WEASEL version 2
WEASEL version 2 runs on Macintosh OS X and on Windows PC (or any other system) with Java2 installed. Apart from the standard functions that are expected from current flow cytometry data analysis programs, it has a number of novel features, a few of which are described below. Weasel, configured for Macintosh, Windows PC or other systems, is available for public download. Version 2.7 was released 22July09 and is available at WEASEL Installation.
Weasel users are offered the opportunity of guiding future development of the program. We invite you to comment on and vote for your favourites among the many suggestions for enhancement received from users. Go to "Weasel Development".
Major Enhancements introduced since version 2.0
Population linked displays
This is a method for displaying multi-parameter data by an enhancement of the traditional display formats. Displays are linked by plotting a common, dynamically chosen population in a number of formats and the results are stored as a QuickTime movie.
Pseudo Imaging
In pseudo imaging, the dots of a standard dot plot are replaced by cartoon caricatures or "sprites" or "pseudo images" of the represented cells. Each sprite is circular, of diameter dependent on a selected scaling parameter (usually forward scatter), and coloured with red, green and blue components according to the respective values of up to three parameters (often, but not necessarily, those for reddish, greenish and bluish fluorochromes).
The additive nature of the red, green and blue components is intuitively obvious to most observers who can readily identify yellow as containing red and green components, magenta as red and blue, and cyan as blue and green. Sprites containing all three components are more or less shades of silver-grey, but more subtle colour variations are easily detectable. The 3-component colouring of the example data is shown top centre of the above figure, and its dot sizing at bottom centre. Thus, a 3D pseudo image plot (as shown above right) can potentially display up to 7 measured parameters for each cell; 3-components of colour + dot size + position in 3D.
Curve fitting
While growing out of version1's background subtraction scheme, the fitting is more generally applicable than just for separation of "negatives" from "positives". Several subpopulations can be fitted by analytical functions of the JohnsonSU form as proposed by Lampariello & Aiello (Cytometry 32, 241 '98). To rein in the degrees of freedom, the user may lock any function characteristic in place or require that all subpopulations have identical values of certain characteristics (e.g. skew).
CFSE data fitting
This may be regarded as a special form of the curve fitting feature geared to the enumeration of proliferating cells after staining with CFSE or other tracking dyes. The percentage of cells at each division number post staining is output.
