PDF(Pubmed)
Abstract：
Drastic increases in myofiber number and size are essential to support vertebrate post-embryonic growth. However, the collective cellular behaviors that enable these increases have remained elusive. Here, we created the palmuscle myofiber tagging and tracking system for in toto monitoring of the growth and fates of ~5000 fast myofibers in developing zebrafish larvae. Through live tracking of individual myofibers within the same individuals over extended periods, we found that many larval myofibers readily dissolved during development, enabling the on-site addition of new and more myofibers. Remarkably, whole-body surveillance of multicolor-barcoded myofibers further unveiled a gradual yet extensive elimination of larval myofiber populations, resulting in near-total replacement by late juvenile stages. The subsequently emerging adult myofibers are not only long-lasting, but also morphologically and functionally distinct from the larval populations. Furthermore, we determined that the elimination-replacement process is dependent on and driven by the autophagy pathway. Altogether, we propose that the whole-body replacement of larval myofibers is an inherent yet previously unnoticed process driving organismic muscle growth during vertebrate post-embryonic development.
摘要：
肌纤维数量和大小的急剧增加对于支持脊椎动物胚胎后生长至关重要。然而,使这些增加的集体细胞行为仍然难以捉摸。这里,我们创建了掌肌肌纤维标记和跟踪系统，用于监测发育中的斑马鱼幼虫中〜5000快速肌纤维的生长和命运。通过长时间实时追踪同一个体中的单个肌纤维，我们发现许多幼虫肌纤维在发育过程中容易溶解，能够现场添加新的和更多的肌纤维。值得注意的是,多色条形码肌纤维的全身监测进一步揭示了幼虫肌纤维种群的逐步而广泛的消除，导致青少年后期几乎完全替代。随后出现的成人肌纤维不仅持久，而且在形态和功能上与幼虫种群不同。此外，我们确定消除-替代过程依赖于自噬途径并由其驱动.总之,我们认为，幼虫肌纤维的全身置换是一个固有的，但以前没有注意到的过程，驱动脊椎动物胚胎后发育过程中的有机肌肉生长。
