Changes in expression level of genes as a function of time of day in the liver of rats

Varsha G. Desai, Carrie L. Moland, William S. Branham, Robert R. Delongchamp, Hong Fang, Peter H. Duffy, Charlotte A. Peterson, Marjorie L. Beggs, James C. Fuscoe

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Daily, rhythmic variation in various biochemical, physiological, and behavioral events is a fundamental property of biological organization. Here, we report analysis of relative levels of gene expression in the liver of 16 Fischer 344 rats as a function of time of day. Expression levels were determined for 3906 genes using high-density oligonucleotide microarrays. Of the 3906 genes, 1171 (30%) were clearly expressed while 2735 (70%) were not expressed or the expression was too low to distinguish from background levels. The maximum estimated changes observed for most genes (1029, 88%) were less than 1.5-fold. Analysis of variance and the Kruskal-Wallis tests were used to identify 67 genes whose expression was significantly altered as a function of time of day. These significantly altered genes were classified according to their functions and fall into key cellular pathways including drug metabolism, ion transport, signal transduction, DNA binding and regulation of transcription, and immune response.

Original languageEnglish
Pages (from-to)115-129
Number of pages15
JournalMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Issue number1-2
StatePublished - May 18 2004


  • Circadian rhythm
  • Liver
  • Microarray analysis

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Health, Toxicology and Mutagenesis


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