Investigation of <i>Drosophila fruitless</i> neurons that express Dpr/DIP cell adhesion molecules.

Abstract

<i>Drosophila</i> reproductive behaviors are directed by <i>fruitless</i> neurons. A reanalysis of genomic studies shows that genes encoding <i>dpr</i> and <i>DIP</i> immunoglobulin superfamily (IgSF) members are expressed in <i>fru P1</i> neurons. We find that each <i>fru P1</i> and <i>dpr/DIP</i> (<i>fru P1</i> ∩ <i>dpr/DIP</i>) overlapping expression pattern is similar in both sexes, but there are dimorphisms in neuronal morphology and cell number. Behavioral studies of <i>fru P1</i> ∩ <i>dpr/DIP</i> perturbation genotypes indicate that the mushroom body functions together with the lateral protocerebral complex to direct courtship behavior. A single-cell RNA-seq analysis of <i>fru P1</i> neurons shows that many <i>DIPs</i> have high expression in a small set of neurons, whereas the <i>dprs</i> are often expressed in a larger set of neurons at intermediate levels, with a myriad of <i>dpr/DIP</i> expression combinations. Functionally, we find that perturbations of sex hierarchy genes and of <i>DIP-ε</i> change the sex-specific morphologies of <i>fru P1</i> ∩ <i>DIP-α</i> neurons.