Data from: Male pregnancy and bi-parental immune priming

In vertebrates, maternal transfer of immunity via the eggs or the placenta provides offspring with crucial information on prevailing pathogens and parasites. Males contribute little to such trans-generational immune priming, either because they do not share the environment and parasite pressure of the offspring, or because sperm are suggested to be too small for transfer of immunity. In the teleost group of Syngnathids (pipefish, seahorses and sea dragons) males brood female eggs in a placenta-like structure. Such sex-role-reversed species provide a unique opportunity to test for adaptive plasticity in immune transfer. Here males in addition to females should influence offspring immunity. We experimentally tested paternal effects on offspring immunity by examining immune cell proliferation and immune gene expression. Maternal and paternal bacterial exposure induced the offspring's immune defence five weeks after hatching, and this effect persisted in four-month-old offspring. For several offspring immune traits double parental exposure (maternal and paternal) enhanced the response, while for another group of immune traits, the trans-generational induction already took place if only one parent was exposed. Our study shows that sex-role reversal in connection with male pregnancy opens the door for bi-parental influences on offspring immunity, and may represent one additional advantage for the evolution of male pregnancy.

在脊椎动物中，通过卵子或胎盘实现的母体免疫传递（maternal transfer of immunity），可为后代提供关于当前流行病原体与寄生虫的关键信息。雄性对这类跨代免疫致敏（trans-generational immune priming）的贡献微乎其微，这要么是因为雄性与后代所处的环境及面临的寄生虫压力并不一致，要么是因为有研究认为精子体积过小，无法完成免疫物质的传递。在硬骨鱼类的海龙科（Syngnathids）类群（包括尖嘴鱼、海马及海龙）中，雄性会在胎盘样结构中抚育雌性所产的卵子。这类性角色逆转（sex-role-reversed）的物种，为研究免疫传递中的适应性可塑性提供了独特的实验契机。在此类类群中，除雌性外，雄性同样会对后代的免疫状态产生影响。我们通过检测免疫细胞增殖（immune cell proliferation）与免疫基因表达（immune gene expression），实验探究了父本对后代免疫的影响。母体与父体的细菌暴露（bacterial exposure）可在后代孵化5周后诱导其免疫防御反应，且该效应在4月龄后代中仍可维持。对于多项后代免疫性状而言，双亲暴露（double parental exposure）可增强免疫应答；而对于另一类免疫性状，仅单一本亲暴露即可触发跨代免疫诱导（trans-generational induction）。我们的研究表明，与雄性妊娠相关的性角色逆转，为双亲对后代免疫的调控打开了可能通路，这或许也代表了雄性妊娠演化过程中的一项额外优势。