RESUMEN
A total of 18 associative learning/memory tests have been applied to Drosophila melanogaster flies lacking mushroom bodies. Only in paradigms involving chemosensory cues as conditioned stimuli have flies been found to be compromised by a block in the mushroom body pathway. Among the learning tasks not requiring these structures are a case of motor learning (yaw torque/heat), a test of the fly's spatial orientation in total darkness, conditioned courtship suppression by mated females, and nine different examples of visual learning. The latter used the reinforcers of heat, visual oscillations, mechanical shaking, or sucrose, and as conditioned stimuli, color, intensity contrast, as well as stationary and moving visual patterns. No forms of consolidated memory have been tested in mushroom body-less flies. With respect to short-term memory the mushroom bodies of Drosophila are specially required for chemosensory learning tasks, but not for associative learning and memory in general.
Asunto(s)
Drosophila melanogaster/fisiología , Animales , Condicionamiento Clásico/fisiología , Femenino , Calor , Aprendizaje/fisiología , Masculino , Actividad Motora/fisiología , Neuronas/fisiología , Neurópilo/fisiología , Vías Olfatorias/fisiología , Refuerzo en Psicología , Conducta Sexual Animal/fisiología , Conducta Espacial/fisiología , Torque , Tacto/fisiología , Visión Ocular/fisiologíaRESUMEN
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. In this experimental design one cannot exclude that flies mark the heated side by an odor that they subsequently avoid during the test. As a final proof for associative learning in the present experiment, flies are trained in one chamber and tested for learning in another, similar one. Handling in the transfer experiment interferes with memory display, even if the fly is returned to the old chamber instead of a new one. Memory can be reactivated, however, by subjecting the fly to an additional brief training (priming), which is too short to establish significant learning in naive flies. For efficient priming, heat has to be applied to the same side as during training in the old chamber. Only then the fly subsequently shows a side preference and avoids the side of the new chamber, which in the old one had been associated with heat. The two chambers are similar but not identical The transfer experiment therefore raises the question as to what the flies use as spatial reference during training and test. In the light, they can be shown to orientate according to visual landmarks associated with the chamber. In complete darkness, where training and memory scores do not differ from those in the light, they are assumed to use a combination of tactile and idiothetic information for orienting.
Asunto(s)
Reacción de Prevención/fisiología , Condicionamiento Clásico/fisiología , Drosophila melanogaster/fisiología , Memoria/fisiología , Percepción Espacial/fisiología , Animales , Oscuridad , Calor , Luz , Tiempo de ReacciónRESUMEN
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.
Asunto(s)
Condicionamiento Operante/fisiología , Aprendizaje/fisiología , Fisiología/métodos , Animales , Drosophila , Factores de TiempoRESUMEN
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.
Asunto(s)
Aprendizaje por Asociación , Drosophila melanogaster/fisiología , Habituación Psicofisiológica , Isoenzimas/genética , Mutación , Fosfoproteínas Fosfatasas/genética , Animales , Reacción de Prevención , Cruzamientos Genéticos , Drosophila melanogaster/enzimología , Drosophila melanogaster/genética , Femenino , Heterocigoto , Homocigoto , Isoenzimas/deficiencia , Aprendizaje , Masculino , Memoria , Odorantes , Fosfoproteínas Fosfatasas/deficiencia , Proteína Fosfatasa 1 , Olfato , Factores de TiempoRESUMEN
P transposon induced modifier mutations of position-effect variegation (PEV) were isolated with the help of hybrid dysgenic crosses (pi 2 strain) and after transposition of the mutator elements pUChsneory+ and P[lArB]. Enhancer mutations were found with a ten times higher frequency than suppressors. The 19 pUChsneory(+)- and 15 P[lArB]-induced enhancer mutations can be used for cloning of genomic sequences at the insertion sites of the mutator elements via plasmid rescue. Together with a large sample of X-ray-induced (48) and spontaneous (93) enhancer mutations a basic genetic analysis of this group of modifier genes was performed. On the basis of complementation and mapping data we estimate the number of enhancer genes at about 30 in the third chromosome and between 50 and 60 for the whole autosome complement. Therefore, enhancer of PEV loci are found in the Drosophila genome as frequently as suppressor genes. Many of the enhancer mutations display paternal effects consistent with the hypothesis that some of these mutations can induce genomic imprinting. First studies on the developmentally regulated gene expression of PEV enhancer genes were performed by beta-galactosidase staining in P[lArB] induced mutations.
Asunto(s)
Elementos Transponibles de ADN/genética , Drosophila melanogaster/genética , Elementos de Facilitación Genéticos , Genes Supresores , Animales , Cruzamientos Genéticos , Elementos de Facilitación Genéticos/efectos de la radiación , Femenino , Prueba de Complementación Genética , Hibridación Genética/genética , Masculino , Mutagénesis , Ovario/química , Monoéster Fosfórico Hidrolasas/genética , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes de Fusión/genética , Testículo/química , Dedos de Zinc/genéticaRESUMEN
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.