Recombinant ß-defensin 126 promotes bull sperm binding to bovine oviductal epithelia.

Primate ß-defensin 126 regulates the ability of spermatozoa to bind to oviductal epithelial cells invitro. Bovine ß-defensin 126 (BBD126) exhibits preferential expression in the cauda epididymis of the bull, but there have been few studies on its functional role in cattle. The aim of the present study was to examine the role of BBD126 in bull sperm binding to bovine oviductal epithelial cell (BOEC) explants. BBD126 has been shown to be highly resistant to the standard methods of dissociation used in other species and, as a result, corpus epididymal spermatozoa, which have not been exposed to the protein, were used to study the functional role of BBD126. Corpus epididymal spermatozoa were incubated with recombinant (r) BBD126 in the absence or presence of anti-BBD126 antibody. Addition of rBBD126 significantly enhanced the ability of epididymal spermatozoa to bind to BOEC explants (P<0.05). Anti-BBD126 antibody blocked the BBD126-mediated increase in sperm binding capacity. Ejaculated spermatozoa, which are coated with native BBD126 protein but also a large number of seminal plasma proteins invivo, were incubated with rBBD126 in the absence or presence of the anti-BBD126 antibody. Addition of rBBD126 significantly enhanced the ability of ejaculated spermatozoa to bind to BOEC explants (P<0.05), whereas rBBD126 also reduced corpus sperm agglutination (P<0.05). These results suggest that, similar to the role of its analogue in the macaque, spermatozoa with more BBD126 in their acrosome may represent spermatozoa with more oviduct binding capacity.

Bovine ß-defensin gene family: opportunities to improve animal health?

Recent analysis of the bovine genome revealed an expanded suite of ß-defensin genes that encode what are referred to as antimicrobial or host defense peptides (HDPs). Whereas primate genomes also encode α- and θ-defensins, the bovine genome contains only the ß-defensin subfamily of HDPs. ß-Defensins perform diverse functions that are critical to protection against pathogens but also in regulation of the immune response and reproduction. As the most comprehensively studied subclass of HDPs, ß-defensins possess the widest taxonomic distribution, found in invertebrates as well as plants, indicating an ancient point of origin. Cross-species comparison of the genomic arrangement of ß-defensin gene repertoire revealed them to vary in number among species presumably due to differences in pathogenic selective pressures but also genetic drift. ß-Defensin genes exist in a single cluster in birds, but four gene clusters exist in dog, rat, mouse, and cow. In humans and chimpanzees, one of these clusters is split in two as a result of a primate-specific pericentric inversion producing five gene clusters. A cluster of ß-defensin genes on bovine chromosome 13 has been recently characterized, and full genome sequencing has identified extensive gene copy number variation on chromosome 27. As a result, cattle have the most diverse repertoire of ß-defensin genes so far identified, where four clusters contain at least 57 genes. This expansion of ß-defensin HDPs may hold significant potential for combating infectious diseases and provides opportunities to harness their immunological and reproductive functions in commercial cattle populations.

A novel subclass of bovine ß-defensins links reproduction and immunology.

ß-defensins are effector molecules of the innate immune system, found in many diverse species. Their presence in invertebrates as well as vertebrates suggests highly conserved functional roles. Most ß-defensins are believed to act as antimicrobial agents at epithelial surfaces, although additional functions have also been described, including immune regulatory activity, wound repair and a role in coat-colour determination. High expression of ß-defensins have been found in testis and epididymidal epithelium as well as in the seminal fluid of humans, macaque, rat, mouse and cow. Human and macaque ß-defensins have recently been shown to affect sperm motility while a mutation in ß-defensin 126 is associated with reduced fertility in men. Genetic variation in bovine defensin genes may explain the increased incidence of low fertility in cattle. Here, we present a summary of the known functions of ß-defensins as well as their emerging role in reproduction and their potential to improve fertility in cattle.

Endometrial biopsy: a valuable clinical and research tool in bovine reproduction.

Studies of postpartum endometrial physiologic and immune mechanisms in cows are compromised by the difficulty in acquiring tissue of suitable quality and in sufficient quantity (Bos taurus). Endometrial biopsy sampling has attracted concern regarding potential animal ill-health and perturbed subsequent fertility. Here, we describe a method of endometrial biopsy that obtains high-quality tissue samples and does not compromise fertility. Using a Hauptner instrument, endometrial biopsies were taken at 15, 30, and 60 d postpartum from 13 mixed-breed beef cows. The effects of repeat biopsy on health (heart rate, respiration rate, color of mucous membranes, rectal temperature), onset of estrous cyclicity, and first service conception rate were monitored. Extensive daily clinical examinations revealed no signs of ill-health. All cows had resumed estrous cyclicity at 60 d postpartum. A conception rate of 77% was achieved after estrus synchronization and artificial insemination. Each biopsy yielded intact endometrial tissue and nucleic acid suitable for extensive histologic and molecular analysis, respectively. We conclude that when carried out appropriately, bovine endometrial biopsy is a safe and reliable technique for assessing postpartum uterine function or health.