The Open Reproductive Science Journal

2009, 2 : 1-7
Published online 2009 September 16. DOI: 10.2174/1874255600902010001
Publisher ID: TORSJ-2-1

Fucosidases of Sperm and Milt in Darters (Percidae: Etheostomatini)

Jennifer J. Venditti , Tamra C. Mendelson and Barry S. Bean
Lehigh University, Department of Biological Sciences, 111 Research Drive, Bethlehem, PA 18015, USA.

ABSTRACT

Darters (Percidae: Etheostomatini) offer attractive opportunities for analysis of the evolution of reproductive barriers and the molecular basis of fertilization. Here we report some basic characteristics of the sperm of darters, and, to our knowledge, the first report of sperm associated -L-fucosidase in fishes. Fluorometric enzyme assays using 4- methylumbelliferyl-alpha-L-fucopyranoside [4-MU-fuc] as a substrate provided direct quantification of enzyme activity in both the soluble and cellular fractions of milt from all six species tested. Further analysis using SDS-PAGE and Western blotting revealed that fish sperm and milt contain -L-fucosidase isoforms with molecular weights similar to those reported for human semen. Fertilization of darter ova by conspecific sperm, as assessed by development of the embryo to the 4 cell stage, was inhibited by pretreatment of sperm with the fucosidase-specific competitive inhibitor DFJ, implicating the sperm fucosidase in fertilization and/or early embryogenesis. Identification of sperm associated -Lfucosidase in darters is consistent with the importance of carbohydrates during fertilization.

Keywords:

Darter, etheostoma, percina.