What mechanisms underlie aging? One theory, the wear-and-tear model, attributes aging to progressive deterioration in the molecular and cellular machinery which eventually lead to death through the disruption of physiological homeostasis. The second suggests that life span is genetically programmed, and aging may be derived from intrinsic processes which enforce a non-random, terminal time interval for the survivability of the organism. We are studying an organism that demonstrates both properties: the colonial ascidian, Botryllus schlosseri. Botryllus is a member of the Tunicata, the sister group to the vertebrates, and has a number of life history traits which make it an excellent model for studies on aging. First, Botryllus has a colonial life history, and grows by a process of asexual reproduction during which entire bodies, including all somatic and germline lineages, regenerate every week, resulting in a colony of genetically identical individuals. Second, previous studies of lifespan in genetically distinct Botryllus lineages suggest that a direct, heritable basis underlying mortality exists that is unlinked to reproductive effort and other life history traits. Here we will review recent efforts to take advantage of the unique life history traits of B. schlosseri and develop it into a robust model for aging research.

中文翻译：

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Botryllus schlosseri 在殖民地脊索动物中老化

衰老背后的机制是什么？一种理论，即磨损模型，将衰老归因于分子和细胞机制的逐渐恶化，最终通过破坏生理稳态导致死亡。第二个表明寿命是遗传编程的，衰老可能源于内在过程，这些过程为生物体的生存能力强制执行了一个非随机的终端时间间隔。我们正在研究一种具有两种特性的生物体：群落海鞘 Botryllus schlosseri。Botryllus 是脊椎动物的姊妹组 Tunicata 的成员，具有许多生活史特征，使其成为研究衰老的绝佳模型。首先，Botryllus 有殖民生活史，通过无性繁殖过程生长，在此期间整个身体，包括所有体细胞和生殖系谱系，每周都会再生，从而产生一群基因相同的个体。其次，先前对遗传上不同的 Botryllus 谱系寿命的研究表明，存在与繁殖努力和其他生活史特征无关的死亡率的直接、遗传基础。在这里，我们将回顾最近为利用 B. schlosseri 独特的生活史特征并将其开发成用于衰老研究的强大模型所做的努力。