Transcriptional profiling of liver tissues in chicken embryo at day 16 and 20 using RNA sequencing reveals differential antioxidant enzyme activity
February
Transcriptional profiling of liver tissues in chicken embryo at day 16 and 20 using RNA sequencing reveals differential antioxidant enzyme activity
Shaohua Yang 1 2 3
Lu Lu Wang 1 2 3
Zhaoyuan Shi 1 2 3
Xiaoqian Ou 1 2 3
Wei Wang 0 1 3
Xue Chen 1 2 3
Guoqing Liu 1 2 3
0 Agricultural Products Quality and Safety Supervision and Management Bureau , Xuancheng, Anhui , P. R. China
1 Fundamental Research Funds for Industry- University-Research in Hefei University of Technology (XC2016JZBZ03), the Fundamental Research Funds for the Central Universities
2 College of Food Science and Engineering, Hefei University of Technology , Hefei, Anhui , P. R. China
3 Editor: Salah A. Sheweita, Alexandria University , EGYPT
Considering the high proportion of polyunsaturated fatty acids, the antioxidant defense of chick embryo tissues is vital during the oxidative stress experienced at hatching. In order to better understand the mechanisms of the defense system during chicken embryo development, we detected the activity of antioxidant enzymes during the incubation of chicken embryo. Results showed that the activity of superoxide dismutase (SOD) and (GSH-PX) in livers were higher than those in hearts. Based on these results, liver tissues were used as the follow-up study materials, which were obtained from chicken embryo at day 16 and day 20. Thus, we used RNA sequencing (RNA-Seq) analysis to identify the transcriptome from 6 liver tissues. In total, we obtained 45,552,777±45,462,856 uniquely mapped reads and 18,837 mRNA transcripts, across the 6 liver samples. Among these, 1,154 differentially expressed genes (p<0.05, foldchange 1) were identified between the high and low groups, and 1,069 GO terms were significantly enriched (p<0.05). Of these, 10 GO terms were related to active oxygen defense and antioxidant enzyme activity. GO enrichment and KEGG pathway analysis indicated that GSTA2, GSTA4, MGST1, GPX3, and HAO2 participated in glutathione metabolism, and were considered as the most promising candidate genes affecting the antioxidant enzyme activity of chicken embryo at day 16 and day 20. Using RNA-Seq and differential gene expression, our study here investigated the complexity of the liver transcriptome in chick embryos and analyzed the key genes associated with the antioxidant enzyme.
Introduction
Oxidative stress is always common in poultry production. During embryo growth, more
oxygen is required to provide energy. However, elevated oxygen concentrations lead to high levels
of reactive oxygen species (ROS) [
1
], which may which may cause protein and lipid oxidation
[
2
]. Therefore, ROS has been proposed to cause many diseases and pathological changes
(JZ2017HGTA0228), the innovation Project for
College Students (2017CXCYS235), Wanjiang
Institute of Poultry Technology (XC2015AKKG002),
and the Science and Technology Bureau of AnHui
(XC2015XKKJ02; XC2015AKKG003).
during chick embryo development [
3
], especially in the cardiovascular system. Wells showed
that excess ROS could have a teratogenic effect on developing embryos[
4
] as well as induce
neural tube defects[
5
]. Meanwhile, it was found that ROS can also cause myocardial
hypertrophy in the developing chick embryo [
6
]. The damaging effects of ROS can be exerted on the
developing embryos in a directly or indirect style. Thus, antioxidant defences play a very
important role in chick embryonic development.
In fact, the integrated antioxidant systems within the egg and embryonic tissues are crucial
for the protection of chick embryo in its development. Of these, the main antioxidant enzymes,
superoxide dismutases (SOD), glutathione peroxidase (GSH-PX), glutathione S transferases
(GSTs), Peroxidase (POD) and catalase(CAT), can clearly serve as a major defense line against
ROS during the oxidative stress experienced at hatching in chick embryo[
7
]. During the
incubation period, SOD converts highly reactive superoxide anions into H2O2 and O2, Catalase
(CAT) catalyzes the dismutation of H2O2 to form the neutral products O2 and H2O, and
GSH-PX catalyzes the reductive destruction of hydrogen and lipid hydroperoxides with
glutathione as an electron donor [
8
]. Meanwhile, the end product of SOD is decomposed then to
scavenge ROS [
9
]. Additionally, GSH-PX degrades hydrogen peroxide and other peroxides.
The activities of these antioxidant enzymes are close relevant to higher levels of
environmental oxygen. Using the chick embryo, van Golde et al[
10
] investigated the relations between
hyperoxia and antioxidant enzyme activity, and found that SOD activity had a 2- to
10-foldincrease and Catalase and GPx enzyme activities remain almost the same in heart, liver, intestine
and lungs during incubation at different time points. Starrs et al [
11
] examined the activities of
catalase, SOD and GPx in the developing lungs of the chicken and showed that SOD activity
decreased, whereas catalase and GPx activities were significantly increased in (...truncated)