Examinando por Autor "Whitlock, Kathleen (Directora de tesis)"

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    Ítem
    Genomic plasticity in the olfactory epithelium mediated by odorant exposure in zebrafish (Danio rerio)
    (Universidad de Valparaíso, 2017-08-25) Calfún Medina, Cristian; Whitlock, Kathleen (Directora de tesis)
    We have previously shown that exposure to phenyl ethyl alcohol (PEA) causes an increase in the expression of the transcription factor otx2 in the olfactory epithelium (OE) of juvenile zebrafish, and this change is correlated with the formation of an odor memory of PEA. Here, we show that the changes in otx2 expression are specific to βPEA: exposure to αPEA did not affect otx2 expression. We identified 34 olfactory receptors (ORs) representing 16 families on 4 different chromosomes as candidates for direct regulation of OR expression via Otx2. Subsequent in silico analysis uncovered Hnf3b binding sites closely associated with Otx2 binding sites in the regions flanking the ORs. Analysis by quantitative polymerase chain reaction and RNA-seq of OR expression in developing zebrafish exposed to different isomers of PEA showed that a subset of ORs containing both Otx2/Hnf3b binding sites were down regulated only in βPEA-exposed juveniles and this change persisted through adult life. Localization of OR expression by in situ hybridization indicates the down regulation occurs at the level of RNA and not the number of cells expressing a given receptor. Finally, analysis of immediate early gene expression in the OE did not reveal changes in c-fos expression in response to either αPEA or βPEA.
  • Miniatura
    Ítem
    GnRH and testosterone treatment generate GnRH neurons in the hypothalamus of adult zebrafish (Danio rerio)
    (Universidad de Valparaíso, 2019-07) Ceriani Fernández, Ricardo; Whitlock, Kathleen (Directora de tesis)
    Gonadotropin-releasing hormone (GnRH) is an essential in the control of reproduction of vertebrates. A decrease in the secretion of GnRH causes reproductive disorders called congenital idiopathic hypogonadotropic hypogonadism (IHH), which is characterized by absence of puberty. Once diagnosed, IHH patients can be treated with reproductive hormone therapy to restore the disease. Interestingly, studies have documented a reversion of the disease after discontinuation of hormone treatment, which improves the reproductive capacities. We suggest the hormone treatment stimulate the neurogenesis of GnRH neurons in the hypothalamus in such a way to produce reversion in IHH patients. Here, we characterized the neurogenesis in the preoptic area (POA) of adult zebrafish. Our results showed that GnRH and not testosterone treatment, significantly increased the neurogenesis in the POA. In addition, results obtained by in situ hybridization to gnrh3 and MALDI TOF, did not detect any GnRH isoform in the hypothalamus. Therefore, our results and recent publications show that GnRH does not affect the control of reproduction in zebrafish. In order to find a potential candidate to replace GnRH, we cloned and characterized phoenixin/smim20 expression, which has a reproductive role in mammals. phoenixin/smim20 is widely expressed in the brain especially in the hypothalamus of adult zebrafish.