Important changes coming to prokaryotic Reference and Representative genome assemblies

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.

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Important changes to the genomes FTP site in February

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.X_t_assemblyFigure 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).


500 organisms annotated with the Eukaryotic Genome Annotation Pipeline

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.

Stony coral (Pocillopora damicornis)

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Designing exon-specific primers for the human genome

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:

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