ABSTRACT
A putative FSH receptor (FSH-R) cDNA was cloned from African catfish testis. Alignment of the deduced amino acid sequence with other (putative) glycoprotein hormone receptors and analysis of the African catfish gene indicated that the cloned receptor belonged to the FSH receptor subfamily. Catfish FSH-R (cfFSH-R) mRNA expression was observed in testis and ovary; abundant mRNA expression was also detected in seminal vesicles. The isolated cDNA encoded a functional receptor since its transient expression in human embryonic kidney (HEK-T) 293 cells resulted in ligand-dependent cAMP production. Remarkably, African catfish LH (cfLH; the catfish FSH-like gonadotropin has not been purified yet) had the highest potency in this system. From the other ligands tested, only human recombinant FSH (hrFSH) was active, showing a fourfold lower potency than cfLH, while hCG and human TSH (hTSH) were inactive. Human CG (as well as cfLH, hrFSH, eCG, but not hTSH) stimulated testicular androgen secretion in vitro but seemed to be unable to bind to the cfFSH-R. However, it was known that hCG is biologically active in African catfish (e.g., induction of ovulation). This indicated that an LH receptor is also expressed in African catfish testis. We conclude that we have cloned a cDNA encoding a functional FSH-R from African catfish testis. The cfFSH-R appears to be less discriminatory for its species-specific LH than its avian and mammalian counterparts.
Subject(s)
Catfishes , Receptors, FSH/genetics , Receptors, FSH/metabolism , Testis/chemistry , Amino Acid Sequence , Androgens/metabolism , Animals , Base Sequence , Cell Line , Chorionic Gonadotropin/pharmacology , Cloning, Molecular , DNA, Complementary/chemistry , DNA, Complementary/genetics , Embryo, Mammalian , Embryo, Nonmammalian , Female , Follicle Stimulating Hormone/metabolism , Gene Expression , Humans , Inositol Phosphates/biosynthesis , Kidney/chemistry , Luteinizing Hormone/metabolism , Male , Molecular Sequence Data , Ovary/chemistry , Phylogeny , RNA, Messenger/analysis , Receptors, FSH/chemistry , Recombinant Proteins/metabolism , Seminal Vesicles/chemistry , Sequence Alignment , Species Specificity , Testis/metabolism , TransfectionABSTRACT
Nuclear orphan receptors are DNA-binding proteins that share the domain structure of the nuclear hormone receptor superfamily, although their ligands are unknown. Members of the nuclear receptor family are involved in the regulation of various developmental and reproductive processes. We have identified such a nuclear orphan receptor in the zebrafish and named it zebrafish germ cell nuclear factor (zfGCNF) based on its high sequence homology to previously described mouse, human, and Xenopus laevis GCNF. Detailed sequence comparison of zfGCNF with mouse, human, and frog GCNF revealed high homologies in the domains conserved in the nuclear receptor family. Homology in the DNA-binding domain is 97% for frog and even 98.5% for mouse and human when compared to the zebrafish sequence. Homology in the E III subdomain of the transactivation/ligand-binding E domain is 100% when compared to the mouse and human sequences. Transcripts of different size were detected by Northern blot analysis in the zebrafish ovary, whereas, in the testis only one transcript was present. In situ hybridization revealed that zfGCNF was predominantly expressed in previtellogenic oocytes in the ovary and in spermatocytes in the testis.
Subject(s)
DNA-Binding Proteins/genetics , Receptors, Cytoplasmic and Nuclear/genetics , Zebrafish/genetics , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , Conserved Sequence , DNA, Complementary/genetics , DNA-Binding Proteins/chemistry , Female , Gene Expression , Humans , In Situ Hybridization , Male , Mice , Molecular Sequence Data , Nuclear Receptor Subfamily 6, Group A, Member 1 , Ovary/metabolism , Protein Structure, Tertiary , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Cytoplasmic and Nuclear/chemistry , Species Specificity , Testis/metabolismABSTRACT
Cells immunoreactive with an anti-LHRH serum were visualized in the brain of the three-spined stickleback, Gasterosteus aculeatus, by means of the PAP technique. Positive cells were found in a periventricular position in the nucleus praeopticus pars magnocellularis, the nucleus dorsomedialis thalami, the nucleus ventromedialis thalami, the nucleus periventricularis posterior, and in the periventricular dorsomedian tegmentum. These cells were frequently observed to contact the CSF.
Subject(s)
Brain Chemistry , Fishes/anatomy & histology , Gonadotropin-Releasing Hormone/analysis , Neurons/analysis , Animals , Diencephalon/analysis , Immunoenzyme Techniques , Male , Mesencephalon/analysis , Thalamus/analysisABSTRACT
For the first time immunoreactive luteinizing hormone-releasing hormone (LH-RH) is demonstrated in both the brain and pituitary gland of a teleost (Xiphophorus maculatus) using an immunoperoxidase procedure. It is specifically localized in the perikarya and their axons of the ventral telencephalon and nucleus lateralis tuberis and within and between the gonadotrops and within some cells of the pars intermedia. These immunoreactions are extinguished when antiserum to LH-RH is preincubated with LH-RH antigen but not with neurohypophysial hormones.
Subject(s)
Brain Chemistry , Fishes/metabolism , Gonadotropin-Releasing Hormone/analysis , Pituitary Gland/analysis , Animals , Female , Gonadotropin-Releasing Hormone/immunology , Histocytochemistry , Hypothalamus/analysis , Immunoenzyme Techniques , Male , Telencephalon/analysisSubject(s)
Amphibians/metabolism , Fishes/metabolism , Hypothalamus/physiology , Melanocyte-Stimulating Hormones/metabolism , Pituitary Gland/metabolism , Reptiles/metabolism , Animals , Catecholamines/physiology , MSH Release-Inhibiting Hormone/physiology , Melanocyte-Stimulating Hormones/physiology , Melanophores/physiology , Peptides/physiology , Pituitary Gland/innervationABSTRACT
Using antibodies against mammalian LH-RH, the double antibody-immunofluorecence technique has been applied to serial cross sections of the brains of adult Rana esculenta. Immunoreactive material was found in perikarya of an unpaired nucleus in front of the preoptic recess. The axons of these perikarya also contain fluorescing material. They form a single bundle which passes under the preoptic recess, than splits into two tracts, one on either side of the optic chiasm. The two tracts reunite just before entering the median eminence. The axons end near the capillaries in the outer zone of the median eminence. The possibility of two separate centres for the stimulation of gonadotropic activity in the brains of anurans is discussed.