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RNA-seq_data_processing

Download programs

NOTE: if running on CHTC, these programs are already in the maeda_share drive

Need:

FastQC

https://www.bioinformatics.babraham.ac.uk/projects/fastqc/

Trimmomatic

download binary release zip: http://www.usadellab.org/cms/?page=trimmomatic

HISAT2

http://daehwankimlab.github.io/hisat2/download/

SAMtools

http://www.htslib.org/download/

Python HTSeq

NOTE: Python should already be installed

on command line:

pip install HTSeq

SRA-Toolkit (if starting from an SRA file)

https://github.com/ncbi/sra-tools/wiki/01.-Downloading-SRA-Toolkit

Note that if the fastq-dump doesn't work, run the code below to save the config for sra toolkit

vdb-config --interactive

1. Checking quality and trimming reads: FastQC and Trimmomatic

Reads should be checked via FastQC, then trimmed of adapters and low quality sequences, then re-checked via FastQC.

Trimmomatic website and options: http://www.usadellab.org/cms/?page=trimmomatic

NOTE: If there are overrepresented sequences, add to the adapter file and rerun.

  1. Run 01a_RNA-seq_processing.py to set up .sh and .sub file for FastQC and Trimmomatic to be submitted to CHTC.

Code and options:

python 01a_RNA_seq_processing.py

Required:

-fastq_list a tab-delimited file with list of fastq files to process, for PE R1 in first column, R2 in second column

-layout PE: paired end, SE: single end

-dir the path to your staging directory on chtc

Optional:

-SRA SRA sample ID (if starting from SRA file); default='NA'

-threads how many threads to be used for multiprocessing on chtc; default=4

-adapters adapter sequences to be trimmed; default='TruSeq3-PE.fa'

-seedMis seed mismatches: specifies the maximum mismatch count which will still allow a full match to be performed; default=2

-pClipThres palindromeClipThreshold: specifies how accurate the match between the two adapter ligated reads must be for PE palindrome read alignment; default=30

-sClipThres simpleClipThreshold: specifies how accurate the match between any adapter etc. sequence must be against a read; default=10

-LEADING Cut bases off the start of a read, if below a threshold quality- Specifies the minimum quality required to keep a base; default=3

-TRAILING Cut bases off the end of a read, if below a threshold quality- Specifies the minimum quality required to keep a base; default=3

-windowSize Specifies the number of bases to average quality across, cutting once the average quality within the window falls below a threshold; default=4

-requiredQuality Specifies the average quality required; default=20

-MINLEN Specifies the minimum length of reads to be kept; default=36

-HEADCROP Specifies number of bases at beginning of read to be removed; default=0

-mem Amount of memory asked to run job; default=100GB

-disk Amount of disk space asked to run job; default=100GB

Example running base code:

python ~/Desktop/Github/RNA-seq_data_processing/01a_RNA-seq_processing.py -fastq_list file_list_initial.txt -layout PE -dir /staging/bmoore22

Output should be fastq_list.csv, fastqc_trimm_loop.sub, fastqc_trimm.sh

See Examples folder for examples of these files.

  1. Transfer output files to chtc- your home directory- and run:

    Make sure .fastq.gz files are in your staging directory

    Make sure fastqc_v0.11.9.zip and Trimmomatic-0.39.zip are in your home directory

    Submit to chtc:

    condor_submit fastqc_trimm_loop.sub

    NOTE: If you are rerunning with new sequences in the adapter file, make sure to add your new adapter file to the Trimmomatic folder and rezip.

2. Mapping and counting reads: HiSAT2 and HTSeq

Read mapping is performed via HiSAT2 and then the reads are sorted via SamTools. Reads are then counted for each gene via HTSeq.

HiSAT2 manual: http://daehwankimlab.github.io/hisat2/manual/

Description of the Hisat2 sam format: http://daehwankimlab.github.io/hisat2/manual/#sam-output

HTSeq manual: https://htseq.readthedocs.io/en/release_0.11.1/count.html

  1. Run 01b_RNA-seq_processing.py to set up .sh file, .sub file, and file_list.csv for HiSAT2 and HTSeq on chtc.

Code and options:

python 01b_RNA-seq_processing.py

Options:

Required:

-trimmed_list tab-delimited file with list of trimmed fastq files to input; for PE R1 in first column, R2 in second column -genome_seq genome sequence fasta file -gff gff3 file -layout PE: paired end, SE: single end -dir the path to your staging directory on chtc -base base name for genome index

Optional:

-threads how many threads to be used; default=4 -mem mem asked for job running; default=60GB -disk disk space asked for job running; default=100GB

Example running base code:

python ~/Desktop/Github/RNA-seq_data_processing/01b_RNA-seq_processing.py -trimmed_list initial_trim_filelist.txt -genome_seq Joinvillea_ascendens_subsp.gabra.faa.mod.fa -gff Jascendensv1.1.gene.gff3 -layout PE -dir /staging/bmoore22 -base Jvasc

Output should be hisat2-htseq_filelist.csv, hisat2-htseq.sub, hisat2-htseq.sh

See Examples folder for examples of these files.

  1. Transfer output files to chtc- your home directory- and run:

    Make sure .fastq.trim.gz files are in your staging directory

    Make sure hisat2-2.2.1-Linux_x86_64.zip, samtools-1.15.1.tar.bz2, and packages2.tar.gz are in your home directory

    Submit to chtc:

    condor_submit hisat2-htseq.sub

3. Combine the read count files

  1. Transfer HTSeqCount files to your computer from chtc
  2. In directory with HTSeqCount files, run 03_combine_read_counts.py:

python 03_combine_read_counts.py

Output:

Read_counts.txt

This is your input for calculating either TPM/FPKM or for differential expression

4. Calculate expression (TPM and FPKM)

Note: if you are only interested in differential expression, skip to step 5.

  1. Calculate transcript length (based on total number of exons for gene, using gff file):

Use:

transcript_length.R

  1. Make tissue-replicate file:

    a tab-delimited file with the .sorted_sam filename in column 1, and the tissue type in column 2

    see tissue-rep_list.txt in Example_data folder

  2. Run 04_TPM-FPKM_calling.R

    INPUTs:

    Read_counts.txt file

    .transcript_length.txt file

    tissue-rep_list.txt file

5. Calculate Differential Expression

  1. Use 05_DEseq.R
  2. Try with sample data in Example_data folder: counts_data.csv first
  3. INPUTS:

Read_counts.txt file

treatments list: currently to edit in code where each "treatment" is specified based on the column order. Replicates of same sample should be specified as the same treatment.