This directory contains alignments of the C. briggsae assembly 
(cb1, Jul. 2002, assembly version cb25.agp8) to the C. elegans
assembly (ce2, Mar. 2004, Release WS120).

Files included in this directory:

  - axtChrom.zip: contains the axt alignments generated by blastz.
    Blastz output was converted to lav format, which was then converted 
    to axt format. 

  - axtNetCb1.zip: contains chained and netted alignments, i.e. the
    best chains in the genome, with gaps in the best chains filled in 
    by next-best chains where possible. 

  - cb1.chain.zip: chained blastz alignments. The chain format is 
    described in http://genome.ucsc.edu/goldenPath/help/chain.html.

  - cb1.net.zip: "net" file that describes rearrangements between the 
    species and the best C. briggsae match to any part of the C. elegans 
    genome.  The net format is described in 
    http://genome.ucsc.edu/goldenPath/help/net.html.

  - md5sum.txt: checksums of the files in this directory

The alignments in the axtChrom and axtNet directories are in "axt" format. 
For a description, see http://genome.ucsc.edu/goldenPath/help/axt.html.

The alignments were produced by the blastz alignment program, which 
is available from Webb Miller's lab at Penn State University 
(http://www.bx.psu.edu/miller_lab/). The blastz scoring matrix used was:

           A    C    G    T
      A   91 -114  -31 -123
      C -114  100 -125  -31
      G  -31 -125  100 -114
      T -123  -31 -114   91

with a gap open penalty of 400 and a gap extension penalty of 30.  The 
minimum score for an alignment to be kept was 3000 for the first pass  
and 2200 for the second pass, which restricted the search space to the 
regions between two alignments found in the first pass.

The .lav format blastz output, which does not include the sequence, was 
converted to .axt with lavToAxt -dropSelf, which excises alignment blocks 
along the diagonal.

The axtNet alignments were processed with chainNet, netSyntenic,
and netClass written by Jim Kent at UCSC.

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If you plan to download a large file or multiple files from this 
directory, we recommend you use ftp rather than downloading the files 
via our website. To do so, ftp to hgdownload.cse.ucsc.edu, then go to 
the directory goldenPath/ce2/vsCb1. To download multiple files, 
use the "mget" command:

    mget <filename1> <filename2> ...
    - or -
    mget -a (to download all the files in the directory) 

All the files in this directory are freely available for public use.