Identification of Proteins in the Accessory Sex Gland Fluid Associated With Fertility Indexes of Dairy Bulls: A Proteomic Approach

Abstract

ABSTRACT:We evaluated the expression of proteins in the accessory sex gland fluid (AGF) and their relationships with fertility indexes of dairy bulls. Fertility was normalized as the percentage point deviation of their nonreturn rates (PD) from the average fertility of all bulls from a given artificial insemination center. Services associated with each sire ranged from 269 to 77 321 and PD values from ϩ7.7% to Ϫ18.1%. AGF, from 37 bulls, was obtained with an artificial vagina after cannulation of the vasa deferentia. Proteins from AGF were separated by 2-dimensional SDS-PAGE followed by staining with Coomassie blue and analysis of polypeptide maps using PDQuest software. Bulls were divided in groups based on PD values and the optical density of spots in the AGF gels used as independent variables to predict bull fertility. Proteins were identified by capillary liquid chromatography nanoelectrospray ionization tandem mass spectrometry (CapLC-MS/MS). An average of 52 Ϯ 5 spots was detected in the AGF gels, but there were no spots unique to groups of either high-(PD Ն 0) or low-(PD Ͻ 0) fertility sires. The former were neither less nor more homogeneous than the latter based on correlations of all matched spots between pairs of AGF maps. However, high fertility of dairy bulls was significantly associated with lower expression of 14-kDa spermadhesin Z13 isoforms and higher amounts of 55-kDa osteopontin and 58-kDa phospholipase A 2 (PLA 2 ) isoforms. The average intensity of 5 spots identified as BSP 30 kDa in the AGF gels had a quadratic association with fertility indexes (R 2 ϭ .18; P ϭ .03). PD values of bulls were related (R 2 ϭ .56) to the quantity of spermadhesin, osteopontin, and BSP 30 kDa in the AGF polypeptide maps. Bull fertility was also determined by another equation (R 2 ϭ .53) with spermadhesin, BSP 30 kDa, and PLA 2 as independent variables. We conclude that interactions among several proteins in accessory sex gland fluid explain a significant proportion of the variation in fertility scores of mature dairy sires.

Binding patterns of seminal plasma plasma proteins on bovine epididymal and ejaculated sperm membrane

“…The specific role played by PGDS in male fertility is still a matter of speculation, but it has been suggested that it works as a transporter of lipophilic substances, such as retinol, across testis/epididymal-blood barriers and to the sperm (Leone et al, 2002). Negative relationships exist between the intensity of PGDS spots detected in the CEF 2-D electrophoresis maps and non-return rates of dairy bulls (Moura et al, 2006a), while positive associations were detected between PGDS spot intensity in 2D maps of seminal plasma and bull fertility (Killian et al, 1993). Other researchers found positive correlations between seminal plasma PGDS and sperm motility in the man (Chen et al, 2005;2007a).…”

“…The intensity of selected protein spots in 2-D maps of seminal plasma (Killian et al, 1993), accessory sex gland fluid (Moura et al, 2006a) and cauda epididymal fluid (Moura et al, 2006b) is related to the fertility of dairy bulls as well. Furthermore there is a relationship of these proteins with the in vitro penetration of bovine oocytes (Moura et al, 2007a).…”

“…Recently, it has been reported that fertilityassociated proteins from bull accessory gland fluid (AGF), such as osteopontin, BSP-30kDa and BSP-A1/A2 (Killian et al, 1993;Moura et al, 2006a;2007ab) are able to bind ejaculated sperm membrane and remain attached to the cells, even after contact with oviductal fluids (Souza et al, 2008). These findings brought new insights to the proposed models of how these proteins affect sperm function, and fertilization itself.…”

“…Transferrin is only present in the epididymal secretion while albumin is present in both cauda epididymal and accessory sex gland fluids from mature bulls (Moura et al, 2006a;Moura et al, 2007a). The presence of transferrin in the epididymis could be explained by the fact that this protein is involved in a scavenging strategy and prevents damages caused by excessive iron.…”

Las proteínas del plasma seminal incrementan la viabilidad espermática post-descongelación del semen de toros Sanmartinero

“…La cantidad relativa de cada banda (entre 26 y 22%) y su aparición en todas las fracciones, demostrada en la electroforesis unidimensional, indicó que estas proteínas son las más abundantes dentro del PS. En este sentido se ha evidenciado que las proteínas BSP, son las más abundantes en el PS bovino (2,19,22,23). La concentración de estas proteínas en el PS está entre 20 y 40 mg/ml, lo que corresponde a una concentración de entre el 30 y el 60% de las proteínas totales del PS.…”