STS mapping from a clone library

STSmapping plays amajor role in genomemapping.
An STS (sequence-tagged site) is a short
stretch (60–1000 bp) of a unique DNA nucleotide
sequence, An STS has a specific location
and can be analyzed by PCR (see p. 66). The relevant
information, i.e., the sequence of the
oligonucleotide primers used for the PCR reaction
and other data can be stored electronically
and does not depend on biological specimens.
One can start with a clone library containing
DNA fragments in unknown order (1). Each end
of the chromosomal fragment is characterized
by a pattern of restriction sites (see p. 64). The
DNA fragments are ordered by determining
which ends overlap, then assembling them as a
contiguous array of overlapping fragments into
a clone contig (2). These are linearly arranged.
This establishes a map that shows the location
and the physical distance of the landmarks,
here A, B, C, etc. (3). Sequence-tagged sites
(STSs) are generated from the two ends of the
overlapping clones. This involves sequencing
100–300 bp of DNA (4).