding cassette transporter A1 expression by a novel signaling pathway

ATP-binding cassette transporter A1 (ABCA1) is a membrane-bound protein that regulates the efflux of cholesterol derived from internalized lipoproteins. Using a mouse macrophage cell line, this report studied the impact of low-density lipoproteins (LDL) on ABCA1 expression and the signaling pathway responsible for lipoprotein-induced ABCA1 expression. Our data demonstrated that treatment of macrophages with LDL increased ABCA1 mRNA and protein levels 4.3- and 3.5-fold, respectively. LDL also induced an ～2-fold increase in macrophage surface expression of ABCA1 and a 14-fold-increase in apolipoprotein AI-mediated cholesterol efflux. In addition, LDL significantly increased the level of phosphorylated specificity protein 1 (Sp1) and the amount of Sp1 bound to the ABCA1 promoter without alteration in total Sp1 protein level. Mutation of the Sp1 binding site in the ABCA1 promoter and inhibition of Sp1 DNA binding with mithramycin A suppressed the ABCA1 promoter activity and reduced the ABCA1 expression level induced by LDL. LDL treatment also elevated protein kinase C-ζ (PKC-ζ) phosphorylation and induced PKC-ζ binding with Sp1. Inhibition of PKC-ζ with kinase inhibitors or overexpression of kinase-dead PKC-ζ attenuated Sp1 phosphorylation and ABCA1 expression induced by LDL. These results demonstrate for the first time that activation of the PKCζ-Sp1 signaling cascade is a mechanism for regulation of LDL-induced ABCA1 expression.     

尿酸酶－鲁米诺化学发光传感器

研制了依赖于鲁米诺化学发光反应和固定化尿酸酶柱的测定血清尿酸的生物传感器。其测定血清样品响应时间47s。测定每份样品需时1．5min,样品体积17μl。工作曲线的线性范围1~20mg／dl。批内不精密度3．22％～4.36％,批间6.18%～7．8%。测定值回收率为93％～109％。与医院常规酶试剂盘方法比较相关系数r=0.9909。固定化尿酸酶柱室温使用,4℃冰箱保存,连续使用5个半月测定样品2000次以上,仍保持原酶柱活力的94%。     

Rice cationic peroxidase accumulates in xylem vessels during incompatible interactions with Xanthomonas oryzae pv oryzae.

A cationic peroxidase, PO-C1 (molecular mass 42 kD, isoelectric point 8.6), which is induced in incompatible interactions between the vascular pathogen Xanthomonas oryzae pv oryzae and rice (Oryza sativa L.), was purified. Amino acid sequences from chemically cleaved fragments of PO-C1 exhibited a high percentage of identity with deduced sequences of peroxidases from rice, barley, and wheat. Polyclonal antibodies were raised to an 11-amino acid oligopeptide (POC1a) that was derived from a domain where the sequence of the cationic peroxidase diverged from other known peroxidases. The anti-POC1a antibodies reacted only with a protein of the same mobility as PO-C1 in extracellular and guttation fluids from plants undergoing incompatible responses collected at 24 h after infection. In the compatible responses, the antibodies did not detect PO-C1 until 48 h after infection. Immunoelectron microscopy was used to demonstrate that PO-C1 accumulated within the apoplast of mesophyll cells and within the cell walls and vessel lumen of xylem elements of plants undergoing incompatible interactions.