title: Microscale MALDI imaging of outer-layer lipids in intact egg chambers from Drosophila melanogaster.
abstract: Fruit fly (Drosophila melanogaster) is a standard model organism used in genetics and molecular biology. Phospholipids are building blocks of cellular membranes, and components of a complex signaling network. Here, we present a facile method, based on matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), for molecular imaging of phospholipid distributions in submillimeter-sized components of the fruit fly reproductive system. Individual egg chambers were deposited on a specially prepared MALDI target comprising an aluminum slide with a rough surface created by ablation with a microsecond-laser: this helped to immobilize biological specimens, remove excess of saline solution by adhesive forces, carry out microscopic observations, and facilitated distribution of the MALDI matrix. A continuous-flow ultrasound-assisted spray was used for the deposition of MALDI matrix (9-aminoacridine) onto the sample. The upper surface of the specimen was then scanned with a 355-nm solid-state laser with a preset beam focus of 10 μm to obtain negative-ion mode MALDI-MS images. Overall, this provided sufficient spatial resolution to reveal micrometer-scale gradient-like patterns of phospholipids along the anterior/posterior axis of egg chambers. Several phosphatidylinositols are seen to be segregated according to the number of unsaturated bonds, with an elevated abundance of polyunsaturated phosphatidylinositols within the oocyte compartment.
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan.
authors.forename: Pawel L
authors.initials: PL
authors.lastname: Urban
authors.forename: Chia-Hsien
authors.initials: CH
authors.lastname: Chang
authors.forename: June-Tai
authors.initials: JT
authors.lastname: Wu
authors.forename: Yu-Chie
authors.initials: YC
authors.lastname: Chen
mesh_terms: D000535:Aluminum / Q000737:chemistry; D000585:Aminacrine / Q000737:chemistry; D000818:Animals; D004331:Drosophila melanogaster / Q000254:growth & development / Q000378:metabolism*; D010063:Ovum / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D010743:Phospholipids; D000585:Aminacrine; D000535:Aluminum