title: Sperm and spermatids contain different proteins and bind distinct egg factors.
abstract: Spermatozoa are more efficient at supporting normal embryonic development than spermatids, their immature, immediate precursors. This suggests that the sperm acquires the ability to support embryonic development during spermiogenesis (spermatid to sperm maturation). Here, using Xenopus laevis as a model organism, we performed 2-D Fluorescence Difference Gel Electrophoresis (2D-DIGE) and mass spectrometry analysis of differentially expressed proteins between sperm and spermatids in order to identify factors that could be responsible for the efficiency of the sperm to support embryonic development. Furthermore, benefiting from the availability of egg extracts in Xenopus, we also tested whether the chromatin of sperm could attract different egg factors compared to the chromatin of spermatids. Our analysis identified: (1) several proteins which were present exclusively in sperm; but not in spermatid nuclei and (2) numerous egg proteins binding to the sperm (but not to the spermatid chromatin) after incubation in egg extracts. Amongst these factors we identified many chromatin-associated proteins and transcriptional repressors. Presence of transcriptional repressors binding specifically to sperm chromatin could suggest its preparation for the early embryonic cell cycles, during which no transcription is observed and suggests that sperm chromatin has a unique protein composition, which facilitates the recruitment of egg chromatin remodelling factors. It is therefore likely that the acquisition of these sperm-specific factors during spermiogenesis makes the sperm chromatin suitable to interact with the maternal factors and, as a consequence, to support efficient embryonic development.
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. mt446@cam.ac.uk.
authors.forename: Marta
authors.initials: M
authors.lastname: Teperek
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. k.miyamoto@gurdon.cam.ac.uk.
authors.forename: Kei
authors.initials: K
authors.lastname: Miyamoto
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. angela.simeone@gurdon.cam.ac.uk.
authors.forename: Angela
authors.initials: A
authors.lastname: Simeone
authors.affiliation: Cambridge Centre for Proteomics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK. rf280@cam.ac.uk.
authors.forename: Renata
authors.initials: R
authors.lastname: Feret
authors.affiliation: Cambridge Centre for Proteomics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK. md289@cam.ac.uk.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Deery
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. j.gurdon@gurdon.cam.ac.uk.
authors.forename: John B
authors.initials: JB
authors.lastname: Gurdon
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. j.jullien@gurdon.cam.ac.uk.
authors.forename: Jerome
authors.initials: J
authors.lastname: Jullien
mesh_terms: D000818:Animals; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D004527:Egg Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D015151:Immunoblotting; D008297:Male; D013058:Mass Spectrometry; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D020033:Protein Isoforms; D013084:Sperm-Ovum Interactions; D013087:Spermatids / Q000378:metabolism*; D013091:Spermatogenesis / Q000502:physiology*; D013094:Spermatozoa / Q000378:metabolism*; D014020:Tissue Extracts; D029867:Xenopus Proteins / Q000302:isolation & purification / Q000378:metabolism*; D014982:Xenopus laevis / Q000378:metabolism
chemical_list: D002843:Chromatin; D004527:Egg Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; D014020:Tissue Extracts; D029867:Xenopus Proteins