GTH I and GTH II in the pituitary gland of swordfish (Xiphias gladius L.)

The pituitary gland of swordfish (Xiphias gladius L.) was studied immunohistochemically using antibodies against h-FSH beta, h-LH beta, GTH I beta and GTH II beta. The immunogold method for detection, at the ultrastructural level, of gonadotropins was also used. The immunostaining methods allowed identification of two distinct GTH I beta (FSH-like) and GTH II beta (LH-like) cells. Both GTH I beta and GTH II beta immunoreactive cells were observed in swordfish, although there were greater numbers of GTH II beta immunoreactive cells. The localization and structure of the two different gonadotropic cells of swordfish are compared with other teleost arrangement. mRNA was isolated from X. gladius pituitaries and a series of oligonucleotides were constructed and used as primers in the polymerase chain reaction (PCR) to amplify GTH cDNAs. PCR products of eight independent PCR amplification reactions were cloned and sequenced for both GTH I beta and GTH II beta to avoid potential errors introduced during the PCR amplification. Two oligonucleotide probes were constructed and used in direct label fluorescence in situ hybridization (FISH) for measuring GTH I and GTH II mRNA expression.