CamoTSS 0.1.3

CamoTSS: Detection alternative TSS in single cells

Installation

You can install from this GitHub repository for latest (often development) version by following command line

pip install -U git+https://github.com/StatBiomed/CamoTSS

In either case, add --user if you don’t have the write permission for your Python environment.

Quick start

Download test file

You can download test file from onedrive.

Run CamoTSS

STEP1: Processing

CamoTSS mainly deal with the output from cellranger (a common alignment tool for 10x data).

The preprocessing procedure based on the output file of cellranger.

1. cd /cellranger_out/outs
2. samtools view  possorted_genome_bam.bam | LC_ALL=C grep "xf:i:25" > body_filtered_sam
3. samtools view -H possorted_genome_bam.bam > header_filted_sam
4. cat header_filted_sam body_filtered_sam > possorted_genome_bam_filterd.sam
5. samtools view -b possorted_genome_bam_filterd.sam > possorted_genome_bam_filterd.bam
6. samtools index possorted_genome_bam_filterd.bam possorted_genome_bam_filterd.bam.bai

STEP2: Run CamoTSS

CamoTSS --gtf $gtfFile --refFastq $fastFile --bam $possorted_genome_bam_filterd.bam -c $cluster_toscTSS.tsv  -o $output_fileFold --mode Unannotation

Want to learn about more parameter, you can use CamoTSS --help to check.

You can find out the example file in the test folder. Please make sure you also have the same column name.

Here, you can select one of the mode from “Unannotation” and “Unannotation_addCTSS”.

Unannotation means that you can detect novel TSS cluster.

Unannotation_addCTSS means that you can detect CTSS within one cluster.

You can check our paper to learn more detail.

Multiple samples preprocessing

For most public single cell data, we can obtain the whole annotation of cell type from different samples.

The sample ID information always show at the cell barcode for each cell.

In order to fully use the annotation described above, we can run cellranger count for each sample independently.

Then manually add sample information to the cell barcode. We can implement it by using following script.

import pysam
inputbamfile=$home+'/cellranger_out/outs/manual_filter/possorted_genome_bam_filterd.bam'
outputbamfile=$home+'/cellranger_out/outs/manual_filter/possorted_genome_bam_filterd_add_suffix.bam'
inputbam=pysam.Samfile(inputbamfile,'rb')
outputbam=pysam.Samfile(outputbamfile,'wb',template=inputbam)
for read in inputbam.fetch():
        cb=read.get_tag('CB')
        assert cb is not None
        cbfix=cb.replace('-1',"")
        cbfix=cbfix+'-sampleID'
        read.set_tag('CB',cbfix)
        outputbam.write(read)
inputbam.close()
outputbam.close()

Then the bam file with changed cellbarcode can be merged with samtools merge

samtools merge $merged_bam -b $bamlist.fofn --write-index

Alternative TSS or CTSS detecting

In CamoTSS, one of output files is Tobrie.h5ad which can be as input to Brie.

To identify alternative TSS usage or alternative CTSS usage, Brie2 (Huang & Sanguinetti, 2021) is recommend to be used.

For more information, please check https://brie.readthedocs.io/en/latest/