Preparation and use of specific antibodies to the beta-I and beta-II subunits of gonadotropic hormone from Fundulus heteroclitus pituitary

Fundulus heteroclitus naturally spawns with a semilunar periodicity through out most of the year in its southernmost habitat, an activity that can be m aintained in the laboratory. The alpha and two beta subunits comprising F. heteroclitus gonadotropic hormones (GtHs) I and II have been sequenced, and antibodies have been raised against unique peptides found in each of the t wo beta subunits. On immunoblots of pituitary proteins, each antibody recog nizes a single band with a molecular mass of 16-17 kDa, somewhat larger tha n the deduced sizes (11-13 kDa) of the unglycosylated subunits. Each antibo dy also recognizes a different subset of pituitary cells in the central (Gt H I) and peripheral (GtH II) proximal pars distalis, regions that display t he typical tinctorial properties of gonadotrops. The distribution and disti nct separation of cells containing GtH beta subunits I and II thus differ f rom those found for previously described teleost species, most of which are salmonids that engage in a single spawning episode during the year. The av ailability of these antibodies thus makes F. heteroclitus an inexpensive, e asily manipulated model system for studies on the hormonal regulation of fr actional spawning common to a large class of commercially important species other than salmonids. (C) 2001 Academic Press.