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Transcription. Translation. mRNA. Protein. SELF-REPAIRING ARABIDOPSIS, Nature March 05, NY Times (R Pruitt) Storage in RNA???. Central Dogma 2. Transcription. Information stored In Gene (DNA). Cells express different subset of the genes
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Transcription Translation mRNA Protein SELF-REPAIRING ARABIDOPSIS, Nature March 05, NY Times (R Pruitt) Storage in RNA??? Central Dogma 2 Transcription Information stored In Gene (DNA) Cells express different subset of the genes In different tissues and under different conditions Reverse Transcription
control M-RNA IS PROCESSED (SPLICED) TRANSCRIPTIONAL CONTROL RNA PROCESSING CONTROL RNA TRANSPORT CONTROL RNA DEGRADATION TRANSLATIONAL CONTROL PROTEIN ACTIVITY REGULATION AT DIFFERENT STEPS
Measure Gene expression A DNA-CHIP MEASURES CONCENTRATIONS OF THOUSANDS OF DIFFERENT MESSENGER RNA MEASURING GENE EXPRESSION PROFILE WHEN A PARTICULAR GENE IS EXPRESSED, THE CONCENTRATIONS OF ITS CORRESPONDING MESSENGER RNA AND PROTEIN ARE HIGH. LATEST AFFYCHIP: U133P2 – 54,675 (probesets)
High Low VISUALIZATION: HOW DOES ONE SHOW SO MANY NUMBERS? COLOR CODE: REPRESENT NUMBERS BY COLORS Color code
Leukemia2 Sample # 57 gene 1000 LEUKEMIA DATA (Rozovskaia, Canaani) Eij = EXPRESSION LEVEL OF GENE i IN SAMPLE j
DNA- DNA hybridization1 RNA- DNA uracil
kT MISMATCH kT kT kT 7-17 PERFECT MATCH hybridization2
cDNA SPOTTED ARRAYS: QUICK OVERVIEW cDNA microarray expt (M.Campbell movie)
B B B B B B B B B B B B Affymetrix Experimental Design: Target Biotin - labeled cRNA transcript Cells Poly (A)+ RNA Or Total RNA IVT Biotin-UTP Biotin-CTP Fragment heat, Mg2+ cDNA Hybridize (16 hours) Wash & Stain Biotin - labeled cRNA fragments Scan (75 minutes) (8 minutes)
Probe preparation: Photolithographic synthesis Lamp Mask Chip
Wafer and Chip Format 11 µm 11 µm Millions of identical oligonucleotide probes per feature (25 base-long single - strand DNA) 49 - 400 chips/wafer 1.28cm up to ~ 1,200,000 features/chip
Perfect Match/MisMatch U133Plus2 – 11 probe pairs / probe set
B B B B B B B B B B B B Affymetrix Experimental Design Biotin - labeled cRNA transcript Cells Poly (A)+ RNA Or Total RNA IVT Biotin-UTP Biotin-CTP Fragment heat, Mg2+ cDNA Hybridize (16 hours) Wash & Stain Biotin - labeled cRNA fragments Scan (75 minutes) (8 minutes)
B B B B B B B B B B B B Affymetrix Experimental Design Biotin - labeled cRNA transcript Cells Poly (A)+ RNA Or Total RNA IVT Biotin-UTP Biotin-CTP Fragment heat, Mg2+ cDNA Hybridize (16 hours) Wash & Stain Biotin - labeled cRNA fragments Scan (75 minutes) (8 minutes)
4F5-74 REVERSE TRANSCRIPTASE
3F6-82 retrovirus life cycle 3F6-82
may.pptWafer and Chip Format 20 - 50 µm 20 - 50 µm Millions of identical oligonucleotide probes per feature 49 - 400 chips/wafer 1.28cm up to ~ 400,000 features/chip
Photolithographic Synthesis Lamp Mask Chip
Synthesis of Ordered Oligonucleotide Arrays Light (deprotection) Mask TTOOO OOOOO HO HO O O O T – Substrate Light (deprotection) Mask CATAT AGCTG TTCCO TTCCG TTOOO C – Substrate REPEAT
Perfect Match/MisMatch U133Plus2 – 11 probe pairs / probe set
Array Hybridized Array cRNA Target Streptravidin-phycoerythrin conjugate Hybridization and Staining
cells RNA cRNA hyb. cocktail chip scan analyze Replicates by Scatter-Plot
cells Same array, 2 scans (diff. scanners, days) RNA cRNA hyb. cocktail chip scan scan analyze analyze Technical Replicate I
cells RNA cRNA hyb. cocktail chip chip scan scan analyze analyze Technical Replicate II Same cRNA, 2 arrays (diff. days)
cells RNA cRNA cRNA hyb. cocktail hyb. cocktail chip chip scan scan analyze analyze Technical Replicate III Same RNA, 2 preps
cells cells RNA RNA cRNA cRNA hyb. cocktail hyb. cocktail chip chip scan scan analyze analyze Biological Replicate 2 RNAs, 2 preps
Experiment Differential expression Different RNAs