title: Effect of in ovo folic acid injection on hepatic IGF2 expression and embryo growth of broilers.
abstract: BACKGROUND
  Insulin-like factor 2 (IGF2) plays an important role in embryonic growth process by modulating intermediary metabolism and cell proliferation. Folic acid is involved in one carbon metabolism and contributes to DNA methylation which is related to gene expression. The purpose of this study was to explore whether folic acid could regulate IGF2 expression via epigenetic mechanism and further promote embryonic growth of new-hatched broilers.
  
  
  METHODS
  In the present study, 360 fertile eggs were selected and randomly assigned to four treatments. On 11 embryonic day of incubation (E11), 0, 50, 100 and 150 μg folic acid were injected into eggs respectively. After hatched, growth performance of broilers were calculated. Hepatic IGF2 expression, methylation level and chromatin structure of promoter region were analyzed.
  
  
  RESULTS
  Results have showed that IGF2 expression was up-regulated in 150 μg folic acid group (P < 0.05) and other two dose of folic acid did not affect gene expression (P > 0.05). Meanwhile, methylation level of IGF2 promoter were lower in 100 and 150 μg groups, which was consistent with lower expression of DNA methyltransferase 1 (DNMT1) (P < 0.05). What's more, chromatin looseness of IGF2 promoter was higher in 150 μg group than control group (P < 0.05). Further, birth weight (BW), liver and bursa index of new-hatched chickens in 150 μg folic acid group were higher than the other groups (P < 0.05). There were positive correlations between hepatic IGF2 expression and BW and organs index (P < 0.05).
  
  
  CONCLUSIONS
  In conclusion, our data have demonstrated that 150 μg folic acid injection on E11 could up-regulate IGF2 expression by modulating DNA hypomethylation and improving chromatin accessibility in the gene promoter region, and ulteriorly facilitate embryonic growth and organ development of broilers.
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 China.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Mathematics and Computer Science, ShanXi Normal University, Linfen, 041000 China.
authors.forename: Lihui
authors.initials: L
authors.lastname: Zhi
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 China.
authors.forename: Jing
authors.initials: J
authors.lastname: Shen
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 China.
authors.forename: Shizhao
authors.initials: S
authors.lastname: Li
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 China.
authors.forename: Junhu
authors.initials: J
authors.lastname: Yao
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Yang
keywords: Broiler; Chromatin structure; Folic acid; Insulin-like growth factor 2; Methylation