Department of Biosciences, Department of Biosciences, University of Oslo, Oslo, Norway; Center for Integrative Neuroplasticity, Department of Biosciences, University of Oslo, Oslo, Norway.
Department of Biosciences, Department of Biosciences, University of Oslo, Oslo, Norway; Center for Integrative Neuroplasticity, Department of Biosciences, University of Oslo, Oslo, Norway; Department of Physics, University of Oslo, Oslo, Norway.
Biophys J. 2020 Dec 1;119(11):2166-2178. doi: 10.1016/j.bpj.2020.10.016. Epub 2020 Oct 27.
Transport distances in skeletal muscle fibers are mitigated by these cells having multiple nuclei. We have studied mouse living slow (soleus) and fast (extensor digitorum longus) muscle fibers in situ and determined cellular dimensions and the positions of all the nuclei within fiber segments. We modeled the effect of placing nuclei optimally and randomly using the nuclei as the origin of a transportation network. It appeared that an equidistant positioning of nuclei minimizes transport distances along the surface for both muscles. In the soleus muscle, however, which were richer in nuclei, positioning of nuclei to reduce transport distances to the cytoplasm were of less importance, and these fibers exhibit a pattern not statistically different from a random positioning of nuclei. We also simulated transport times for myoglobin and found that they were remarkably similar between the two muscles despite differences in nuclear patterning and distances. Together, these results highlight the importance of spatially distributed nuclei to minimize transport distances to the surface when nuclear density is low, whereas it appears that the distribution are of less importance at higher nuclear densities.
这些细胞具有多个细胞核，从而减轻了骨骼肌纤维中的运输距离。我们在原位研究了小鼠的慢肌（比目鱼肌）和快肌（趾长伸肌）纤维，并确定了细胞尺寸以及纤维段内所有细胞核的位置。我们使用细胞核作为运输网络的原点，通过最优和随机放置细胞核来模拟其效果。对于两种肌肉，细胞核等距定位似乎可以使沿表面的运输距离最小化。然而，在富含细胞核的比目鱼肌中，将细胞核定位以减少向细胞质的运输距离的重要性较小，并且这些纤维表现出的模式与细胞核随机定位没有统计学上的差异。我们还模拟了肌红蛋白的运输时间，发现尽管核模式和距离存在差异，但它们在两种肌肉之间非常相似。这些结果共同强调了在核密度较低时，空间分布的细胞核对于将运输距离最小化到表面的重要性，而在核密度较高时，这种分布的重要性似乎较小。
