Date of Award

10-1-2021

Publication Type

Thesis

Degree Name

M.Sc.

Department

Biological Sciences

Keywords

Drosophila courtship behavior, Frq protein, Synaptic function, Courtship levels

Supervisor

J. Dason

Supervisor

H. Zhang

Rights

info:eu-repo/semantics/embargoedAccess

Abstract

The Drosophila calcium-binding proteins Frequenin1 (Frq1) and Frequenin2 (Frq2), and their mammalian homologue Neuronal Calcium Sensor-1 (NCS-1), have been extensively reported to regulate several aspects of synaptic function. Although Frq/NCS-1 is well studied at the molecular level and is expected to regulate normal neurological development, as it is implicated in several diseases, less is known about its role in behaviour. Thus, in the present study, I aimed to determine if the role of Frq1 and Frq2 in synaptic function leads to a role in the complex Drosophila behaviour, courtship. I tested naïve courtship levels of two frq null mutants, frqdel1 and frqdel3, both with no detectable Frq protein. Here, courtship levels were significantly reduced in the frqdel1 mutants and not in the frqdel3 mutants. Next, to determine if Frq1 or Frq2 are involved in courtship, I tested naive courtship levels on frq1 and frq2 loss-of-function single mutants that each carry insertion elements designed to disrupt Frq1 or Frq2 transcription, respectively. Both mutants displayed significantly reduced courtship levels. Next, I found that the impaired courtship levels seen in the frqdel1 mutants was rescued by expressing Frq in the nervous system using the UAS/GAL4 system. Finally, overexpressing frq1 and frq2 in the nervous system yielded inconclusive results, as the Frq1 overexpresser showed an effect compared to one control and but not the other, while the frq2 overexpresser showed no effect. Courtship impairments are also seen in Fragile-X Syndrome dfmr1 mutants, where Frq levels are also reduced; I confirmed this finding. Collectively, I used a frqdel1 null mutant, frq loss-of-function mutants, and rescue genotypes to demonstrate a novel role for Frq1 and Frq2 in Drosophila courtship behaviour. Drosophila courtship is a complex behavior involving multiple sensory modalities; future studies will address which of these are regulated by Frq. Furthermore, Frq’s expression patterns, its downstream targets and its effects on synaptic function in this courtship circuit will be deciphered.

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