Oxidative Stress Alters the Profile of Transcription Factors Related to Early Development on In Vitro Produced Embryos.

Roberta Ferreira Leite,Patricia Kubo Fontes,Camila Bruna De Lima,Jessica Ispada,Marcella Pecora Milazzotto,Marcelo Fábio Gouveia Nogueira,Érika Cristina Dos Santos,Kelly Annes

doi:10.1155/2017/1502489

Abstract

High oxygen levels during in vitro culture (IVC) can induce oxidative stress through accumulation of reactive oxygen species (ROS), negatively affecting embryo development. This study evaluated the effect of different O2 tensions during IVC on bovine blastocyst development and transcriptional status, considering transcription factors that play an essential role during early embryo development. For this purpose, embryos were produced in vitro by conventional protocols and cultured in two different oxygen tensions, physiological (5%) and atmospheric (20%). Expanded blastocysts were subjected to transcript quantitation analysis by RT-qPCR with Biomark™ HD System (Fluidigm, US), using 67 TaqMan assays specific for Bos taurus. Differences were observed in genes related to oxidation-reduction processes, DNA-dependent transcription factors, and factors related to important functional pathways for embryo development. Blastocyst rate was higher in the 5% O2 group and the number of cells was assessed, with the 5% O2 group having a higher number of cells. ROS concentration was evaluated, with a higher ROS presence in the 20% O2 group. Taken together, these results allow us to conclude that IVC of embryos at atmospheric O2 tension affects the expression of important transcription factors involved in multiple cell biology pathways that can affect embryo development, quality, and viability.

Highlights

The study of the embryo in vitro production (IVP) leads to a better knowledge of cellular and molecular aspects that occur and control the early embryonic development
In vivo embryo development occurs in the lower oxygen tension of the oviduct and relies on factors that maintain the balance between the production of reactive oxygen species (ROS) and antioxidant enzymes, due to an efficient reduction-oxidation reaction system, which can guarantee an ideal environment for embryonic development [12, 13]
Considering the oxidative stress’ effects on transcription factors that have important roles during early embryo development are still unclear, we evaluated the interference of different oxygen tensions during in vitro culture (IVC) on the transcriptional status of bovine embryos, especially considering DNA-dependent transcription factors related to development, stress, and embryo morphophysiological characteristics

Summary

Introduction

The study of the embryo in vitro production (IVP) leads to a better knowledge of cellular and molecular aspects that occur and control the early embryonic development. In vivo embryo development occurs in the lower oxygen tension of the oviduct and relies on factors that maintain the balance between the production of reactive oxygen species (ROS) and antioxidant enzymes, due to an efficient reduction-oxidation reaction (redox) system, which can guarantee an ideal environment for embryonic development [12, 13]. During IVC, embryos cannot rely on the protection of the enzymatic or nonenzymatic antioxidants present in the physiological environment and there are studies that show that the culture media, depending on the composition, can be itself a source of ROS [14]. IVC of embryos in high atmospheric oxygen tension can lead to ROS accumulation and induce oxidative stress in embryo cells without the enzymatic protection of antioxidants [10, 11, 13, 15]

Methods

Results

Conclusion