Figure 3.—

Primers used to distinguish between different classes of terminal deficiency structure. (A) A P element is depicted (double-headed arrow), with the proximal P inverted repeat (PrP) and distal inverted repeat (DiP) primers, as well as the respective proximal (Pr) and distal (Dl) genomic primers used to verify the position of the P element in the terminal deficiencies. The sequence of the chromosome, increasing in cytology, is arbitrarily represented as a b c d e f g h. (B) Terminal deficiencies that derive from dicentric breakage are expected to generate a reverse duplication of the proximal genomic DNA (d c b a) after the distal end of the P element. Only events deriving from breakage of a dicentric produce PCR products when the DiP and Pr primer pair is used.