Development of microsatellite PCR typing methodology for the sea louse, Lepeophtheirus salmonis (Kroyer)

In order to develop a microsatellite typing system for Lepeophtheirus salmo nis (Kroyer), a DNA preparation method for individual sea lice suitable for analysis by polymerase chain reaction (PCR) was designed, and the DNA sequ ences of 50 L. salmonis microsatellite elements were determined. The micros atellites were composed of 60% perfect, 25% imperfect, and 15% compound rep eats. Based on the flanking DNA sequences, four microsatellite-PCR assays w ere optimized and used in a pilot study to analyse L. salmonis samples coll ected in Ireland, Norway and Scotland. Two of the microsatellite-PCR assays targeted polymorphic loci amplifying seven and 10 alleles respectively. Th e results showed that microsatellite-PCR typing could detect genetic variat ion both within and between the L. salmonis groups, and also was capable of amplifying group-specific alleles.