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Author

Aidan Dineen

Date of Award

9-2009

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Supervisor

ANA REGINA CAMPOS

Language

English

Abstract

Wild-type Drosophila larvae display photophobic behaviour when confronted with a light stimulus. This behaviour is mediated by changes in larval locomotion including increased direction change and pausing in addition to decreased contraction frequency. Foraging third instar larvae that are homozygous mutant for the Drosophila Ran Binding Protein in the Microtubule Organizing Center (dRanBPM) gene exhibit a reduced response to light and two alleles display a severe locomotion deficit. dRanBPM functional domains show a considerable number of identical amino acids when compared with orthologous genes. The human orthologue RanBPM binds to Fragile X Mental Retardation Protein (FMRP), a protein for which the loss of expression causes Fragile X syndrome. Wandering Drosophila fragile X mental retardation 1 (dfmr1) mutant larvae show increased direction change and reduced time spent in linear locomotion in a dark assay. Double mutant larvae homozygous for a dfmr1 mutant allele and carrying one copy of a dRanBPM mutant allele were tested for turning and response to light phenotypes. The results presented here indicate that dRanBPM and dfmr1 act independently to modulate aspects of larval locomotion. Expression of dRanBPM is found in distinct sets of neurons in the larval CNS including the mushroom bodies (MBs). Neuronal silencing of the MBs in foraging third instar larvae resulted in a reduction in response to light. Finally, this reduction in response to light stimuli was characterized as a decrease in mean direction change during the light.

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