jbrowse-plugin-mafviewer

A viewer for multiple alignment format (MAF) files in JBrowse 2

This is a port of the JBrowse 1 plugin https://github.com/cmdcolin/mafviewer to JBrowse 2

Demo

https://jbrowse.org/code/jb2/main/?config=%2Fdemos%2Fmaf%2Fhg38%2Fdistconfig.json&session=share-bJXbDiWcc9&password=87GhV

GUI usage (e.g. in JBrowse Desktop)

This short screenshot workflow shows how you can load your own custom MAF files via the GUI

First install the plugin via the plugin store

Then use the custom "Add track workflow"

Manual config entry

Add plugin to your jbrowse 2 config.json

{
  "plugins": [
    {
      "name": "MafViewer",
      "url": "https://unpkg.com/jbrowse-plugin-mafviewer/dist/jbrowse-plugin-mafviewer.umd.production.min.js"
    }
  ]
}

Example MafTabixAdapter config

can use nhLocation or samples array on adapter

{
  "type": "MafTrack",
  "trackId": "chrI.bed",
  "name": "chrI.bed",
  "adapter": {
    "type": "MafTabixAdapter",
    "samples": ["ce10", "cb4", "caeSp111", "caeRem4", "caeJap4", "caePb3"],
    "bedGzLocation": {
      "uri": "chrI.bed.gz"
    },
    "index": {
      "location": {
        "uri": "chrI.bed.gz.tbi"
      }
    }
  },
  "assemblyNames": ["c_elegans"]
}

Example BigMafAdapter config

can use nhLocation or samples array on adapter

{
  "type": "MafTrack",
  "trackId": "bigMaf",
  "name": "bigMaf (chr22_KI270731v1_random)",
  "adapter": {
    "type": "BigMafAdapter",
    "samples": [
      "hg38",
      "panTro4",
      "rheMac3",
      "mm10",
      "rn5",
      "canFam3",
      "monDom5"
    ],
    "bigBedLocation": {
      "uri": "bigMaf.bb"
    }
  },
  "assemblyNames": ["hg38"]
}

Example with customized sample names and colors

{
  "trackId": "MAF",
  "name": "example",
  "type": "MafTrack",
  "assemblyNames": ["hg38"],
  "adapter": {
    "type": "MafTabixAdapter",
    "bedGzLocation": {
      "uri": "data.txt.gz"
    },
    "index": {
      "location": {
        "uri": "data.txt.gz.tbi"
      }
    },
    "samples": [
      {
        "id": "hg38",
        "label": "Human",
        "color": "rgba(255,255,255,0.7)"
      },
      {
        "id": "panTro4",
        "label": "Chimp",
        "color": "rgba(255,0,0,0.7)"
      },
      {
        "id": "gorGor3",
        "label": "Gorilla",
        "color": "rgba(0,0,255,0.7)"
      },
      {
        "id": "ponAbe2",
        "label": "Orangutan",
        "color": "rgba(255,255,255,0.7)"
      }
    ]
  }
}

The samples array is either string[]|{id:string,label:string,color?:string}[]

Creating MAF files as Cactus pangenome/HAL

You can create a MAF file from a Cactus pangenome graph using ComparativeGenomeToolkit

This page discusses some examples

https://github.com/ComparativeGenomicsToolkit/cactus/blob/master/doc/progressive.md#maf-export

Thanks to Sam Talbot (https://github.com/SamCT) for initially creating the Cactus -> JBrowse 2 MAF example

Please note that MAFViewer wants non-overlapping blocks, please check if this is the case

Prepare data

1. BigMaf format, which can be created following UCSC guidelines (https://genome.ucsc.edu/FAQ/FAQformat.html#format9.3)

2. MAF tabix based format, based on a custom BED created via conversion tools in this repo (see maf2bed)

Note: All these formats generally start with a MAF as input. Note that your MAF file should contain the species name and chromosome name e.g. hg38.chr1 in the sequence identifiers.

Option 1. Preparing BigMaf

Follow instructions from https://genome.ucsc.edu/FAQ/FAQformat.html#format9.3

Option 2. Preparing MAF tabix

Start by converting the MAF into a pseudo-BED format using the maf2bed tool

# from https://github.com/cmdcolin/maf2bed
cargo install maf2bed
cat file.maf | maf2bed hg38 | sort -k1,1 -k2,2n | bgzip > out.bed.gz
tabix out.bed.gz

The second argument to maf2bed is the genome version e.g. hg38 used for the main species in the MAF (if your MAF comes from a pipeline like Ensembl or UCSC, the identifiers in the MAF file will say something like hg38.chr1, therefore, the argument to maf2bed should just be hg38 to remove hg38 part of the identifier.

If your MAF file does not include the species name as part of the identifier, you should add the species into them the those scaffold/chromosome e.g. create hg38.chr1 if it was just chr1 before)

If all is well, your BED file should have 6 columns, with chr, start, end, id, score, alignment_data, where alignment_data is separated between each species by ; and each field in the alignment is separated by :.

Note: If you can't use the cargo install maf2bed binary, there is a bin/maf2bed.pl perl version of it in this repo