title: Sperm ubiquitination in epididymal feline semen.
abstract: Ubiquitin is a 8.5-kDa peptide that tags other proteins for proteasomal degradation. It has been proposed that ubiquitination might be responsible for the elimination of defective spermatozoa during transit through the epididymis in humans and cattle, but its exact biological function in seminal plasma has not yet been clarified. In the domestic cat (Felis catus), the percentage of immature, unviable, and abnormal spermatozoa decreases during the epididymal transit, indicating the existence of a mechanism that removes defective spermatozoa. Magnetic cell separation techniques, based on the use of magnetic beads coated with anti-ubiquitin antibodies, may allow the selective capture of ubiquitinated spermatozoa from semen, thus contributing to the identification of a potential correlation between semen quality and ubiquitination process. Moreover, the selective identification of all the ubiquitinated proteins in different epididymal regions could give a better understanding of the ubiquitin role in feline sperm maturation. The aims of this study were as follows: (1) to verify the possibility of separating ubiquitinated spermatozoa with magnetic ubiquitin beads and identify the morphological and acrosomal differences between whole sample and unbound gametes, (2) to characterize all the ubiquitinated proteins in spermatozoa retrieved in the three epididymal regions by a proteomic approach. The data indicated the presence of ubiquitinated proteins in cat epididymal semen. However, a correlation between abnormal and ubiquitinated spermatozoa has not been found, and ubiquitin cannot be considered as a biomarker of quality of epididymal feline spermatozoa. To the author's knowledge, this is the first identification of all the ubiquitinated proteins of cat spermatozoa collected from different epididymal regions. The proteomic pattern allows a further characterization of cat epididymal semen and represents a contribute to a better understanding of the ubiquitin role in feline sperm maturation.
authors.affiliation: Dipartimento di Scienze Veterinarie per la Salute, la Produzione Animale e la Sicurezza Alimentare, Università degli Studi di Milano, Milano, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Vernocchi
authors.affiliation: Dipartimento di Scienze Veterinarie per la Salute, la Produzione Animale e la Sicurezza Alimentare, Università degli Studi di Milano, Milano, Italy.
authors.forename: Maria Giorgia
authors.initials: MG
authors.lastname: Morselli
authors.affiliation: Dipartimento di Scienze Veterinarie per la Salute, la Produzione Animale e la Sicurezza Alimentare, Università degli Studi di Milano, Milano, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Varesi
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milano, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Nonnis
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milano, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Maffioli
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milano, Italy.
authors.forename: Armando
authors.initials: A
authors.lastname: Negri
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milano, Italy. Electronic address: gabriella.tedeschi@unimi.it.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Tedeschi
authors.affiliation: Dipartimento di Scienze Veterinarie per la Salute, la Produzione Animale e la Sicurezza Alimentare, Università degli Studi di Milano, Milano, Italy. Electronic address: cecilia.luvoni@unimi.it.
authors.forename: Gaia Cecilia
authors.initials: GC
authors.lastname: Luvoni
mesh_terms: D000818:Animals; D002415:Cats / Q000378:metabolism*; D004822:Epididymis / Q000166:cytology; D008297:Male; D040901:Proteomics / Q000379:methods; D013094:Spermatozoa / Q000378:metabolism*; D054875:Ubiquitination
keywords: Cat; Epididymal semen; Shot-gun proteomics; Ubiquitin