Effect of follicle size on mRNA expression in cumulus cells and oocytes of Bos indicus: an approach to identify marker genes for developmental competence
Ester Siqueira Caixeta A , Paula Ripamonte C , Maurício Machaim Franco A B , José Buratini Junior C and Margot Alves Nunes Dode A B D
+ Author Affiliations
- Author Affiliations
A Faculdade de Agronomia e Veterinária, Ciências Animais, Universidade de Brasília, Brasília, DF 70910-970, Brazil.
B Embrapa Recursos Genéticos e Biotecnologia, Brasília, DF 70770-900, Brazil.
C Departamento de Fisiologia, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, SP 18618-000, Brazil.
D Corresponding author. Email: margot@cenargen.embrapa.br
Reproduction, Fertility and Development 21(5) 655-664 https://doi.org/10.1071/RD08201
Submitted: 18 September 2008 Accepted: 8 March 2009 Published: 21 May 2009
Abstract
To identify the genes related to oocyte competence, we quantified transcripts for candidate genes in oocytes (H1Foo, H2A, H3A, GHR, GDF9, BMP15, OOSP1) and cumulus cells (FSHR, EGFR, GHR, PTX3, IGFII) using the follicle size model to select oocytes of better developmental quality. Follicles were dissected and distributed into four groups according to diameter as follows: 1.0–3.0, 3.1–6.0, 6.1–8.0 and ≥8.1 mm. Cumulus–oocyte complexes (COCs) were released, classified morphologically, matured, fertilised and cultured in vitro or denuded for measurement of diameter and determination of gene expression. Denuded germinal vesicle oocytes and their cumulus cells were used for gene expression analysis by reverse transcription–polymerase chain reaction. The blastocyst rate was highest for oocytes recovered from follicles >6 mm in diameter. In the oocyte, expression of the H2A transcript only increased gradually according to follicle size, being greater (P < 0.05) in oocytes from follicles ≥8.1 mm in diameter than in oocytes from follicles <6.0 mm in diameter. In cumulus cells, expression of FSHR, EGFR and GHR mRNA increased with follicular size. In conclusion, we confirmed the importance of H2A for developmental competence and identified important genes in cumulus cells that may be associated with oocyte competence.
Additional keywords: bovine, gene expression.
Acknowledgements
The authors thank Grazieli Marinheiro Machado for helping with in vitro embryo production. This work was supported by Embrapa and CAPES.
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