MAGMA: analysis of two-channel microarrays made easy - PubMed (original) (raw)

. 2007 Jul;35(Web Server issue):W86-90.

doi: 10.1093/nar/gkm302. Epub 2007 May 21.

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MAGMA: analysis of two-channel microarrays made easy

Hubert Rehrauer et al. Nucleic Acids Res. 2007 Jul.

Abstract

The web application MAGMA provides a simple and intuitive interface to identify differentially expressed genes from two-channel microarray data. While the underlying algorithms are not superior to those of similar web applications, MAGMA is particularly user friendly and can be used without prior training. The user interface guides the novice user through the most typical microarray analysis workflow consisting of data upload, annotation, normalization and statistical analysis. It automatically generates R-scripts that document MAGMA's entire data processing steps, thereby allowing the user to regenerate all results in his local R installation. The implementation of MAGMA follows the model-view-controller design pattern that strictly separates the R-based statistical data processing, the web-representation and the application logic. This modular design makes the application flexible and easily extendible by experts in one of the fields: statistical microarray analysis, web design or software development. State-of-the-art Java Server Faces technology was used to generate the web interface and to perform user input processing. MAGMA's object-oriented modular framework makes it easily extendible and applicable to other fields and demonstrates that modern Java technology is also suitable for rather small and concise academic projects. MAGMA is freely available at www.magma-fgcz.uzh.ch.

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Figures

Figure 1.

Figure 1.

Structural representation of MAGMA's architecture. MAGMA implements the Model-View-Controller paradigm and has the HTML pages (View), the rules for the HTML page flow (Controller) and the actual data processing (Model) decoupled. This allows for independent modification or extension of MAGMA.

Figure 2.

Figure 2.

MAGMA's result navigation panel. For each analyzed experiment, the results are organized in an explorer-like hierarchy. Each folder of the tree represents a single processing step and clicking on it, displays the corresponding result in the lower part of the page. More processing steps can be added after the current processing step by selecting a step from the Next box.

Figure 3.

Figure 3.

Graphs visualizing diagnostic statistics. In the example, the percentage of flagged and negative probes as well as the median log ratio is shown for six uploaded arrays. These overview plots allow for the identification of outliers as well as general trends.

Figure 4.

Figure 4.

Result of a statistical analysis that included two comparisons. Each comparison is shown as a row with two plots. The first plot shows the number of significantly differentially expressed genes (red) selected using the current _P_-value threshold and compares it to results expected from random data. The second figure shows a Volcano plot displaying the _P_-values and fold changes of all genes with significant genes highlighted in red. The results can be retrieved in tabular form from the links in the rightmost column.

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