Nitric oxide synthase imunolabeling in the molluscan CNS and peripheral tissues.

NOS immunoreactivity was assayed in CNS and peripheral tissues of the sea slugs Pleurobranchaea californica, Tritonia diomedea and Aplysia californica using different antisera against mammalian nitric oxide synthase in Western blots. Polyclonal anti-nNOS labeled at 250, 185, 170, 155, 100, 75, and 65 kD in extracts of Pleurobranchaea CNS, salivary gland and esophagus but not of gills or muscle. The labeling pattern for Tritonia in bands at 250, 200, 120/110, 100, 69, 65, and 60 kD differed somewhat. Anti-nNOS labeling in Aplysia was markedly different, with bands labeled only at 69 and 60 kD in CNS extracts, and at 200, 190, 69 and 60 kD in salivary and esophagus extracts. The wide variation in NOS immunoreactivity is consistent with species differences in tissue localization and biochemical properties of molluscan NOS isoforms.