National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan.
Sugashima Marine Biological Laboratory Graduate School of Science, Nagoya University, 429-63 Sugashima, Toba 517-0004, Japan.
Biochem Biophys Res Commun. 2014 Aug 1;450(3):1218-24. doi: 10.1016/j.bbrc.2014.04.076. Epub 2014 Apr 24.
In the coastal squid Loligo bleekeri, each male produces one of two types of fertilization-competent spermatozoa (eusperm) that exhibit morphological and behavioral differences. Large "consort" males produce short-tailed spermatozoa that display free-swimming behavior when ejaculated into seawater. Small "sneaker" males, on the other hand, produce long-tailed spermatozoa that exhibit a self-swarming trait after ejaculation. To understand the molecular basis for adaptive traits employed by alternative male mating tactics, we performed the transcriptome deep sequencing (RNA-seq) and proteome analyses to search for differences in testicular mRNAs and sperm proteins, respectively. From mature male testes we identified a total of 236,455 contigs (FPKM ≧1) where 3789 and 2789 were preferentially (≧10-fold) expressed in consort and sneaker testes, respectively. A proteomic analysis detected 4302 proteins in the mature sperm as post-translational products. A strongly biased (≧10-fold) distribution occurred in 55 consort proteins and 61 sneaker proteins. There was no clear mRNA-protein correlation, making a ballpark estimate impossible for not only overall protein abundance but also the degree of biased sperm type expressed in the spermatozoa. A family encoding dynein heavy chain gene, however, was found to be biased towards sneakers, whereas many enzymes involving energy metabolism were heavily biased towards consort spermatozoa. The difference in flagellar length matched exactly the different amount of tubulins. From these results we hypothesize that discrete differential traits in dimorphic eusperm arose from a series of innovative alterations in the intracellular components of spermatozoa.
在沿海鱿鱼 Loligo bleekeri 中，每个雄性个体产生两种类型的具有受精能力的精子（优精），它们表现出形态和行为上的差异。大型“配偶”雄性产生短尾精子，当排入海水中时，这些精子表现出自由游动的行为。另一方面，小型“偷偷摸摸”雄性产生长尾精子，这些精子在射出后表现出自旋行为。为了了解替代雄性交配策略所采用的适应性特征的分子基础，我们分别进行了转录组深度测序（RNA-seq）和蛋白质组分析，以分别寻找睾丸 mRNA 和精子蛋白的差异。从成熟的雄性睾丸中，我们总共鉴定出 236455 个连续（FPKM ≧1），其中 3789 和 2789 个连续在配偶和偷偷摸摸的睾丸中分别优先（≧10 倍）表达。蛋白质组分析在成熟精子中检测到 4302 种翻译后产物的蛋白质。在 55 种配偶蛋白和 61 种偷偷摸摸蛋白中出现强烈的偏置（≧10 倍）分布。mRNA-蛋白相关性不强，不仅使整体蛋白丰度，而且使精子中表达的偏向精子类型的程度无法进行大致估计。然而，我们发现一个编码动力蛋白重链基因的家族偏向于偷偷摸摸的精子，而许多涉及能量代谢的酶则严重偏向于配偶精子。鞭毛长度的差异与微管蛋白的数量完全吻合。根据这些结果，我们假设两种形态优精之间的离散差异特征是由于精子细胞内成分的一系列创新改变而产生的。
