ANALYSIS OF COPIES OF THE SUFFIX ELEMENT, DROSOPHILA RETROPOSON, PRODUCED BY PCR AMPLIFICATION OF GENOMIC DNA

Nineteen DNA clones, containing copies of the suffix element retroposo n of the Drosophila genome and produced by a polymerase chain reaction (PCR), were sequenced. Insertions of the copies in both orientations into microsatellite sequences (CAACA)(n)/(TGTTG)(n) and (TTTGT)(n)/(CA CAAA)(n) were revealed. It was found that, if the microsatellite seque nce has both a decanucleotide GCGGCCCGGG (GC-box) and a colinear alter nating sequence (A)(5)(T)(4)(A)(3)(T)(2)(A)(1)(t)(n) (AT-box), the ins ertion of the suffix occurs in only one orientation. It is suggested, that in such apparently heterochromatic sequences, suffix element copi es and probably some other retroposons can be inserted a particular or ientation by means of site-specific recombination. An approach to anal ysis of the molecular organization of such sequences is proposed.