title: Percentage of ubiquitinated spermatozoa does not correlate with fertilizing capacity of thawed bovine semen.
abstract: In the spermatozoa of some species, the ubiquitin-proteasome system detects altered proteins and tags them for elimination by the proteasome. In some species' ejaculates, a high proportion of ubiquitinated spermatozoa (i.e. those having ubiquitin bound to the altered or damaged membrane proteins) has been related to infertility. The aim of this study was to assess whether the percentage of ubiquitinated spermatozoa relates to fertility of dairy bulls and whether ubiquitination increases during protein remodelling that occurs during in vitro spermatic capacitation. Thirty-two frozen semen straws from four high-fertility (ReproMax(®) ) and four normal-fertility (Normal) Holstein-Friesian sires were evaluated. Ubiquitinated and capacitated spermatozoa were quantified by sperm ubiquitin tag immunoassay and chlortetracycline stain, respectively. Fertilizing capacity of sires was assessed by in vitro fertilization. No differences were found between Normal and ReproMax(®) sires with regard to the observed percentage of ubiquitinated spermatozoa (42.97 ± 3.69% and 49.68 ± 9.27%, respectively; p > 0.05). Additionally, no differences were found in the percentage of ubiquitinated spermatozoa as a consequence of spermatic capacitation in either Normal (42.97 ± 3.69% before capacitation vs 44.67 ± 7.5% after; p > 0.05) or ReproMax(®) sires (49.68 ± 9.27% before vs 45.05 ± 7.51% after; p > 0.05). The percentage of ubiquitinated spermatozoa in a thawed sperm samples did not correlate with its in vitro fertilizing capacity; thus, this assay does not prove useful to detect in vivo fertility differences between sires. Additionally, protein degradation occurring during remodelling of the spermatozoon plasma membrane during the capacitation process does not seem to involve the ubiquitin-proteasome system.
authors.affiliation: Laboratorio de Bioquímica de la Reproducción, Departamento de Producción Agrícola y Animal, Universidad Autónoma Metropolitana, Unidad Xochimilco, Mexico City, Mexico.
authors.forename: I
authors.initials: I
authors.lastname: Rodríguez-Lozano
authors.forename: A
authors.initials: A
authors.lastname: Ávalos-Rodríguez
authors.forename: H
authors.initials: H
authors.lastname: Castillo-Juárez
authors.forename: F
authors.initials: F
authors.lastname: Borderas-Tordesillas
authors.forename: J J
authors.initials: JJ
authors.lastname: Roa-Vidal
authors.forename: A M
authors.initials: AM
authors.lastname: Rosales-Torres
mesh_terms: D000818:Animals; D002417:Cattle; D015925:Cryopreservation / Q000662:veterinary; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro / Q000662:veterinary; D006358:Hot Temperature; D008297:Male; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013075:Sperm Capacitation; D013076:Sperm Count / Q000662:veterinary; D013094:Spermatozoa / Q000737:chemistry* / Q000502:physiology*; D054875:Ubiquitination