Monoclonal antibodies to canine intra-acrosomal sperm proteins recognizing acrosomal status during capacitation and acrosome reaction

Publisher Website
Google Scholar
Abstract
Summary Monoclonal antibodies Ds‐1 and Ds‐2 specifically labelling dog sperm acrosome were prepared by immunization of mice with acetic acid extracts of dog spermatozoa. Electron microscopy and indirect immunofluorescence localized the site of Ds‐1 and Ds‐2 proteins inside the acrosomal vesicle. Ds‐1 antibody detected 55, 76, 115, 120 and 190kDa proteins under non‐reducing conditions, and 73 kDa and 54 kDa proteins after reduction (p73/Ds‐1 and p54/Ds‐1). 92 kDa and 40 kDa proteins recognized by Ds‐2 (p92/Ds‐2 and p40/Ds‐2) migrated at > 200 kDa in the absence of reducing agent. In vivo, p73/Ds‐1 and p54/Ds‐1 are therefore likely to be present both in free and complexed form, while all of p92/Ds‐2 and p40/Ds‐2 form disulfide‐bonded complexes. Decrease in the rate of acrosomes stained with Ds‐1 and Ds‐2 was correlated with the progress of capacitation resulting in the increased rate of spontaneous acrosome reactions, as suggested by a dramatic effect of A23187. Monoclonal antibody to boar acrosin (ACR‐2) recognized dog sperm acrosin homologue. A higher rate of ACR‐2‐negative spermatozoa was observed after capacitation and A23187 treatment compared to Ds‐1 and Ds‐2, indicating that proteins recognized by Ds‐1 and Ds‐2 are localized in a specific compartment of acrosome, distinct from acrosin and possibly representing fraction of acrosomal matrix.