MicroRNA775 regulates intrinsic leaf size and reduces cell wall pectin levels by targeting a galactosyltransferase gene in Arabidopsis.

Plants possess unique primary cell walls made of complex polysaccharides that play critical roles in determining intrinsic cell and organ size. How genes responsible for synthesizing and modifying the polysaccharides in the cell wall are regulated by microRNAs (miRNAs) to control plant size remains largely unexplored. Here we identified 23 putative cell wall-related miRNAs, termed as CW-miRNAs, in Arabidopsis thaliana and characterized miR775 as an example. We showed that miR775 post-transcriptionally silences GALT9, which encodes an endomembrane-located galactosyltransferase belonging to the glycosyltransferase 31 family. Over-expression of miR775 and deletion of GALT9 led to significantly enlarged leaf-related organs, primarily due to increased cell size. Monosaccharide quantification, confocal Raman imaging, and immunolabeling combined with atomic force microscopy revealed that the MIR775A-GALT9 circuit modulates pectin levels and the elastic modulus of the cell wall. We also showed that MIR775A is directly repressed by the transcription factor ELONGATED HYPOCOTYL5 (HY5). Genetic analysis confirmed that HY5 is a negative regulator of leaf size that acts through the HY5-MIR775A-GALT9 repression cascade to control pectin levels. These findings demonstrate that miR775-regulated cell wall remodeling is an integral determinant of intrinsic leaf size in A. thaliana. Studying other CW-miRNAs would provide more insights into cell wall biology.

Dietary wood pulp-derived sterols modulation of cholesterol metabolism and gut microbiota in high-fat-diet-fed hamsters.

Evidence indicates that wood pulp-derived sterols (WS) have beneficial effects on cardiovascular diseases. The present study aimed to (i) investigate the serum cholesterol-lowering activity of dietary WS and (ii) investigate the effects of dietary WS on the balance of gut microbiota in hamsters fed with a high-fat diet. Thirty-six hamsters were divided into four groups fed on a normal chow diet (NCD), a high-fat diet (HFD), or HFD plus 0.1% or 0.5% wood pulp-derived sterols (WSL, WSH), respectively, for 6 weeks. Levels of serum total cholesterol, triglyceride, HDL-C, non-HDL-C, and non-HDL-C/HDL-C ratio in hamsters fed the NCD were originally 120.4 mg dL-1, 235.8 mg dL-1, 71.7 mg dL-1, 48.7 mg dL-1 and 0.68 mg dL-1, which were elevated by being fed the HFD to 187.7 mg dL-1, 389.5 mg dL-1, 92.3 mg dL-1, 95.3 mg dL-1 and 1.03 mg dL-1, and alleviated completely by being fed the WSH. The excretion of total fecal neutral sterols was dose-dependently increased with the amounts of dietary WS. Furthermore, dietary supplementation with WS modulated the relative abundance of gut microbiota compared with the HFD group. Spearman's correlation analysis revealed that Bacteroides, Allobaculum, Coprobacillus, Lactobacillus, Akkermansia, Coprococcus, and Oscillospira were correlated negatively with most of the serum metabolic parameters and cholesterol metabolic parameters, whereas Desulfovibrio was positively correlated with most of the lipid metabolism-associated parameters. Taken together, dietary supplementation with WS was found to have cholesterol-lowering activity, in part mediated by modulating the gut microbiota in a positive way and regulating the cholesterol absorption and metabolism-related genes.

Hypoglycemic effect of D-chiro-inositol in type 2 diabetes mellitus rats through the PI3K/Akt signaling pathway.

In this investigation, a model of type 2 diabetes mellitus (T2DM) was used on Sprague-Dawley (SD) rats to clarify more details of the mechanism in the therapy of T2DM. D-chiro-inositol (DCI) was administrated to the diabetic rats as two doses [30, 60 mg/(kg·body weight·day)]. The biochemical indices revealed that DCI had a positive effect on hypoglycemic activity and promoted the glycogen synthesis. The rats in DCI high-dosage group had a blood glucose reduction rate of 21.5% after 5 weeks of treatment, and had insulin content in serum about 15.3 ± 2.37 mIU/L which was significantly decreased than diabetes control group. Real-time polymerase chain reaction (RT-PCR) results revealed that DCI gave a positive regulation on glycogen synthase (GS) and protein glucose transporter-4 (Glut4). Western blotting suggested that DCI could up-regulated the expression of the phosphatidylinositol-3-kinase (PI3K) p85, PI3Kp110, GS as well as the phosphorylation of protein kinase B (Akt) both in the liver and the skeletal muscle. The results also revealed that DCI enhanced the Glut4 expression on skeletal muscle. Above all, DCI played a positive role in regulating insulin-mediated glucose uptake through the PI3K/Akt signaling pathway in T2DM rats.

Optimization of ultrasonic-stimulated solvent extraction of sinigrin from Indian mustard seed (Brassica Juncea L.) using response surface methodology.

INTRODUCTION: Sinigrin, a major glucosinolate present in Indian mustard (Brassica juncea L.) seeds as the precursor of the anticancer compound allyl isothiocyanate, shows a wide range of biological activities. It's necessary to optimize the extraction methods and conditions, in order to improve the extraction productivity and save raw material. OBJECTIVE: To systemically investigate and optimize the most important factors affected the productivity of sinigrin in the process of extraction using response surface methodology. METHODOLOGY: The ranges of three main factors including the ethanol concentration, extraction time and extraction temperature were selected by the one-factor-at-a-time method. The conditions of ultrasonic-stimulated extraction of sinigrin from defatted Indian mustard seed powder were optimized by Box-Behnken design to obtain the maximum productivity. RESULT: The predicted productivity (3.81%) was obtained using 57% ethanol concentration at 81 °C for 60 min, with the coefficient of the model R² > 0.96 (n = 17). The actual productivity (3.84 ± 0.02%) of sinigrin under the optimized condition was increased by 70.67% compared with the result of conventional extraction. Meanwhile, HPLC, UV and IR were applied to examine if there is a difference between the ultrasonic-stimulated solvent extraction and conventional extraction, and the improvement of productivity of sinigrin depended on the destruction of cell wall caused by the elimination of outer pectinous material was explained by SEM and composition content analysis. CONCLUSION: The ultrasonic-stimulated solvent extraction was suggested to be a promising method to improve the productivity of sinigrin. And the results demonstrated that sinigrin productivity may be related to pectinous materials existed in the seeds.