A freely walking single fly (Drosophila melanogaster) can be conditioned to avoid one side of a small test chamber if the chamber is heated whenever the fly enters this side. In a subsequent memory test without heat it keeps avoiding the heat-associated side. The memory mutants dunce and rutabaga successfully avoid the heated side but show no avoidance in the memory test. Wildtype flies can be trained to successively avoid alternating sides in a reversal conditioning experiment. Every single fly shows strong avoidance and a positive memory score. The new conditioning apparatus has several advantages: (1) Statistically significant learning scores can be obtained for individual flies. (2) Learning scores are obtained fully automatically without interference of the experimenter. (3) The procedure is fast, robust and requires little handling. Therefore the apparatus is suitable for largescale mutant screening. (4) Animals are not attached to a hook and thus can easily be used for breeding.
The dose dependent effects of position-effect variegation (PEV) modifying genes were studied in chromosome arms 2L, 2R and 3R. Four groups of PEV modifying genes can be distinguished: haplo-abnormal suppressor and enhancer loci with or without a triplo-effect. Using duplications four triplo-abnormal suppressor and four triplo-abnormal enhancer functions were localized. In two cases we proved that these functions correspond to a converse haplo-abnormal one. Altogether 43 modifier loci were identified. Most of these loci proved not to display significant triplo-effects (35). The group of haplo-abnormal loci with a triplo-effect may represent genes which play an important role in heterochromatin packaging.
A paradigm for operant conditioning of freely walking single Drosophila flies has been described previously. A fly can be conditioned to avoid one side of a small test chamber if the chamber is heated whenever the fly enters this side. In a subsequent memory test without heat the fly continues to avoid the previously heat-associated side.
The learning and memory of Drosophila melanogaster strains carrying the Su-var(3)6(01) mutation, which is known to affect the structural gene of a protein phosphatase 1 isoenzyme, PP1(87B), were studied in various behavioral paradigms. Three lines of Drosophila comprising the Su-var(3)6(01) mutation in different genetic backgrounds were shown to have diminished protein phosphatase 1 activity and behavioral anomalies. Associative olfactory learning and visual conditioning were impaired. Olfactory acuity for the odorants used and response to electric shock were largely unchanged in the mutant lines. The motility and flight activity of the mutants were reduced. Habituation of the landing response, a nonassociative learning process, was more pronounced in heterozygotes of the mutants than in the wild-type control strains. Taken together with earlier data, the results indicate that protein phosphatase PP1(87B), while affecting several cellular processes, is also part of the biochemical machinery of various forms of neuromodulation in Drosophila.
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