Neuroendocrine Regulation of Reproduction in Fish
Notice bibliographique
Résumé
Fish is an essential source of food, and it is important to improve fish yield in aquaculture to enhance food production and sustainability. Several lines of research are in progress to increase reproductive capacity in cultured fishes. Hormones play a critical role in fish reproductive success and endocrine approaches are being successfully tested in stimulating fish reproduction. In this context, my thesis research aimed to further characterize three relatively new orphan ligands and their role in the regulation of reproductive hormones and oocyte maturation in fish. Phoenixin-20 (PNX-20) is a newly identified peptide with endocrine-like functions in mammals. Nesfatin-1 is an 82 amino acid multifunctional peptide with hormone-like actions in vertebrates. Nesfatin-1-like peptide (NLP) is 77 amino acids long, resembles nesfatin-1, and share similar biological actions. Based on the available information from mammals and fish, I hypothesized that PNX is stimulatory, while both nesfatin-1 and NLP are inhibitory to reproductive hormones and oocyte maturation in teleosts. I tested this hypothesis using goldfish and zebrafish, two well-characterized models in neuroendocrinology. qPCR-based gene expression results indicated a widespread distribution of PNX in central and peripheral tissues of zebrafish. Immunohistochemical localization of PNX and its putative receptor (SREB3) in the gonads suggested a role of PNX in zebrafish reproduction. In vivo administration of PNX-20 upregulated reproductive regulatory hormonal transcripts in the hypothalamus and gonads of zebrafish. In vitro incubation of PNX-20 upregulated all vitellogenin transcripts in zebrafish liver cells. In addition, incubation of ovarian follicles with PNX-20 promoted oocyte maturation in zebrafish. Together, my research outcomes supported my hypothesis that PNX-20 promotes reproductive functions in zebrafish, by positively influencing hormones, vitellogenesis and oocytes. For both nesfatin-1 and NLP studies, I used male and female goldfish as a research model. Single intraperitoneal (IP) injection of synthetic gfnesfatin-1 and gfNLP (50 ng/g body weight) suppressed several reproductive regulatory hormonal mRNAs in both sexes. These include the gonadotropin-releasing hormones (hypothalamus), kisspeptin system (multiple tissues), gonadotropin β subunits (pituitary), gonadotropin receptors and genes involved in sex steroidogenic synthetic pathway (gonads). In addition, both peptides upregulated the expression of several reproductive suppressors in goldfish, including the gonadotropin inhibitory hormone and anti-Müllerian hormone. Both nesfatin-1 and NLP decreased serum testosterone and estradiol levels in male and female goldfish at 60 minutes post-injection. Incubation of ovarian follicles with NLP suppressed oocyte maturation in zebrafish. Overall, my results suggested that both nesfatin-1 and NLP negatively influence aspects of reproductive biology in fish by suppressing the expression of critical hormonal mRNAs, gonadal steroids, and oocyte maturation. The results supported my hypotheses about nesfatin-1 and NLP. While limitations exist, my research identified PNX-20 as a positive regulator, and both nesfatin-1 and NLP as negative regulators of reproductive biology of fish. This is the major contribution of my thesis research. Future research to extend these findings to male fish and commercially cultured fish, and to understand the mechanism of action of these hormones is essential.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».