EMBOSS Stretcher (Nucleotide Alignment)

Introduction

EMBOSS Stretcher calculates an optimal global alignment of two sequences using a modification of the classic dynamic programming algorithm which uses linear space.

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How to use this tool

Running a tool from the web form is a simple multiple steps process, starting at the top of the page and following the steps to the bottom.

Each tool has at least 2 steps, but most of them have more:

  • The first steps are usually where the user sets the tool input (e.g. sequences, databases...)
  • In the following steps, the user has the possibility to change the default tool parameters
  • And finally, the last step is always the tool submission step, where the user can specify a title to be associated with the results and an email address for email notification. Using the submit button will effectively submit the information specified previously in the form to launch the tool on the server

Note that the parameters are validated prior to launching the tool on the server and in the event of a missing or wrong combination of parameters, the user will be notified directly in the form.

Step 1 - Input Sequences

First Input Sequence

A free text (raw) list of sequences is simply a block of characters representing several DNA/RNA or Protein sequences. A sequence can be be in GCG, FASTA, EMBL, GenBank, PIR, NBRF, Phylip or UniProtKB/Swiss-Prot format. Partially formatted sequences are not accepted. Adding a return to the end of the sequence may help certain applications understand the input. Note that directly using data from word processors may yield unpredictable results as hidden/control characters may be present.

First Sequence File Upload

A file containing valid sequences in any format (GCG, FASTA, EMBL, GenBank, PIR, NBRF, Phylip or UniProtKB/Swiss-Prot) can be used as input for the sequence similarity search. Word processors files may yield unpredictable results as hidden/control characters may be present in the files. It is best to save files with the Unix format option to avoid hidden Windows characters.

Second Input Sequence

A free text (raw) list of sequences is simply a block of characters representing several DNA/RNA or Protein sequences. A sequence can be be in GCG, FASTA, EMBL, GenBank, PIR, NBRF, Phylip or UniProtKB/Swiss-Prot format. Partially formatted sequences are not accepted. Adding a return to the end of the sequence may help certain applications understand the input. Note that directly using data from word processors may yield unpredictable results as hidden/control characters may be present.

Second Sequence File Upload

A file containing valid sequences in any format (GCG, FASTA, EMBL, GenBank, PIR, NBRF, Phylip or UniProtKB/Swiss-Prot) can be used as input for the sequence similarity search. Word processors files may yield unpredictable results as hidden/control characters may be present in the files. It is best to save files with the Unix format option to avoid hidden Windows characters.

Step 2 - Set alignment options

Matrix

Default substitution scoring matrices.

Matrix Name Abbreviation
DNAfull EDNAFULL
DNAmat EDNAMAT

Default value is: DNAfull [EDNAFULL]

Additional information

Gap Open Penalty

Pairwise alignment score for the first residue in a gap.

Default value is: 16

Additional information

Gap Extend Penalty

Pairwise alignment score for each additional residue in a gap.

Default value is: 4

Additional information

Output formats

Pairwise sequences format

Value Description
pair The sequences have the markup line between them
markx0 This is the standard default output format used by Bill Pearson's suite of FASTA programs
markx1 This is an alternative output format used by Bill Pearson's suite of FASTA programs in which identities are not marked. Instead conservative replacements are denoted by 'x' and non-conservative substitutions by 'X'
markx2 This is an alternative output format used by Bill Pearson's suite of FASTA programs in which the residues in the second sequence are only shown if they are different from the first
markx3 This is an alternative output format used by Bill Pearson's suite of FASTA programs in which the aligned sequences are displayed in FASTA sequence format. These can be used to build a primitive multiple alignment
markx10 This is an alternative output format used by Bill Pearson's suite of FASTA programs in which the aligned sequences are displayed in FASTA sequence format and the sequence length, alignment start and stop information is given in lines starting with a ';' character just after the title line for each sequence. It is intended to be easily parsed by other programs
srspair This is very similar in style to pair format
score This does not display the sequence alignment. It shows only the names of the sequences, the length of the alignment and the score

Default value is: pair

Step 3 - Submission

Job title

It's possible to identify the tool result by giving it a name. This name will be associated to the results and might appear in some of the graphical representations of the results.

Email Notification

Running a tool is usually an interactive process, the results are delivered directly to the browser when they become available. Depending on the tool and its input parameters, this may take quite a long time. It's possible to be notified by email when the job is finished by simply ticking the box "Be notified by email". An email with a link to the results will be sent to the email address specified in the corresponding text box. Email notifications require valid email addresses.

Email Address

If email notification is requested, then a valid Internet email address in the form joe@example.org must be provided. This is not required when running the tool interactively (The results will be delivered to the browser window when they are ready).

References

EMBOSS: the European Molecular Biology Open Software Suite.
(2000 Jun) Trends in genetics : TIG 16 (6) :276-7
A new bioinformatics analysis tools framework at EMBL-EBI.
(2010 Jul) Nucleic acids research 38 (Web Server issue) :W695-9
Analysis Tool Web Services from the EMBL-EBI.
(2013 Jul) Nucleic acids research 41 (Web Server issue) :W597-600