Get breadth of coverage of a reference genome. How many bases of my reference genome are covered by my short reads sample at a level of 5X or higher? # set shell variables to your file-names REF_GENOME_FILE=my_ref_genome.fnaWGS_SAMPLE=my_short_read_sample.fastq MIN_COVERAGE_DEPTH=51) Map short reads against reference genome (bowtie2)# create bowtie2 index database (database name: refgenome)bowtie2-build ${REF_GENOME_FILE} refgenomelsrefgenome.1.bt2 refgenome.2.bt2 refgenome.3.bt2 refgenome.4.bt2 refgenome.rev.1.bt2 refgenome.rev.2.bt2 # map reads and sort bam file bowtie2 -x refgenome --no-unal -U ${WGS_SAMPLE} -S - -p 12 | \ -U ${WGS_SAMPLE} consider all reads as unpaired reads -S - bowtie output in SAM format, write to standard out -x refgenome use reference genome bowtie2-database --no-unal suppress SAM records for reads that failed to align -p 12 use 12 processors2) Get breadth of coverage (SAMtools)# create samtools index samtools index mapping_result_sorted.bam# get total number of bases covered at MIN_COVERAGE_DEPTH or higher samtools mpileup mapping_result_sorted.bam | awk -v X="${MIN_COVERAGE_DEPTH}" '$4>=X' | wc -l32876 # get length of reference genome bowtie2-inspect -s refgenome | awk '{ FS = "\t" } ; BEGIN{L=0}; {L=L+$3}; END{print L}'45678 Result: breadth of reference genome coverage total number of covered bases: 32876 (with >= 5X coverage depth) Depth of coverage (average per-base coverage): 0.719 X (32876 ÷ 45678) (total number of covered bases divided by reference genome length) |
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