Diffusible highly glycosylated protein fromBufo arenarum egg-jelly coat: Biological activity

Abstract

L‐HGP is a highly glycosylated protein from Bufo arenarum egg‐jelly coat that diffuses into the surrounding medium when the strings of oocytes are incubated in saline solutions. L‐HGP was purified from egg water and the estimated percentage of L‐HGP/total protein in egg water was estimated in 30%. In the present study we examine, by indirect immunofluorescence, the effect of L‐HGP on acrosome status of homologous spermatozoa. A high percentage (77%) of sperm lost the acrosome when incubated in 10% Ringer solution buffered with 10 mM Tris‐HCl, pH 7.6, during 60 min, a condition that resembles egg‐jelly osmolarity. The addition of purified L‐HGP to the incubation medium prevents acrosome breakdown. The acrosome integrity is maintained for at least 1 hr. This effect is specific for L‐HGP at concentration ranging from 0.01 to 0.1 mg/ml since neither BSA nor fetuin seems to have similar activity at similar concentrations. The same effect was observed when spermatozoa were incubated in egg water. Preliminary results suggest that L‐HGP binds to B. arenarum spermatozoan membranes.