Cann Paul, Le Danvic Chrystelle, Porte Chantal, Chesneau Didier, Keller Matthieu, Nagnan-Le Meillour Patricia
Université de Lille, CNRS, INRAE, Glycobiologie Structurale et Fonctionnelle, UMR8576, INRAE USC 1409, Lille, France.
ELIANCE, Paris, France.
Front Vet Sci. 2023 Jan 9;9:1033412. doi: 10.3389/fvets.2022.1033412. eCollection 2022.
Under temperate latitudes, reproduction in displays a marked seasonality, governed by the photoperiod. In natural conditions, the transition between sexual rest and sexual activity in both sexes is induced by the decrease of day light. Meanwhile, specific odors emitted by a sexually active male are able to reactivate the gonadotropic axis of anovulatory ewes. This physiological effect is called "male effect", precisely ram effect in the ovine species. We have previously shown that the secreted proteins, namely Olfactory Binding Proteins (OBP), contained in the nasal mucus constitute the olfactory secretome (OS), the composition of which is determined by the status of oestrus cycle of females and differs between sexual rest and sexual activity periods. The objective of this study was to test the hypothesis that exposure to sexually active male can also modify the composition of ewes olfactory secretome during a male effect, as well as hormones produced by the reactivation of the oestrus cycle in sexual activity period under natural conditions.
We have set up a new non-invasive protocol of nasal mucus sampling and collected it from 12 ewes at different times during a ram effect. We analyzed the composition of their olfactory secretome by proteomics, mainly SDS-PAGE and MALDI-TOF mass spectrometry. As post-translational modifications of OBPs were a hallmark of ewes' sexual activity period, we were looking for glycosylation by western-blot and mass spectrometry.
The efficiency of male effect was low in stimulated ewes as only 3 females displayed elevated progesterone levels in their blood. Besides, half of control ewes (non-stimulated ones) were cycled. We noticed a common OS profile in ewes in anoestrus, versus OS of cycled ones. A very clear and important result was the apparition of -GlcNAcylation, previously detected only in sexual activity, after only 30 min of male introduction into the flock.
This exploratory study paves the way for further experiments with larger flock to confirm and reinforce these results, and for eventually exploiting the nasal mucus as an indicator of females' receptivity to male odors.
在温带地区，绵羊的繁殖呈现出明显的季节性，受光周期的调控。在自然条件下，两性从性静止到性活动的转变是由日照时间的减少引发的。与此同时，处于性活跃期的雄性绵羊释放的特定气味能够重新激活无排卵母羊的促性腺轴。这种生理效应被称为“雄性效应”，在绵羊物种中确切地说是“公羊效应”。我们之前已经表明，鼻黏液中含有的分泌蛋白，即嗅觉结合蛋白（OBP），构成了嗅觉分泌组（OS），其组成由雌性发情周期的状态决定，并且在性静止期和性活动期有所不同。本研究的目的是检验这样一个假设：在雄性效应期间，接触性活跃的雄性也会改变母羊嗅觉分泌组的组成，以及在自然条件下性活动期发情周期重新激活所产生的激素。
我们建立了一种新的非侵入性鼻黏液采样方案，并在公羊效应的不同时间从12只母羊身上采集鼻黏液。我们通过蛋白质组学，主要是SDS - PAGE和MALDI - TOF质谱分析其嗅觉分泌组的组成。由于OBP的翻译后修饰是母羊性活动期的一个标志，我们通过蛋白质印迹法和质谱法寻找糖基化修饰。
在受刺激的母羊中，雄性效应的效率较低，因为只有3只雌性血液中的孕酮水平升高。此外，一半的对照母羊（未受刺激的）出现了发情周期。我们注意到处于乏情期的母羊与处于发情周期的母羊的嗅觉分泌组图谱存在差异。一个非常明确且重要的结果是，在将公羊引入羊群仅30分钟后，就出现了此前仅在性活动期检测到的β - N -乙酰葡糖胺糖基化修饰。
这项探索性研究为进一步用更大的羊群进行实验以证实和强化这些结果铺平了道路，并最终为将鼻黏液用作雌性对雄性气味接受度的指标奠定了基础。
