Characteristic Transcriptional Profiling of Rhythmic mRNA Expression in the Murine Distal Colon

To identify a cohort of rhythmically expressed genes in the murine Distal Colon,microarrays were used to measure gene expression over a 24-hour light/dark cycle.The rhythmic transcripts were classified according to expression patterns, functions and association with physiological and pathophysiological processes of the colon including motility, colorectal cancer formation and inflammatory bowel disease. Keywords: time series Mice were maintained for 2 weeks on a 12 hour light/dark (LD) cycle (lights on 7 AM, lights off 7 PM) prior to all experiments. For the reference experiment, mice had ad libitum access to food. Samples were collected every four hours, at 0400, 0800, 1200, 1600, 2000 and 2400, starting 1 hour after the lights went on. Total RNA was isolated by modified guanidinium thicyanate-phenol-chloroform extraction method and was treated with DNase I (Promega, Madison, WI) at 37 oC for 30 minutes.Hybridizations and Scaning were done as per Affymetrix techniques. Three MOE 430 plus 2.0 chips were used per time point.