Dory: a computational method for differential chromatin tracing analysis

• Installation
• Usage
• Output
• Example
• Contact us

Installation

1. Download Dory from GitHub and navigate into the directory:

git clone https://github.com/mzxj/Dory.git && cd Dory

2. Make the bash script executable:

chmod +x Dory

3. To make Dory globally runnable, add its path to your environment's PATH variable. Append export PATH=/path/to/Dory/:$PATH to your ~/.bashrc or ~/.bash_profile. Replace /path/to/Dory with the actual path to the Dory directory. Then reload your shell:

source ~/.bashrc  # or source ~/.bash_profile

4. Install required R packages manually, one by one, for the most reliable setup, including ggplot2, optparse, reshape2, dplyr, data.table, future, parallel, and furrr. Alternatively, you can install all of them automatically using the provided script:

Rscript ./R/install_packages.R

or inside R: source("./R/install_packages.R"). Note: If installation fails for some packages in all of the above methods, please update your R installation to a newer version (R ≥ 4.4 recommended).

Verify installation

Test the Dory is available globally:

Dory -h

You should see the help message printed in your terminal.

Usage

Compare Two Conditions, Cell Types, or Cell States

Dory -m $FileFormat -a $Input1 -b $Input2 -o $OutputPath -c $ChrNum

• -m $FileFormat: (Required) Format of the input data ["4DN" or "csv"].
  • "4DN": If the input data is directly downloaded from the 4DN data portal.
  • "csv": If the input data is standard .csv file. The 3D_coordinates.csv file requires these columns:
    • Trace_ID: The ID for each chromatin trace.
    • X, Y, Z: 3D spatial coordinates of the genomic region.
    • Chrom, Chrom_Start, Chrom_End or Region_ID: Indicate genomic location either by chromosome name, start and end coordinate, or by the genomic region ID (e.g., 1,2, ...). If "Chrom, Chrom_Start Chrom_End" columns are not provided, then the "Region_ID" column is required.
• -a $Input1: (Required). File containing 3D coordinates of genomic regions for foreground condition.
• -b $Input2: (Required). File containing 3D coordinates of genomic regions for background condition.
• -o $OutputPath: (Optional). Output directory path. Defaults to the current directory "./" if not specified.
• -c $ChrNum: (Optional). Number of traced chromosomes ["one" or "more"]. Required if the 3D coordinate file uses "Region_ID" instead of "Chrom, Chrom_Start Chrom_End". Optional otherwise.

Compare Multiple Cell Types (More Than Two)

Dory -m $FileFormat -i $InputCoordFile -l $LabelFile -n $LabelColame -o $OutputPath -c $ChrNum

• -m $FileFormat: (Required) Format of the input data ["4DN" or "csv"].

  • "4DN": If input files are directly downloaded from the 4DN data portal.
  • "csv": If the input data is standard .csv file.
    • The 3D_coordinates.csv file requires these columns:
      • Trace_ID: The ID for each chromatin trace.
      • X, Y, Z: 3D spatial coordinates of the genomic region.
      • Chrom, Chrom_Start, Chrom_End or Region_ID: Indicate genomic location either by chromosome name, start and end coordinate, or by the genomic region ID (e.g., 1,2, ...). If "Chrom, Chrom_Start Chrom_End" columns are not provided, then the "Region_ID" column is required.
      • Cell_ID: The ID for the cell.
    • The cell_label.csv file requires these columns:
      • Cell_ID: The ID for the cell.
      • Cell_Type: The cell-type label or classification assigned to the corresponding cell.

• -i $InputCoordFile: (Required). File containing 3D coordinates of genomic regions for all cells.

• -l $LabelFile: (Optional) File with cell-type labels or classifications for cells. Required if cell-type labels or classifications are not included in the input 3D coordinate file.

• -n $LabelColname: (Optional). The column name for the cell-type label or classification. Defaults to "Cell_Type" if not specified.

• -o $OutputPath: (Optional). Output directory path. Defaults to the current directory "./" if not specified.

• -c $ChrNum: (Optional). Number of traced chromosomes ["one" or "more"]. Required if using "Region_ID" instead of "Chrom, Chrom_Start Chrom_End" in the input 3D coordinate file. Optional otherwise.

Output

If the traced genomic regions are located on one chromosome, the output includes:

• S0_DataInfo

  • Region.tsv: Contains traced genomic regions with columns for Chrom, Chrom_Start, Chrom_End and Region_ID.
  • TraceCount.pdf: Displays the number of traces for each condition.

• S1_Distance

  • RegionPairByTrace_CT_x.tsv: The Euclidean distances between region pairs (rows) across all chromatin traces (columns) for each condition (CT_x).

• S2_DiffScore

  • DiffScore_CT_xVSCT_y.tsv: The lower triangle of the DiffScore matrix generated by Dory for comparing condition CT_x (foreground) with CT_y (background). A positive DiffScore indicates that the region pair distance is greater in CT_x than in CT_y; while a negative DiffScore indicates the opposite.
  • DiffScoreHeatmap_CT_xVSCT_y.pdf/.png: The heatmap visualization of the DiffScore matrix.
  • DRP_greater_CT_xVSCT_y.tsv: The significantly differential (p < 0.05) region pairs with greater distance in CT_x than in CT_y. Region pairs are ranked according to their DiffScore values.
  • DRP_less_CT_xVSCT_y.tsv: The significantly differential (p < 0.05) region pairs with less distance in CT_x than in CT_y. Region pairs are ranked according to their DiffScore values.

  Note: These DRP lists are defined using the most relaxed significance threshold (p < 0.05). For a more stringent selection, users may choose the top-ranked region pairs from these lists based on DiffScore.

Special Case: Multiple Chromosomes

If the traced genomic regions span multiple chromosomes, the output directory structure changes slightly:

• Because Dory performs intra-chromosomal analysis, the results are separated by chromosome (Chrom).
• Each main output folder (S0_DataInfo, S1_Distance and S2_DiffScore) contains subdirectories named "chr_Chrom" (e.g., chr_chr1, chr_chr2, etc.), corresponding to each chromosome.
• Each "chr_Chrom" subdirectory contains the same types of output files as described above, but limited to the genomic regions on corresponding chromosome.

Example

Using the two datasets 4DNFIHSXQZIV.csv and 4DNFITZBMT6Q.csv downloaded from the 4DN data portal as an example. Both files are located in the folder tests.

Dory -m 4DN -a /path/to/4DNFIHSXQZIV.csv -b /path/to/4DNFITZBMT6Q.csv -o output/to/path 

Contact us

For any questions regarding Dory, please contact Zhaoxia Ma (prm2zt@virginia.edu).