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Expression profiling & functional genomics Exercises
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Differential expression
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Use the normalized data to find statistically differentially expressed genes: CyberT software oefnbaldi.xls http://visitor.ics.uci.edu/genex/cybert/ The file contain the 4 normalised ratios (see SNOMAD) T test on the ratios Condition 1 Dye1 Replica L Condition 1 dye1 Replica R Condition 2 dye2 Replica L Condition 2 dye2 Replica R Condition 2 dye1 Replica L Condition 2 dye1 Replica R Condition 1 dye2 Replica L Condition 1 dye2 Replica R Array 1 Array 2 Per gene, per condition 4 measurements available Paired samples CyberT
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Results CyberT Mn: mean ratio # obs: number of ratios available to calculate the statistics SD: standard deviation on the ratio estimates T, p calculated t and p value that indicate the significance of the measurement
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Results CyberT
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SAM
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MARAN ANOVA based Filtering Linearisation Bootstrapping Log transformation
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Two typical cDNA designs Reference design (Spellman data set) Reference: unsynchronized cells Condition: synchronized cells during cell cycle at distinct time intervals (18) Condition 1 Dye1 Replica L Condition 2 Dye1 Replica L Condition 3 Dye1 Replica L Condition 4 Dye1 Replica L. … Condition 19 Dye2 Replica L Condition 19 Dye2 Replica L Condition 19 Dye2 Replica L Condition 19 Dye2 Replica L Array 1 Experimental design Exercises
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Data were precalculated Login: username userGGS Password: Njoedel Uploaded data: Spellman: test cell cycle (reference design) Mouse: latin sqaure design (log transformed) MARAN
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Spellman non log transformed
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MARAN
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Complex cDNA design Latin Square (mouse data set) Reference: normal mouse Condition: pygmee mouse Two experiments T=1, T=2 reflects two sample time points 2 batches: not all genes of the genome on one array A 1, T 1 B1 Test = R Ref = G A 2, T 1 B1 Test = G Ref = R A 5, T 2 B1 Test = R Ref = G A 6, T 2 B1 Test = G Ref = R A 3, T 1 B2 Test = R Ref = G A 4, T 1 B2 Test = R Ref = G A 7, T 2 B2 Test = R Ref = G A 8, T 2 B2 Test = G Ref = R Exercises
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Clustering of expression profiling experiments
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Complex cDNA design Latin Square (mouse data set) Reference: normal mouse Condition: pygmee mouse Two experiments T=1, T=2 reflects two sample time points 2 batches: not all genes of the genome on one array A 1, T 1 B1 Test = R Ref = G A 2, T 1 B1 Test = G Ref = R A 5, T 2 B1 Test = R Ref = G A 6, T 2 B1 Test = G Ref = R A 3, T 1 B2 Test = R Ref = G A 4, T 1 B2 Test = R Ref = G A 7, T 2 B2 Test = R Ref = G A 8, T 2 B2 Test = G Ref = R Experimental design 8 Arrays 2 Batches 2 Dyes 2 Conditions Exercises
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Dataset Yeast cell cycle data set –Data set is preprocessed (slide by slide) –Expression level of each gene is expressed as the log of the ratio –15 experiments, 7000 genes –Filtering based on variance => retain 3000 genes –Rescaling (mean variance) –Cluster the experiment using Kmeans (EPCLUST) Hierarchical clustering (EPCLUST) AQBC (INCLUsive)
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Exercises Clustering INCLUsive
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Exercises Clustering INCLUsive http://www.esat.kuleuven.ac.be/~thijs/AQBC/testkat_157088/testkat_157088.html
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Exercises Clustering INCLUsive Average profile
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Exercises EPCLUST
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Exercises EPCLUST Remember the ID of the file
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Check if your data were uploaded Go back and refresh the page to return to the original page Exercises EPCLUST Continue here
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Exercises EPCLUST
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Exercises EPCLUST Make a selection of the most interesting genes, because a filtering was already performed select all data
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Exercises EPCLUST Try hierarchical clustering and K- means clustering
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K-means 30 clusters, Euclidea n distance Exercises EPCLUST: result Kmeans
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Exercises EPCLUST Try hierarchical clustering and K- means clustering
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The comparison between the content of these two clusters can be seen in the file vergelijkingcluster.xls
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Exercises EPCLUST: hierarchical clustering Analyze the tree Try to detect the number of clusters in the dataset Click on a node and view the profile of a subcluster
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Exercises EPCLUST: automatic linking to other tools
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Exercises EPCLUST: automatic linking to other tools
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Exercises EPCLUST: automatic linking to other tools
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FATIGO: calculating statistical overrepresentation using GO
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