PARENT SESSION

(86) IDENTIFICATION OF PROTEINS FROM THE ACCESSORY SEX GLAND FLUID THAT INFLUENCE THE OOCYTE PENETRATING CAPACITY OF BOVINE CAUDA EPIDIDYMAL SPERM IN VITRO.

Moura, Arlindo¹, Chapman, David¹, Killian, Gary¹, ¹ Pennsylvania State University, State College, PA

ABSTRACT- We previously reported that the accessory sex gland fluid (AGF) positively or negatively influenced cauda epididymal sperm (CES) function depending on the fertility of the bull providing the AGF. This study determined if the amounts of certain proteins in the AGF of high (HF) and low (LF) fertility Holstein bulls were correlated with these effects. Fertility was based on bull non-return rates. AGF was collected by artificial vagina from bulls with cannulated vasa deferentia. AGF proteins were separated by 2D electrophoresis, stained with coomassie blue and identified by tandem mass spectrometry (CapLC-MS/MS). Spot quantities calculated by PDQuest software were used to predict, by regression analysis, the outcome of competitive IVF assays with zona-free bovine oocytes. Assay 1: (CES from HF bull + AGF from homologous HF bull) x (CES from HF bull + AGF from LF bull); Assay 2: (CES from LF bull + AGF from homologous LF bull) x (CES from LF bull + AGF from HF bull). There were 8 and 19 pairwise comparisons in assays 1 and 2, respectively. For assay 1, the number of oocytes penetrated by sperm (from HF bulls) treated with AGF from LF bulls, in contrast to sperm treated with AGF from HF bulls, was inversely related to relative the amount of 14-kDa spermadhesins and positively related to that of BSP A1/A2 and A3 (R² = 0.97; p < 0.01). Lower expression of 40-kDa clusterin isoforms and higher of 58-kDa phospholipase A2 isoforms (R² = 0.96; p < 0.01) in the AGF maps were also related to results of assay 1. For assay 2, the number of oocytes penetrated by sperm (from LF bulls) treated with AGF from HF bulls was positively associated with the relative amount of a 55-kDa osteopontin (R² = 0.38; p < 0.01) and linked to higher expression of phospholipase A2 and lower amounts of a 58-kDa nucleobindin (R² = 0.54; p < 0.01) in the AGF gels. Thus, oocyte penetrating ability in vitro of cauda epididymal sperm is influenced by the relative amounts of several proteins present in the AGF. We suggest that differences in the expression of these AGF proteins likely influence the field fertility of bulls. Supported by USDA grants 2003-34437-13460 and 2004-34437-15106, and a fellowship from the Brazilian Research Council (CAPES).

KEY WORDS: accessory sex gland, proteins, cauda epididymal sperm, fertility