Mauduit F, Segarra A, Mandic M, Todgham A E, Baerwald M R, Schreier A D, Fangue N A, Connon R E
Department of Anatomy, Physiology & Cell Biology, University of California Davis, 95616 Davis, CA, USA.
Department of Animal Science, University of California Davis, 95616 Davis, CA, USA.
Conserv Physiol. 2022 Jan 21;10(1):coab102. doi: 10.1093/conphys/coab102. eCollection 2022.
The greatest concentration of at-risk anadromous salmonids is found in California (USA)-the populations that have been negatively impacted by the degradation of freshwater ecosystems. While climate-driven environmental changes threaten salmonids directly, they also change the life cycle dynamics and geographic distribution of pathogens, their resulting host-pathogen interactions and potential for disease progression. Recent studies have established the correlation between pathogen detection and salmonid smolt mortality during their migration to the ocean. The objective of the present study was to screen for up to 47 pathogens in juvenile Chinook salmon () that were held in cages at two key sites of the Sacramento River (CA, USA) and measure potential consequences on fish health. To do so, we used a combination of transcriptomic analysis, enzymatic assays for energy metabolism and hypoxia and thermal tolerance measures. Results revealed that fish were infected by two myxozoan parasites: and within a 2-week deployment. Compared to the control fish maintained in our rearing facility, infected fish displayed reduced body mass, depleted hepatic glycogen stores and differential regulation of genes involved in the immune and general stress responses. This suggests that infected fish would have lower chances of migration success. In contrast, hypoxia and upper thermal tolerances were not affected by infection, suggesting that infection did not impair their capacity to cope with acute abiotic stressors tested in this study. An evaluation of long-term consequences of the observed reduced body mass and hepatic glycogen depletion is needed to establish a causal relationship between salmon parasitic infection and their migration success. This study highlights that to assess the potential sublethal effects of a stressor, or to determine a suitable management action for fish, studies need to consider a combination of endpoints from the molecular to the organismal level.
面临风险的溯河产卵鲑科鱼类最集中的区域位于美国加利福尼亚州，这些种群受到淡水生态系统退化的负面影响。虽然气候驱动的环境变化直接威胁着鲑科鱼类，但它们也改变了病原体的生命周期动态和地理分布、由此产生的宿主 - 病原体相互作用以及疾病进展的可能性。最近的研究已经确定了病原体检测与鲑科幼鱼向海洋洄游期间死亡率之间的相关性。本研究的目的是在美国加利福尼亚州萨克拉门托河的两个关键地点，对圈养在网箱中的奇努克鲑幼鱼（）进行多达47种病原体的筛查，并测量对鱼类健康的潜在影响。为此，我们结合了转录组分析、能量代谢酶促测定以及缺氧和耐热性测量。结果显示，在为期2周的养殖期间，鱼类感染了两种粘孢子虫寄生虫： 和 。与我们养殖设施中饲养的对照鱼相比，受感染的鱼体重减轻、肝脏糖原储备耗尽，并且参与免疫和一般应激反应的基因调控存在差异。这表明受感染的鱼成功洄游的机会较低。相比之下，缺氧和耐热上限不受感染影响，这表明感染并未损害它们应对本研究中测试的急性非生物应激源的能力。需要对观察到的体重减轻和肝脏糖原消耗的长期后果进行评估，以确定鲑鱼寄生虫感染与其洄游成功之间的因果关系。本研究强调，为了评估应激源的潜在亚致死效应，或确定适合鱼类的管理措施，研究需要考虑从分子到生物体水平的多个终点指标。
