Now that the Sequence Read Archive (SRA) is publicly available on the cloud, you can harness the power of high-performance cloud computing to analyze all the data you wish without having to download a single byte. To help you programmatically find datasets of interest to you, we’ve loaded BigQuery with the SRA Metadata Table, which contains the descriptive information supplied at the time of sequence submission. Searches of the SRA Metadata Table are dependent on the quality and consistency of the metadata as submitted which means it can sometimes be a challenge to identify a complete and relevant set of suitable sequences. However, the Taxonomy Analysis Table can be a useful tool to overcome this challenge. Here’s why.
NCBI indexes SRA runs with one or more taxonomy terms when species-specific sequence k-mers are matched in the submitted sequences. The Taxonomy Analysis Table (tax_analysis) thus becomes a catalog of all taxonomic IDs detected in every run, based on the specificity and accuracy characteristics of these unique hashes sampled from reference genomes. We have now added the Taxonomy Analysis Table to BigQuery so you can filter hundreds of thousands of runs by this calculated taxonomic content to gather target datasets. Use this in conjunction with the BigQuery Taxonomy Table (which connects scientific names to taxonomic IDs) and link back to the BigQuery Metadata Table.
Explore/link to these four new tables in BigQuery:
- tax_analysis_info: a summary table for the results of the STAT tool
- tax_analysis: use the taxonomy analysis table to locate any number of runs based on kmer hits to a particular organism or branch in a taxonomic tree.
- taxonomy: NCBI Taxonomy database where you can locate the taxid based on organism names.
- kmer: contains kmers mapped to a particular organism and allows you to continue exploring organismal content further. You can leverage kmer tables in your downstream analysis by building custom kmer libraries.
Figure 1. SRA runs found using the taxonomy tables and BigQuery for taxid:694002, Betacoronavirus.
Check out our helpful summary information for additional information on taxonomic analysis.
We are actively working on new tools and ways to help you use the cloud to access and compute on SRA data. We are piloting this new feature in BigQuery, and plan to add this information to Amazon Cloud’s (AWS) Athena soon.
Contact us at email@example.com to let us know what you think!
If you need help getting started, refer to our tutorials and how-to video playlist on YouTube!