title: Lipid remodeling of murine epididymosomes and spermatozoa during epididymal maturation.
abstract: We have isolated vesicular structures from mouse epididymal fluid, referred to as epididymosomes. Epididymosomes have a roughly spherical aspect and a bilayer membrane, and they are heterogeneous in size and content. They originate from the epididymal epithelium, notably from the caput region, and are emitted in the epididymal lumen by way of apocrine secretion. We characterized their membranous lipid profiles in caput and cauda epididymidal fluid samples and found that epididymosomes were particularly rich in sphingomyelin (SM) and arachidonic acid. The proportion of SM increased markedly during epididymal transit and represented half the total phospholipids in cauda epididymidal epididymosomes. The cholesterol:phospholipid ratio increased from 0.26 in the caput to 0.48 in the cauda epididymidis. Measures of epididymosomal membrane anisotropy revealed that epididymosomes became more rigid during epididymal transit, in agreement with their lipid composition. In addition, we have characterized the membrane lipid pattern of murine epididymal spermatozoa during their maturation. Here, we have shown that mouse epididymal spermatozoa were distinguished by high percentages of SM and polyunsaturated membranous fatty acids (PUFAs), principally represented by arachidonic, docosapentanoic, and docosahexanoic acids. Both SM and PUFA increased throughout the epididymal tract. In particular, we observed a threefold rise in the ratio of docosapentanoic acid. Epididymal spermatozoa had a constant cholesterol:phospholipid ratio (average, 0.30) during epididymal transit. These data suggest that in contrast with epididymosomes, spermatozoal membranes seem to become more fluid during epididymal maturation.
authors.affiliation: Laboratoire Epididyme et Maturation des Gamètes, Université Blaise Pascal, CNRS UMR 6547 GEEM, 63177 Aubière, France.
authors.forename: Hanae
authors.initials: H
authors.lastname: Rejraji
authors.forename: Benoit
authors.initials: B
authors.lastname: Sion
authors.forename: Gerard
authors.initials: G
authors.lastname: Prensier
authors.forename: Martine
authors.initials: M
authors.lastname: Carreras
authors.forename: Claude
authors.initials: C
authors.lastname: Motta
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Frenoux
authors.forename: Evelyne
authors.initials: E
authors.lastname: Vericel
authors.forename: Genevieve
authors.initials: G
authors.lastname: Grizard
authors.forename: Patrick
authors.initials: P
authors.lastname: Vernet
authors.forename: Joël R
authors.initials: JR
authors.lastname: Drevet
mesh_terms: D000818:Animals; D016880:Anisotropy; D016718:Arachidonic Acid / Q000032:analysis; D002784:Cholesterol / Q000032:analysis; D004822:Epididymis / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D045604:Extracellular Fluid; D005227:Fatty Acids / Q000032:analysis / Q000737:chemistry; D005231:Fatty Acids, Unsaturated / Q000032:analysis; D008297:Male; D008563:Membrane Lipids / Q000032:analysis* / Q000737:chemistry; D051379:Mice; D015388:Organelles / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure; D010743:Phospholipids / Q000032:analysis; D022142:Secretory Vesicles / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure; D012741:Sexual Maturation / Q000502:physiology*; D013079:Sperm Maturation / Q000502:physiology; D013094:Spermatozoa / Q000737:chemistry* / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D013109:Sphingomyelins / Q000032:analysis
chemical_list: D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008563:Membrane Lipids; D010743:Phospholipids; D013109:Sphingomyelins; D016718:Arachidonic Acid; D002784:Cholesterol; C026219:docosapentaenoic acid