通常会使用基因组浏览器来查看特定区域的染色质景观。整合基因组查看器有两种版本:一个是网络应用程序版本,另一个是本地桌面版本,这两种版本都很容易操作。UCSC 基因组浏览器则提供了最为全面的基因组补充信息。
还希望研究一系列已注释位点的染色质特征,比如基因启动子区域的组蛋白修饰信号。为此,将利用 deepTools 软件包中的 computeMatrix 和 plotHeatmap 函数来绘制热图。
##== linux command ==##
mkdir -p $projPath/alignment/bigwig
samtools sort -o $projPath/alignment/bam/${histName}.sorted.bam $projPath/alignment/bam/${histName}_bowtie2.mapped.bam
samtools index $projPath/alignment/bam/${histName}.sorted.bam
bamCoverage -b $projPath/alignment/bam/${histName}.sorted.bam -o $projPath/alignment/bigwig/${histName}_raw.bw
##== linux command ==##
cores=8
computeMatrix scale-regions -S $projPath/alignment/bigwig/K27me3_rep1_raw.bw \
$projPath/alignment/bigwig/K27me3_rep2_raw.bw \
$projPath/alignment/bigwig/K4me3_rep1_raw.bw \
$projPath/alignment/bigwig/K4me3_rep2_raw.bw \
-R $projPath/data/hg38_gene/hg38_gene.tsv \
--beforeRegionStartLength 3000 \
--regionBodyLength 5000 \
--afterRegionStartLength 3000 \
--skipZeros -o $projPath/data/hg38_gene/matrix_gene.mat.gz -p $cores
plotHeatmap -m $projPath/data/hg38_gene/matrix_gene.mat.gz -out $projPath/data/hg38_gene/Histone_gene.png --sortUsing sum
利用 SEACR 返回的信号块的中点来对热图中的信号进行对齐。SEACR 输出的第六列是一个以 chr:start-end 形式的条目,表示该区域内信号最强区域的起始和终止碱基。先生成一个新的 bed 文件,把中点信息放在第六列,然后使用 deeptools 来进行热图可视化。
##== linux command ==##
awk '{split($6, summit, ":"); split(summit[2], region, "-"); print summit[1]"\t"region[1]"\t"region[2]}' $projPath/peakCalling/SEACR/${histName}_${repName}_seacr_control.pe\
aks.stringent.bed >$projPath/peakCalling/SEACR/${histName}_${repName}_seacr_control.peaks.summitRegion.bed
computeMatrix reference-point -S $projPath/alignment/bigwig/${histName}_${repName}_raw.bw \
-R $projPath/peakCalling/SEACR/${histName}_${repName}_seacr_control.peaks.summitRegion.bed \
--skipZeros -o $projPath/peakCalling/SEACR/${histName}_${repName}_SEACR.mat.gz -p $cores -a 3000 -b 3000 --referencePoint center
plotHeatmap -m $projPath/peakCalling/SEACR/${histName}_SEACR.mat.gz -out $projPath/peakCalling/SEACR/${histName}_SEACR_heatmap.png --sortUsing sum --startLabel "Peak Start" -\
-endLabel "Peak End" --xAxisLabel "" --regionsLabel "Peaks" --samplesLabel "${histName} ${repName}"