Avalos Jessica G, Champagne Cory D, Crocker Dan E, Khudyakov Jane I
Department of Biological Sciences, University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211, USA.
National Marine Mammal Foundation, 2240 Shelter Island Dr., Ste. 200, San Diego, CA 92106, USA.
Conserv Physiol. 2024 Nov 4;12(1):coae075. doi: 10.1093/conphys/coae075. eCollection 2024.
Animals in nature potentially experience multiple stressors, and those of anthropogenic origin are likely to be repeated or chronic. However, stress hormone levels are highly context-dependent and are not consistent predictors of chronic stress in wildlife. Profiling the downstream consequences of repeated stress responses, such as changes in metabolism or gene expression, may be more informative for predicting their individual-level health consequences and population-level impacts, which are key objectives for wildlife conservation. We previously found that in free-ranging juvenile elephant seals, the blubber transcriptome and proteome, but not cortisol levels, could distinguish between responses to single versus repeated stress axis stimulation. However, the blubber proteome response to stress was limited and mainly involved extra-cellular matrix proteins. In this study, we examined the plasma proteome response of four of the same animals to the repeated stress experiment, since multiple organs secrete proteins into the circulation, providing a readout of their activity and integration. We isolated plasma proteins, identified and quantified them using liquid chromatography and tandem mass spectrometry (LC-MS/MS) and compared their abundance between sampling times. We identified >200 proteins in plasma, of which 42 were altered in abundance, revealing complex protein dynamics in response to repeated stress challenges. These changes were delayed but sustained, suggesting that the plasma proteome may reflect longer term integration of multi-organ responses to recent, rather than immediate, challenges. Differentially abundant proteins included components of the osmoregulatory system, acute phase and complement proteins, organokines, apolipoproteins and hormone transport proteins, which coordinate physiological processes with significant implications for marine mammal health and may explain several aspects of marine mammal stress physiology, such as insulin resistance and high aldosterone levels. We identified several potentially novel biomarkers, such as AGT, HPX, TTR and APOA4, that may be useful for detecting recent and repeated stress exposure in marine mammals.
自然界中的动物可能会经历多种应激源，而那些人为来源的应激源很可能是反复出现或慢性的。然而，应激激素水平高度依赖于环境，并非野生动物慢性应激的一致预测指标。剖析反复应激反应的下游后果，如新陈代谢或基因表达的变化，对于预测其个体层面的健康后果和种群层面的影响可能更具信息价值，而这正是野生动物保护的关键目标。我们之前发现，在自由放养的幼年海象中，脂肪组织的转录组和蛋白质组，而非皮质醇水平，能够区分对单次与反复应激轴刺激的反应。然而，脂肪组织蛋白质组对应激的反应有限，主要涉及细胞外基质蛋白。在本研究中，我们检测了同四只动物在反复应激实验中的血浆蛋白质组反应，因为多个器官会将蛋白质分泌到循环系统中，从而反映它们的活动和整合情况。我们分离血浆蛋白，使用液相色谱和串联质谱（LC-MS/MS）对其进行鉴定和定量，并比较不同采样时间的丰度。我们在血浆中鉴定出>200种蛋白质，其中42种的丰度发生了变化，揭示了对反复应激挑战的复杂蛋白质动态变化。这些变化出现延迟但持续存在，表明血浆蛋白质组可能反映了多器官对近期而非即时挑战的长期整合反应。差异丰度的蛋白质包括渗透调节系统成分、急性期蛋白和补体蛋白、器官因子、载脂蛋白和激素转运蛋白，它们协调生理过程，对海洋哺乳动物健康具有重要意义，可能解释了海洋哺乳动物应激生理学的几个方面，如胰岛素抵抗和高醛固酮水平。我们鉴定出了几种潜在的新型生物标志物，如AGT、HPX、TTR和APOA4，它们可能有助于检测海洋哺乳动物近期和反复的应激暴露情况。
