DETECTION AND CHARACTERIZATION OF 2 NOVEL HYPERVARIABLE MICROSATELLITE REPEAT REGIONS WITHIN INTRON-2 OF THE ALPHA-GLOBIN GENE OF THE BIVALVE MOLLUSK ANADARA-TRAPEZIA

Synthetic oligonucleotide primers based on cDNA sequence were used to amplify the region spanning intron 2 of the alpha-globin gene of the b ivalve mollusc Anadara trapezia. Amplification of this region from ind ividual clams showed highly polymorphic patterns. The sequence of this intron was found to include a number of mono- [d(T)(n) and d(C)(n)], di- [d(CA)(n) and d(CT)(n)] and tetranucleotide d(CTGT)(n) repeats whi ch were found to be polymorphic with respect to the types and numbers of repeats present. Two separate repeat-containing polymorphic regions were located near each end of this intron. The repeat at the 3' end c onsisted of an unusual example of a d(T)(n) polymorphism at the positi on of the polypyrimidine tract usually involved in intron splicing. Th irteen individual cloned intron 2 sequences, derived by PCR amplificat ion from pooled genomic DNA, were sequenced without finding two identi cal sequences. All of the sequenced clones contained microsatellite se quences.