A Drosophila toolkit for defining gene function in spermatogenesis

Expression profiling and genomic sequencing methods enable the accumulation of vast quantities of data that relate to the expression of genes during the maturation of male germ cells from primordial germ cells to spermatozoa and potential mutations that underlie male infertility. However, the determination of gene function in specific aspects of spermatogenesis or linking abnormal gene function with infertility remain rate limiting, as even in an era of CRISPR analysis of gene function in mammalian models, this still requires considerable resources and time. Comparative developmental biology studies have shown the remarkable conservation of spermatogenic developmental processes from insects to vertebrates and provide an avenue of rapid assessment of gene function to inform the potential roles of specific genes in rodent and human spermatogenesis. The vinegar fly, Drosophila melanogaster, has been used as a model organism for developmental genetic studies for over one hundred years, and research with this organism produced seminal findings such as the association of genes with chromosomes, the chromosomal basis for sexual identity, the mutagenic properties of X-irradiation and the isolation of the first tumour suppressor mutations. Drosophila researchers have developed an impressive array of sophisticated genetic techniques for analysis of gene function and genetic interactions. This review focuses on how these techniques can be utilised to study spermatogenesis in an organism with a generation time of 9 days and the capacity to introduce multiple mutant alleles into an individual organism in a relatively short time frame.