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Sickle is a tool that uses sliding windows along with quality and length thresholds to determine when quality is sufficiently low to trim the 3'-end of reads and also determines when the quality is sufficiently high enough to trim the 5'-end of reads. You can find more information on sickle here.

Environment Setup

To use Sickle first we need to load the software. The easiest way to do this is to edit your .bashrc file in your $HOME directory.

module load sickle

In you $HOME directory create a folder to run sickle jobs and where the test data will be stored.

razor-l2:jokinsey:~$ mkdir SICKLE-JOBS
razor-l2:jokinsey:~$ cp /share/apps/bioinformatics/sickle-1.33/test/* SICKLE-JOBS/

Example Job

Create a PBS script names sickle.pbs with the information below that will be submitted to the queue to run the job.

#PBS -N sickle
#PBS -q tiny12core
#PBS -j oe
#PBS -o sickle.$PBS_JOBID
#PBS -l nodes=1:ppn=12
#PBS -l walltime=0:05:00

cp test.fastq /scratch/$PBS_JOBID
cd /scratch/$PBS_JOBID

sickle se -f test.fastq -t illumina -o trimmed_test.fastq

cp trimmed_test.fastq $PBS_O_WORKDIR

The line that calls sickle is doing a single end trim on the test.fastq file with the quality setting illumina, and the output file will be trimmed_test.fastq. Sickle also supports paired end trimming and different quality settings, your can find more information here

All that's left to do is submit the job.

razor-l2:jokinsey:~/SICKLE-JOBS$ qsub sickle.pbs

You should see the trimmed out put file trimmed_test.fastq in the directory you submitted the job from.

sickle.txt · Last modified: 2017/11/09 21:58 by jokinsey