Sexually dimorphic social spacing after isolation in Drosophila melanogaster: Determining the neural circuitry involved

Wes Robinson, Abigail Bechard, Micah Evans

 

The decision of where an animal settles relative to others is dependent on its ability to recognize and respond appropriately. These responses have been observed to be sexually dimorphic in some species and influenced by previous social experience, such as isolation. I studied these responses through measuring social space, the distance between an individual to its closest neighbour in a stable group, which precedes more complex behaviours such as mating and aggression. Distances between flies with altered neuronal activity of doublesex (dsx)- and fruitless (fru)-expressing neurons were measured to determine social space. Manipulations of dsx-expressing neurons did not result in significantly different distances between flies. Increasing and decreasing activity levels fruP1-expressing neurons in females caused them to settle farther apart, however only hyper-activation of fruP1-expressing neurons in males altered their social space. This study has allowed for a better understanding of the sex-specific neural circuitry that is involved in processing social space cues.

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Modulation of social spacing by dopamine receptors in the Drosophila melanogaster mushroom bodies

Micah Evans

 

Social spacing is the maintenance of a preferred distance between individuals when in a group. Many species display this form of social behaviour, and the underlying neural circuitry can be investigated using the vinegar fly (Drosophila melanogaster) as a genetic model. Factors known to be involved in Drosophila social space regulation include the neurotransmitter dopamine and the mushroom body (MB) brain region, which is considered the functional equivalent to the mammalian hippocampus. There is extensive dopaminergic signalling into the MB, and these signals are transmitted by four dopamine receptors in Drosophila (Dop1R1, Dop1R2, Dop2R, DopEcR). To determine the involvement of the dopamine receptors in social space determination, receptor expression was manipulated in the MB using the Gal4/UAS system. All four receptors were found to play a role in social spacing, but their effect varied based on both sex and genetic background, highlighting the complexity of biological systems. Current work is investigating dopamine receptor expression within specific MB lobes (αβ, α‘β’, γ) to examine social space circuitry with greater spatial resolution. What we learn in Drosophila may provide insights into regulation of social space in other organisms, as pathways governing social behaviour are believed to be conserved in many species.

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Evolutionary and functional analysis of neuroligin-3 variants in longevity, behaviour, and aging

Judy Kurbaj

Neuroligin-3 is a postsynaptic adhesion protein critical for synapse formation, maintenance, and function. In human, NLGN3 genetics variants are implicated in neurodevelopmental disorders such as autism. This project employs Drosophila melanogaster and humanized fly models to dissect the behavioural, and evolutionary significance of nlg3 and its variants. Using tissue-specific knockdown of the endogeneous fly neuroligins (dnlg3, its closest orthologs, as well as nlg1, 2, and 4) and overexpression of the human NLGN3, the study evaluates the impact of nlg3 on social interaction, and lifespan. By linking molecular function with organismal behaviour and evolutionary persistence, we seek to clarify how neuroligin-3 variants have been maintained in populations and explore their potential as therapeutic targets in neurodevelopmental and age-associated disorders.

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