[Novel memory mutants in Drosophila: behavioral characteristics of the P-insertional mutant in the Ent2P locus].

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 dark-light 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.