gain of function allele

Associated with In(2R)Arp2 with P-derived sequences at either end. Deficiency analysis shows that lethality common to Su(z)2^Arp2 and Su(z)2^Arp1 associated with the 49A12-B3 breakpoint. Reverts by reinversion in dysgenic (1/200) and control (1/2000) crosses.

In situ hybridization with P element probe shows P element at both ends of the inversion. P element at the proximal breakpoint thought not to be in exon, and to be phenotypically silent, and is 0.8kb smaller in Su(z)2^Arp2 than it is in Su(z)2^Arp1.

Unstable, reverting spontaneously at a frequency of 0.02%, and, under dysgenic conditions, at a frequency of 2%. Wild type revertants show wild type cytology.