Data from: Immune response genes and pathogen presence predict migration survival in wild salmon smolts

We present the first data to link physiological responses and pathogen presence with subsequent fate during migration of wild salmonid smolts. We tagged and non-lethally sampled gill tissue from sockeye salmon (Oncorhynchus nerka) smolts as they left their nursery lake (Chilko Lake, BC, Canada) to compare gene expression profiles and freshwater pathogen loads with migration success over the first ~1150 km of their migration to the North Pacific Ocean using acoustic telemetry. Fifteen percent of smolts were never detected again after release and these fish had gene expression profiles consistent with an immune response to one or more viral pathogens compared with fish that survived their freshwater migration. Among the significantly up-regulated genes of the fish that were never detected post-release were MX (Interferon-induced GTP-binding Protein Mx) and STAT1 (Signal transducer and activator of transcription 1-alpha/beta), which are characteristic of a type I interferon response to viral pathogens. The most commonly detected pathogen in the smolts leaving the nursery lake was infectious hematopoietic necrosis virus (IHNV). Collectively, these data show that some of the fish assumed to have died after leaving the nursery lake appeared to be responding to one or more viral pathogens and had elevated stress levels that could have contributed to some of the mortality shortly after release. We present the first evidence that changes in gene expression may be predictive of some of the fresh water migration mortality in wild salmonid smolts.

本研究首次提供了关联野生鲑科幼鲑（salmonid smolts）洄游期间生理应答、病原体存在与后续存活结局的数据集。研究人员对离开育幼湖（加拿大不列颠哥伦比亚省奇尔科湖）的红大麻哈鱼（Oncorhynchus nerka）幼鲑进行了标记，并非致死性采集其鳃组织样本，借助声学遥测技术，在其向北太平洋洄游的前约1150公里行程中，对比分析了基因表达谱、淡水病原体负荷与洄游成功率之间的关联。放流后，有15%的幼鲑未被再次检测到；与成功完成淡水洄游的个体相比，该类未被检测到的个体的基因表达谱与针对一种或多种病毒病原体的免疫应答特征高度吻合。在放流后未被检测到的个体中，显著上调的基因包括MX（干扰素诱导GTP结合蛋白MX，Interferon-induced GTP-binding Protein Mx）与STAT1（信号转导与转录激活因子1-α/β，Signal transducer and activator of transcription 1-alpha/beta），二者均为针对病毒病原体的Ⅰ型干扰素（type I interferon）应答的标志性基因。在离开育幼湖的幼鲑中，最常被检测到的病原体为传染性造血器官坏死病毒（infectious hematopoietic necrosis virus, IHNV）。综合分析结果表明，部分被认为在离开育幼湖后死亡的个体，似乎正处于针对一种或多种病毒病原体的免疫应答状态，且应激水平升高，这可能是放流后短期内部分个体死亡的重要诱因之一。本研究首次提供证据显示，基因表达变化或可预测野生鲑科幼鲑的部分淡水洄游死亡率。