Hawthorn (Crataegus pinnatifida) berries ripeness induced pectin diversity: A comparative study in physicochemical properties, structure, function and fresh-keeping potential.

The effect of hawthorn berries ripeness on the physicochemical, structural and functional properties of hawthorn pectin (HP) and its potential in sweet cherry preservation were investigated. With the advanced ripeness of hawthorn berries, the galacturonic acid (GalA) content decreased from 59.70 mol% to 52.16 mol%, the molecular weight (Mw) reduced from 368.6 kDa to 284.3 kDa, the microstructure exhibited variable appearance from thick lamella towards porous cross-linked fragment, emulsifying activity and emulsions stability, antioxidant activities, α-amylase and pancreatic lipid inhibitory capacities significantly increased. The heated emulsion stored for 30 d presented higher creaming index and more ordered oil droplets compared to the unheated emulsion. With the extended berries ripeness, the firmness of HP gels remarkably decreased from 225.69 g to 73.39 g, while the springiness increased from 0.78 to 1.16, HP exhibited a superior inhibitory effect in water loss, browning, softening, and bacterial infection in sweet cherries preservation.

Transcriptomic and metabolomic correlation analysis: effect of initial SO2 addition on higher alcohol synthesis in Saccharomyces cerevisiae and identification of key regulatory genes.

Introduction: Higher alcohols are volatile compounds produced during alcoholic fermentation that affect the quality and safety of the final product. This study used a correlation analysis of transcriptomics and metabolomics to study the impact of the initial addition of SO2 (30, 60, and 90 mg/L) on the synthesis of higher alcohols in Saccharomyces cerevisiae EC1118a and to identify key genes and metabolic pathways involved in their metabolism. Methods: Transcriptomics and metabolomics correlation analyses were performed and differentially expressed genes (DEGs) and differential metabolites were identified. Single-gene knockouts for targeting genes of important pathways were generated to study the roles of key genes involved in the regulation of higher alcohol production. Results: We found that, as the SO2 concentration increased, the production of total higher alcohols showed an overall trend of first increasing and then decreasing. Multi-omics correlation analysis revealed that the addition of SO2 affected carbon metabolism (ko01200), pyruvate metabolism (ko00620), glycolysis/gluconeogenesis (ko00010), the pentose phosphate pathway (ko00030), and other metabolic pathways, thereby changing the precursor substances. The availability of SO2 indirectly affects the formation of higher alcohols. In addition, excessive SO2 affected the growth of the strain, leading to the emergence of a lag phase. We screened the ten most likely genes and constructed recombinant strains to evaluate the impact of each gene on the formation of higher alcohols. The results showed that ADH4, SER33, and GDH2 are important genes of alcohol metabolism in S. cerevisiae. The isoamyl alcohol content of the EC1118a-ADH4 strain decreased by 21.003%; The isobutanol content of the EC1118a-SER33 strain was reduced by 71.346%; and the 2-phenylethanol content of EC1118a-GDH2 strain was reduced by 25.198%. Conclusion: This study lays a theoretical foundation for investigating the mechanism of initial addition of SO2 in the synthesis of higher alcohols in S. cerevisiae, uncovering DEGs and key metabolic pathways related to the synthesis of higher alcohols, and provides guidance for regulating these mechanisms.

Regulator DegU can remarkably influence alkaline protease AprE biosynthesis in Bacillus licheniformis 2709.

Alkaline protease AprE, produced by Bacillus licheniformis 2709 is an important edible hydrolase, which has potential applications in nutrient acquisition and medicine. The expression of AprE is finely regulated by a complex transcriptional regulation system. However, there is little study on transcriptional regulation mechanism of AprE biosynthesis in Bacillus licheniformis, which limits system engineering and further enhancement of AprE. Here, the severely depressed expression of aprE in degU and degS deletion mutants illustrated that the regulator DegU and its phosphorylation played a crucial part in AprE biosynthesis. Further electrophoretic mobility shift assay (EMSA) in vitro indicated that phosphorylated DegU can directly bind to the regulatory region though the DNase I foot-printing experiments failed to observe protected region. The plasmid-mediated overexpression of degU32 (Hy) obviously improved the yield of AprE by 41.6 % compared with the control strain, which demonstrated the importance of phosphorylation state of DegU on the transcription of aprE in vivo. In this study, the putative binding sequence of aprE (5'-TAAAT……AAAAT…….AACAT…TAAAA-3') located upstream -91 to -87 bp, -101 to -97 bp, -195 to -191 bp, -215 to -211 bp of the transcription start site (TSS) in B. licheniformis was computationally identified based on the DNA-binding sites of DegU in Bacillus subtilis. Overall, we systematically investigated the influence of the interplay between phosphorylated DegU and its cognate DNA sequence on expression of aprE, which not only contributes to the further AprE high-production in a genetically modified host in the future, but also significantly increases our understanding of the aprE transcription mechanism.

