page_title: European Nucleotide Archive
section_title: Sequence Read Archive
hierarchical_section_title: European Nucleotide Archive / Sequence Read Archive
context_page_description: The European Nucleotide Archive is a repository providing free and unrestricted access to annotated DNA and RNA sequences. It also stores complementary information such as experimental procedures, details of sequence assembly and other metadata related to sequencing projects.
  The archive is composed of three main databases: the Sequence Read Archive, the Trace Archive and the EMBL Nucleotide Sequence Database. The ENA is produced and maintained by the European Bioinformatics Institute and is a member of the International Nucleotide Sequence Database Collaboration along with the DNA Data Bank of Japan and GenBank.
  The ENA has grown out of the EMBL Data Library which was released in 1982 as the first internationally supported resource for nucleotide sequence data. As of early 2012, the ENA and other INSDC member databases each contained complete genomes of 5,682 organisms and sequence data for almost 700,000.
  Moreover, the volume of data is increasing exponentially with a doubling time of approximately 10 months.
context_section_description: The ENA operates an instance of the Sequence Read Archive (SRA), an archival repository of sequence reads and analyses which are intended for public release. Originally called the Short Read Archive, the name was changed in anticipation of future sequencing technologies being able to produce longer sequence reads. Currently, the archive accepts sequence reads generated by next-generation sequencing platforms such as the Illumina Genome Analyzer and ABI SOLiD as well as some corresponding analyses and alignments. The SRA operates under the guidance of the International Nucleotide Sequence Database Collaboration (INSDC) and is the fastest-growing repository in the ENA.
  In 2010 the Sequence Read Archive made up approximately 95% of the base pair data available through the ENA, encompassing over 500,000,000,000 sequence reads made up of over 60 trillion (6×10¹³) base pairs. Almost half of this data was deposited in relation to the 1000 Genomes Project wherein the researchers published their sequence data to the SRA in real-time. In total, as of September 2010, 65% of the Sequence Read Archive was human genomic sequence, with another 16% relating to human metagenome sequence reads.
  The preferred data format for files submitted to the SRA is the BAM format, which is capable of storing both aligned and unaligned reads. Internally the SRA relies on the NCBI SRA Toolkit, used at all three INSDC member databases, to provide flexible data compression, API access and conversion to other formats such as FASTQ.
caption: The SRA has grown rapidly since 2008.[21] As of 2011, most SRA sequence data was produced by Illumina's Genome Analyzer.[22]