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Species

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ENA link

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Description

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Human

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https://www.ebi.ac.uk/ena/browser/view/PRJEB5212?show=publications

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RNA-seq of micro RNAs (miRNAs) in Human prefrontal cortex to identify differentially expressed miRNAs between Huntington's Disease and control brain samples

1. Connect to an rVDI virtual desktop machine

To access and run an rVDI virtual desktop:

Go to https://rvdi.qut.edu.au/

Click on ‘VMware Horizon HTML Access

Log on with your QUT username and password

*NOTE: you need to be connected to the QUT network first, either being on campus or connecting remotely via VPN.

2. Open PuTTY terminal

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Click on the PuTTY icon

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Double click on “Lyra”

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Overview

  • Create a metadata “samplesheet.csv” for small RNAseq datasets.

  • Learn to use a “nextflow.config” file in the working directory to override Nextflow parameters (e.g., specify where to find the pipeline assets).

  • Learn how to prepare a PBS script to run the expression profiling of small RNAs against the reference miRBase database annotated microRNAs.

Preparing the pipeline inputs

The pipeline requires preparing at least 2 files:

  • Metadata file (samplesheet.csv) thatspecifies the name of the samples, location of FASTQ files ('Read 1' and ‘Read 2’), and strandedness (forward, reverse, or auto. Note: auto is used when the strandedness of the data is unknown)

  • PBS Pro script (launch_nf-core_RNAseq_QC.pbs) with instructions to run the pipeline

  • Nextflow.config - revision 2.3.1 of the nf-core/smrnaseq pipeline may not be able to identify the location of reference adapter sequences, thus, we will use a local nextflow.config file to tell Nextflow where to find the reference adapters necessary to trim the raw small_RNA-Seq data

Create the metadata file (samplesheet.csv):

Change to the data folder directory:

Code Block
cd $HOME/workshop/2024-2/session4_RNAseq/data/mouse

Copy the bash script to the working folder

Code Block
cp /work/training/2024/rnaseq/scripts/create_samplesheet_nf-core_RNAseq_SEdata.sh $HOME/workshop/2024-2/session4_RNAseq/data/mouse
  • Note: you could replace ‘$HOME/workshop/data’ with “.” A dot indicates ‘current directory’ and will copy the file to the directory where you are currently located

View the content of the script:

Code Block
cat create_samplesheet_nf-core_RNAseq_SEdata.sh

Example for Single-End data (when only ‘Read 1’ is available):

STEP1: copy metadata (samplesheet.csv) into the working folder (run2_RNAseq)

Code Block
cp $HOME/workshop/2024-2/session4_RNAseq/data/mouse/samplesheet.csv $HOME/workshop/2024-2/session4_RNAseq/runs/run2_RNAseq
cd $HOME/workshop/2024-2/session4_RNAseq/runs/run2_RNAseq
  • Line 1: Copy the samplesheet.csv file to the working directory

  • Line 2: move to the working directory

Copy the PBS Pro script to run the nf-core/rnaseq pipeline:

Code Block
cp $HOME/workshop/2024-2/session4_RNAseq/scripts/launch_nf-core_RNAseq_pipeline.pbs $HOME/workshop/2024-2/session4_RNAseq/runs/run2_RNAseq

NOTE: if you had issues with the above lines. Alternatively, run the following code to copy the sample sheet.csv and launch files:

Code Block
cp /work/training/2024/rnaseq/data/samplesheet.csv $HOME/workshop/2024-2/session4_RNAseq/runs/run2_RNAseq
cp /work/training/2024/rnaseq/scripts/launch_nf-core_RNAseq_pipeline.pbs
cd $HOME/workshop/2024-2/session4_RNAseq/runs/run2_RNAseq

Adjusting the Trim Galore (read trimming) options

Print the content of the launch_RNAseq.pbs script:

Code Block
cat launch_nf-core_RNAseq_pipeline.pbs

...

Submitting the job

Code Block
qsub launch_nf-core_RNAseq_pipeline.pbs

Monitoring the Run

Code Block
qjobs

Outputs

The pipeline will produce two folders, one called “work,” where all the processing is done, and another called “results,” where we can find the pipeline's outputs. The content of the results folder is as follows:

The quantification of the gene and transcript expressions can be found in the ‘star_salmon’ directory.

Code Block
cd results/star_salmon

The following feature count tables are generated:

Copying data for hands-on exercises

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Code Block
mkdir -p $HOME/workshop/small_RNAseq/scripts
cp /work/training/smallRNAseq/scripts/* $HOME/workshop/small_RNAseq/scripts/
ls -l $HOME/workshop/small_RNAseq/scripts/
  • Line 1: The -p indicates create 'parental directories as required. Thus the line 1 command creates both /workshop/ and the subfolder /workshop/scripts/

  • Line 2: Copies all files from /work/datasets/workshop/scripts/ as noted by an asterisk to the newly created folder $HOME/workshop/scripts/

  • Line 3: List the files in the script folder

Copy multiple subdirectories and files using rsync

Code Block
mkdir -p $HOME/workshop/small_RNAseq/data/
rsync -rv /work/training/smallRNAseq/data/ $HOME/workshop/small_RNAseq/data/
  • Line 1: The first command creates the folder /scripts/

  • Line 2: rsync copies all subfolders and files from the specified source folder to the selected destination folder. The -r = recursively will copy directories and files; -v = verbose messages of the transfer of files

Create a folder for running the nf-core small RNA-seq pipeline

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Code Block
mkdir -p $HOME/workshop/small_RNAseq
mkdir $HOME/workshop/small_RNAseq/run1_test
mkdir $HOME/workshop/small_RNAseq/run2_smallRNAseq_human
cd $HOME/workshop/small_RNAseq/
  • Lines 1-4: create sub-folders for each exercise

  • Line 5: change the directory to the folder “small_RNAseq”

Exercise 1: Running a test with nf-core sample data

First, let’s assess the execution of the nf-core/rnaseq pipeline by running a test using sample data.

