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1997-11-03
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CLUSTAL W Multiple Sequence Alignment Program
(version 1.7, June 1997)
Please send bug reports, comments etc. to one of:-
gibson@embl-heidelberg.de
thompson@embl-heidelberg.de
d.higgins@ucc.ie
******************************************************************************
POLICY ON COMMERCIAL DISTRIBUTION OF CLUSTAL W
Clustal W is freely available to the user community. However, we have had
several years of instability with regard to Clustal W maintenance and
development. Clustal W is now being distributed in a number of commercial
packages. To help us safeguard future maintenance and development, commercial
distributors of Clustal W are requested to donate a grant to the Clustal W
authors which will be spent on Clustal W-related development. Anyone wishing to
distribute version 1.7 of Clustal W should contact the authors.
******************************************************************************
Changes since version 1.6
-------------------------
1. The static arrays used by clustalw for storing the alignment data have been
replaced by dynamically allocated memory. There is now no limit on the number
or length of sequences which can be input.
2. The alignment of DNA sequences now offers a new hard-coded matrix, as well
as the identity matrix used previously. The new matrix is the default scoring
matrix used by the BESTFIT program of the GCG package for the comparison of
nucleic acid sequences. X's and N's are treated as matches to any IUB ambiguity
symbol. All matches score 1.9; all mismatches for IUB symbols score 0.0.
3. The transition weight option for aligning nucleotide sequences has been
changed from an on/off toggle to a weight between 0 and 1. A weight of zero
means that the transitions are scored as mismatches; a weight of 1 gives
transitions the full match score. For distantly related DNA sequences, the
weight should be near to zero; for closely related sequences it can be useful
to assign a higher score.
4. The RSF sequence alignment file format used by GCG Version 9 can now be
read.
5. The clustal sequence alignment file format has been changed to allow
sequence names longer than 10 characters. The maximum length allowed is set in
clustalw.h by the statement:
#define MAXNAMES 10
For the fasta format, the name is taken as the first string after the '>'
character, stopping at the first white space. (Previously, the first 10
characters were taken, replacing blanks by underscores).
6. The bootstrap values written in the phylip tree file format can be assigned
either to branches or nodes. The default is to write the values on the nodes,
as this can be read by several commonly-used tree display programs. But note
that this can lead to confusion if the tree is rooted and the bootstraps may
be better attached to the internal branches: Software developers should ensure
they can read the branch label format.
7. The sequence weighting used during sequence to profile alignments has been
changed. The tree weight is now multiplied by the percent identity of the
new sequence compared with the most closely related sequence in the profile.
8. The sequence weighting used during profile to profile alignments has been
changed. A guide tree is now built for each profile separately and the
sequence weights calculated from the two trees. The weights for each
sequence are then multiplied by the percent identity of the sequence compared
with the most closely related sequence in the opposite profile.
9. The adjustment of the Gap Opening and Gap Extension Penalties for sequences
of unequal length has been improved.
10. The default order of the sequences in the output alignment file has been
changed. Previously the default was to output the sequences in the same order
as the input file. Now the default is to use the order in which the sequences
were aligned (from the guide tree/dendrogram), thus automatically grouping
closely related sequences.
11. The option to 'Reset Gaps between alignments' has been switched off by
default.
12. The conservation line output in the clustal format alignment file has been
changed. Three characters are now used:
'*' indicates positions which have a single, fully conserved residue
':' indicates that one of the following 'strong' groups is fully conserved:-
STA
NEQK
NHQK
NDEQ
QHRK
MILV
MILF
HY
FYW
'.' indicates that one of the following 'weaker' groups is fully conserved:-
CSA
ATV
SAG
STNK
STPA
SGND
SNDEQK
NDEQHK
NEQHRK
FVLIM
HFY
These are all the positively scoring groups that occur in the Gonnet Pam250
matrix. The strong and weak groups are defined as strong score >0.5 and weak
score =<0.5 respectively.
13. A bug in the modification of the Myers and Miller alignment algorithm
for residue-specific gap penalites has been fixed. This occasionally caused
new gaps to be opened a few residues away from the optimal position.
14. The GCG/MSF input format no longer needs the word PILEUP on the first
line. Several versions can now be recognised:-
1. The word PILEUP as the first word in the file
2. The word !!AA_MULTIPLE_ALIGNMENT or !!NA_MULTIPLE_ALIGNMENT
as the first word in the file
3. The characters MSF on the first line in the line, and the
characters .. at the end of the line.
15. The standard command line separator for UNIX systems has been changed from
'/' to '-'. ie. to give options on the command line, you now type
clustalw input.aln -gapopen=8.0
instead of clustalw input.aln /gapopen=8.0
ATTENTION SOFTWARE DEVELOPERS!!
-------------------------------
The CLUSTAL sequence alignment output format has been modified:
1. Names longer than 10 chars are now allowed. (The maximum is specified in
clustalw.h by '#define MAXNAMES'.)
2. The consensus line now consists of three characters: '*',':' and '.'. (Only
the '*' and '.' were previously used.)
3. An option (not the default) has been added, allowing the user to print out
sequence numbers at the end of each line of the alignment output.
4. Both RNA bases (U) and base ambiguities are now supported in nucleic acid
sequences. In the past, all characters (upper or lower case) other than
a,c,g,t or u were converted to N. Now the following characters are recognised
and retained in the alignment output: ABCDGHKMNRSTUVWXY (upper or lower case).
5. A Blank line inadvertently added in the version 1.6 header has been taken
out again.