Introduction

sanger-tol/ensemblrepeatdownload is a pipeline that downloads repeat annotations from Ensembl into a Tree of Life directory structure.

The pipeline is built using Nextflow, a workflow tool to run tasks across multiple compute infrastructures in a very portable manner. It uses Docker/Singularity containers making installation trivial and results highly reproducible. The Nextflow DSL2 implementation of this pipeline uses one container per process which makes it much easier to maintain and update software dependencies. Where possible, these processes have been submitted to and installed from nf-core/modules in order to make them available to all nf-core pipelines, and to everyone within the Nextflow community!

On release, automated continuous integration tests run the pipeline on a full-sized dataset on the GitHub CI infrastructure. This ensures that the pipeline runs in a third-party environment, and has sensible resource allocation defaults set to run on real-world datasets.

Pipeline summary

Overview

The pipeline takes a CSV file that contains assembly accession number, Ensembl species names (as they may differ from Tree of Life ones !), output directories. Assembly accession numbers are optional too. If missing, the pipeline assumes it can be retrieved from files named ACCESSION in the standard location on disk. The pipeline downloads the repeat annotation as the masked Fasta file and a BED file. All files are compressed with bgzip, and indexed with samtools faidx or tabix.

Steps involved:

• Download the masked fasta file from Ensembl.
• Extract the coordinates of the masked regions into a BED file.
• Compress and index the BED file with bgzip and tabix.

Quick Start

1. Install Nextflow (>=22.04.0)

2. Install any of Docker, Singularity (you can follow this tutorial), Podman, Shifter or Charliecloud for full pipeline reproducibility (you can use Conda both to install Nextflow itself and also to manage software within pipelines. Please only use it within pipelines as a last resort; see docs).

3. Download the pipeline and test it on a minimal dataset with a single command:

   nextflow run sanger-tol/ensemblrepeatdownload -profile test,YOURPROFILE --outdir 
   

   Note that some form of configuration will be needed so that Nextflow knows how to fetch the required software. This is usually done in the form of a config profile (YOURPROFILE in the example command above). You can chain multiple config profiles in a comma-separated string.

   • The pipeline comes with config profiles called docker, singularity, podman, shifter, charliecloud and conda which instruct the pipeline to use the named tool for software management. For example, -profile test,docker.
   • Please check nf-core/configs to see if a custom config file to run nf-core pipelines already exists for your Institute. If so, you can simply use -profile in your command. This will enable either docker or singularity and set the appropriate execution settings for your local compute environment.
   • If you are using singularity, please use the nf-core download command to download images first, before running the pipeline. Setting the NXF_SINGULARITY_CACHEDIR or singularity.cacheDir Nextflow options enables you to store and re-use the images from a central location for future pipeline runs.
   • If you are using conda, it is highly recommended to use the NXF_CONDA_CACHEDIR or conda.cacheDir settings to store the environments in a central location for future pipeline runs.

4. Start running your own analysis!

   nextflow run sanger-tol/ensemblrepeatdownload --input $PWD/assets/samplesheet.csv --outdir  -profile 
   

Documentation

The sanger-tol/ensemblrepeatdownload pipeline comes with documentation about the pipeline usage and output.

Credits

sanger-tol/ensemblrepeatdownload was originally written by @muffato.

Contributions and Support

If you would like to contribute to this pipeline, please see the contributing guidelines.

For further information or help, don't hesitate to get in touch on the Slack #pipelines channel. Please create an issue on GitHub if you are not on the Sanger slack channel.

Citations

If you use sanger-tol/ensemblrepeatdownload for your analysis, please cite it using the following doi: 10.5281/zenodo.7183380

An extensive list of references for the tools used by the pipeline can be found in the CITATIONS.md file.

This pipeline uses code and infrastructure developed and maintained by the nf-core community, reused here under the MIT license.

The nf-core framework for community-curated bioinformatics pipelines.

Philip Ewels, Alexander Peltzer, Sven Fillinger, Harshil Patel, Johannes Alneberg, Andreas Wilm, Maxime Ulysse Garcia, Paolo Di Tommaso & Sven Nahnsen.

Nat Biotechnol. 2020 Feb 13. doi: 10.1038/s41587-020-0439-x.