Inhaltszusammenfassung

A fly, memorizing its body reach, adjusts its behavior at a gap according to the own body size. Therefore, this fly will not try surmounting a gap that exceeds its reach by far. Formation of such a body-size memory is achieved by connecting parallax-motion experience with locomotion while walking in a visually structured environment. Regarding the biochemical pathway, learning and consolidation is mediated by activation of the cAMP/PKA signalling cascade and the transcription factor dCREB2 in...A fly, memorizing its body reach, adjusts its behavior at a gap according to the own body size. Therefore, this fly will not try surmounting a gap that exceeds its reach by far. Formation of such a body-size memory is achieved by connecting parallax-motion experience with locomotion while walking in a visually structured environment. Regarding the biochemical pathway, learning and consolidation is mediated by activation of the cAMP/PKA signalling cascade and the transcription factor dCREB2 in Δ7-neurons of the protocerebral bridge (PB). Conversely, neurons, that connect the PB with the fan-shaped body and the noduli (PFN), require low activity of dCREB2. Once formed, body-size memory is the most enduring memory known to date in Drosophila melanogaster. In the present study, a network-analysis was performed, showing that Δ7- neurons project to and build synaptic contacts with PFN-neurons. Additionally, the actual PFN-cell types responsible for acquiring body-size memory could be further defined by comparing them to published cell types of the protocerebral bridge. Moreover, it could be shown that learning the individual body reach is independent of a sensitive period in a fly’s life. Thus, learning is not restricted to the immediate post- hatching period, but possible even 8 - 9 days thereafter. Once consolidated, body- size memory can be retrieved 12 – 14 hours after learning. Investigating mechanisms guaranteeing maintenance of the learned information, data were collected showing that dCREB2-activity in Δ7-neurons is required on a sustained basis, outlasting even the early maintenance period. Supportingly, feeding the protein synthesis inhibitor Cycloheximid revealed that synthesis of new proteins is required even after consolidation. With an alternative approach focusing on maintenance mechanisms, it was asked, whether the expression of dCREB2-target genes in Δ7-neurons is continuously achieved by epigenetic modification. An RNAi-screen unraveled that eleven candidates, in addition to the dCREB2-co-activators dCBP und CRTC, exhibited a Δ7-specific climbing phenotype. Those flies showed extensive leg-over- head strokes at an unsurmountable gap. However, whether the function of the epigenetic factors are required during learning and consolidation or memory maintenance needs to be analyzed. According to the results of the study, it is likely that dCREB2 and the epigenetic modulators act synergistically to achieve memory maintenance.» weiterlesen» einklappen

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Klassifikation

DDC Sachgruppe:
Biowissenschaften, Biologie