The genetic variant Voila causes gustatory defects during Drosophila development.

Voila(1), an enhancer-trap strain in Drosophila melanogaster, expresses GAL4 in most gustatory neurons, both before and after metamorphosis. Voila(1) expression starts at embryonic stage 10. In the periphery, it labels larval gustatory sensilla in the antennomaxillary complex as well as in the pharynx. GAL4 is also expressed in the CNS in a manner that prefigures expression in adult flies. Most Voila(1/1) homozygotes die between second larval instar and early adulthood. Moreover, escaping Voila(1/1) larvae do not show gustatory responses to NaCl and sucrose. The simultaneous rescue of normal larval gustation together with adult viability after removal of the transposable PGAL4 element suggests that both these phenotypes are caused by the same inserted element.