Novel memory mutants in Drosophila: Behavioral characteristics of the P-Insertional mutant Ent2 P124

The Drosophila mutant P124, carrying insertion of P (lacW) vector in the second chromosome on the background of the w mutation in the X chromosome, was previously isolated as showing memory deficiency after courtship conditioning. Here we report additional features of the mutant phenotype: (1) abnormal adaptation to darklight transition; (2) impaired perception by males of nuances of visual image of a female, specifically, of her fine movements such as preening and ovipositor extrusion; (3) subnormal performance index after odor-shock conditioning. These abnormalities are not related to a deficit of the eye screening pigments because they are also revealed on the background of the normal w ⁺ allele in the X chromosome. The visual and cognitive impairments are independent pleiotropic effects of the mutation. The mutation is caused by insertion of the P vector 12 nucleotides upstream of the transcription start of the gene Ent2 (equilibrative nucleoside transporter 2). Ent2 P¹²⁴ is the second mutant allele of this gene found in Drosophila. The genetic variability in Ent2 locus should be considered as a factor of risk for development of mental retardation and disorders of visual perception.