title: Comparative epigenomics: defining and utilizing epigenomic variations across species, time-course, and individuals.
abstract: Epigenomic profiling, by revealing genome-wide distributions of epigenetic modifications, generated a large amount of structural information about the chromosomes. Epigenomic analysis has quickly become a big data science, posing tremendous challenges on its translation into knowledge. To meet this challenge, comparative analysis of epigenomes, dubbed comparative epigenomics, has emerged as an active research area. Here, we summarize the recent developments in comparative epigenomic analyses into three major directions, namely the comparisons across species, the time-course of a biological process, and individuals. We review the main ideas, methods, and findings in each direction, and discuss the implications to understanding the regulatory functions of the genomes.
  
  
  BACKGROUND
  The authors have declared no conflicts of interest for this article.
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
authors.forename: Shu
authors.initials: S
authors.lastname: Xiao
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Cao
authors.forename: Sheng
authors.initials: S
authors.lastname: Zhong
mesh_terms: D057890:Epigenomics / Q000639:trends; D014644:Genetic Variation; D006801:Humans; D013045:Species Specificity; D013997:Time Factors