PRIMER-DIRECTED SYNTHESIS OF A MOLECULAR-WEIGHT MARKER

Marker primer-directed synthesis (MPDS) is a technique that allows the easy synthesis of DNA base pair (bp) ladders. This method involves th e amplification of a DNA target with two different Sets of primers: a set of range primers, which will define the absolute length of the lad der, and a set of spacer primers which will determine the size differe nce between each one of the fragments of the DNA ladder. The ladders o btained with this technique can be used as molecular weight standards to analyse the size of DNA fragments. In this way, we have synthesized a 6 bp ladder ranging from 90 to 204 bp which results particularly us eful in the typing of microsatellites in ethidium bromide (EB) or silv er nitrate (SN) stained polyacrylamide gels. (C) 1996 Elsevier Science B.V.