BOL: Related items

BLAST nr version 5 database, (nr_v5)

Jit — Fri, 23 Aug 2019 11:35:35 -0500

NCBI have made changes the nr version 5 database, (nr_v5), to facilitate better search results and improved performance by reducing the number of redundant titles in the nr_v5 database used by webBLAST, which is also available for BLAST+ users.

The changes in nr preserve the taxonomic diversity of the entries in the database while reducing the number of titles for identical sequences. GenPept accessions are still accessible via www.ncbi.nlm.nih.gov/protein/$GENBANK_ACCESSION or the IPG website https://www.ncbi.nlm.nih.gov/ipg/.

The "Identical Proteins" link in the alignments section of the webBLAST results takes you to a full list of all accessions associated with a sequence.

For BLAST+ users downloading nr_v5: the database is now approximately 50% smaller, resulting in faster downloads and BLAST searches, and smaller disk space requirements. The database is downloadable at: ftp://ftp.ncbi.nlm.nih.gov/blast/db/v5/

For BLAST+ there is a cleanup script to help you manage the transition to this smaller database. The script removes unused database volumes: ftp://ftp.ncbi.nlm.nih.gov/blast/temp/cleanup-blastdb-volumes.py

Here are the new rules on how we keep titles in nr_v5:

1. We keep all refseq, swissprot, pir and PDB titles.

2. We keep any GenPept titles with a TAXID that has not already been seen in the record.

3. We keep at least five GenPept titles regardless of whether the TAXIDS have been seen before or not in this record.

Primer BLAST !

BioStar — Tue, 28 Apr 2020 00:28:49 -0500

BLAST team added a new feature (Max 3' match), shown in Figure 1, to Primer-BLAST that limits the length of 3' exon matches when designing exon-exon spanning primers. This makes it less likely that primers specifically designed to amplify transcripts will also amplify genomic DNA contamination in expression assays. See the NCBI Insights post (https://go.usa.gov/xvUT4) for more details.

If you have any questions or concerns, please contact blast-help@ncbi.nlm.nih.gov

Cleaner BLAST Databases for More Accurate Results

LEGE — Tue, 23 Apr 2024 01:23:08 -0500

Do you use BLAST to identify a sequence or the evolutionary scope of a gene? That can be challenging if contaminated and misclassified sequences are in the BLAST databases and show up in your search results. To address this problem, we now use the NCBI quality assurance tools listed below to systematically remove these misleading sequences from the default nucleotide (nt) and protein (nr) BLAST databases.

Foreign Contamination Screen tool for genome cross-species screening (FCS-GX) detects contamination from foreign organisms in genomes and other sequences using the genome cross-species aligner (GX)
Average Nucleotide Identity (ANI) evaluates the taxonomic classification of prokaryotic genome assemblies. Sequences from genomes marked up as ‘unverified source organism’ are considered suspect and removed.

Ref https://ncbiinsights.ncbi.nlm.nih.gov/2024/04/22/cleaner-blast-databases-more-accurate-results/

Circoletto: visualizing sequence similarity with Circos

Jit — Fri, 09 Feb 2018 10:23:40 -0600

Circoletto, an online visualization tool based on Circos, which provides a fast, aesthetically pleasing and informative overview of sequence similarity search results.

Online version and downloadable software package for offline use (source code in PERL) freely available at http://bat.ina.certh.gr/tools/circoletto/

Contact:ndarz@certh.gr

Address of the bookmark: http://tools.bat.infspire.org/circoletto/

REST API

Neel — Mon, 04 Oct 2021 12:46:40 -0500

REST API

The Representational State Transfer (REST) sample clients are provided for a number of programming languages. For details of how to use these clients, download the client and run the program without any arguments.

Language	Download	Requirements
Perl	psiblast.pl	LWP and XML::Simple
Python	psiblast.py	xmltramp2

For details see Environment setup for REST Web Services and Examples for Perl REST Web Services Clients pages.

BEAP: Blast Extension and Assembly Program

Shruti Paniwala — Mon, 11 Jun 2018 04:52:56 -0500

The Blast Extension and Assembly Program (BEAP) is a computer program that uses a short starting DNA fragment, often a EST or partial gene segment, as "primer", to recursively blast nucleotide databases in an attempt to obtain all sequences that overlaps, directly or indirectly, with the "primer" therefore help to "extend" the length of the original sequence for constructing a "full length" sequence for functional analysis, or at least to obtain neighboring regions of the segment for SNP discovery and linkage disequilibrium analysis. The confidence of assembling the resulting sequences is achieved by using a known genome, such as human genome, as a reference. https://www.animalgenome.org/tools/beap/

Address of the bookmark: https://www.animalgenome.org/tools/beap/

Kraken: ultrafast metagenomic sequence classification using exact alignments

Jit — Mon, 27 Jun 2016 11:01:44 -0500

Kraken is an ultrafast and highly accurate program for assigning taxonomic labels to metagenomic DNA sequences. Previous programs designed for this task have been relatively slow and computationally expensive, forcing researchers to use faster abundance estimation programs, which only classify small subsets of metagenomic data. Using exact alignment of k-mers, Kraken achieves classification accuracy comparable to the fastest BLAST program. In its fastest mode, Kraken classifies 100 base pair reads at a rate of over 4.1 million reads per minute, 909 times faster than Megablast and 11 times faster than the abundance estimation program MetaPhlAn. Kraken is available at http://ccb.jhu.edu/software/kraken/.

Krona

https://sourceforge.net/p/krona/home/krona/

Address of the bookmark: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4053813/

CRBHits: From Conditional Reciprocal Best Hits to Codon Alignments and Ka/Ks in R

Shruti Paniwala — Wed, 11 Nov 2020 23:06:03 -0600

CRBHits is a coding sequence (CDS) analysis pipeline in R (R Core Team, 2019). It reimplements the Conditional Reciprocal Best Hit (CRBH) algorithm crb-blast and covers all necessary steps from sequence similarity searches, codon alignments to Ka/Ks calculations and synteny. The new R package targets ecology, population and evolutionary biologists working in the field of comparative genomics.

Address of the bookmark: https://gitlab.gwdg.de/mpievolbio-it/crbhits

pbalign: maps PacBio reads to reference sequences and saves alignments to a BAM file

Jit — Thu, 24 May 2018 10:06:52 -0500

pbalign aligns PacBio reads to reference sequences, filters aligned reads according to user-specific filtering criteria, and converts the output to either the SAM format or PacBio Compare HDF5 (e.g., .cmp.h5) format. The output Compare HDF5 file will be compatible with Quiver if --forQuiver option is specified.

Address of the bookmark: https://github.com/PacificBiosciences/pbalign