Schema for Chain/Net - Chain and Net Alignments
  Database: mm39    Primary Table: chainGalGal6    Row Count: 187,061   Data last updated: 2020-11-25
Format description: Summary info about a chain of alignments
On download server: MariaDB table dump directory
fieldexampleSQL type info description
bin 9smallint(5) unsigned range Indexing field to speed chromosome range queries.
score 1355282double range score of chain
tName chr1varchar(255) values Target sequence name
tSize 195154279int(10) unsigned range Target sequence size
tStart 3269953int(10) unsigned range Alignment start position in target
tEnd 7240840int(10) unsigned range Alignment end position in target
qName chr2varchar(255) values Query sequence name
qSize 149682049int(10) unsigned range Query sequence size
qStrand -char(1) values Query strand
qStart 38683458int(10) unsigned range Alignment start position in query
qEnd 40214593int(10) unsigned range Alignment end position in query
id 242int(10) unsigned range chain id

Connected Tables and Joining Fields
        mm39.chainGalGal6Link.chainId (via chainGalGal6.id)
      mm39.netGalGal6.chainId (via chainGalGal6.id)

Sample Rows
 
binscoretNametSizetStarttEndqNameqSizeqStrandqStartqEndid
91355282chr119515427932699537240840chr2149682049-3868345840214593242
61029000chr119515427932862313287201chr2013897287-3798746379972820415
61029824chr119515427932862473287207chr3110838418+10694288810694387019541
6118198chr119515427934918813492134chr2013897287-37997843800027114907
6118655chr119515427934919193492187chr3110838418+106961179106961435108877
61247290chr119515427936018583602961chr1197608386+35393828353973169559
61321566chr119515427937407453741884chr3110838418+10708940010709043232274
61317229chr119515427937410173741866chr2013897287-3804284380503143930
61894988chr119515427943263844330733chr32725831-6380846436542946
61870186chr119515427943264574330733chr559809098-31300922313185494881

Note: all start coordinates in our database are 0-based, not 1-based. See explanation here.

Chain/Net (mm39ChainNet) Track Description
 

Description

Chain Track

The chain track shows alignments of mouse (Jun. 2020 (GRCm39/mm39)/mm39) to other genomes using a gap scoring system that allows longer gaps than traditional affine gap scoring systems. It can also tolerate gaps in both mouse and the other genome simultaneously. These "double-sided" gaps can be caused by local inversions and overlapping deletions in both species.

The chain track displays boxes joined together by either single or double lines. The boxes represent aligning regions. Single lines indicate gaps that are largely due to a deletion in the other assembly or an insertion in the mouse assembly. Double lines represent more complex gaps that involve substantial sequence in both species. This may result from inversions, overlapping deletions, an abundance of local mutation, or an unsequenced gap in one species. In cases where multiple chains align over a particular region of the other genome, the chains with single-lined gaps are often due to processed pseudogenes, while chains with double-lined gaps are more often due to paralogs and unprocessed pseudogenes.

In the "pack" and "full" display modes, the individual feature names indicate the chromosome, strand, and location (in thousands) of the match for each matching alignment.

Net Track

The net track shows the best mouse/other chain for every part of the other genome. It is useful for finding orthologous regions and for studying genome rearrangement. The mouse sequence used in this annotation is from the Jun. 2020 (GRCm39/mm39) (mm39) assembly.

Display Conventions and Configuration

Multiple species are grouped together in a composite track. In the display and on the configuration page, an effort was made to group them loosely into "clades." These groupings are based on the taxonomic classification at NCBI, using the CommonTree tool. Some organisms may be pulled from a larger group into a subgroup, to emphasize a relationship. For example, members of an Order may be listed together, while other organisms in the same Superorder may be grouped separately under the Superorder name.

Chain Track

By default, the chains to chromosome-based assemblies are colored based on which chromosome they map to in the aligning organism. To turn off the coloring, check the "off" button next to: Color track based on chromosome.

To display only the chains of one chromosome in the aligning organism, enter the name of that chromosome (e.g. chr4) in box next to: Filter by chromosome.

Net Track

In full display mode, the top-level (level 1) chains are the largest, highest-scoring chains that span this region. In many cases gaps exist in the top-level chain. When possible, these are filled in by other chains that are displayed at level 2. The gaps in level 2 chains may be filled by level 3 chains and so forth.

In the graphical display, the boxes represent ungapped alignments; the lines represent gaps. Click on a box to view detailed information about the chain as a whole; click on a line to display information about the gap. The detailed information is useful in determining the cause of the gap or, for lower level chains, the genomic rearrangement.

Individual items in the display are categorized as one of four types (other than gap):

  • Top - the best, longest match. Displayed on level 1.
  • Syn - line-ups on the same chromosome as the gap in the level above it.
  • Inv - a line-up on the same chromosome as the gap above it, but in the opposite orientation.
  • NonSyn - a match to a chromosome different from the gap in the level above.

Methods

Chain track

The lastz alignments were converted into axt format using the lavToAxt program. The axt alignments were fed into axtChain, which organizes all alignments between a single mouse chromosome and a single chromosome from the other genome into a group and creates a kd-tree out of the gapless subsections (blocks) of the alignments. A dynamic program was then run over the kd-trees to find the maximally scoring chains of these blocks.

See also: lastz parameters and other details (e.g., update time) and chain minimum score and gap parameters used in these alignments.

Net track

Chains were derived from lastz alignments, using the methods described on the chain tracks description pages, and sorted with the highest-scoring chains in the genome ranked first. The program chainNet was then used to place the chains one at a time, trimming them as necessary to fit into sections not already covered by a higher-scoring chain. During this process, a natural hierarchy emerged in which a chain that filled a gap in a higher-scoring chain was placed underneath that chain. The program netSyntenic was used to fill in information about the relationship between higher- and lower-level chains, such as whether a lower-level chain was syntenic or inverted relative to the higher-level chain. The program netClass was then used to fill in how much of the gaps and chains contained Ns (sequencing gaps) in one or both species and how much was filled with transposons inserted before and after the two organisms diverged.

Credits

lastz was developed by: Harris RS. Improved pairwise alignment of genomic DNA. Ph.D. Thesis. Pennsylvania State University, USA. 2007.

blastz was developed at Pennsylvania State University by Minmei Hou, Scott Schwartz, Zheng Zhang, and Webb Miller with advice from Ross Hardison.

Lineage-specific repeats were identified by Arian Smit and his RepeatMasker program.

The axtChain program was developed at the University of California at Santa Cruz by Jim Kent with advice from Webb Miller and David Haussler.

The browser display and database storage of the chains and nets were created by Robert Baertsch and Jim Kent.

The chainNet, netSyntenic, and netClass programs were developed at the University of California Santa Cruz by Jim Kent.

References

Chiaromonte F, Yap VB, Miller W. Scoring pairwise genomic sequence alignments. Pac Symp Biocomput. 2002:115-26. PMID: 11928468

Kent WJ, Baertsch R, Hinrichs A, Miller W, Haussler D. Evolution's cauldron: duplication, deletion, and rearrangement in the mouse and human genomes. Proc Natl Acad Sci U S A. 2003 Sep 30;100(20):11484-9. PMID: 14500911; PMC: PMC208784

Schwartz S, Kent WJ, Smit A, Zhang Z, Baertsch R, Hardison RC, Haussler D, Miller W. Human-mouse alignments with BLASTZ. Genome Res. 2003 Jan;13(1):103-7. PMID: 12529312; PMC: PMC430961