CLASS-SPECIFIC EPITOPES DETECTED BY POLYCLONAL ANTIBODIES AGAINST THESECRETORY PRODUCTS OF THE SUBCOMMISSURAL ORGAN OF THE DOGFISH SCYLIORHINUS-CANICULA

We have raised antisera against extracts of the subcommissural organ ( SCO) of the dogfish, Scyliorhinus canicula L. Brains of 2900 specimens were collected in acetone, and the region containing the SCO and post erior commissure was removed and extracted in three different media. A ntisera against these crude extracts were raised in rats and rabbits. Sequential absorptions of the antisera with extracts from different re gions of the dogfish brain were performed to eliminate unwanted antibo dies. When used to immunostain sections of the whole central nervous s ystem of the dogfish, these purified antisera reacted selectively with the SCO-Reissner's fiber complex. An antiserum against bovine Reissne r's fiber was also used. The antisera against the dogfish SCO and bovi ne Reissner's fiber showed the same staining pattern in the SCO and th e Reissner's fiber of the dogfish. For comparative purposes, the brain s of 15 vertebrate species from all vertebrate classes were immunostai ned with both antisera. The anti-dogfish SCO serum reacted with the SC O of the dogfish and that of other phylogenetically related elasmobran ch species. Neither the SCO of a primitive elasmobranch species, Heptr anchias perlo, nor the SCO of the other classes of vertebrates reacted with the anti-dogfish SCO serum. However, the antiserum against bovin e Reissner's fiber reacted with the SCO of all the investigated specie s. It is concluded that some epitopes (or compounds) in the secretory material of the SCO are class-specific, whereas others are conserved a nd are synthesized by the SCO in most vertebrate