Collaborative Research: Aging in Weddell Seals: Proximate Mechanisms of Age-Related Changes in Adaptations to Breath-Hold Hunting in an Extreme Environment

本研究的主要目的是探讨衰老对威德尔海豹潜水能力的直接影响，并通过生理和行为描述衰老可能影响觅食生态的机制。在南极洲的麦克默多湾，这种典型的鳍状物种一直是三十年来研究的焦点。与对鳍状潜水早期发育和成年早期生理生态的了解相比，对接近正常生殖年龄范围上限的个体知之甚少。进化衰老理论预测，老年潜水海豹应该表现出衰老。在屏气潜水和狩猎期间，缺氧再氧化会使氧自由基的产生激增，这可能会加剧这种情况，这与年龄相关的细胞线粒体损伤有关。令人惊讶的是，对未受威胁的鳍足类种群的有限观察表明，衰老并没有发生到影响生殖产出的程度。鳍足类动物避免明显衰老的能力提出了两个主要问题：随着年龄的增长，鳍足类动物会发生哪些特定的生理和形态变化？这些动物会做出哪些微妙的调整来应对这些变化？这项研究将集中在与年龄增长有关的潜水能力的具体、功能性生理和行为变化上。研究人员将量化与年龄相关的总体健康和身体状况的变化，并结合以潜水形式进行工作的外部和内部能力的精细评估。具体来说，氧化状态和氧的使用模式与年龄将被检查。年龄对肌肉功能的影响，血管平滑肌的收缩能力，以及通过骨骼肌运动表现的运动能力将被检查。将比较威德尔海豹在繁殖年龄范围的高峰期和接近尾声时的数据。将评估做外部工作（如潜水）的能力以及肌肉功能（做内部工作的能力）。研究人员假设，衰老确实发生在威德尔海豹的小规模、近似的生理影响和表现水平上，但行为可塑性允许一定程度的补偿。更广泛的影响包括培训学生和外联活动，包括采访和为大众媒体撰写文章。有兴趣的公众可以在项目网站上获得照片和项目摘要。本研究也为潜水海豹作为研究衰老心血管和肌肉生理的新模型奠定了基础。对威德尔海豹的研究可以验证这一模型，从而为对其他物种的类似研究奠定基础。近年来，医学对衰老的认识取得了令人印象深刻的进展，研究衰老的新模型的发展对整个社会都有巨大的潜在好处

The primary objectives of this research are to investigate the proximate effects of aging on diving capability in the Weddell Seal and to describe mechanisms by which aging may influence foraging ecology, through physiology and behavior. This model pinniped species has been the focus of three decades of research in McMurdo Sound, Antarctica. Compared to the knowledge of pinniped diving physiology and ecology during early development and young adulthood, little is known about individuals nearing the upper limit of their normal reproductive age range. Evolutionary aging theories predict that elderly diving seals should exhibit senescence. This should be exacerbated by surges in the generation of oxygen free radicals via hypoxia-reoxygenation during breath-hold diving and hunting, which are implicated in age-related damage to cellular mitochondria. Surprisingly, limited observations of non-threatened pinniped populations indicate that senescence does not occur to a level where reproductive output is affected. The ability of pinnipeds to avoid apparent senescence raises two major questions: what specific physiological and morphological changes occur with advancing age in pinnipeds and what subtle adjustments are made by these animals to cope with such changes? This investigation will focus on specific, functional physiological and behavioral changes relating to dive capability with advancing age. The investigators will quantify age-related changes in general health and body condition, combined with fine scale assessments of external and internal ability to do work in the form of diving. Specifically, patterns of oxidative status and oxygen use with age will be examined. The effects of age on muscular function, contractile capacity in vascular smooth muscle, and exercise capacity via exercise performance in skeletal muscle will be examined. Data will be compared between Weddell seals in the peak, and near the end, of their reproductive age range. An assessment will be made of the ability to do external work (i.e. diving) as well as muscle functionality (ability to do internal work). The investigators hypothesize that senescence does occur in Weddell seals at the level of small-scale, proximate physiological effects and performance, but that behavioral plasticity allows for a given degree of compensation. Broader impacts include the training of students and outreach activities including interviews and articles written for the popular media. Photographs and project summaries will be available to the interested public on the project website. This study should also establish diving seals as a novel model for the study of cardiovascular and muscular physiology of aging. Research on Weddell seals could validate this model and thus develop a foundation for similar research on other species. Advancement of the understanding of aging by medical science has been impressive in recent years and the development of new models for the study of aging has tremendous potential benefits to society at large