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Rationale and Background
LASTDB prepares the necessary nucleotide databases necessary for the LAST (Local Alignment Search Tool) program (Kielbasa et. al., 2011; Genome Research).
- Genome file: Path to the subject genome (or other nucleotide sequence) for which a database will be made. Nucleotide sequences in fasta format. File extensions can be FA, FASTA, FNA, or FAA.
- Database ID: Name of the database generated, as well as prefix given to all database associated files.
- Nucleotides to index: This tells the program which nucleotides to index. Default is 2, which means that every other nucleotide is indexed. For comparison, BLAT indexes every 11th position, whereas MegaBLAST indexes every 5th. Increasing this number will decrease memory and disk usage as well as overall run time, but will reduce sensitivity in the LAST alignment step.
All files are located in the Community Data directory of the CyVerse Discovery Environment at the following path:
Community Data > iplantcollaborative > example_data > LAST > LASTDB (/iplant/home/shared/iplantcollaborative/example_data/LASTDB)
- Genome file: Gmax_genome_chr1.fasta
- Database ID: Gmax_Chr1_DB
- Nucleotides to index: 2
This Test Run will take approximately 5-10 minutes to complete in the DE. An analysis folder will be created containing all the files generated by LASTDB. There should be seven files total as well as the log folder. All seven database files are necessary for LAST alignment to search properly.