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.

本研究首次提供了将野生鲑科幼鲑（smolt）的生理响应、病原体存在状态与其洄游过程中后续存活命运相关联的数据集。研究人员在红大马哈鱼（Oncorhynchus nerka）幼鲑离开其育幼湖——加拿大不列颠哥伦比亚省奇尔科湖（Chilko Lake）时，对其进行了标记并开展非致死性鳃组织采样；随后借助声学遥测（acoustic telemetry）技术，在这些幼鲑前往北太平洋的前约1150千米洄游路径中，对比分析其基因表达谱（gene expression profiles）、淡水病原体载量与洄游成功率的关联。有15%的幼鲑在放流后未被再次检测到，与成功完成淡水洄游的个体相比，该类个体的基因表达谱呈现出针对一种或多种病毒病原体的免疫应答特征。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型干扰素应答的标志性基因。在离开育幼湖的幼鲑中，最常被检出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，确实呈现出针对一种或多种病毒病原体的免疫应答，且应激水平升高，这或为放流后短期内部分个体死亡的潜在诱因。本研究首次提供证据证实，基因表达变化可用于预测野生鲑科幼鲑部分淡水洄游死亡率。