/ 
BioPerl-Run-1.007003
River stage one • 2 direct dependents • 2 total dependents
/ Bio::Tools::Run::Phylo::Phast::PhastCons

NAME

Bio::Tools::Run::Phylo::Phast::PhastCons - Wrapper for footprinting using phastCons

SYNOPSIS

use Bio::Tools::Run::Phylo::Phast::PhastCons;

# Make a PhastCons factory
$factory = Bio::Tools::Run::Phylo::Phast::PhastCons->new();

# Pass the factory an alignment and the corresponding species tree
$align_filename = 't/data/apes.multi_fasta';
$species_tree_filename = 't/data/apes.newick';
@features = $factory->run($align_filename, $species_tree_filename);

# or get a Bio::Align::AlignI (SimpleAlign) object from somewhere, and
# generate the species tree automatically using a Bio::DB::Taxonomy database
$tdb = Bio::DB::Taxonomy->new(-source => 'entrez');
@features = $factory->run($aln_obj, $tdb);

# @features is an array of Bio::SeqFeature::Annotated, one feature per
# alignment sequence and prediction

DESCRIPTION

This is a wrapper for running the phastCons application by Adam Siepel. You can get details here: http://compgen.bscb.cornell.edu/~acs/software.html phastCons is used for phylogenetic footprinting/ shadowing.

Currently the interface is extremely simplified, allowing only one analysis method. The focus here is on ease of use, allowing phastCons to estimate as many parameters as possible and having it output just the 'most conserved' blocks it detects. You can, however, try supplying normal phastCons arguments to new(), or calling arg-named methods (excluding initial hyphens and converting others to underscores, eg. $factory->indels_only(1) to set the --indels-only arg).

The particular analysis carried out here is to:

1. Use phyloFit to generate a tree model for initialization of the nonconserved
   model from the supplied alignment (all data) and species tree
2. Run phastCons in 'training' mode for parameter estimation using all the
   alignment data and the model from step 1
3. Run phastCons with the trees from step 2 to discover the most conserved
   regions

See the 'HowTo' at http://compgen.bscb.cornell.edu/~acs/phastCons-HOWTO.html for details on how to improve results.

WARNING: the API is likely to change in the future to allow for alternative analysis types.

You will need to enable this phastCons wrapper to find the phast programs (at least phastCons and phyloFit). This can be done in (at least) three ways:

1. Make sure the phastCons and phyloFit executables are in your path.
2. Define an environmental variable PHASTDIR which is a 
   directory which contains the phastCons and phyloFit applications:
   In bash:

   export PHASTDIR=/home/username/phast/bin

   In csh/tcsh:

   setenv PHASTDIR /home/username/phast/bin

3. Include a definition of an environmental variable PHASTDIR in
   every script that will use this PhastCons wrapper module, e.g.:

   BEGIN { $ENV{PHASTDIR} = '/home/username/phast/bin' }
   use Bio::Tools::Run::Phylo::Phast::PhastCons;

FEEDBACK

Mailing Lists

User feedback is an integral part of the evolution of this and other Bioperl modules. Send your comments and suggestions preferably to the Bioperl mailing list. Your participation is much appreciated.

bioperl-l@bioperl.org                  - General discussion
http://bioperl.org/wiki/Mailing_lists  - About the mailing lists

Support

Please direct usage questions or support issues to the mailing list:

bioperl-l@bioperl.org

rather than to the module maintainer directly. Many experienced and reponsive experts will be able look at the problem and quickly address it. Please include a thorough description of the problem with code and data examples if at all possible.

Reporting Bugs

Report bugs to the Bioperl bug tracking system to help us keep track of the bugs and their resolution. Bug reports can be submitted via the web:

http://redmine.open-bio.org/projects/bioperl/

AUTHOR - Sendu Bala

Email bix@sendu.me.uk

APPENDIX

The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _

program_name

Title   : program_name
Usage   : $factory>program_name()
Function: holds the program name
Returns : string
Args    : None

program_dir

Title   : program_dir
Usage   : $factory->program_dir(@params)
Function: returns the program directory, obtained from ENV variable.
Returns : string
Args    : None

new

Title   : new
Usage   : $factory = Bio::Tools::Run::Phylo::Phast::PhastCons->new(@params)
Function: Creates a new PhastCons factory
Returns : Bio::Tools::Run::Phylo::Phast::PhastCons
Args    : Optionally, provide any of the following (defaults are not to use,
          see the same-named methods for information on what each option does):
          {
           -target_coverage  => number between 0 and 1
           AND
           -expected_length  => int
          }
          -rho => number between 0 and 1
          -quiet => boolean (turn on or off program output to console)

          Most other options understood by phastCons can be supplied as key =>
          value pairs in this way. Options that don't normally take a value
          should be given a value of 1. You can type the keys as you would on
          the command line (eg. '--indels-only' => 1) or with only a single
          hyphen to start and internal hyphens converted to underscores (eg.
          -indels_only => 1) to avoid having to quote the key.

          These options can NOT be used with this wrapper currently:
          estimate_trees / T
          estimate_rho / O
          gc / G
          msa_format / i
          score / s
          no_post_probs / n
          seqname / N
          idpref / P
          help / h
          alias / A
          most_conserved / V / viterbi
          refidx / r

target_coverage

Title   : target_coverage
Usage   : $factory->target_coverage(0.25);
Function: Constrain transition parameters such that the expected fraction of
          sites in conserved elements is the supplied value.
Returns : number (default undef)
Args    : None to get, number (between 0 and 1) to set

expected_length

Title   : expected_length
Usage   : $factory->expected_length(5);
Function: Set transition probabilities such that the expected length of a
          conserved element is the supplied value. target_coverage() must also
          be set.
Returns : int (default undef)
Args    : None to get, int to set

rho

Title   : rho
Usage   : $factory->rho(0.3);
Function: Set the *scale* (overall evolutionary rate) of the model for the
          conserved state to be the supplied number times that of the model for
          the non-conserved state (default 0.3).
Returns : number (default undef)
Args    : None to get, number (between 0 and 1) to set

run

Title   : run
Usage   : $result = $factory->run($fasta_align_file, $newick_tree_file);
          -or-
          $result = $factory->run($align_object, $tree_object);
          -or-
          $result = $factory->run($align_object, $db_taxonomy_object);
Function: Runs phastCons on an alignment to find the most conserved regions
          ('footprinting').
Returns : array of Bio::SeqFeature::Annotated (one feature per alignment
          sequence and prediction)
Args    : The first argument represents an alignment, the second argument
          a species tree.
          The alignment can be provided as a multi-fasta format alignment
          filename, or a Bio::Align::AlignI compliant object (eg. a
          Bio::SimpleAlign).
          The species tree can be provided as a newick format tree filename
          or a Bio::Tree::TreeI compliant object. Alternatively a
          Bio::DB::Taxonomy object can be supplied, in which case the species
          tree will be generated by using the alignment sequence names as
          species names and looking for those in the supplied database.

          In all cases, the alignment sequence names must correspond to node
          ids in the species tree. Multi-word species names should be joined
          with underscores to form the sequence names, eg. Homo_sapiens

_setparams

Title   : _setparams
Usage   : Internal function, not to be called directly
Function: Creates a string of params to be used in the command string
Returns : string of params
Args    : alignment file name for result production, AND filename of phyloFit
          generated init.mod file to estimate trees