Beaulaton J
Histochem J. 1986 Oct;18(10):527-36. doi: 10.1007/BF01675193.
The intersegmental muscles in the metamorphosing silkmoth Antheraea polyphemus were examined by two electron cytochemical procedures for demonstration of calcium compartmentation during the two-day period of degeneration after emergence. Muscle fibres were treated with either oxalate-pyroantimonate, or phosphate-pyroantimonate procedures. The elemental composition of the reaction product arising from the oxalate procedure was determined with electron probe X-ray microanalysis of unstained thin sections by energy dispersive spectrometry and wavelength dispersive spectrometry. The wavelength dispersive data revealed high peaks of calcium and antimony in the electron-dense precipitates. No reaction was obtained in muscles after treatment with the phosphate-pyroantimonate method. Shortly after the emergence of the moth, very few calcium deposits were found in the mitochondria, which also contained amorphous matrix densities. During the rapid lytic phase (17 and 30 h after ecdysis), the mitochondria, autophagic vacuoles sequestering mitochondria, and lysosomal dense bodies issuing from the latter were highly reactive in each muscle fibre. These results demonstrate that the collapse of tracheae (hypoxic conditions) is correlated with the calcium overload of mitochondria when the cell calcium homeostasis is apparently lost. Such calcium overload of the mitochondria appears to cause irreversible damage to these organelles which are then sequestered in autophagic vacuoles. This mitochondrial autophagic process leads to calcium translocation into a lysosomal compartment. We suggest that the calcium lysosomal stores may have a transient function of cell detoxification and stimulation of calcium-dependent degradative processes prior to the final muscle collapse.
采用两种电子细胞化学方法，对变态期的多音天蚕蛾（Antheraea polyphemus）羽化后两天退变过程中的节间肌进行了检查，以证明钙的区室化。对肌纤维分别采用草酸盐-焦锑酸盐法或磷酸盐-焦锑酸盐法处理。通过能量色散光谱法和波长色散光谱法对未染色薄片进行电子探针X射线微分析，确定了草酸盐法产生的反应产物的元素组成。波长色散数据显示，电子致密沉淀物中有钙和锑的高含量峰。用磷酸盐-焦锑酸盐法处理后的肌肉未获得反应。蛾羽化后不久，线粒体中发现的钙沉积物很少，线粒体中还含有无定形的基质密度。在快速溶解阶段（蜕皮后17小时和30小时），线粒体、隔离线粒体的自噬泡以及由后者产生的溶酶体致密体在每根肌纤维中都具有高反应性。这些结果表明气管塌陷（缺氧条件）与细胞钙稳态明显丧失时线粒体的钙超载相关。线粒体的这种钙超载似乎会对这些细胞器造成不可逆的损伤，然后这些细胞器被隔离在自噬泡中。这种线粒体自噬过程导致钙转运到溶酶体区室。我们认为，在最终肌肉塌陷之前，溶酶体钙储存可能具有细胞解毒和刺激钙依赖性降解过程的短暂功能。
