Targeted Gene Disruption in Zebrafish Reveals Noncanonical Functions of LH Signaling in Reproduction

The pivotal role of gonadotropin signaling in regulating gonadal development and functions has attracted much research attention in the past 2 decades. However, the precise physiological role of gonadotropin signaling is still largely unknown in fish. In this study, we have established both LH beta-subunit (lhb) and LH receptor (lhr) knockout zebrafish lines by transcription activator-like effector nucleases. Intriguingly, both homozygous lhb and lhr mutant male fish are fertile. The fertilization rate, sperm motility, and histological structure of the testis were not affected in either lhb or lhr mutant males. On the contrary, homozygous lhb mutant females are infertile, whereas homozygous lhr mutant females are fertile. Folliculogenesis was not affected in either lhb or lhr mutants, but oocyte maturation and ovulation were disrupted in lhb mutant, whereas only ovulation was affected in lhr mutant. Differential expression of genes in the ovary involved in steroidogenesis, oocyte maturation, and ovulation was found between the lhb and lhr mutants. These data demonstrate the essential role of LH signaling in oocyte maturation and ovulation, and support the notion that LH acts through the FSH receptor in the absence of LH receptor. Moreover, the defects of lhb mutant could be partially restored by administration of human chorionic gonadotropin. This in vivo evidence in the present study demonstrates, for the first time in any vertebrate species, that LH signaling is indispensable in female reproduction but not in male reproduction. LH signaling is demonstrated to control oocyte maturation and ovulation in the ovary

Age and gender invariance of self-concept factor structure: An investigation of a newly developed Chinese self-concept instrument

A new instrument, the Chinese Adolescent Self-Esteem Scales (CASES), was developed to measure the self-concepts of the young people in Hong Kong in seven aspects: social, academic, appearance, moral, family, physical/sport, and general selfesteem. LISREL procedures were utilized to test the extent of factorial invariance for age and gender based on the responses to CASES of 551 Hong Kong adolescents. It was found that CASES possesses the necessary invariance properties for between-group measurement in terms of the number and pattern of the underlying factors, item factor loadings, and inter-factor relations, but not in terms of item uniqueness. Implications of these findings are discussed in terms of the use of CASES and of empirical support for the equivalence of self-concept factor structure for age and gender groups for both Western and non-Western adolescents. Dans cet étude, un nouvel instrument, le CASES (Chinese Adolescent Self-Esteem Scales), est développé pour mesurer sept aspects du concept de soi chez de jeunes personnes de Hong Kong: l'aspect social, l'aspect scolaire, l'apparance, l'aspect moral, la famille, le sport/activité physique et l'estime de soi générale. Des procédures LISREL servent à tester, à partir des réponses données au CASES par 551 adolescents, l'étendue de la variance factorielle pour l'âge et le sexe. Les résultats indiquent qu'en termes de nombre et de patron de facteurs sous-jacents, de poids factoriel des items et des relations entre facteurs mais non en termes d'unicité des items, le CASES possèdent les propriétés d'invariance nécessaires pour la mesure inter-groupe. La discussion examine ces résultats en relation avec l'utilisation du CASES et avec l'appui empirique qu'il fournit à l'équivalence de la structure des facteurs du concept de soi pour l'âge et le sexe, chez les adolescents occidentaux et non occidentaux

Discovery of a new reproductive hormone in teleosts: Pituitary adenylate cyclase-activating polypeptide-related peptide (PRP)

Pituitary adenylate cyclase-activating polypeptide (PACAP)-related peptide (PRP) is a peptide encoded with PACAP in the same precursor protein. Non-mammalian PRPs were previously termed growth hormone-releasing hormone (GHRH)-like peptide, and was regarded as the mammalian GHRH homologue in non-mammalian vertebrates until the discovery of authentic GHRH genes in teleosts and amphibians. Although a highly specific receptor for PRP, which is lost in mammals, is present in non-mammals, a clear function of PRP in vertebrates remains unknown. Using goldfish as a model, here we show the expression of PRP and its cognate receptor in the brain-pituitary-gonadal (BPG) axis, thus suggesting a function of goldfish (gf) PRP in regulating reproduction. We found that gfPRP controls the expression of reproductive hormones in the brain, pituitary and ovary. Goldfish PRP exerts stimulatory effects on the expression of salmon gonadotropin-releasing hormone (sGnRH) in the brain, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in pituitary primary culture cells, but inhibits the expression of LH in the ovary. Using the same technique, we showed that gfPRP did not alter the mRNA level of growth hormone in the pituitary primary culture. In summary, we have discovered the first function of vertebrate PRP in regulating reproduction, which provides a new research direction in studying the neuroendocrine control of reproduction not only in teleosts, but also in other non-mammalian vertebrates. © 2011 Elsevier Inc.link_to_subscribed_fulltex

Real-time evaluation of human secretin receptor activity using cytosensor microphysiometry

Human secretin receptor is a G protein-coupled receptor thai is functionally linked to the cAMP second messenger system by stimulation of adenylate cyclase. To functionally characterize the receptor and evaluate its signal transduction pathway, the full-length human secretin receptor cDNA was subcloned into the mammalian expression vector pRc/CMV and expressed in cultured CHO cells. Intracellular cAMP accumulation of the stably transfected cells was measured by a radioimmunoassay (RIA), while the extracellular acidification rate was measured by the Cytosensor microphysiometer. Human secretin and biotinylated human secretin were equipotent in both assays in a dose-dependent manner. The EC50 values of stimulating the intracellular cAMP accumulation and the extracellular acidification rate were 0.2-0.5 nM and 0.1 nM, respectively, indicating that microphysiometry is more sensitive than the cAMP assay in monitoring ligand stimulation of the human secretin receptor. The secretin-stimulated response could be mimicked by forskolin and augmented by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine, indicating that the extracellular acidification response is positively correlated with intracellular cAMP level. The response could be abolished by the protein kinase A inhibitor H-89, suggesting that protein kinase A plays an essential role in the intracellular signaling of the receptor. Upon repeated stimulation by the ligand, the peak acidification responses did not change significantly at both physiological (0.03 nM and 3 nM) and pharmacological (0.3 μM) concentrations of human secretin, suggesting that the human secretin receptor did not exhibit robust homologous desensitization.link_to_subscribed_fulltex