Meeting Abstract
The primary function of sperm has long been assumed to be solely for the transference of genetic material to the next generation. However, not all sperm are able to fertilize eggs, yet somehow are maintained during spermatogenesis. Numerous taxa have been documented as predictably transferring non-fertilizing sperm to females during copulation. The most striking example of non-fertilizing sperm comes from Lepidoptera, the butterflies and moths. Males produce two distinct morphs of sperm: the nucleated, fertilizing sperm (eupyrene), and an anucleated, non-fertilizing sperm (apyrene). Despite the fact that apyrene sperm are incapable of fertilizing a female’s eggs, they are not only consistently produced and transferred to females, but also appear to play a vital role in the success of eupyrene sperm. We hypothesized that the apyrene sperm may support the function of eupyrene sperm through a difference in expression of small, non-coding RNA (sncRNA). Transfer of sncRNA have been documented in vertebrate sperm cells, including mammals and birds. Further, the sncRNA have been implicated in several vital transgenerational processes, such as epigenetic inheritance patterns and proper embryo development. No work to date has explored sncRNA in lepidopteran sperm and the dual nature of sperm morphs provides an exciting new frontier in reproductive biology. Using monarch butterflies, Danaus plexippus, we explored the differences and similarities in expression levels for sncRNA in both eupyrene and apyrene sperm. Our results are discussed in the context of sperm cell specialization and reproductive trait evolution.
