Abstract
The identification of mutations in the gene fruitless (fru) paved the way for understanding the genetic basis of male sexual behavior in the vinegar fly Drosophila melanogaster. D. melanogaster males perform an elaborate courtship display to the female, ultimately leading to copulation. Mutations in fru have been shown to disrupt most aspects of the male's behavioral display, rendering males behaviorally sterile. The fru genomic locus encodes for multiple transcription factor isoforms from several promoters; only those under the regulation of the most distal P1 promoter are under the control of the sex determination hierarchy and play a role in male-specific behaviors. In this study, we used CRISPR/Cas9-based targeted genome editing of the fru gene, to remove the P1 promoter region. We have shown that removal of the P1 promoter leads to a dramatic decrease in male courtship displays towards females and male-specific sterility. We have expanded the analysis of fru P1-dependent behaviors, examining male's response to courtship song and general activity levels during12-hour light: dark cycles. Our novel allele expands the mutant repertoire available for future studies of fru P1-derived function in D. melanogaster. Our fruΔP1 mutant will be useful for future studies of fru P1-derived function, as it can be homozygosed without disrupting additional downstream promoter function and can be utilized in heterozygous combinations with other extant fru alleles.
Highlights
In 1963, Kulbir Gill published a small research note in Drosophila Information Service entitled ‘A mutation causing abnormal courtship and mating behavior in males of Drosophila melanogaster’
We extended our analysis to examine for the first time the effects of fru P1 promoter loss on male activity and their ability to respond to courtship song stimuli
We found that fruDP1 mutant males over this observation period showed lower levels of activity, especially apparent was the differences in the magnitude of the peak of activity before lights-off (Figure 4(C) left and right, respectively)
Summary
In 1963, Kulbir Gill published a small research note in Drosophila Information Service entitled ‘A mutation causing abnormal courtship and mating behavior in males of Drosophila melanogaster’. The effects of the mutation were male-specific, in that homozygous mutant females showed no noticeable phenotypic or behavioral differences from wild-type (Hall, 1978). Homozygous mutant males, exhibited several overt differences from normal male courtship behavior: they did not curl their abdomens at females to attempt copulation and were considered behaviorally sterile, in addition, they courted other mutant males and wild-type males (Hall, 1978). The mutation was given the moniker fruitless (fru), which seems fitting as mutant males will father no offspring. The identification of this first mutant allele (fru1) paved the way for understanding the genetic basis of male sexual behavior in the vinegar fly D. melanogaster
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