Gene Expression in Rats Fed a Western Diet. Rattus norvegicus

Resistant starches (RS), fed as high amylose maize starch (HAMS) or butyrylated HAMS (HAMSB), oppose dietary protein-induced colonocyte DNA damage in rats. In this study, rats were fed diets high in fat (19%) and protein (20%) with different forms of digestible starch (low amylose maize starch (LAMS) or low amylose whole wheat (LAW)) or RS (HAMS, HAMSB, or a whole high amylose wheat (HAW) generated by RNA interference (RNAi)) for 11 wk. A control diet contained 7% fat, 13% protein and LAMS. The aim of this study was to detect changes in the expression of DNA damage and repair genes in response to the above dietary treatments. Overall design: Distal colon tissues from Sprague Dawley rats fed a variety of diets (see summary) were removed from RNAlater stabilisation reagent (Sigma, Australia) they had been stored in,, placed in 1 ml of TRIzol® Reagent (Invitrogen, Australia) and homogenised usingbeads (mix of 2.5 mm glass and 0.1 - 1.0 mm diameter silicon-zirconian beads) in a MiniBeadbeater-8 (BioSpec Products Inc., USA). Total RNA was extracted (using TRIzol® Reagent manufacturer's instructions) and further purified using RNAeasy mini spin columns (QIAGEN, Australia) with a DNase on-column digestion as per manufacturer's instructions.RNA integrity was checked using a Bioanalyzer 2100 (Agilent Technologies, USA) andquantified using a NanoDrop® ND-1000 Spectrophotometer (Thermo Fisher Scientific, USA). RNA samples with insufficinet quality and quantity were not assayed. The numbers of rats arrayed from each diet were as follows: CON, 5;LAMS, 7; HAMS, 8; HAMSB, 9; LAW, 6; HAW , 8. This gives a total of 43 arrays.