An important role for triglyceride in regulating spermatogenesis

Drosophilais a powerful model to study how lipids affect spermatogenesis. Yet, the contribution of neutral lipids, a major lipid group which resides in organelles called lipid droplets (LD), to sperm development is largely unknown. Emerging evidence suggests LD are present in the testis and that loss of neutral lipid- and LD-associated genes causes subfertility; however, key regulators of testis neutral lipids and LD remain unclear. Here, we show LD are present in early-stage somatic and germline cells within theDrosophilatestis. We identified a role for triglyceride lipasebrummer(bmm) in regulating testis LD, and found that whole-body loss ofbmmleads to defects in sperm development. Importantly, these represent cell-autonomous roles forbmmin regulating testis LD and spermatogenesis. Because lipidomic analysis ofbmmmutants revealed excess triglyceride accumulation, and spermatogenic defects inbmmmutants were rescued by genetically blocking triglyceride synthesis, our data suggest thatbmm-mediated regulation of triglyceride influences sperm development. This identifies triglyceride as an important neutral lipid that contributes toDrosophilasperm development, and reveals a key role forbmmin regulating testis triglyceride levels during spermatogenesis.