BLAST

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Chapter 6

CHAPTER 6

Anatomy of a BLAST Report

This chapter explores the standard BLAST format. NCBI-BLAST and WU-BLAST

are very similar, and their few important differences are described below. NCBI-

BLAST offers several additional output options described in Appendix A.

Basic Structure

A standard BLAST report has four parts (see Figure 6-1).

Header

The first line contains the name of the program, its version, and its build date. If

BLAST crashes or has some kind of unexpected behavior, include this informa-

tion when you report the problem to the authors. The next piece of information

is a reference to the scientific literature, which should be cited if you publish

research that employed BLAST. The most important information in the header,

the names of the query sequence and the database, appear next. The last line is a

progress meter that is updated during the search.

One-line summaries

Each line indicates the name of the sequence, the highest scoring alignment

found and the lowest E-value for any HSP or group of HSPs. The one-line sum-

maries are often hyperlinked to the alignments farther below when the output

comes from a web page. If you just want to know for example, the names of the

top matches, these one-line summaries are convenient.

Alignments

The alignments usually make up the ...