Metabolic mechanism of nitrogen modified atmosphere storage on delaying quality deterioration of rice grains.

Nitrogen modified atmosphere was an effective way to control pest infestation in grains. In this study, the quality changes of rice during nitrogen modified atmosphere packaging storage (N2-MAPS) were monitored. An un-targeted metabolomics method was used to detect the rice metabolites and explore the mechanism of N2-MAPS for delaying rice deterioration. In this study, two rice species were studied under N2-MAPS and conventional storage at 30 °C for 150 days. The quality changes of rice during storage were monitored. The results showed that N2-MAPS could retard the increase of fatty acid value and amylose content, and defer the decrease of enzyme activities. And N2-MAPS had no significant influence on texture characteristics of rice. The metabolomics results suggested some metabolites and pathways were affected by N2-MAPS and revealed that N2-MAPS could protect rice cells from oxidative damage, maintain cell integrity and stability by regulating the metabolism to delay the rice deterioration.

The phosphatidylglycerol phosphate synthase PgsA utilizes a trifurcated amphipathic cavity for catalysis at the membrane-cytosol interface.

Phosphatidylglycerol is a crucial phospholipid found ubiquitously in biological membranes of prokaryotic and eukaryotic cells. The phosphatidylglycerol phosphate (PGP) synthase (PgsA), a membrane-embedded enzyme, catalyzes the primary reaction of phosphatidylglycerol biosynthesis. Mutations in pgsA frequently correlate with daptomycin resistance in Staphylococcus aureus and other prevalent infectious pathogens. Here we report the crystal structures of S. aureus PgsA (SaPgsA) captured at two distinct states of the catalytic process, with lipid substrate (cytidine diphosphate-diacylglycerol, CDP-DAG) or product (PGP) bound to the active site within a trifurcated amphipathic cavity. The hydrophilic head groups of CDP-DAG and PGP occupy two different pockets in the cavity, inducing local conformational changes. An elongated membrane-exposed surface groove accommodates the fatty acyl chains of CDP-DAG/PGP and opens a lateral portal for lipid entry/release. Remarkably, the daptomycin resistance-related mutations mostly cluster around the active site, causing reduction of enzymatic activity. Our results provide detailed mechanistic insights into the dynamic catalytic process of PgsA and structural frameworks beneficial for development of antimicrobial agents targeting PgsA from pathogenic bacteria.

The presence of 3-hydroxypropionate and 1,3-propanediol suggests an alternative path for conversion of glycerol to Acetyl-CoA.

BACKGROUND: In our recent study using [U-13C3]glycerol, a small subset of hamsters showed an unusual profile of glycerol metabolism: negligible gluconeogenesis from glycerol plus conversion of glycerol to 1,3-propanediol (1,3PDO) and 3-hydroxypropionate (3HP) which were detected in the liver and blood. The purpose of the current study is to evaluate the association of these unusual glycerol products with other biochemical processes in the liver. METHODS: Fasted hamsters received acetaminophen (400 mg/kg; n = 16) or saline (n = 10) intraperitoneally. After waiting 2 h, all the animals received [U-13C3]glycerol intraperitoneally. Liver and blood were harvested 1 h after the glycerol injection for NMR analysis and gene expression assays. RESULTS: 1,3PDO and 3HP derived from [U-13C3]glycerol were detected in the liver and plasma of eight hamsters (two controls and six hamsters with acetaminophen treatment). Glycerol metabolism in the liver of these animals differed substantially from conventional metabolic pathways. [U-13C3]glycerol was metabolized to acetyl-CoA as evidenced with downstream products detected in glutamate and ß-hydroxybutyrate, yet 13C labeling in pyruvate and glucose was minimal (p < 0.001, 13C labeling difference in each metabolite). Expression of aldehyde dehydrogenases was enhanced in hamster livers with 1,3PDO and 3HP (p < 0.05). CONCLUSION: Detection of 1,3PDO and 3HP in the hamster liver was associated with unorthodox metabolism of glycerol characterized by conversion of 3HP to acetyl-CoA followed by ketogenesis and oxidative metabolism through the TCA cycle. Additional mechanistic studies are needed to determine the causes of unusual glycerol metabolism in a subset of these hamsters.

3-O-Acetyl-11-keto- ß -boswellic acid ameliorated aberrant metabolic landscape and inhibited autophagy in glioblastoma.

