tracyspot

Tracy

Note: Tracy is still in beta

• Install
• Getting started
  • Start Tracy
  • Load your movie
  • Browse spots
  • Generate kymographs
  • Generate trajectories
  • Browse trajectories
  • Modify points
• Additional features
  • Drift correction
  • Colocalization
  • Custom column
  • Color by value
• Save & Load
  • Save trajectories
  • Load trajectories
  • Load TrackMate data
• License

Install

• Open your terminal
  • Mac: just open Terminal
  • Windows: install Anaconda and use the Anaconda prompt as the terminal
• conda create -n tracy python=3.10 -y
• conda activate tracy
• pip install tracyspot

Getting started

Start Tracy

• Open your terminal
• conda activate tracy if not already active
• pip install tracyspot --upgrade always update while tracy is in beta
• tracy & it might be slow to open the first time

Load your movie

• Click Load Movie (also in the Load menu)
• Choose any single- or multi-channel movie (.tif format)
• If the pixel size and frame interval could not be loaded from the metadata, you will be prompted to enter them
• Click and drag using the middle button to pan (or Ctrl + left click / Cmd + left click) and middle wheel scroll to zoom
• Once loaded, toggle between channels by clicking the channel label (shortcut: 1, 2, etc.)
• The maximum projection can be shown by toggling it under the movie (shortcut: m)
• Adjust the contrast using the contrast slider

Browse spots

• Click on the movie to find a spot using the click position as the search center
  • The blue square marks the search area around the center
  • The magenta circle marks the spot that was found (the circle radius is 2 standard deviations)
• Hover over the top-right inset to see a 3D representation of the fit (scroll to zoom, click and drag to rotate)
• You can modify the search radius by holding down the r key and scrolling (or in the Spot menu)
• Use the slider under the movie to browse frames

Generate kymographs

• To generate a kymograph, enter Line mode using the switch under the movie (shortcut: n)
• Optionally, look at the maximum-projection (shortcut: m) to better see where you should draw lines
• Draw the segmented line by placing green anchors on the movie (Escape cancels a sequence)
• Double-click to complete the sequence and generate a kymograph
• If your movie has multiple channels, a kymograph will be generated for each, which will show when you toggle between channels (shortcut: 1, 2, etc.)
• You can use the , and . keys to quickly go to the previous or next kymograph, respectively

Generate trajectories

• To track a spot in the movie using the kymograph as a reference, draw a segmented line by placing blue anchors on the kymograph (Escape cancels a sequence)

• Double-click to complete the sequence to generate a trajectory, where spot centers are searched in the movie from the linear interpolation between clicks using the currently set search radius and tracking mode (see below)

• Optionally, press the space bar to play a movie of the trajectory

• Assess the plots

  • The spot histogram shows the pixel intensities in the search range around the spot center and highlights the intensities within the spot
  • The intensity plot shows each spot's integrated intensity
  • The speed histogram shows the frame-to-frame speeds of the spots and overlay sthe net speed (only considering the start and end point)

• If necessary, modify the search radius (hold down r and scroll) and recalculate the trajectory (Enter key or in the Trajectory menu)

• If necessary, toggle between tracking mode with the t key and recalculate the trajectory (Enter key or in the Trajectory menu)

  • Independent: each frame is treated independently using the search center from the interpolated line
  • Tracked: each frame's search center is based on the previous frame's spot center
  • Smooth: equivalent to Independent mode but goes through a filtering step at the end to remove spots that are far off the main track

• Click any point in the kymograph or in the intensity plot to jump to that point, or browse sequentially with the arrow keys (→, ←)

  !! Trajectories do not belong to kymographs, and their presence within one is determined on-the-fly for visualisation

Browse trajectories

• Adding trajectories will append the data to the trajectory table, which can be clicked or selected with the arrow keys (↑, ↓)
• Right click a trajectory in the table to show some helpful options, like Go to kymograph ch1-001
• The backspace key removes the selected trajectory(ies)

Modify points

• When a point is highlighted, use the X key to either invalidate the spot or re-attempt a fit if it is already invalid

Additional features

Drift correction

• If your movie drifts, find a spot that is present throughout the movie and is stationary
• Click the spot (any frame) and make sure it has been found (magenta circle)
• In the Movie menu, click Correct Drift, which will track the spot to the beginning and end of the movie and apply a shift to each frame accordingly
• Check the result in the pop-up and save/load the movie if acceptable

Colocalization

• If your movie has multiple channels, colocalization with other channels can be toggled on under the Spot menu
• If trajectories are already available that have not had their colocalization analysed, it will prompt to analyse them
• New columns will show up in the table representing the percentage of spots within a trajectory that are colocalized
• As long as the colocalization option is toggled, every subsequent trajectory will have its colocalization analysed
• Colocalization is determined by performing a search using the same spot center coordinates but in a different channel, and marking as colocalized if a spot is found within 4 pixels of the original spot center coordinate

Custom columns

• Right click on any column header to show the options for column types to add (also in the Trajectories menu)
  • Binary column: adds a column composed of Yes/No, which can be assiged to each trajectory
  • Value column: adds a column that can hold any value, which can be assiged to each trajectory
• After adding a column, right click on a trajectory in the table or on any trajectory label in the kymograph to either Mark as X or Set X, respectively
• Optionally, colour by this value (see [below])

Color by value

• All data can be coloured by binary, value, or colocalization values under the Trajectories menu

Save & Load

Save trajectories

• Save trajectories in the Save menu, which saves an excel file with three sheets

  • Data points: All spots and their corresponding data
  • Per-trajectory: Data corresponding to individual trajectories
  • Per-kymograph: Analysis of points belonging to the same kymograph

  !! Make sure two kymographs do not contain the same trajectory or the Per-kymograph statistics will be wrong

• You do not need to save kymographs or line ROIs along with trajectories since the clicks you used to build them are embedded in the trajectories. Use Draw from trajectories in the Kymograph menu to redraw them after loading trajectories.

Load trajectories

• Trajectories can be loaded back as they were saved by Tracy (.xlsx file) or any similar file with a Data Points sheet with at least Trajectory, Channel, Frame, Search Center X, and Search Center Y (it will recalculate trajecotires when spot centers are missing in this case)
• You do not need to save kymographs or line ROIs along with trajectories since the clicks you used to build them are embedded in the trajectories. Use Draw from trajectories in the Kymograph menu to redraw them after loading trajectories.

Load TrackMate data

• TrackMate data (.csv) can be loaded using the same Load trajectories option, which will trigger a calculation using the TrackMate spot data ("TRACK_ID", "FRAME", "POSITION_X", "POSITION_Y") as search centers, generating a Tracy trajectory for each TrackMate track

License

This project is licensed under the MIT License - see the LICENSE.txt file for details.