Expression profiling of F2 progenies from C57BL/6J x DBA/2J

Expression profiling of a cohort of mice was derived from a standard F2 intercross using two standard inbred strains, C57BL/6J and DBA/2J. In this study, we selected 127 male animals that had been raised on a standard rodent chow diet (Purina Chow from Ralston-Purina Co., St. Louis, MO) for eight weeks and then switched to a high fat diet for sixteen additional weeks. At 20 weeks of age, the mice were euthanized and liver tissues were collected and flash frozen in liquid nitrogen and stored at -80 degrees C prior to RNA isolation. All procedures of housing and treatment of animals were performed in accordance with IACUC regulations. RNA preparation and array hybridizations were performed at Rosetta Inpharmatics. The custom ink-jet microarrays were manufactured by Agilent Technologies (Palo Alto, CA). A custom array was designed for this study and consisted of 39,280 non-control oligonuceotides extracted from the mouse Unigene clusters and combined with RefSeq sequences and RIKEN full-length cDNA clones. Arrays were quantified on the basis of spot intensity relative to background, adjusted for experimental variation between arrays using average intensity over multiple channels, and fitted to a previously described error model to determine significance (type I error).