...

Code Block
cat launch_nf-core_smallRNAseq_test.pbs

#!/bin/bash -l

#PBS -N nfsmrnaseq

#PBS -l select=1:ncpus=2:mem=4gb

#PBS -l walltime=24:00:00

#work on current directory (folder)

cd $PBS_O_WORKDIR

#load java and set up memory settings to run nextflow

module load java

export NXF_OPTS='-Xms1g -Xmx4g'

# run the test

nextflow run nf-core/smrnaseq -profile test,singularity --outdir results -r 2.1.0

where:

  • nextflow command: nextflow run

  • pipeline name: nf-core/smrnaseq

  • pipeline version: -r 2.1.0

  • container type and sample data: -profile test,singularity

  • output directory: --outdir results

Submitting the job

Now we can submit the small RNAseq test job to the HPC scheduler:

Code Block
qsub launch_nf-core_smallRNAseq_test.pbs

Monitoring the Run

Code Block
qjobs

Exercise 2: Running the small RNA pipeline using public human data

The pipeline requires preparing at least 2 files:

  • Metadata file (samplesheet.csv) thatspecifies the “sample name” and “location of FASTQ files” ('Read 1').

  • PBS Pro script (launch_nf-core_smallRNAseq_human.pbs) with instructions to run the pipeline

Create the metadata file (samplesheet.csv):

Change to the data folder directory:

...

Code Block
cp /work/training/smallRNAseq/scripts/create_nf-core_smallRNAseq_samplesheet.sh $HOME/workshop/small_RNAseq/data/human
  • Note: you could replace ‘$HOME/workshop/data’ with “.” A dot indicates ‘current directory’ and will copy the file to the directory where you are currently located

View the content of the script:

Code Block
cat create_nf-core_smallRNAseq_samplesheet.sh

#!/bin/bash -l

#User defined variables.

##########################################################

DIR='$HOME/workshop/small_RNAseq/data/human'

INDEX='samplesheet.csv'

##########################################################

#load python module

module load python/3.10.8-gcccore-12.2.0

#fetch the script to create the sample metadata table

wget -L https://raw.githubusercontent.com/nf-core/rnaseq/master/bin/fastq_dir_to_samplesheet.py

chmod +x fastq_dir_to_samplesheet.py

#generate initial sample metadata file

./fastq_dir_to_samplesheet.py  $DIR index.csv \

        --strandedness auto \

        --read1_extension .fastq.gz

#format index file

cat index.csv | awk -F "," '{print $1 "," $2}' > ${INDEX}

#Remove intermediate files:

rm index.csv fastq_dir_to_samplesheet.py

...

Copy the PBS Pro script for running the full small RNAseq pipeline (launch_nf-core_smallRNAseq_human.pbs)

Copy and paste the code below to the terminal:

Code Block
cp $HOME/workshop/small_RNAseq/data/human/samplesheet.csv $HOME/workshop/small_RNAseq/run2_smallRNAseq_human
cp $HOME/workshop/small_RNAseq/scripts/launch_nf-core_smallRNAseq_human.pbs $HOME/workshop/small_RNAseq/run2_smallRNAseq_human
cd $HOME/workshop/small_RNAseq/run2_smallRNAseq_human
  • Line 1: Copy the samplesheet.csv file to the working directory

  • Line 2: copy the launch_nf-core_smallRNAseq_human.pbs submission script to the working directory

  • Line 3: move to the working directory

View the content of the launch_nf-core_RNAseq_QC.pbs script:

Code Block
cat launch_nf-core_smallRNAseq_human.pbs

#!/bin/bash -l

#PBS -N nfsmallRNAseq

#PBS -l select=1:ncpus=2:mem=4gb

#PBS -l walltime=24:00:00

#PBS -m abe

 

#run the tasks in the current working directory

cd $PBS_O_WORKDIR

#load java and assign up to 4GB RAM memory for nextflow to use

module load java

export NXF_OPTS='-Xms1g -Xmx4g'

 

#run the small RNAseq pipeline

nextflow run nf-core/smrnaseq -r 2.1.0 \

        -profile singularity \

        --outdir results \

        --input samplesheet.csv \

        --genome GRCh38-local \

        --mirtrace_species hsa \

        --three_prime_adapter 'TGGAATTCTCGGGTGCCAAGG' \

        --fastp_min_length 18 \

        --fastp_max_length 30 \

        --hairpin /work/training/smallRNAseq/data/mirbase/hairpin.fa \

        --mature /work/training/smallRNAseq/data/mirbase/mature.fa \

        --mirna_gtf /work/training/smallRNAseq/data/mirbase/hsa.gff3 \

        -resume

...

Note: the “mature_counts.csv” needs to be transposed prior running the statistical analysis. This can be done either user the R script or using a script called “transpose_csv.py”.

Let’s initially create a “DESeq2” folder and copy the files needed for the statistical analysis:

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