NCBI RefSeq has finished its initial annotation of the new rat reference assembly, mRatBN7.2, recently released by the Darwin Tree of Life Project at the Wellcome Sanger Institute. This is the first coordinate-changing update to the rat reference since the 2014 release of Rnor_6.0 from the Rat Genome Sequencing Consortium and brings the rat assembly into the modern age with a nearly 300x increase in contig N50 and 9x increase in scaffold N50 lengths. It’s a major improvement!
Tag: Reference genome
We have updated the collection of representative genome assemblies for Bacteria and Archaea. As announced in April, this set is now recalculated three times a year. We selected a total of 11,727 prokaryotic assemblies to represent their respective species among the 192,000 assemblies in RefSeq. Six hundred and thirty-five species were included in the collection for the first time, while 395 organisms from undefined species (such as Bacillus bacterium) were removed. We were able to choose a higher-quality representative than in the previous set for 18% of Bacterial and Archaeal species due to improvements in the logic of the selection that is now based on the assembly length, number of pseudo CDSs called in the PGAP annotation, number of scaffolds, whether Gene IDs are available in the Gene database for the assembly that is currently representative, and type strain status. You can see the exact criteria in order of importance on the Prokaryotic RefSeq Genomes page. Now that the new selection process is in place, we expect future updates to have fewer changes. We will replace a representative only if the assembly has changed RefSeq status or if a substantially better assembly becomes available.
You can download the reference and representative set from the Assembly resource. If you are interested in the annotation on these genomes, you can limit searches to proteins annotated on representative genomes by adding “refseq_select[filter]” to any query in the Protein database. For example, you can find all proteins annotated on representative genomes in the genus Klebsiella by using the query: “Klebsiella[organism] AND refseq_select[filter]“. A BLAST database of proteins annotated on representative genomes will be coming soon. Stay tuned!
We have updated our annotation for the mouse reference genome, GRCm38.p6. It includes:
- Markup for RefSeq Select, which identifies one representative transcript and protein for every protein-coding gene. Find features with the ‘tag=RefSeq Select’ attribute in GFF3 for those analyses where you need just a single transcript or protein for each coding gene. You can also find these RefSeqs in Entrez using the query ‘refseq_select[filter].’
- Annotation updates made in the last year for over 2000 genes, including over 4000 new or revised curated transcripts. This includes targeted curation to ensure we are representing well-expressed and conserved transcripts for inclusion in RefSeq Select.
- Annotation of over 2300 regulatory and other functional element features from over 900 biological regions. These are now identified with the source “RefSeqFE” in GFF3 column 2 for easy parsing.
When citing, please refer to this annotation as NCBI Mus musculus Annotation Release 108.20200622. You can find the data in:
- NCBI Datasets
- NCBI Assembly
- Genomes FTP
- NCBI’s Genome Data Viewer
- BLAST nr/nt and custom RefSeq databases
This is our last update before upgrading to the new major assembly version just released by the Genome Reference Consortium, GRCm39. We expect to be cranking up our compute farm in the next few weeks to produce a full annotation based on our latest curation and extensive short (Illumina) and long (PacBio IsoSeq and nanopore) RNA-seq data, which should be released later this summer. Stay tuned!
We have updated the collection of representative and reference assemblies for Bacteria and Archaea to better reflect the taxonomic breadth of the prokaryotes in RefSeq. We chose the 11,478 representative assemblies in the new collection from the 180,000+ prokaryotic assemblies in RefSeq today. We have selected one representative or reference assembly for every species based on several criteria including contiguity, completeness and whether the assembly is from type material. We have also updated the reference and representative microbial Blast database to reflect these changes. This reference and representative set will be updated three times a year to reflect changes in RefSeq. In addition, as we announced on Feb 14, we have reduced the number of reference genome assemblies — the subset of representative assemblies with annotation provided by outside experts — to 15. See the list in our previous post . We have re-annotated the 104 assemblies that are no longer reference with or Prokaryotic Genome Annotations Pipel (PGAP).
We are making changes to the set of bacterial and archaeal RefSeq Reference and Representative assemblies in February 2020.
- We will reduce the number of Reference assemblies to 15 that have annotation provided by outside experts (Table 1) and re-annotate the 105 other current Reference assemblies using the latest Prokaryotic Genome Annotation Pipeline (PGAP) software. The re-annotated assemblies will lose reference status.
- We will reassess and revise the set of Representative assemblies so that there is one assembly per species to better reflect the taxonomic diversity of the RefSeq bacterial and archaeal assemblies.
We have added the latest NCBI Eukaryotic Genome Annotation Pipeline results for the more than 580 species that we annotate to the genomes/refseq directory on the genomes FTP area. As we announced in December, we will stop publishing annotation results to the genus_species directories (example: genomes/Xenopus_tropicalis) on the genomes FTP site effective February 1, 2020. We will also move existing genus_species directories to genomes/archive/old_refseq during the month of February.Figure 1. The Assembly page for the Xenopus tropicalis UCB Xtro 10.0 (GCF_000004195.4) showing the blue download button. Annotation results such as the RefSeq transcript alignments that can be downloaded from the web page are now also under the genomes/refseq directory on the FTP site. The FTP path to the .bam alignment files is in red.
These FTP changes do not affect the Assembly download function. As always, you can download assembly data using the blue Download button on the web pages (Figure 1).
This month, the NCBI Eukaryotic Genome Annotation Pipeline annotated its 500th organism! The lucky winner is Pocillopora damicornis, a stony reef-building coral frequently used as an experimental model, whose larval dispersal and development are affected by environmental changes in the oceans.
A common task facing geneticists is to assay for sequence changes at particular locations in genes. These assays are often looking for changes in the coding exon of genes, and the target sequences are typically amplified using PCR from genomic DNA using a pair of specific primers. In this article, we will show you how to use NCBI Reference Sequences and Primer-BLAST, NCBI’s primer designer and specificity checker, to design a pair of primers that will amplify a single exon (exon 15) of the human breast cancer 1 (BRCA1) gene.
Here are the steps to follow to design primers to amplify exon 15 from human BRCA1: