Department of Biology, Tufts University, Medford, MA, 02155, USA.
Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA, 02142, USA.
Sci Rep. 2016 Dec 22;6:38556. doi: 10.1038/srep38556.
Postcopulatory sexual selection is recognized as a key driver of reproductive trait evolution, including the machinery required to produce endogenous nuptial gifts. Despite the importance of such gifts, the molecular composition of the non-gametic components of male ejaculates and their interactions with female reproductive tracts remain poorly understood. During mating, male Photinus fireflies transfer to females a spermatophore gift manufactured by multiple reproductive glands. Here we combined transcriptomics of both male and female reproductive glands with proteomics and metabolomics to better understand the synthesis, composition and fate of the spermatophore in the common Eastern firefly, Photinus pyralis. Our transcriptome of male glands revealed up-regulation of proteases that may enhance male fertilization success and activate female immune response. Using bottom-up proteomics we identified 208 functionally annotated proteins that males transfer to the female in their spermatophore. Targeted metabolomic analysis also provided the first evidence that Photinus nuptial gifts contain lucibufagin, a firefly defensive toxin. The reproductive tracts of female fireflies showed increased gene expression for several proteases that may be involved in egg production. This study offers new insights into the molecular composition of male spermatophores, and extends our understanding of how nuptial gifts may mediate postcopulatory interactions between the sexes.
交配后性选择被认为是生殖特征进化的关键驱动力，包括产生内源性结婚礼物所需的机制。尽管这些礼物很重要，但雄性精液中非配子成分的分子组成及其与雌性生殖道的相互作用仍知之甚少。在交配过程中，雄性萤火虫会将由多个生殖腺制造的精荚礼物转移给雌性。在这里，我们结合了雄性和雌性生殖腺的转录组学、蛋白质组学和代谢组学，以更好地了解常见的东部萤火虫 Photinus pyralis 中精荚的合成、组成和命运。我们对雄性腺体的转录组分析显示，蛋白酶的上调可能会增强雄性的受精成功率并激活雌性的免疫反应。通过自上而下的蛋白质组学分析，我们鉴定了 208 种具有功能注释的蛋白质，这些蛋白质会在雄性的精荚中传递给雌性。靶向代谢组学分析还首次提供了证据表明，萤火虫的结婚礼物中含有萤光素酶，这是一种萤火虫防御毒素。雌性萤火虫的生殖道中几种蛋白酶的基因表达增加，这些蛋白酶可能参与卵子的产生。本研究为雄性精荚的分子组成提供了新的见解，并扩展了我们对结婚礼物如何介导性别间交配后相互作用的理解。
