TSS Dato ciascun TSS, calcolare quante sequenze mappano tra e bp rispetto al TSS Contare quante sequenze mappano a -1000, -999, ,0 +1,+2, ,+999,+1000 Sommare per tutti i TSS i conteggi a ciascuna distanza (-1000, -999, -998,...,-1,0,+1,+2, ,+999,+1000) Algoritmo! TSS Attenzione! TSS Le coordinate rispetto al TSS dipendono dalla direzione della trascrizione!! Output: histone modifications at TSS Distance from TSS Read count (peak height) I risultati! PolII is found bound to DNA at the TSS of transcribed genes H3K4me3 is found just before and after the TSS of transcribed genes H3K4me2 (not me3!) is found just before and after the TSS of transcribed genes, but farther away than H3K4me3 H3K4me1 is found just before and after the TSS of transcribed genes, but farther away than H3K4me3 and H3K4me2 H3K27me3 covers the whole locus of silent genes - no transcription here H3K27me1 (not me3!) is vice versa associated before and after loci of transcribed genes H3K36me3 is found within the transcribed region - a bit downstream of the TSS - as if it lets polymerase proceed with transcription H3K9me1 is similar in profile to H3K4me3 Barski et. al. High-Resolution Profiling of Histone Methylations in the Human Genome, Cell 129(4) Histone modifications at transcribed regions Expression level Read count (peak height) HighLow What you should always remember