Homozygous flies show abnormal temperature-preference behaviour; their avoidance index against low temperatures is 26% of wild type.

Escapers exhibit an extreme Ddc phenotype.

Recently eclosed hemizygous adults have an underpigmented cuticle which darkens on aging, producing abnormally dark adults with obvious concentrations of melanisation in the joints of the legs and axillae of the wings. The bristles are wild-type in colour. Hemizygous pupal cases are wild-type in appearance. Homozygous embryos, CNS at pupariation and newly eclosed adult epidermis have approximately 5% as much dopa decarboxylase activity compared to wild-type. In contrast, epidermis at pupariation has approximately 50% wild-type activity. Homozygous tissues have between 3.7 and 7.3 times as much dopa decarboxylase activity as the corresponding hemizygous tissues.

Hemizygous adults (9% of expected eclose) exhibit an extreme 'escaper' phenotype (see Ddc above) except macrochaetae are normally pigmented suggesting that Ddc^DE1 is differentially active in the epidermis vis-a-vis the bristle-forming cells. Pupa cases of Ddc^DE1 homo- and hemizygotes are wild type. DDC activity in newly eclosed adult Ddc^DE1 homozygotes is 4.4 +/- 0.2% and in hemizygotes is 0.6 +/- 0.1% of wild-type controls. Homozygous late embryos have 4.8 +/- 2.3% activity. In striking contrast homozygous white prepupae have 46.5 +/- 2.8% DDC activity. However, central nervous systems dissected from these Ddc^DE1 homozygous white prepupae show a tissue specific difference having 4.8 +/- 2.3% DDC activity compared to wild-type CNS. Specific DDC activity in Ddc^DE1 homozygotes ranges significantly more than two times DDC levels in Ddc^DE1/Df(2L)TW130 hemizygotes. DDC from Ddc^DE1 homozygotes, crawling third instar larvae and adults, is less thermostable in vitro in comparison to controls. Late Ddc^DE1/Ddc^DE1 embryos (16-20 hr) have no detectable mature 2.0 kb Ddc RNA and have reduced levels of the 2.3 kb RNA. The precise reason for the differential expression has yet to be established but is not due to position effect variegation (Bishop and Wright, 1987). Ddc^DE1 phenotype rescued by a 7.5kb transformant of Ddc⁺ DNA.

Ddc^DE1/Ddc⁵ has partially lethal phenotype, non-suppressible by Tcr⁴⁵

Ddc^DE1/Ddc⁸ has partially lethal phenotype, non-suppressible by Tcr⁴⁵