13.2kb of D.melanogaster per with the central 700bp thr-gly repeat region replaced by that of D.simulans.
A SstI-BamHI fragment (carrying the Thr-Gly repeat) of D.simulans Dsim\per is substituted into D.melanogaster per+t13.2.
Construct: D.melanogaster per Thr-Gly repeat has been replaced with Dsim\per Thr-Gly repeat.
Circadian periodicity longer than that of wild type.
Male D.melanogaster per01 flies carrying per::Dsim\perTGs produce courtship songs with a period of about 35 seconds, characteristic of D.simulans.
Introduction of the P{ per::Dsim \perTGs} construct into per01 gives song rhythms with a simulans-like period, short 35 to 40 second song cycles.