Project description:Samples were purchased from Clontech as mRNA. Hybridization material was generated through a random-priming amplification procedure (RP-AMP) using primers with a random sequence at the 3' end and a fixed motif at the 5' end. shDNP256 (first strand synthesis): 5'- TAG ATG CTG TTG NNN NNN NNN -3' shT7N9 (second strand synthesis): 5'- ACT ATA GGG AGA NNN NNN NNN -3' 1.5 g of mRNA was reverse-transcribed with Superscript II and the DP256 random primer for 20 minutes at 42 C (10 mM DTT, 50 mM Tris-HCl pH 8.3, 75 mM KCl, 8 mM MgCl2, 0.5 mM dNTPs, 5 U/ l Superscript II). The RNA was degraded with the addition of 20 l volume of 0.5N sodium hydroxide and 0.25 M EDTA for 20 minutes at 65 C. The single stranded cDNA was purified using a commercial kit (Qiagen Qiaquick). The resulting product of single stranded cDNA was placed in its entirety in a second strand reaction. Second strand synthesis reactions utilized shT7N9 random primer and the Klenow fragment of DNA polymerase utilizing standard reaction conditions (37 C for 60 minutes, 0.2 mM DTT, 2.1 mM Tris-HCl pH 7.9, 2.1 mM MgCl2, 10.7 mM NaCl, 1.07 mM dNTPs, 0.1U/ l Klenow), followed by another Qiaquick purification. Multiple polymerase chain reactions were run using 0.15 g of double stranded DNA and standard reaction conditions. Amplification was achieved using 10 cycles of PCR with the DP256 and T7 primers (20 mM Tris-HCl pH 8.4, 50 mM KCl, 0.01 mM dNTPs, 1.5 mM MgCl2, 0.01 U/ l Taq Polymerase) DP256: 5'- GTT CGA GAC CTC TAG ATG CTG TTG -3' T7: 5'- AA TTA ATA CGA CTC ACT ATA GGG AGA -3' followed by Qiaquick purification. Further amplification was achieved using in vitro transcription reactions with X0.5 g dsDNA and T7 RNA Polymerase (7.5 mM DTT, 40 mM Tris-HCl pH 7.5, 14.25 mM MgCl2, 10 mM NaCl, 2 mM Spermidine, 125 U/ml RNAguard, 2.5 mM dNTPs, 15 U/ml IPPase, 25kU/ml T7 Polymerase) for 16 hours at 42 C. The cRNA was purified (RNeasy) and reverse transcribed using Superscript and random 9-mers and amino-allyl dUTP (42 C for 20 minutes, 10 mM DTT, 50mM Tris-HCl pH 8.3, 75 mM KCl, 8 mM MgCl2, 0.5 mM dNTPs, 0.5 mM aa-dUTP, 5 U/ l Superscript II). The cDNA for each channel was covalently coupled separately with Cy5 and Cy3 monoreactive fluors, respectively, in 1M sodium bicarbonate, pH 9.0, followed by quenching with 4.0 M hydroxylamine. The Cy5 and Cy3 labelled cDNAs were purified with a QIAquick PCR purification kit and the percentage dye incorporation and total cDNA yield was determined spectrophotometrically. Cy5 and Cy3 labelled cDNAs were combined and added to 2 mls 30% formamide with Herring Sperm DNA for hybridization to the microarray. Further details can be found in Castle et al., Genome Biol 2003;4(10):R66, http://genomebiology.com/2003/4/10/R66 , Roberts CJ et al., Science 2000, 287:873-880, and Schadt, Edwards, et al., unpublished. Normalization of single channel data is described in Ying, et al., "Identification of Chromosomal Regions Containing Transcribed Sequences Using Microarrays and Computational Methods" , 2003 Proceedings of the American Statistical Association, Biopharmaceutical Section [CD-ROM], Alexandria, VA: American Statistical Association, 2003. Briefly, an invariant set of probes was selected based on their intensity ranks. Then, a LOESS regression model was fit for Cy5 vs. Cy3 intensities for all probes in the invariant set. Finally, for all probes on the array the Cy5 intensities were normalized to the corresponding Cy3 intensities using prediction values from the regression model. Note that the normalized intensity values given here were used for all analyses reported in the accompanying paper. The ratio values reported here were not used for the analysis described in the manuscript and are not calculated from the normalized intensity values given below. Keywords: other
2004-03-04 | GSE1097 | GEO
