Whittington Emma, Zhao Qian, Borziak Kirill, Walters James R, Dorus Steve
Department of Biology, Syracuse University, Syracuse, NY, USA.
Ecology and Evolutionary Biology, Kansas University, Lawrence, KS, USA.
Insect Biochem Mol Biol. 2015 Jul;62:183-93. doi: 10.1016/j.ibmb.2015.02.011. Epub 2015 Feb 28.
The application of mass spectrometry based proteomics to sperm biology has greatly accelerated progress in understanding the molecular composition and function of spermatozoa. To date, these approaches have been largely restricted to model organisms, all of which produce a single sperm morph capable of oocyte fertilisation. Here we apply high-throughput mass spectrometry proteomic analysis to characterise sperm composition in Manduca sexta, the tobacco hornworm moth, which produce heteromorphic sperm, including one fertilisation competent (eupyrene) and one incompetent (apyrene) sperm type. This resulted in the high confidence identification of 896 proteins from a co-mixed sample of both sperm types, of which 167 are encoded by genes with strict one-to-one orthology in Drosophila melanogaster. Importantly, over half (55.1%) of these orthologous proteins have previously been identified in the D. melanogaster sperm proteome and exhibit significant conservation in quantitative protein abundance in sperm between the two species. Despite the complex nature of gene expression across spermatogenic stages, a significant correlation was also observed between sperm protein abundance and testis gene expression. Lepidopteran-specific sperm proteins (e.g., proteins with no homology to proteins in non-Lepidopteran taxa) were present in significantly greater abundance on average than those with homology outside the Lepidoptera. Given the disproportionate production of apyrene sperm (96% of all mature sperm in Manduca) relative to eupyrene sperm, these evolutionarily novel and highly abundant proteins are candidates for possessing apyrene-specific functions. Lastly, comparative genomic analyses of testis-expressed, ovary-expressed and sperm genes identified a concentration of novel sperm proteins shared amongst Lepidoptera of potential relevance to the evolutionary origin of heteromorphic spermatogenesis. As the first published Lepidopteran sperm proteome, this whole-cell proteomic characterisation will facilitate future evolutionary genetic and developmental studies of heteromorphic sperm production and parasperm function. Furthermore, the analyses presented here provide useful annotation information regarding sex-biased gene expression, novel Lepidopteran genes and gene function in the male gamete to complement the newly sequenced and annotated Manduca genome.
基于质谱的蛋白质组学在精子生物学中的应用极大地加速了我们对精子分子组成和功能的理解。迄今为止，这些方法主要局限于模式生物，所有这些模式生物都产生单一形态的、能够使卵母细胞受精的精子。在此，我们应用高通量质谱蛋白质组学分析来表征烟草天蛾（Manduca sexta）的精子组成，这种昆虫会产生异形精子，包括一种具有受精能力的（真核精子）和一种无受精能力的（无核精子）精子类型。这使得我们从两种精子类型的混合样本中高度可靠地鉴定出了896种蛋白质，其中167种由在黑腹果蝇（Drosophila melanogaster）中具有严格一对一直系同源关系的基因编码。重要的是，这些直系同源蛋白质中超过一半（55.1%）此前已在黑腹果蝇精子蛋白质组中被鉴定出来，并且在两种物种的精子中蛋白质丰度的定量方面表现出显著的保守性。尽管精子发生各阶段的基因表达具有复杂性，但在精子蛋白质丰度与睾丸基因表达之间也观察到了显著的相关性。鳞翅目特异性精子蛋白（例如，与非鳞翅目类群中的蛋白质无同源性的蛋白质）平均丰度明显高于在鳞翅目之外具有同源性的蛋白质。鉴于无核精子的产量相对于真核精子过高（占烟草天蛾所有成熟精子的96%），这些在进化上新颖且高度丰富的蛋白质可能具有无核精子特异性功能。最后，对睾丸表达基因、卵巢表达基因和精子基因的比较基因组分析确定了鳞翅目昆虫中共享的一组新的精子蛋白，它们可能与异形精子发生的进化起源相关。作为首次发表的鳞翅目精子蛋白质组，这种全细胞蛋白质组学表征将有助于未来对异形精子产生和副精子功能的进化遗传学及发育研究。此外，本文所呈现分析提供了有关性别偏向基因表达、新的鳞翅目基因以及雄配子中基因功能的有用注释信息，以补充新测序和注释的烟草天蛾基因组。
