Quantitative expression analysis of Bodhesin genes in the buck (Capra hircus) reproductive tract by real-time polymerase chain reaction (qRT-PCR)

Proteomic characterization and cross species comparison of mammalian seminal plasma

Seminal plasma contains a large protein component which has been implicated in the function, transit and survival of spermatozoa within the female reproductive tract. However, the identity of the majority of these proteins remains unknown and a direct comparison between the major domestic mammalian species has yet to be made. As such, the present study characterized and compared the seminal plasma proteomes of cattle, horse, sheep, pig, goat, camel and alpaca. GeLC-MS/MS and shotgun proteomic analysis by 2D-LC-MS/MS identified a total of 302 proteins in the seminal plasma of the chosen mammalian species. Nucleobindin 1 and RSVP14, a member of the BSP (binder of sperm protein) family, were identified in all species. Beta nerve growth factor (bNGF), previously identified as an ovulation inducing factor in alpacas and llamas, was identified in this study in alpaca and camel (induced ovulators), cattle, sheep and horse (spontaneous ovulators) seminal plasma. These findings indicate that while the mammalian species studied have common ancestry as ungulates, their seminal plasma is divergent in protein composition, which may explain variation in reproductive capacity and function. The identification of major specific proteins within seminal plasma facilitates future investigation of the role of each protein in mammalian reproduction.

BIOLOGICAL SIGNIFICANCE

This proteomic study is the first study to compare the protein composition of seminal plasma from seven mammalian species including two camelid species. Beta nerve growth factor, previously described as the ovulation inducing factor in camelids is shown to be the major protein in alpaca and camel seminal plasma and also present in small amounts in bull, ram, and horse seminal plasma.

Expression, purification and structural analysis of recombinant rBdh-2His6, a spermadhesin from buck (Capra hircus) seminal plasma

Spermadhesins, a family of secretory proteins from the male genital tract of ungulate species, belong to the group of animal lectins. Spermadhesins have a prominent role in different aspects of fertilisation, such as spermatozoid capacitation, acrosomal stabilisation, sperm–oviduct interaction and during sperm–oocyte fusion. Proteins (spermadhesins) in buck seminal plasma were described. In the present study, bodhesin Bdh-2 cDNA present in buck seminal plasma was subcloned with the expression plasmid pTrcHis TOPO used to transform Escherichia coli Top10 One shot cells. The recombinant clones were selected by growth in 50 µg mL–1 ampicillin-containing LB broth and polymerase chain reaction amplification. Recombinant rBdh-2His6 synthesis was monitored by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and followed by immunoblotting using monoclonal anti-His antibody. Production of rBdh-2 using low temperatures was not satisfactory. Greater production of rBdh-2 occurred with 1.5 mM isopropyl β-d-thiogalactoside after 2 h of induction. The method used to purify rBdh-2 was affinity chromatography on a His-Trap column following ion-exchange chromatography on a DEAE-Sephacel column. The secondary structure of the rBdh-2His6 was evaluated by spectral profile circular dichroism (CD). The prevalence of secondary structures like β-sheets, with fewer unfolded structures and α-helices, was confirmed. The structure of rBdh-2His6 remained stable up to 35°C. However, significant structural changes were observed at temperatures higher than 40°C related to a distortion of the CD spectrum.