ABSTRACT
An important consideration in microarray analysis of nucleic acids is the efficiency with which the target molecule is captured by, or hybridized to, surface-immobilized oligos. For RNA, secondary and tertiary structure of the target strand can significantly decrease capture efficiency. To overcome this limitation, RNA is often fragmented to reduce structural effects. In this study, the metal ion-catalyzed base hydrolysis fragmentation conditions for viral RNA extracted from influenza viruses were evaluated and the hybridization efficiency of the resulting fragments was determined as a function of fragment length. The amount of RNA captured was evaluated qualitatively by fluorescence intensity normalized to an internal standard. Optimized conditions for influenza RNA were determined to include a fragmentation time of 20-30 min at 75 degrees C. These conditions resulted in a maximum concentration of fragments between 38 and 150 nt in length and a maximum in the capture and label efficiency.
Subject(s)
Oligonucleotide Array Sequence Analysis/methods , RNA, Viral/analysis , RNA, Viral/genetics , Base Sequence , DNA Primers/genetics , DNA, Viral/genetics , Hot Temperature , Influenza A virus/genetics , Molecular Sequence Data , Nucleic Acid Hybridization , RNA, Viral/isolation & purificationABSTRACT
BACKGROUND: Although acute renal failure (ARF) is a relatively common disorder with major morbidity and mortality, its molecular basis remains incompletely defined. The present study examined global gene expression in the well-characterized ischemia-reperfusion model of ARF using DNA microarray technology. METHODS: Male Wistar rats underwent bilateral renal ischemia (30 min) or sham operation, followed by reperfusion for 1, 2, 3 or 4 days. Plasma creatinine increased approximately fivefold over baseline, peaking on day 1. Renal total RNA was used to probe cDNA microarrays. RESULTS: Alterations in expression of 18 genes were identified by microarray analysis. Nine genes were up-regulated (ADAM2, HO-1, UCP-2, and thymosin beta4 in the early phase and clusterin, vanin1, fibronectin, heat-responsive protein 12 and FK506 binding protein in the established phase), whereas another nine were down-regulated (glutamine synthetase, cytochrome p450 IId6, and cyp 2d9 in the early phase and cyp 4a14, Xist gene, PPARgamma, alpha-albumin, uromodulin, and ADH B2 in the established phase). The identities of these 18 genes were sequence-verified. Changes in gene expression of ADAM2, cyp2d6, fibronectin, HO-1 and PPARgamma were confirmed by quantitative real-time polymerase chain reaction (PCR). ADAM2, cyp2d6, and PPARgamma have not previously been known to be involved in ARF. CONCLUSION: Using DNA microarray technology, we identified changes in expression of 18 genes during renal ischemia-reperfusion injury in the rat. We confirmed changes in five genes (fibronectin, ADAM2, cyp 2d6, HO-1 and PPARgamma) by quantitative real-time PCR. Several genes, not previously been identified as playing a role in ischemic ARF, may have importance in this disease.
