Metabolite profiles of brown planthopper-susceptible and resistant rice (Oryza sativa) varieties associated with infestation and mechanical stimuli.

Understanding brown planthopper (BPH) resistance mechanism will expedite selective breeding of better BPH resistant lines of rice (Oryza sativa). Metabolic responses during BPH infestation derived from wound stress imposed by insect feeding, comparing with mechanical piercing will provide an insight into resistance mechanism in rice. Therefore, this study aimed to compare the metabolic responses of needle piercing treatment and BPH feeding treatment in BPH-susceptible (KD) and BPH-resistant (RH) varieties at four different time points (0, 6, 24 and 96 h) using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Phenotypes of RH were not different among the treatments, whereas KD exhibited hopperburn symptom at 96 h post-BPH infestation. Principal component and cluster analyses revealed that metabolite profiles between KD and RH were different in response to both insect and mechanical stimuli. Metabolite profiles of RH under BPH and mechanical treatments at 24 and 96 h were different from the untreated, whereas metabolite profiles of KD after BPH infestation at 24 and 96 h were distinct from needle piercing and no treatment, suggesting that the resistant variety has an ability to adapt and defend both mechanical and insect stimuli. Metabolomics result showed that BPH infestation perturbed purine salvage biosynthesis (e.g., inosine, hypoxanthine) in both varieties, amino acid biosynthesis (e.g., phenylalanine, tryptophan) in KD, while the infestation perturbed lysine metabolism (pipecolic acid) and phenylpropanoid pathway (2-anisic acid) only in RH. BPH and mechanical stimuli perturbed phenylamide only in RH, but not in KD. These findings revealed that different rice varieties utilize different metabolites in response to insect and mechanical stimuli, resulting in different degrees of resistance.

WinMLR program for the determination of sorbic and benzoic acids in food samples.

The program WinMLR has been developed to quantify sorbic and benzoic acids in soft drinks, fruit juices, and soy sauce by making a multilinear regression treatment of experimental data to a linear combination of standard signals. The spectra of sorbic and benzoic acid and samples were obtained from a conventional spectrophotometer, which has been saved in an ASCII file to be applied with the WinMLR program. Before to determine sorbic and benzoic acids in samples, the wavelength validation and calibration parameters were studied. Standard solutions of sorbic and benzoic acids were used for the calibration parameters to measure the individual analyte. If the sample has simultaneously both compounds, it is better to choose the synthetic mixture for the calibration parameters. This technique provides a good recovery in the range of 80.4-104.8% without a complicated and expensive instrument.

Optimization of metabolite extraction and analytical methods from shrimp intestine for metabolomics profile analysis using LC-HRMS/MS.

INTRODUCTION: Intestinal microbiota and metabolites play important roles for further improvement of animal production. Metabolomics of shrimp intestine to understand roles and their relationship to the host is hampered by the lack of metabolome profiling method. OBJECTIVES: This study aims to develop extraction and analytical methods to allow accurate metabolic analysis in shrimp intestine. METHODS: Conditions for extraction and LC-HRMS/MS analysis were optimized. RESULTS: Extraction with ethyl acetate:acetone (15:2 v/v) acidified with 0.5% acetic acid, elution with acetonitrile:water acidified with 0.01% acetic acid for 25 min, and mass fragmentation at 15% HCD were the optimal conditions, yielding the highest signal intensity and numbers of putative metabolites. CONCLUSION: Our method enabled in-depth study for shrimp-microbial interaction at metabolite level.