IMMUNOREACTIVITY OF THE CORPUSCLES OF STANNIUS OF THE GARPIKE, LEPISOSTEUS-OSSEUS, TO ANTISERA AGAINST SALMON AND TROUT STANNIOCALCINS

Stanniocalcin-immunoreactive cells were localized in the corpuscles of Stannius of a holostean fish, the garpike (lepisosteus osseus), using antisera against salmon and trout stanniocalcins and the peroxidase-a ntiperoxidase and protein A-gold immunohistochemical methods. The stan niocalcin-immunoreactive cells were periodic acid-Schiff-positive, and antibody staining was abolished if the antiserum was preabsorbed with corpuscle homogenate. Immunocytochemistry revealed two reactive cell types in the glandular parenchyma, and immunoreactivity was confined t o the secretory granules. Staining of the granules was also abolished when the antisera were blocked with crude corpuscle homogenate. When c orpuscle extracts from garpike were subjected to sodium dodecyl sulpha te-polyacrylamide gel electrophoresis and Western blot analysis, a sin gle dense band was evident with a molecular weight of similar to 68 kD a under non-reducing conditions, whereas three bands were observed (si milar to 29, similar to 31, and similar to 34 kDa) under reducing cond itions. Staining of all bands disappeared following preabsorption of t he antiserum with salmon stanniocalcin, trout stanniocalcin, or garpik e corpuscle extract. The results are compared with stanniocalcins from another extant holostean, the bowfin (Amia calva), and from more mode rn bony fishes, the teleosts.