Figure 5.

Models for the origin of the various classes of bz-s derivatives and for chromosome breakage in bz-m2(D2) Ac6067.

(A) Macrotransposition: classes 9 and 10.

(B) Intertransposon recombination: classes 12 and 13.

(C) TE-adjacent deletion: classes 6 and 7.

(D) ITS deletion/adjacent inversion: class 8.

(E) ITS rearrangement: class 11.

(F) Chromosome breakage.

The Ac transposase can carry out two types of alternative transposition reactions, recognizing either the two external ends (A) or internal ends ([C] to [F]) of the MTn. The symbols follow Figure 1, except that when the two internal ends are cut ([C] to [F]), the b and c designations are reversed relative to Figure 1 and refer to the Ds 3′ end and the Ac 5′ end, respectively.