Abstract
Abstract: :
Purpose: Rats exposed to high intensity green light starting at 1AM show extensive photoreceptor cell loss, while rats exposed to light starting at 5PM are tolerant of the light treatment (Organisciak et al. IOVS 2000 41:3694-3701). Preliminary studies have shown that there is a differential expression of genes at these two time points (Grewal et al. IOVS (2000): 41:140). Here we describe the large-scale investigation of gene expression at the 1AM and 5PM time points by cDNA array analysis. Methods: Retinas were extracted from dark reared rats at 1AM or 5PM, and total RNA was isolated. Radiolabelled cDNA probes were generated and used to screen cDNA arrays (Atlas Array, Clontech, Inc). Membranes were analyzed by visual inspection and with Atlas Image software to determine relative levels of gene expression. Northern analysis of selected clones was used to verify gene expression patterns Results: In total, 3528 genes were examined by cDNA array analysis. Preliminary results suggest that approximately 5% of the genes examined are upregulated at 1AM and approximately 5% are upregulated at 5PM. The preliminary interpretation of the global gene expression profile suggests that genes involved in heat shock/stress response appear to be differentially expressed at 5PM. Conclusion: cDNA array analysis has allowed us to screen a large number of genes for «time» specific gene expression. This can be used as a starting point to define the molecular environment for a retina that is resistant to light induced damage (5PM), and one that is highly susceptible to light induced damage (1AM)
Keywords: 554 retina • 323 apoptosis/cell death • 349 circadian rhythms