Swiss Institute of Equine Medicine ISME, Agroscope and University of Berne, Avenches, Switzerland.
Department of Clinical Research, Vetsuisse Faculty, University of Berne, Berne, Switzerland.
Mol Ecol. 2018 Feb;27(4):1025-1035. doi: 10.1111/mec.14490. Epub 2018 Feb 19.
The major histocompatibility complex (MHC) has repeatedly been found to influence mate choice of vertebrates, with MHC-dissimilar mates typically being preferred over MHC-similar mates. We used horses (Equus caballus) to test whether MHC matching also affects male investment into ejaculates after short exposure to a female. Semen characteristics varied much among stallions. Controlling for this variance with a full-factorial within-subject experimental design, we found that a short exposure to an MHC-dissimilar mare enhanced male plasma testosterone and led to ejaculates with elevated sperm numbers as compared to exposure to an MHC-similar mare. Sperm velocity seemed not affected by the treatment. Overall genetic similarity between stallions and mares (determined from polymorphic microsatellites on 20 different chromosomes) played no significant role here. The MHC type of the teaser mare also affected characteristics of cold-stored sperm after 24 and 48 hr. As expected from ejaculate economics, sperm viability was elevated after exposure to an MHC-dissimilar mare. However, oxidative stress and the percentage of sperm with a high DNA fragmentation were mostly increased after exposure to an MHC-dissimilar mare, depending also on whether the teaser mare was in oestrous or not. We conclude that males can quickly adjust ejaculate quality relative to a female's MHC, and that this male reaction to the social environment can also affect important characteristics of cold-stored semen.
主要组织相容性复合体 (MHC) 已多次被发现影响脊椎动物的配偶选择，通常情况下，MHC 不同的配偶比 MHC 相似的配偶更受欢迎。我们使用马（Equus caballus）来测试 MHC 匹配是否也会影响雄性在短时间暴露于雌性后对精液的投入。种马的精液特征差异很大。我们采用完全析因的实验设计来控制这种变异性，结果发现，与接触 MHC 相似的母马相比，短时间接触 MHC 不同的母马会增加雄性血浆中的睾丸激素，并导致精液中精子数量增加。处理似乎不会影响精子速度。种马和母马之间的总体遗传相似性（通过 20 个不同染色体上的多态微卫星确定）在这里没有起到显著作用。挑逗母马的 MHC 类型也会影响 24 小时和 48 小时后冷藏精子的特性。正如从精液经济学中预期的那样，与 MHC 不同的母马接触后，精子活力升高。然而，暴露于 MHC 不同的母马后，氧化应激和具有高 DNA 碎片化的精子比例大多增加，这也取决于挑逗母马是否处于发情期。我们得出的结论是，雄性可以根据雌性的 MHC 快速调整精液质量，而雄性对社会环境的这种反应也会影响冷藏精液的重要特性。
