BINDING OF ANTIBIOTICS TO GLYCOPROTEINS OF THE VITELLINE AND FERTILIZATION ENVELOPES OF CHERRY SALMON EGGS

The binding of antibiotics (gentamicin, oleandomycin and chloramphenic ol) to vitelline and fertilization envelopes and their extracts was in vestigated by immunohistochemical and immunocytochemical techniques an d immunoblot analysis using mature and artificially activated eggs of the fish Oncorhynchus masou. Binding of antibiotics was detected in th e vitelline and fertilization envelope outermost layers, the fertiliza tion envelope inner Surface and cortical alveolus exudates, with diffe rences in immunoreactive intensity and deposition. The fertilization e nvelope outermost layer had the capacity to bind much greater amounts of the antibiotics than the vitelline envelope outermost layer. The gr eater capacity was caused by the deposition of cortical alveolus exuda tes, which were known to be responsible for functional roles of protec tion against bacteria, fungi and noxious materials. Treatment of the v itelline and fertilization envelopes with neuraminidase markedly reduc ed the binding of gentamicin and chloramphenicol but slightly increase d that of oleandomycin; binding of the latter to the vitelline and fer tilization envelope outermost layers was considerably reduced after tr eatment with alpha-fucosidase. Treatment of the two envelopes with alp ha-mannosidase, beta-galactosidase or beta-D-glucosaminidase did not c ause any alteration in immunoreactive intensity or number of immunorea ctive deposits. Immunoblot analysis of the vitelline or fertilization envelope extracts indicated that many of the antibiotic-binding substa nces were glycoproteins, and several major bands were bound by all thr ee antibiotics. These results suggest that the vitelline or fertilizat ion envelopes may have the ability to protect the egg itself, or the e mbryo, respectively, by trapping antibiotics, and the trapping may be related to the presence of carbohydrate moieties, such as sialyl or fu cosyl residues.