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MALDI MS Analysis to Investigate the Lipid Composition of Sperm

Author(s):

Kathrin M. Engel, Ulrike Jakop, Karin Müller, Sonja Grunewald, Uwe Paasch and Jürgen Schiller   Pages 1 - 12 ( 12 )

Abstract:


Background: The sperm plasma membrane meets the requirements of sperm transit through the female genital tract and subsequent fertilization. Commonly, the (phospho) lipid composition of sperm is characterized by tremendous amounts of highly unsaturated fatty acyl residues such as docosahexaenoic and docosapentaenoic acid. While human sperm contains almost exclusively diacyl lipids, many animal sperms additionally contain significant amounts of ether lipids such as alkyl- acyl- and alkenyl-acyl lipids (plasmalogens). Hypothesis/Objective: It is suggested that deviations from the typical lipid composition are indicative of pathological changes. Therefore, simple methods to elucidate the sperm lipid composition are essential. Method: Matrix-assisted laser desorption and ionization (MALDI) mass spectrometry (MS) is a fast and simple method. Since the selection of the most suitable matrix is a crucial step in MALDI MS, this topic will be highlighted. It will also be shown that MALDI MS can be easily combined with thin-layer chromatography (TLC) to overcome ion suppression effects. Results: The lipid composition of sperm from different species can be elucidated by MALDI MS. However, different matrix compounds have to be used to record positive and negative ion mass spectra. Since some sperm (glyco) lipids are characterized by the presence of sulfate residues which suppress the detection of less acidic lipids in the negative ion mode, previous separation is often necessary. It will be also emphasized that plasmalogens can be easily identified by either enzymatic digestion or treatment with acids. Conclusion: MALDI MS is a reliable method to obtain sperm lipid fingerprints in a simple and convenient way.

Keywords:

Sperm, MALDI, Mass Spectrometry, Phospholipids, Lipid Oxidation, TLC

Affiliation:

University of Leipzig, Faculty of Medicine, Institute of Medical Physics and Biophysics, Härtelstr. 16-18, D-04107 Leipzig, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, D-10315 Berlin, University Hospital Leipzig, Dermatology, Venerology and Allergology Clinic, Andrological Unit, Philipp-Rosenthal-Straße 23, D-04103, Leipzig, University Hospital Leipzig, Dermatology, Venerology and Allergology Clinic, Andrological Unit, Philipp-Rosenthal-Straße 23, D-04103, Leipzig, University Hospital Leipzig, Dermatology, Venerology and Allergology Clinic, Andrological Unit, Philipp-Rosenthal-Straße 23, D-04103, Leipzig, Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig



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