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Phan N.T.N.,Gothenburg University | Phan N.T.N.,National Center Imaging Mass Spectrometry | Fletcher J.S.,Gothenburg University | Fletcher J.S.,National Center Imaging Mass Spectrometry | And 5 more authors.
Surface and Interface Analysis | Year: 2014

Drosophila melanogaster (fruit fly) has a relatively simple nervous system but possesses high order brain functions similar to humans. Therefore, it has been used as a commonmodel system in biological studies, particularly drug addiction. Here, the spatial distribution of biomolecules in the brain of the fly was studied using time-of-flight SIMS. Fly brains were analyzed frozen to prevent molecular redistribution prior to analysis. Different molecules were found to distribute differently in the tissue, particularly the eye pigments, diacylglycerides, and phospholipids, and this is expected to be driven by their biological functions in the brain. Correlations in the localization of these moleculeswere also observed using principal components analysis of image data, and this was used to identify peaks for further analysis. Furthermore, consecutive analyses following 10 keV Ar2500 + sputtering showed that different biomolecules respond differently to Ar2500 + sputtering. Significant changes in signal intensities between consecutive analyses were observed for high mass molecules including lipids. Copyright © 2014 John Wiley & Sons, Ltd.

Phan N.T.N.,Gothenburg University | Phan N.T.N.,National Center Imaging Mass Spectrometry | Mohammadi A.S.,National Center Imaging Mass Spectrometry | Mohammadi A.S.,Chalmers University of Technology | And 5 more authors.
Analytical Chemistry | Year: 2016

Laser desorption ionization mass spectrometry (LDI-MS) is used to image brain lipids in the fruit fly, Drosophila, a common invertebrate model organism in biological and neurological studies. Three different sample preparation methods, including sublimation with two common organic matrixes for matrix-assisted laser desorption ionization (MALDI) and surface-assisted laser desorption ionization (SALDI) using gold nanoparticles, are examined for sample profiling and imaging the fly brain. Recrystallization with trifluoroacetic acid following matrix deposition in MALDI is shown to increase the incorporation of biomolecules with one matrix, resulting in more efficient ionization, but not for the other matrix. The key finding here is that the mass fragments observed for the fly brain slices with different surface modifications are significantly different. Thus, these approaches can be combined to provide complementary analysis of chemical composition, particularly for the small metabolites, diacylglycerides, phosphatidylcholines, and triacylglycerides, in the fly brain. Furthermore, imaging appears to be beneficial using modification with gold nanoparticles in place of matrix in this application showing its potential for cellular and subcellular imaging. The imaging protocol developed here with both MALDI and SALDI provides the best and most diverse lipid chemical images of the fly brain to date with LDI. © 2015 American Chemical Society.

Phan N.T.N.,Gothenburg University | Phan N.T.N.,National Center Imaging Mass Spectrometry | Fletcher J.S.,Gothenburg University | Fletcher J.S.,National Center Imaging Mass Spectrometry | And 4 more authors.
Analytical Chemistry | Year: 2015

We use time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging to investigate the effects of orally administrated methylphenidate on lipids in the brain of Drosophila melanogaster (fruit fly), a major invertebrate model system in biological study and neuroscience. TOF-SIMS imaging was carried out using a recently designed high energy 40 keV Ar4000+ gas cluster ion gun which demonstrated improved sensitivity for intact lipids in the fly brain compared to the 40 keV C60+ primary ion gun. In addition, correlation of TOF-SIMS and SEM imaging on the same fly brain showed that there is specific localization that is related to biological functions of various biomolecules. Different lipids distribute in different parts of the brain, central brain, optical lobes, and proboscis, depending on the length of the carbon chain and saturation level of fatty acid (FA) branches. Furthermore, data analysis using image principal components analysis (PCA) showed that methylphenidate dramatically affected both the distribution and abundance of lipids and their derivatives, particularly fatty acids, diacylglycerides, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol in the fly brains. Our approach using TOF-SIMS imaging successfully visualizes the effects of methylphenidate on the chemical structure of the fly brain. © 2015 American Chemical Society.

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