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:py:mod:`ecoPCR`: *in silico* PCR
=================================
:py:mod:`ecoPCR` *in silico* PCR preserves the taxonomic information
of the selected sequences, and allows various specified conditions for the
*in silico* amplification.
Additionally to the different options, the command requires two arguments corresponding
to the two primers.
References
----------
Bellemain E, Carlsen T, Brochmann C, Coissac E, Taberlet P, Kauserud H (2010) ITS as an environmental DNA barcode for fungi: an *in silico* approach reveals potential PCR biases BMC Microbiology, 10, 189.
Ficetola GF, Coissac E, Zundel S, Riaz T, Shehzad W, Bessiere J, Taberlet P, Pompanon F (2010) An *in silico* approach for the evaluation of DNA barcodes. BMC Genomics, 11, 434.
:py:mod:`ecoPCR` specific options
---------------------------------
.. cmdoption:: -d <filename>
Filename containing the database used for the *in silico* PCR. The database
must be in the ``ecoPCR format`` (see :doc:`obiconvert <./obiconvert>`).
.. WARNING:: This option is compulsory.
.. cmdoption:: -e <INTEGER>
Maximum number of errors (mismatches) allowed per primer (default: 0).
See example 2 for avoiding errors on the 3' end of the primers.
.. cmdoption:: -l <INTEGER>
Minimum length of the *in silico* amplified DNA fragment, excluding primers.
.. cmdoption:: -L <INTEGER>
Maximum length of the *in silico* amplified DNA fragment, excluding primers.
.. cmdoption:: -r <TAXID>
Only the sequence records corresponding to the taxonomic group identified by its
``TAXID`` are considered for the *in silico* PCR. The ``TAXID`` is an integer that
can be found either in the NCBI taxonomic database, or using the :doc:`ecofind <./ecofind>` program.
.. cmdoption:: -i <TAXID>
The sequences of the taxonomic group identified by its ``TAXID`` are not considered for
the *in silico* PCR.
.. cmdoption:: -c
Considers that the sequences of the database are circular (e.g. mitochondrial
or chloroplast DNA).
.. cmdoption:: -D <INTEGER>
Keeps the specified number of nucleotides on each side of the *in silico*
amplified sequences, (including the amplified DNA fragment plus the two target
sequences of the primers).
.. cmdoption:: -k
Print in the programme output the kingdom of the *in silico* amplified
sequences (default: print the superkingdom).
.. cmdoption:: -m <1|2>
Defines the method used for estimating the Tm (melting temperature) between
the primers and their corresponding target sequences (default: 1).
1 SantaLucia method (SantaLucia J (1998) A unified view of polymer, dumbbell, and oligonucleotide DNA nearest-neighbor thermodynamics. PNAS, 95, 1460-1465).
2 Owczarzy method (Owczarzy R, Vallone PM, Gallo FJ *et al.* (1997) Predicting sequence-dependent melting stability of short duplex DNA oligomers. Biopolymers, 44, 217-239).
.. cmdoption:: -a <FLOAT>
Salt concentration used for estimating the *Tm* (default: 0.05).
.. cmdoption:: -h
Print help.
Output file
-----------
The output file contains several columns, with '|' as separator, and describes
the properties of the *in silico* amplified sequences.
column 1: sequence identification in the reference database (= accession number when using EMBL or GenBank for building the reference database)
column 2: length of the original sequence
column 3: scientific name as indicated in the reference database
column 4: taxonomic rank as indicated in the reference database
column 5: *taxid* of the species
column 6: scientific name of the species
column 7: *taxid* of the genus
column 8: genus name
column 9: *taxid* of the family
column 10: family name
column 11: *taxid* of the super kingdom (or of the kingdom if the ``-k`` option is set)
column 12: super kingdom name (or kingdom name if the ``-k`` option is set)
column 13: strand (D or R, corresponding to direct or reverse, respectively)
column 14: target sequence of the first primer
column 15: number of mismatches for the first primer
column 16: target sequence of the second primer
column 17: number of mismatches for the second primer
column 18: length of the amplified fragment (excluding primers)
column 19: sequence
column 20: definition
Examples
--------
*Example 1:*
.. code-block:: bash
> ecoPCR -d mydatabase -e 3 -l 50 -L 500 \
TCACAGACCTGTTATTGC TYTGTCTGSTTRATTSCG > mysequences.ecopcr
Launches an *in silico* PCR on mydatabase (see :doc:`obiconvert <./obiconvert>` for a description
of the database format), with a maximum of three mismatches for each primer. The minimum and
maximum amplified sequence lengths (excluding primers) are 50 bp and 500 bp, respectively. The
primers used are TCACAGACCTGTTATTGC and TYTGTCTGSTTRATTSCG (possibility to use
:doc:`IUPAC codes <../iupac>`). They amplify a short portion of the nuclear 18S gene. The
results are saved in the *mysequence.ecopcr* file.
*Example 2:*
.. code-block:: bash
> ecoPCR -d mydatabase -e 2 -l 80 -L 120 -D 50 -r 7742 \
TTAGATACCCCACTATG#C# TAGAACAGGCTCCTCTA#G# > mysequences.ecopcr
Launches an *in silico* PCR on mydatabase (see :doc:`obiconvert <./obiconvert>` for a description
of the database format), with a maximum of two mismatches for each primer, but with a perfect match
on the last two nucleotides of the 3' end of each primer (a perfect match can be enforced by adding
a '#' after the considered nucleotide). The minimum and maximum amplified sequence lengths (excluding
primers) are 80 bp and 120 bp, respectively. The ``-D`` option keeps 50 nucleotides on each side of
the *in silico* amplified sequences, (including the amplified DNA fragment plus the two target
sequences of the primers). The primers used are TTAGATACCCCACTATGC and TAGAACAGGCTCCTCTAG. They
amplify a short portion of the mitochondrial 12S gene. The ``-r`` option restricts the search to
vertebrates (7742 is the :doc:`taxid <../attributes/taxid>` of vertebrates). The results are saved
in the ``mysequence.ecopcr`` file.
:py:mod:`ecoPCR` used sequence attributes
-----------------------------------------
- :doc:`taxid <../attributes/taxid>`
|
