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HALO - Precise transcript half-life determination in Java
Recent improvements in experimental technologies for metabolic tagging and isolation of newly transcribed RNA now allow combined measurements of de novo transcription and RNA decay at whole transcriptome level in a single experimental setting.
Thus, transcript half-lives can be determined with a so far unreached accuracy. As several studies have shown, such transcript half-lives provide important insights into the regulation of biological processes on a much more general level than individual measurements of differential gene expression. In this article, we present HALO, the first software for the precise determination of transcript half-lives from measurements of RNA de novo transcription. In addition, methods for quality control, filtering and normalization are supplied. HALO provides a graphical user interface, command line tools and a well-documented Java API. Thus, it can be used both by biologists to determine transcript half-lives fast and reliably with the user interfaces provided as well as software developers integrating transcript half-life analysis into other gene expression profiling pipelines.
HALO is freely available to all academic users
First steps
For all user interfaces the functions of HALO are described in the documentation on a step-by-step basis for an example use case (half-lives in mouse fibroblasts) [see use case documentation for GUI , commandline version and Java API ].
The data for this use case can be downloaded together with the HALO distribution or separately (see Downloads ).
Alternatively you can test the GUI (e.g. using the Java Webstart version available below) with an example session which automatically performs the most important steps with HALO. Simply download the session from the Download section and load it by choosing the Load session option from the Session menu in the top left of the GUI. All steps will then be performed automatically and you only need to decide whether to save plots and plotting information or not. Note: After loading the session, it may take a few moments until you see the result.
Thus, the easiest way to get familiar with HALO (after installing it or using the webstart version) is to follow this step-by-step introductions or load the example session.
Downloads
Current release version: 1.3
We provide packages containing both the HALO program files and a set of example data files as well as packages
containing only the program or data files. Furthermore, source code and HTML documentation as well as necessary library files (JFreeChart) are supplied with the program files.
Webstart
You can directly start the HALO graphical user interface from within your webbrowser if
Java Webstart is installed on your system. The Webstart version does not contain any data files. These can be downloaded from the Download section above.
To test HALO using the Webstart version you can either
load an example session which automatically performs the most important steps with HALO. Simply download the session from the Download section and load it by choosing the Load session option from the Session menu on the top left of the GUI. All steps will then be performed automatically and you only need to decide whether to save plots and plotting information or not. Note: After loading the session, it may take a few moments until you see the result.
or follow the step-by-step instruction for the GUI . The necessary datafiles are available at the Download section.
Webstart automatically ensures that you run the latest version of HALO and that the correct Java Runtime Environment is installed on your computer.
Note: The webstart version uses a maximum heap size of 500MB (available RAM). If you want to analyze larger datasets than provided in the Example file, this may not be sufficient. In this case, please download the GUI and set the maximum heapsize according to your needs using the -Xmx option (see README.txt).
Note for firewall users: Please make sure that the Java Web Start application is allowed to access the internet.
How to use R in HALO for transcript length bias correction
HALO uses R for the correction of a transcript length bias. For this purpose, R needs to be installed. You can download R from
http://www.r-project.org/ . To Use R within HALO, the executable program must be in the PATH of your system environment. Alternatively, you can specify the location of the R binaries in the user interfaces.
Documentation
The HALO HTML documentation is available
online and also included in the download packages below.
Contact
If you have questions or suggestions concerning HALO, please contact Caroline Friedel .
References
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