Number and spatial distribution of nuclei in the muscle fibres of normal mice studied in vivo
Number and spatial distribution of nuclei in the muscle fibres of normal mice studied in vivo
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DOI：
10.1113/jphysiol.2003.045328
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发表时间：
2003-09-01
影响因子：
5.5
通讯作者：
Gundersen, K
中科院分区：
文献类型：
--
作者：
Bruusgaard, JC;Liestol, K;Gundersen, K
我们在这里提出了一种新的技术，其中可视化细胞核在活的肌肉纤维在完整的动物，包括注射标记的DNA到单细胞。这种方法使我们能够在不标记卫星细胞的情况下确定肌膜内所有细胞核的位置。与组织培养中的报道相反，我们发现细胞核是固定的，即使观察了几天也是如此。除了终板和一些肌腱连接处的细胞核密度较高外，沿纤维的细胞核密度沿着是均匀的。连接周围区的细胞核数目与纤维的其余部分相同。在趾长伸肌（EDL）肌肉，连接外核被拉长，并精确地对齐的纤维的长轴。在比目鱼肌中，细胞核更圆，排列不整齐。当比较小的和大的纤维在比目鱼肌，细胞核的数量变化约成比例的细胞质体积，而在EDL的数量成比例的表面积。统计分析表明，核不是随机分布在两个EDL或比目鱼肌。对于每一个纤维，实际分布进行了比较，在计算机模拟中，假设原子核相互排斥，这优化了原子核的分布，最大限度地减少运输距离。当核密度较低时，模拟的图案规则，具有清晰的行状结构。因此，在肌纤维中观察到的核的非随机且通常呈排状分布可能反映了核相互排斥以最小化运输距离的调节机制。
We present here a new technique with which to visualize nuclei in living muscle fibres in the intact animal, involving injection of labelled DNA into single cells. This approach allowed us to determine the position of all of nuclei within a sarcolemma without labelling satellite cells. In contrast to what has been reported in tissue culture, we found that the nuclei were immobile, even when observed over several days. Nucleic density was uniform along the fibre except for the endplate and some myotendinous junctions, where the density was higher. The perijunctional region had the same number of nuclei as the rest of the fibre. In the extensor digitorum longus (EDL) muscle, the extrajunctional nuclei were elongated and precisely aligned to the long axis of the fibre. In the soleus, the nuclei were rounder and not well aligned. When comparing small and large fibres in the soleus, the number of nuclei varied approximately in proportion to cytoplasmic volume, while in the EDL the number was proportional to surface area. Statistical analysis revealed that the nuclei were not randomly distributed in either the EDL or the soleus. For each fibre, actual distributions were compared with computer simulations in which nuclei were assumed to repel each other, which optimizes the distribution of nuclei with respect to minimizing transport distances. The simulated patterns were regular, with clear row-like structures when the density of nuclei was low. The non-random and often row-like distribution of nuclei observed in muscle fibres may thus reflect regulatory mechanisms whereby nuclei repel each other in order to minimize transport distances.