Marilia D. Nunes Rodrigues¹ , Cecilia Calabuig² , Carla G. Ávila Moreira³ , Janaina Camacho da Silva⁴ , Diones Bender Almeida⁵ , Harold J. Perez Gutierrez¹ , Heden L. Marques Moreira⁵

1. Departamento de Zootecnia, Universidade Federal de Pelotas, Brazil
2. Departamento de Ciencias Animais, Faculdade de Ecologia, Universidade Federal Rural do Semi-Árido, Brazil
3. Programa Pos-graduacao em Genetica e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Brazil
4. Instituto de Biologia, Departamento de Fisiologia Animal Comparada, Fundacao Universidade Federal do Rio Grande, Brazil
5. Instituto de Biologia, Departamento de Zoologia e Genetica, Universidade Federal de Pelotas, Brazil
Author    Correspondence author
Animal Molecular Breeding, 2015, Vol. 5, No. 2   doi: 10.5376/amb.2015.05.0002
Received: 20 Feb., 2015    Accepted: 23 Apr., 2015    Published: 21 May, 2015

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Rodrigues et al., 2015, The Expression of CYP19a Gene at two Temperature Levels During the Thermosensitive Period of the Nile Tilapia (Oreochromis niloticus), Animal Molecular Breeding, Vol.5, No.2, 1-6 (doi: 10.5376/amb.2015.05.0002)

The gene expression of ovarian aromatase is regulated according to the period of exposure to different post-fertilization temperatures. Previous studies show that high temperatures regulate aromatase gene expression, or transcription factors responsible for gene expression during sex differentiation in fish. The fact that this enzyme is part of the reproductive hormone estrogen synthesis pathway, leads researchers to study how the differential expression of this gene can influence the proportion of males and females in the process of sexual reversion. The objective of this study was to evaluate the effect of temperatures at 25? and 35? on the expression of ovarian aromatase during the period of sexual reversion in Supreme strain of the Nile Tilapia (Oreochromis niloticus). We conducted two times the same experiment under the same conditions and at an interval of 12 months between both. We used 1500 larvae three days after hatching, in the final phase of resorption of the yolk sac per experiment maintained in water in a closed recirculatory system. For each experiment we used eight experimental units, each containing 93 larvae that were separated into two groups of four repetitions for each temperature treatment. Treatments lasted a total period of 30 days, with a 12L:12D photoperiod. Total RNA was extracted from a sample of four larvae that was collected every week from each treatment using a Quick-RNATM MiniPrep (R1054) extraction kit. The synthesis of cDNA was performed using 10ng of RNA with the GoScript™ Reverse Transcription System kit. We were not able to completely block the expression of aromatase in the 35? treatments in the Supreme strain since we found a variation in the responses to the expression of aromatase. Gene expression was detected during the thermosensitive period (TSP) in both treatments. We suggest that the bands that present low levels of expression in the treatment at 35°C probably belong to male individuals, while the high intensity bands in the 25? treatment are most probably females.

Aromatase; Temperature; Sex Reversal; Supreme Strain; RT-PCR