The fine structure and mechanism of breakdown of larval intersegmental muscles in the blowfly Calliphora erythrocephala
The fine structure and mechanism of breakdown of larval intersegmental muscles in the blowfly Calliphora erythrocephala
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DOI：
10.1016/0022-1910(68)90174-1
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发表时间：
1968-10
影响因子：
2.2
通讯作者：
A. Crossley
中科院分区：
文献类型：
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作者：
A. Crossley
丽丽的节间肌由一系列粗细肌丝组成，其中平均每根粗肌丝周围有十根细肌丝。 Z 形盘上有穿孔，当肌肉完全收缩时，粗肌丝和细肌丝都会穿过穿孔。在蛹形成过程中，节间肌肉仅部分收缩，以使粗肌丝的末端接触但不穿透Z盘。研究表明，吞噬细胞对肌肉的侵袭是在体液控制下的，并且可以通过注射甲壳素来提前或人为诱导。甲壳素引起的血细胞群变化是变态开始的第一个形态学指标。Calliphorais 节间肌肉的破坏不是由神经刺激介导的。邀请血细胞入侵单个肌肉的信号尚不清楚，但注定要发生的肌肉的形态变化先于入侵。血细胞质膜的衰减褶皱穿透具有正常收缩元件的肌肉。相邻的折叠结合在一起，将血细胞细胞质内的肌肉片段隔离开。可溶性或胶体元素通过包被的囊泡进入血细胞，这些囊泡排列在血细胞和肌肉之间的血淋巴袋中。循环血细胞中的包被囊泡能够分离非蛋白质物质，例如二氧化钍，并将它们运输到细胞中，在细胞中积聚在液泡中。在吞噬血细胞内，肌肉碎片在发育良好的液泡装置中被降解。许多液泡中都显示出酸性磷酸酶活性。液泡装置内的分解代谢过程导致脂质和糖原储备的积累。蛋白质和蛋白质+RNA空泡也会积累，但大分子的降解程度未知。血细胞质膜的破裂导致所有修饰的肌肉成分最终释放到血淋巴中。
The intersegmental muscles ofCalliphoraare composed of an array of thick and thin myofilaments, in which an average of ten thin myofilaments surrounds each thick myofilament. TheZ-disks are perforated, and both thick and thin myofilaments pass through the perforations when the muscle is fully contracted. During puparium formation the intersegmental muscles contract only partially, so as to bring the ends of the thick myofilaments into contact with, but not to penetrate, theZ-disk.It is shown that invasion of muscles by phagocytes is under humoral control, and can be prematurely or artificially induced by injection of crustecdysone. A change in the haemocyte population induced by crustecdysone is the first morphological indication of the onset of metamorphosis.Breakdown of intersegmental muscles inCalliphorais not mediated by nervous stimuli. The signal inviting invasion of haemocytes into individual muscles is unknown, but morphological changes in the doomed muscles precede invasion.Attenuated folds of haemocyte plasma membrane penetrate muscles which possess normal contractile elements. Adjacent folds unite, isolating muscle fragments within the haemocyte cytoplasm.Soluble or colloidal elements are taken into the haemocyte by coated vesicles, which line the pockets of haemolymph between haemocyte and muscle. Coated vesicles in circulating haemocytes are capable of isolating non-proteinaceous substances such as thorium dioxide, and transporting them into the cell, where they accumulate in vacuoles.Within the phagocytic haemocyte muscle fragments are degraded in a well-developed vacuolar apparatus. Acid phosphatase activity is demonstrated in many vacuoles.The catabolic process within the vacuolar apparatus leads to the accumulation of lipid and glycogen reserves. Protein and protein+RNA vacuoles also accumulate, but the extent of degradation of macromolecules is unknown. Rupture of the haemocyte plasma membrane leads to the eventual release of all modified muscle components into the haemolymph.