Analysis of gene expression profiling of normal retina and brain cortices

Using a canine custom retinal cDNA microarray our aim is to identify normal gene expression profiling for retina and frontal, occipital and temporal brain cortices Keywords: retina-brain comparisons Total RNA was isolated using Trizol reagent (Invitrogen, Carlsbad, CA) and further purified by Rneasy mini kit (Qiagen, Valencia, CA). Purity and RNA quality were evaluated by absorbance at 260 nm and by denaturing formaldehyde agarose gel electrophoresis. High quality RNAs with A260/280 ratio over 1.8 and intact 28S and 18S RNA bands were used for microarray analysis. To generate an RNA reference sample for microarray hybridizations, we pooled equal amounts of total RNA from the occipital, temporal, and frontal brain regions collected from three 16-week-old beagles to achieve a homogeneous pool of transcripts. The pooled RNA was divided into aliquots (2μg/μl) and stored at -80 °C until use. For the purpose of this work, four tissue groups have been established, containing five biological replicates for normal retina and three for each respective brain region. After initial validation of reproducibility, only one microarray experiment was used for each sample.