Transcription Profile of Candidate Genes for the Acquisition of Competence During Oocyte Growth in Cattle

Abstract

The aim of this study was to investigate the expression profile of candidate genes involved in competence during oocyte growth. The candidate genes (BMP15, OOSP1, H1FOO, H2A, H3A, H4, SLBP, DNMT1, DNMT3B, HAT1, HDAC2 and SUV39H1) were selected because of their possible involvement in determining oocyte developmental competence. Pre-antral and antral follicles were isolated from the ovaries of Zebu (Bos indicus) cows, measured and classified into the following categories according to their diameter: (i) oocytes from primordial follicles: diameter <20 μm, (ii) oocytes from primary follicles: 25-35 μm, (iii) oocytes from small secondary follicles: 40-60 μm, (iv) oocytes from large secondary follicles: 65-85 μm, (v) oocytes from small antral follicles: 100-120 μm, and (vi) oocytes from large antral follicles: >128 μm. Total RNA was extracted from four pools of 25 oocytes for each category of follicles, and the genes were quantified by qPCR. Target gene expression was normalized using the gene PPIA. The results suggest that stocks of the studied transcript genes accumulate before the final phase of folliculogenesis. The HDAC2 gene was the only gene in which a differential expression was observed at stage associated with competence acquisition.

Characterization of the IGF2 Imprinted Gene Methylation Status in Bovine Oocytes during Folliculogenesis

“…To characterize the DNA methylation pattern during bovine folliculogenesis for the imprinted gene IGF2, we used oocytes from follicles representing the initial and final phases of the two stages of folliculogenesis, the preantral and antral stages. Thus, we have collected oocytes from primordial, final secondary, small antral and large antral follicles using methodologies that were previously established in our laboratory [ 17 , 27 , 28 ].…”

“…Cumulus oocyte complexes (COCs) were recovered and classified according to procedures previously established in our laboratory [ 27 , 28 ]. Briefly, the ovarian cortex was separated with a scalpel blade and cut longitudinally, transversally and obliquely with a Tissue Chopper (The Mickle Laboratory Engineering Co. Ltd., Gomshall, Surrey, England).…”

“…Oocytes < 20 μm, 65–85 μm, 100–120 μm (from 1–3 mm follicles) and >128 μm (from ≥ 6 mm follicles) in diameter, were classified as oocytes from primordial follicles, final secondary follicles, small antral follicles and large antral follicles, respectively. Oocytes from primordial and final secondary follicles represent the preantral phase of folliculogenesis [ 27 ]. The antral groups were selected according to a study that was performed in our laboratory, which showed that oocytes from 1–3 mm follicles are less competent for embryo production than the oocytes from follicles ≥6 mm in size [ 28 ].…”

Marcadores moleculares para qualidade de ovocitos bovino

“…Estudos com esse objetivo foram realizados por vários grupos de pesquisa, o que resultou na identificação de vários marcadores potenciais (Tabela 1), com diversas funções biológicas (Robert et al, 2000;Donnison and Pfeffer, 2004;Mourot et al, 2006;Pfeffer et al, 2006;Ghanem et al, 2007;Patel et al, 2007;Racedo et al, 2008;Caixeta et al, 2009;Bessa et al, 2013). Apesar desse tipo de estudo fornecer informações importante para o entendimento sobre a regulação da capacidade de desenvolvimento, é necessário a destruição do ovócito para realizar a análise molecular.…”

Vesículas secretadas por células, proteínas e miRNAs associados à competência oocitária em bovinos: um modelo retrospectivo no microambiente folicular

“…Assim como nesse trabalho, em um estudo prévio de Bessa e colaboradores 2012o gene da HDAC2 demonstrou uma relação entre mudança de expressão e competência (BESSA et al, 2013). Além da HDAC2, o outro gene relacionado à modificações epigenéticas H2AFZ também estavam em menor expressão nas células do cumulus dos oócitos maturados in vivo, deixando mais uma vez clara a relação do cultivo in vitro com as alterações epigenéticas.…”