
                                EMBOSS: cai
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                                  Program cai
                                       
Function

   CAI codon adaptation index
   
Description

   cai calculates the Codon Adaptation Index. This is a simple, effective
   measure of synonymous codon usage bias.
   
   The index uses a reference set of highly expressed genes from a
   species to assess the relative merits of each codon, and a score for a
   gene is calculated from the frequency of use of all codons in that
   gene. The index assesses the extent to which selection has been
   effective in moulding the pattern of codon usage. In that respect it
   is useful for predicting the level of expression of a gene, for
   assessing the adaptation of viral genes to their hosts, and for making
   comparisons of codon usage in different organisms. The index may also
   give an approximate indication of the likely success of heterologous
   gene expression.
   
Usage

   Here is a sample session with cai:
   
% cai embl:AB009602
CAI codon adaptation index
Codon usage file [Eyeastcai.cut]:
Output file [ab009602.cai]:

Command line arguments

   Mandatory qualifiers:
  [-seqall]            seqall     Sequence database USA
   -cfile              codon      Codon usage file
  [-outfile]           outfile    Output file name

   Optional qualifiers: (none)
   Advanced qualifiers: (none)
   General qualifiers:
  -help                bool       report command line options. More
                                  information on associated and general
                                  qualifiers can be found with -help -verbose
   

   Mandatory qualifiers Allowed values Default
   [-seqall]
   (Parameter 1) Sequence database USA Readable sequence(s) Required
   -cfile Codon usage file Codon usage file in EMBOSS data path
   Eyeastcai.cut
   [-outfile]
   (Parameter 2) Output file name Output file <sequence>.cai
   Optional qualifiers Allowed values Default
   (none)
   Advanced qualifiers Allowed values Default
   (none)
   
Input file format

   cai reads a nucleic acid sequence of a gene.
   
Output file format

   cai writes the Codon Adaptation Index to the output file.
   
   The output from the above example follows:
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CAI = 0.188
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Data files

   cai reads a reference codon usage table prepared from a set of genes
   which are known to be highly expressed.
   
   The default codon usage table 'Eyeastcai.cut' was prepared from a set
   of S. pombe genes by Peter Rice.
   
   You should prepare your own codon usage table for your organism of
   interest.
   
   EMBOSS data files are distributed with the application and stored in
   the standard EMBOSS data directory, which is defined by the EMBOSS
   environment variable EMBOSS_DATA.
   
   To see the available EMBOSS data files, run:
   
% embossdata -showall

   To fetch one of the data files (for example 'Exxx.dat') into your
   current directory for you to inspect or modify, run:

% embossdata -fetch -file Exxx.dat

   Users can provide their own data files in their own directories.
   Project specific files can be put in the current directory, or for
   tidier directory listings in a subdirectory called ".embossdata".
   Files for all EMBOSS runs can be put in the user's home directory, or
   again in a subdirectory called ".embossdata".
   
   The directories are searched in the following order:
     * . (your current directory)
     * .embossdata (under your current directory)
     * ~/ (your home directory)
     * ~/.embossdata
       
Notes

   None.
   
References

   Sharp PM., Li W-H. "The codon adaptation index - a measure of
   directional synonymous codon usage bias, and its potential
   applications." Nucleic Acids Research 1987 vol 15, pp 1281-1295.
   
Warnings

   None.
   
Diagnostic Error Messages

   None.
   
Exit status

   It always exits with status 0.
   
Known bugs

   None.
   
See also

   Program name                  Description
   chips        Codon usage statistics
   codcmp       Codon usage table comparison
   cusp         Create a codon usage table
   syco         Synonymous codon usage Gribskov statistic plot
   
Author(s)

   This application was written by Alan Bleasby (ableasby@hgmp.mrc.ac.uk)
   
History

   Written (March 2001) - Alan Bleasby.
   
Target users

   This program is intended to be used by everyone and everything, from
   naive users to embedded scripts.
   
Comments
