Mitochondrial capture by a transmissible cancer

Canine transmissible venereal tumor (CTVT) is an infectious cell line circulating in many feral dog populations. It originated once, about 10,000 years ago. Phylogenetic analyses of mitochondrial sequences from dogs, wolves, and a geographically diverse collection of CTVT samples indicate that the cancer has periodically acquired mitochondria from its host. We suggest that this may be because the cancer’s own mitochondria have a tendency to degenerate, due to high mutation rates and relaxed selection, resulting in host mitochondria being more fit.犬传染性生殖道肿瘤（Canine transmissible venereal tumor, CTVT）是一种在多种野犬种群中传播的感染性细胞系，其起源可追溯至约1万年前的单次事件。对犬、狼以及地理分布广泛的CTVT样本的线粒体序列开展的系统发育分析显示，该肿瘤会周期性地从宿主处获取线粒体。我们推测，该现象的成因可能是肿瘤自身的线粒体因突变率较高、选择压力松弛而发生退化，进而使得宿主线粒体更具适应性。