Expression of a fragment carrying Alup\AFP1.5 transcription unit and 3' untranslated sequences is driven by the Yp1 promoter from a fragment of the Yp1-Yp2 intergenic region.
In transgenic P{YP1,2;wAFP2} individuals ice crystals are needle-shaped during thermal hysteresis (0.1-0.35oC), ice in the haemolymph of untransformed individuals grows rapidly as a flat hexagonal crystal.
Female transgenic flies bearing the construct synthesize Alup\AFP1.5 and secrete it into their haemolymph, male transgenics produce no Alup\AFP1.5 and serve as controls.