Workflow

A simple workflow is described in the following for measuring subcellular localizations of organelle by the distance from the nucleus. For example, you can quantify how far some type of vesicles or protein aggregates are apart from the nucleus border. This workflow is for analyzing 3D data.

Data requirements:

• 3D data, 2 channels
• Channel 1: nucleus stain = Channel 2: stain for marker you want to quantify the distance to nucleus for

Workflow:

1. Nucleus detection: Imaris

• Add a new SURFACE object, name it "nuclei"
• Follow the object detection wizard to segment nucleus objects

2. Marker object detection: Imaris

• Add a new SURFACE object
• Follow the object detection wizard to segment nucleus objects

3. Creating of distance map channel: Imaris

• In the image processing menu, go to SurfacesFunctions>>Distance Transformation

4. MATLAB:

• select nucleus objects and "distance outside objects"
• A new image channel should be created now by the Matlab script

5. Distance measurement

• The generated distance map channel represents the distance from the nucleus border in pixel values. Thus, the distance of an organelle from the nucleus is equivalent to its mean gray value of the distance map channel.
  For distance measurement, just export the mean gray value of the distance channel for each object.

** Please note:**
In the described workflow, the distance is always calculated to the closest nucleus border. This could be also the nucleus of a neighboring cell, which generates some error. A more complex approach to avoid this error would incorporate a cell segmentation step to assign certain organelle objects to certain cells. Therefore, a cell region marker is needed.

This protocol first extracts the cell nuclei from a given fluorescence channel (full labeling), and grows a contour from each nucleus to extract the cell edge in another fluorescence channel (membrane-labeling).

The original paper describes a method to analyze mitochondrial morphology in 2D and 3D.

The goal of this workflow is to track cells captured in a time-lapse movie of a syncytial blastoderm stage Drosophila embryo and quantify their movement.

This example shows an example of object tracking. This pipeline analyzes a time-lapse experiment to identify the cells and track them from frame to frame, which is challenging since the cells are also moving. In addition, this pipeline also extracts metadata from the filename and uses groups the images by metadata in order to independently process several sequences of images and output the measurements of each.

Sample images

A portion of a time lapse movie of a syncytial blastoderm stage Drosophila embryo with a GFP-histone gene which renders chromatin fluorescent in live embryos. The movie shows nuclear divisions 10 through 13.

Victoria Foe made this movie on a Bio-Rad Radiance 2000 laser scanning confocal microscope using a 40X 1.3NA oil objective. The frames are 7 seconds apart and plays at 30 frames per second

GFP-histone transformed files provided by Rob Saint

V.Foe and G.Odell, . 26 July 2001