Glioblastoma is the most common and aggressive primary tumor in the central nervous system, accounting for 12%-15% of all brain tumors. 3-O-Acetyl-11-keto-ß-boswellic acid (AKBA), one of the most active ingredients of gum resin from Boswellia carteri Birdw., was reported to inhibit the growth of glioblastoma cells and subcutaneous glioblastoma. However, whether AKBA has antitumor effects on orthotopic glioblastoma and the underlying mechanisms are still unclear. An orthotopic mouse model was used to evaluate the anti-glioblastoma effects of AKBA. The effects of AKBA on tumor growth were evaluated using MRI. The effects on the alteration of metabolic landscape were detected by MALDI-MSI. The underlying mechanisms of autophagy reducing by AKBA treatment were determined by immunoblotting and immunofluorescence, respectively. Transmission electron microscope was used to check morphology of cells treated by AKBA. Our results showed that AKBA (100 mg/kg) significantly inhibited the growth of orthotopic U87-MG gliomas. Results from MALDI-MSI showed that AKBA improved the metabolic profile of mice with glioblastoma, while immunoblot assays revealed that AKBA suppressed the expression of ATG5, p62, LC3B, p-ERK/ERK, and P53, and increased the ratio of p-mTOR/mTOR. Taken together, these results suggested that the antitumor effects of AKBA were related to the normalization of aberrant metabolism in the glioblastoma and the inhibition of autophagy. AKBA could be a promising chemotherapy drug for glioblastoma.

3--Acetyl-11-keto- -boswellic acid ameliorated aberrant metabolic landscape and inhibited autophagy in glioblastoma

Glioblastoma is the most common and aggressive primary tumor in the central nervous system, accounting for 12%-15% of all brain tumors. 3--Acetyl-11-keto--boswellic acid (AKBA), one of the most active ingredients of gum resin from Birdw., was reported to inhibit the growth of glioblastoma cells and subcutaneous glioblastoma. However, whether AKBA has antitumor effects on orthotopic glioblastoma and the underlying mechanisms are still unclear. An orthotopic mouse model was used to evaluate the anti-glioblastoma effects of AKBA. The effects of AKBA on tumor growth were evaluated using MRI. The effects on the alteration of metabolic landscape were detected by MALDI-MSI. The underlying mechanisms of autophagy reducing by AKBA treatment were determined by immunoblotting and immunofluorescence, respectively. Transmission electron microscope was used to check morphology of cells treated by AKBA. Our results showed that AKBA (100 mg/kg) significantly inhibited the growth of orthotopic U87-MG gliomas. Results from MALDI-MSI showed that AKBA improved the metabolic profile of mice with glioblastoma, while immunoblot assays revealed that AKBA suppressed the expression of ATG5, p62, LC3B, p-ERK/ERK, and P53, and increased the ratio of p-mTOR/mTOR. Taken together, these results suggested that the antitumor effects of AKBA were related to the normalization of aberrant metabolism in the glioblastoma and the inhibition of autophagy. AKBA could be a promising chemotherapy drug for glioblastoma.

Evaluation of Diabetes Care parameters in capillary blood collected with a novel sampling device.

The aim of this study was to determine whether the Hem-Col method of obtaining and storing blood is an acceptable alternative to venepuncture for measuring Diabetes Care parameters. Design and methods : Hem-Col is a novel blood collection device that is designed to collect capillary blood drawn with a finger prick. Hem-Col is a microtube containing an anticoagulant and a preservation buffer to enhance analyte stability in whole blood. The Diabetes Care parameters cholesterol, creatinine, HbA1c, high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, and triglycerides were measured both in blood/plasma collected via Hem-Col and blood/plasma collected with venepuncture. The results were compared to assess the agreement between the two methods. Results : HbA1c shows agreement after storage for up to 120 hours at temperatures ranging from 4 to 37 °C. Cholesterol, HDL cholesterol, LDL cholesterol, triglycerides and creatinine can be measured after 120 hours of storage in Hem-Col buffer, if high temperatures are avoided, and with the use of correction factors or adaptations to reported reference intervals. Conclusion : Hem-Col is suitable for the measurement of HbA1c after storage for up to 120 hours at temperatures ranging from 4 to 37 °C. Cholesterol, creatinine, HDL cholesterol, LDL cholesterol and triglycerides can be measured after 120 hours of storage in Hem-Col buffer, if high temperatures are avoided. Further studies are required to determine whether Hem-Col can replace the venepuncture for the Diabetes Care parameters.