Data from: Female-induced remote regulation of sperm physiology may provide opportunities for gamete-level mate choice

In sedentary externally fertilizing species, direct interactions between mating partners are limited and pre-fertilization communication between sexes occur largely at the gamete level. Certain combinations of eggs and sperm often have higher fertilization success than others, which may be contingent on egg-derived chemical factors that preferentially attract sperm from compatible males. Here, we examine the mechanisms underlying such effects in the marine mussel Mytilus galloprovincialis, where differential sperm attraction has recently been shown to be associated with variation in offspring viability. Specifically, we focus on the sperm surface glycans, an individually unique layer of carbohydrates that moderate self-recognition and other cellular-level interactions. In many species egg-derived factors trigger remarkable changes in the sperm’s glycan layer, physiology and swimming behavior, and thus potentially moderate mate choice at the gamete level. Here we show that sperm glycan modifications and the strength of acrosome reaction are both dependent on specific male-female interactions (male-female combination). We also find associations between female-induced sperm glycan changes and the Ca2+ influx into sperm – a key regulator of fertilization processes from sperm capacitation to gamete fusion. Together, our results suggest that female-induced remote regulation of sperm physiology may constitute a novel mechanism of gamete-level mate choice.

在固着生活的体外受精物种中，交配伴侣间的直接互动十分有限，两性间的受精前交流大多发生在配子（gamete）层面。精卵的特定组合往往较其他组合拥有更高的受精成功率，这一效应可能取决于卵源化学因子——这类因子会优先吸引相容性雄性的精子。

本研究以海贻贝紫贻贝（Mytilus galloprovincialis）为研究对象，探究此类效应背后的作用机制；近期已有研究证实，该物种中精子吸引的差异与后代存活力的变异存在关联。我们重点关注精子表面聚糖（glycans）：这是一层具有个体独特性的碳水化合物层，可介导自我识别及其他细胞层面的相互作用。在诸多物种中，卵源因子可引发精子聚糖层、生理状态及游动行为的显著改变，进而可能在配子层面调控配偶选择。

本研究证实，精子的聚糖修饰与顶体反应（acrosome reaction）强度均取决于特定的雌雄相互作用（雌雄组合）。我们还发现，雌性诱导的精子聚糖变化与钙离子内流（Ca2+ influx）进入精子存在关联——该过程是从精子获能（sperm capacitation）到配子融合（gamete fusion）的受精过程的关键调控因子。

综上，本研究结果表明，雌性诱导的精子生理远程调控，或可代表一种全新的配子层面配偶选择机制。