UniVec build 10.0 now available for VecScreen searches and FTP


UniVec, NCBI’s non-redundant database of vector sequences, has been updated to build 10.0, which enables searches run using NCBI’s VecScreen tool to detect more of the foreign sequences introduced during the cloning or sequencing process. UniVec build 10.0 is also available via FTP.

This build added 174 complete vector sequences and 214 adapter, primer and other sequences, including 133 RNA Spike-In sequences, bringing the total number of sequences represented in the UniVec database to 3,039.

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New releases from NCBI: IgBLAST 1.7.0 and Sequence Viewer 3.21


IgBLAST 1.7.0 release

A new version of IgBLAST is now available on FTP, with the following new features:

  1. Specify whether overlapping nucleotides at VDJ junctions are allowed in matching V, D, and J genes.
  2. Set a custom J gene mismatch penalty
  3. Report the CDR3 start and stop positions in the sub-region table
  4. Use alignment length instead of percent identity as the tie-breaker for hits with identical blast scores, improving accuracy in the V, D, J gene assignment.

IgBLAST was developed at the NCBI to facilitate the analysis of immunoglobulin and T cell receptor variable domain sequences.

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Visualize and Interpret Alignment Data with the Multiple Sequence Alignment Viewer


The NCBI Multiple Sequence Alignment Viewer (MSAV) is a versatile web application that helps you visualize and interpret MSAs for both nucleotide and amino acid sequences. You can display alignment data from many sources, and the viewer is easily embedded into your own web pages with customizable options. An even simpler way to use MSAV is to use our page, upload your data, and share the link to a fully functional viewer displaying your results.

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Converting GI Numbers to Accession.version


As you may have read in previous posts, NCBI is in the process of changing the way we handle GI numbers for sequence records.

In short, we are moving to a time when accession.version identifiers, rather than GI numbers, will be the primary identifiers for sequence records.

As part of this transition, an obvious question for any of you currently using GI numbers is how to convert a GI number to an accession.version, so that you can make appropriate updates. The good news is that it’s pretty easy if you have no more than a few thousand GIs to convert.

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The Future of Existing GI Numbers at NCBI


NCBI has announced that we will be changing the way we handle GI numbers for sequence records in September 2016. (Read more, in case you missed it).

In this post, we’ll address a key question:

What is the future of existing GI numbers?

The short answer is that nothing is happening to these GI numbers.

If a nucleotide or protein record already has a GI, it will continue to have that GI indefinitely. You will also be able to retrieve such a record using its GI either on the NCBI web site or using the E-utilities.

Moreover, GIs will remain part of the XML and ASN.1 formats of sequence records.

If not GIs, then what?

Accession.version identifiers. All sequence records, both new and old, will have a unique accession.version identifier.

Existing records will keep the accessions they already have; new sequences will only receive an accession.version identifier.

So what’s all the fuss about?

Two things:

Stay tuned for additional posts about this topic, and please contact us if you have questions.

NCBI is Phasing Out Sequence GIs – Here’s What You Need to Know


You may have heard that NCBI is changing the way we handle GI numbers for sequence records in September 2016. Well, you heard right! Here’s the announcement, in case you missed it.

There are a number of issues raised by these changes, but we’re going to answer two questions in this post:

  1. What pieces of your code will break in September?
  2. Are GI numbers gone for good?

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The Human Reference Genome – Understanding the New Genome Assemblies


What is a genome assembly?

The haploid human genome consists of 22 autosomal chromosomes and the Y and the X chromosomes. Each of the chromosomes represents a single DNA molecule, a sequence of millions of nucleotide bases.  These molecules are linear, so one might expect that we should represent each chromosome by a single, continuous sequence.

Unfortunately, this is not the case for two main reasons: 1) because of the nature of genomic DNA and the limitations of our sequencing methods, some parts of the genome remain unsequenced, and 2) emerging evidence suggests that some regions of the genome vary so much between individual people that they cannot be represented as a single sequence.

In response to this, modern genomic data sets present a model of the genome known as a genome assembly. This post will introduce the basic concepts of how we produce such assemblies as well as some basic vocabulary.

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How To Format Sequence Data For GenBank Submissions


Submitting sequences to GenBank can seem complicated at first, but starting with a solid foundation in the form of a properly formatted file will make the process go smoothly.

Before submitting sequence data to GenBank, the data must be formatted correctly, the most common file format being FASTA. This post will show you how to create a FASTA file for submitting single- and multiple-nucleotide sequences.

Submitters can upload FASTA-formatted sequence files using NCBI’s stand-alone software Sequin, command line tbl2asn or our web-based submission tool BankIt.

The image below depicts a single sequence in FASTA format. For multiple sequences, such as those of population or phylogenetic studies, environmental samples, and batch sequences of the same gene, create the file using the steps below and put the set of sequences together in a single FASTA file.

Image

Here is how to create the FASTA file:

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