[Effects of modified Xiaoyao San on TLR4/NF-κB pathway in hippocampal microglia of LPS-induced depression model rats].

OBJECTIVE: To investigate the effects of modified Xiaoyao San on TLR4/NF-κB pathway in hippocampal microglia of LPS-induced depression model rats, and to explore its antidepressant mechanism. METHODS: SD rats were randomly divided into control, model, fluoxetine (10 mg·kg-1), low and high dose of modified Xiaoyao San (3.64, 7.28g·kg-1) group. The depression model was established by chronic LPS injection (ip, 0.5 mg·kg-1) and rats were treated by intragastric administration for 14 days. After the model was established, the depression-like behavior of rats was evaluated by open field and forced swimming test. The expression of microglia marker protein Iba-1 was detected by immunohistochemistry. The levels of TNF-α and IL-6 in hippocampal homogenate were detected by ELISA method and the expressions of TLR4 and NF-κB protein in hippocampus were detected by Western blot. RESULTS: Compared with control group, the depression-like behavior was significant in model group rats (P＜0.01), the microglia in the brain was activated (P＜0.01), the contents of TNF-α and IL-6 in the hippocampus were increased (P＜0.01), and the expression levels of TLR4 and NF-κB proteins were up-regulated (P＜0.01). Compared with model group, the depression-like behavior of the rats in the fluoxetine and high-dose modified Xiaoyao San group was significantly alleviated (P＜0.05), the expression of Iba-1 in microglia returned to normal (P＜0.01), the contents of TNF-α and IL-6 were decreased (P＜0.01), and the expression levels of TLR4 and NF-κB protein were decreased (P＜0.05). Compared with fluoxetine group, the high-dose modified Xiaoyao San group had no statistically significant difference in each index, suggesting that there was no significant difference in the antidepressant effect between the two groups. CONCLUSION: Modified Xiaoyao San can significantly improve the depression-like behavior in rats, and its mechanism may be related to inhibiting the TLR4/NF-κB pathway of microglia and down-regulating the expression of inflammatory factors.

[Effects of Ganmai Dazao Tang on synaptic structure of hippocampal neurons in depression model rats].

Objective: To investigate the effects of Ganmai Dazao Tang on behavior and monoamine neurotransmitters in rats with depression, and to explore its potential mechanism from synaptic structure. Methods: Sixty SD rats were randomly divided into 5 groups: normal control group, model group, fluoxetine group (10.8 mg/kg), Ganmai Dazao Tang high and low dose group (9.72, 4.86 g/kg), 12 rats in each group. Except the control group, the rats in the other groups were all chronically unpredictable mild stress (CUMS) to establish a depression model, and were treated by intragastric administration for 21 days. The depression-like behaviors of rats were evaluated by sucrose consumption test and open field test. The contents of serotonin (5-HT) and norepinephrine (NE) in hippocampus were detected by ELISA. The synaptic damage of neurons was observed by Golgi staining. The synaptic structure protein expression levels of MAP-2 and GAP-43 of hippocampus were detected by Immunohistochemistry and Western blot. Results: Compared with control group, the sucrose preference and autonomic activity scores of the depression model rats were decreased significantly (P＜0.01), the levels of 5-HT and NE in hippocampus were decreased significantly (P＜0.01), and the dendritic spines were absent, and the expressions of MAP-2 and GAP-43 were down-regulated significantly (P＜0.01). After treated with Ganmai Dazao Tang, the depression-like behavior of the model rats was significantly relieved (P＜0.01), and the levels of 5-HT and NE were increased (P＜ 0.05). Dendritic spine density, length and branching were increased, the expressions of MAP-2 and GAP-43 were increased (P＜ 0.01). Conclusion: Ganmai Dazao Tang can improve the depression-like behavior of depression model rats and increase the monoamine neurotransmitter content in hippocampus, which may be related to up-regulation of synaptic structural proteins and relief of synaptic damage in neurons.