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| Author(s): |
Juliana Morena Bonita Ricci
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Botucatu. 2020-11-03. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu |
| Defense date: | 2020-08-31 |
| Advisor: | Rafael Henrique Nóbrega |
| Abstract | |
The commom snook (Centropomus undecimalis) is a protandric hermaphrodite fish of high economic importance. One of the main bottlenecks in the production of common snook consists in obtaining the captive females. As an alternative, wild females are captured or sex-reversed by using sex steroids. However, little is known about the genetic information related to reproduction and sex differentiation in this species. Based on this scenario, this thesis aims to unravel the effects of sex steroids on the reproductive axis during gonadal differentiation. For this, we analyzed the expression of brain kisspeptin, gonadal morphology, and transcriptomic profiles (RNA-seq) of gonads after steroid treatment. For this purpose, 450 undifferentiated animals were divided into 3 groups which received a basal diet (control), supplemented with 17α-methyltestosterone (MT) or supplemented with 17β-estradiol (E2) for 45 days. The encephalon and gonads were collected immediately after hormonal treatment and at 4-month intervals during 1 year. The results revealed that MT and E2 increased brain kiss1 mRNA levels compared to control. kissr2 receptor transcripts did not vary between treatments. As regards to the morphology, the group treated with MT showed an advanced gonadal development with morphological features of a testis. The group that received E2 also had more developed gonads, but with morphological characteristics of the ovary. RNA-seq analysis was performed using de novo transcriptome of C. undecimalis. The assembly of the transcriptome generated 45,579 transcripts with a complete ratio of 85.6% and a mapping rate of 67%. Differentially expressed genes (DEGs) were identified between treatments, some related to sex differentiation, including the pro-testis genes (nr5a2, tbx1 dmrt3, ptch3, ptch2, shh, etc.) in the MT group and the E2 group the pro-ovarian DEGs (cyp19a1, foxl2, irx5, wnt4a, rspo1, fst, etc). Our results suggested that kiss1 neurons are sensitive to the action of sex steroids. Treatment with MT stimulated testicular development, on the other hand, E2 seems to have reversed the fate of sex differentiation of the gonads, resulting in an ovary at the beginning of development. Finally, de novo gonadal transcriptome in the thesis has resulted in a valuable genomic resource for screening potential pathways and genes involved in the sexual differentiation of C. undecimalis. (AU) | |
| FAPESP's process: | 18/16595-7 - Kisspeptins and its role in reproduction and gonadal development in teleost fish. |
| Grantee: | Juliana Morena Bonita Ricci |
| Support Opportunities: | Scholarships in Brazil - Doctorate |