Mitochondria-driven cell elongation mechanism for competing sperms.

Sexual competition has selected a number of extreme phenotypes like the tail ornament of peacock male. Sperm tail of Drosophilidae elongate up to 6 cm as a result of evolutionary selection for reproductive fitness among competing sperms. Sperm elongation takes place post meiotically and can proceed in the absence of an axoneme. Here, we used primary cultures of elongating spermatids of D. melanogaster to demonstrate that sperm elongation is driven by interdependent extension of giant mitochondria and microtubule array that is formed around the mitochondrial surface. This work established that, in addition to functioning as an energy source, mitochondria can serve as internal skeleton for shaping cell morphology.