Department of Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan.
Rapid Commun Mass Spectrom. 2010 Sep;24(18):2723-9. doi: 10.1002/rcm.4693.
Rice is one of the most important food crops in the world and new varieties have been bred for specific purposes, such as the development of drought-resistance, or the enrichment of functional food factors. The localization and composition of metabolites in such new varieties must be investigated because all artificial interventions are expected to change the metabolites of rice. Imaging mass spectrometry using matrix-assisted laser desorption/ionization (MALDI-IMS) is a suitable tool for investigating the localization and composition of metabolites; however, suitable methodologies for the MALDI-IMS analysis of rice have not yet been established. In this study, we optimized the methods for analyzing rice grains by MALDI-IMS using adhesive film and found the characteristic distribution of metabolites in rice. Lysophosphatidylcholine (LPC) was localized in the endosperm. Phosphatidylcholine (PC), gamma-oryzanol and phytic acid were localized in the bran (germ and seed coat), and alpha-tocopherol was distributed in the germ (especially in the scutellum). In addition, MALDI-IMS revealed the LPC and PC composition of the rice samples. The LPC composition, LPC (1-acyl 16:0), LPC (1-acyl 18:2), LPC (1-acyl 18:1) and LPC (1-acyl 18:0), was 59.4 +/- 4.5%, 19.6 +/- 2.5%, 14.2 +/- 4.5% and 6.8 +/- 1.4%. The PC composition, PC (diacyl 16:0/18:2), PC (diacyl 16:0/18:1), PC (diacyl 18:1/18:3), PC (diacyl 18:1/18:2) and PC (diacyl 18:1/18:2), was 19.6 +/- 1.0%, 21.0 +/- 1.0%, 15.0 +/- 1.4%, 26.7 +/- 0.7% and 17.8 +/- 1.9%. This approach can be applied to the assessment of metabolites not only in rice, but also in other foods for which the preparation of sections is a challenging task.
水稻是世界上最重要的粮食作物之一，为了特定目的，如培育抗旱性或丰富功能性食品因子，已经培育了新品种。必须研究这些新品种中代谢物的定位和组成，因为所有的人工干预都预计会改变水稻的代谢物。利用基质辅助激光解吸/电离（MALDI-IMS）的成像质谱是研究代谢物定位和组成的合适工具；然而，尚未建立适合水稻 MALDI-IMS 分析的方法。在这项研究中，我们使用粘性薄膜优化了 MALDI-IMS 分析水稻籽粒的方法，并发现了水稻中代谢物的特征分布。溶血磷脂酰胆碱（LPC）定位于胚乳中。磷脂酰胆碱（PC）、γ-谷维素和植酸定位于麸皮（胚和种皮）中，α-生育酚分布于胚中（特别是盾片中）。此外，MALDI-IMS 揭示了水稻样品中 LPC 和 PC 的组成。LPC 组成，LPC（1-酰基 16:0）、LPC（1-酰基 18:2）、LPC（1-酰基 18:1）和 LPC（1-酰基 18:0），分别为 59.4 +/- 4.5%、19.6 +/- 2.5%、14.2 +/- 4.5%和 6.8 +/- 1.4%。PC 组成，PC（二酰基 16:0/18:2）、PC（二酰基 16:0/18:1）、PC（二酰基 18:1/18:3）、PC（二酰基 18:1/18:2）和 PC（二酰基 18:1/18:2），分别为 19.6 +/- 1.0%、21.0 +/- 1.0%、15.0 +/- 1.4%、26.7 +/- 0.7%和 17.8 +/- 1.9%。这种方法不仅可以应用于水稻，也可以应用于其他制备切片具有挑战性的食品的代谢物评估。
