Agilent 7890 gas chromatography system

At the end of the 7-day-experimental period (1 × 10⁸ CFU C. butyricum/mL), mice were euthanized, and uterus and blood samples were collected. Blood was kept on ice for 30 min and centrifuged at 3,500 rpm for 10 min at 4°C, and serum was obtained for analysis. The samples obtained for measurement of butyric acid (a short-chain fatty acid) were immediately frozen at −20°C and stored at −80°C until quantification. Butyric acid measurement was determined following a modified protocol, as previously described. First, a standard curve sample was prepared. Next, the SCFA-containing ether layers were obtained and pooled for GC-MS analysis using an Agilent 7890 gas chromatography system coupled with an Agilent 7000D mass spectrometer. The mass spectrometry data were acquired in MRM mode with a solvent delay of 3 min.

An untargeted primary metabolic analysis of macaque gut tissue was performed by gas chromatography-time of flight (GC-TOF) mass spectrometry (MS). Ten to 20 mg of cryopreserved gut tissue was obtained from SIV-infected animals during the early stage at 60 h postinfection (n = 3) or during chronic stage at 10 weeks postinfection (n = 4) and from SIV-negative controls (n = 4). Tissue samples were homogenized in an extraction mixture of acetonitrile, isopropanol, and water (3:3:2) and centrifuged, and supernatants were evaporated. Dried pellets were dissolved in 50% acetonitrile, evaporated, and subjected to a two-step derivatization using methoximation and trimethylsilylation. The GC-MS analysis was performed using an Agilent 7890 gas chromatography system coupled to an Agilent 5977A mass spectrometer by the West Coast Metabolomics Center at UC Davis, as previously described (45 (link)). Overrepresentation analysis (ORA) was performed in Metabolites Set Enrichment Analysis (MSEA) software (http://www.metaboanalyst.ca) using the metabolic pathways library from MSEA for all metabolites showing a 1.3-fold change.