Question: Picard-Tools Or Trimmomatic Flip Read From Fr Or Rf??
gravatar for mengqingying
6.6 years ago by
United States
mengqingying30 wrote:

I have some PE RNAseq reads contaminated with adapter sequences.

Before removing the adapters, i mapped the reads using bowtie2 -> samtools -> picard-tools "CollectInsertSizeMetrics.jar" and got histogram as shown in the first figure.

After removing the adapters with Trimmomatic, i again run bowtie2 -> samtools -> "CollectInsertSizeMetrics.jar" and got the 2nd histogram with many RF reads, as shown in blue color in the plot. Actually here i already set bowtie2 parameter --no-discordant to remove discordant reads.

I cannot figure out the reason there are so many reads flip their orientations from FR -> RF? I wonder if this change are caused by Trimmomatic, or picard? How this happened?! Any one can help?

Figure1_beforeQC Figure2_afterQC

rnaseq • 2.0k views
ADD COMMENTlink modified 6.6 years ago by Devon Ryan95k • written 6.6 years ago by mengqingying30

Can't see the figure 2. Can you repost it?

ADD REPLYlink written 6.6 years ago by Ashutosh Pandey12k

It was just a formatting issue, it should be fixed now.

ADD REPLYlink written 6.6 years ago by Devon Ryan95k
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