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

这项研究的主要目的是调查衰老对韦德尔海豹潜水能力的直接影响，并描述衰老可能通过生理和行为影响觅食生态的机制。这种模式鳍足物种一直是南极洲麦克默多海峡30年来研究的重点。与羽足动物早期发育和成年期的生理和生态学知识相比，人们对接近正常生育年龄上限的个体知之甚少。进化衰老理论预测，年长的潜水海豹应该会出现衰老。在屏气潜水和狩猎过程中，通过缺氧-复氧产生的氧自由基激增应该会加剧这种情况，这与年龄相关的细胞线粒体损伤有关。令人惊讶的是，对未受威胁的羽脚类种群的有限观察表明，衰老不会发生到影响生殖输出的水平。鳍脚类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，鳍脚类动物发生了哪些具体的生理和形态变化，以及这些动物做出了哪些微妙的调整来应对这些变化？这项研究将集中在与潜水能力相关的特定的、机能的生理和行为随年龄增长的变化。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，并结合对外部和内部以跳水形式进行工作的能力的精细评估。具体地说，将检查氧化状态和氧气使用随年龄变化的模式。本课程将研究年龄对肌肉功能、血管平滑肌收缩能力和骨骼肌运动能力的影响。将对处于繁殖年龄高峰期和接近尾声的韦德尔海豹进行数据比较。将对做外部工作的能力(即跳水)以及肌肉功能(做内部工作的能力)进行评估。研究人员假设，韦德尔海豹确实在小规模、最接近的生理效应和表现水平上发生衰老，但行为可塑性允许特定程度的补偿。更广泛的影响包括对学生的培训和外联活动，包括为大众媒体撰写的采访和文章。照片和项目摘要将在项目网站上向感兴趣的公众提供。这项研究还应建立潜水海豹作为研究衰老的心血管和肌肉生理学的新模型。对韦德尔海豹的研究可以验证这一模型，从而为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具有巨大的潜在好处

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