小地老虎变态期间马氏管超微结构与酯酶活性的变化

本实验用光镜和电镜观察了小地老虎Agrotis ypsilon Rottemberg幼虫在变态期间马氏管超微结构的变化及成虫马氏管的重组过程,同时还研究了变态期马氏管酯酶的活性。结果表明:(1)变态期间马氏管外形完整,除至预蛹期隐肾复合体解体外,其余无明显变化。(2)变态期间管壁细胞变化显著。幼虫6龄末期马氏管细胞结构开始变化,主要特点为:细胞质电子密度高,充满了核糖体颗粒,微绒毛萎缩,线粒体从萎缩的微绒毛中退出进入细胞质,基膜内褶破坏。进入预蛹期幼虫马氏管细胞解体:基膜内褶、顶端微绒毛、线粒体及细胞质内的其它细胞器消失,并形成自体吞噬泡,细胞质内仅存细胞核及各种类型的液泡。但是在变态期间因底膜始终存在,故马氏管外形不变;至蛹后期,成虫马氏管细胞在原位重组,基膜内褶由浅变深,微绒毛由短变长,线粒体内嵴从无到有。(3)变态过程中羧酸酯酶和酸性磷酸酯酶的活性变化趋势基本相同,以六龄幼虫最强,预蛹期次之,蛹期最低。

CHANGES OF ULTRASTRUCTURE AND ACTIVITIES OF ESTERASES OF BLACK CUTWORM MALPIGHIAN TUBULES DURING METAMORPHOSIS

The morphological and ultrastrurtural changes of larval Malpighian tubules and the reconstruction of adult Malpighian tabules of black cutworm,Agratis ypsilon (Rottembergh during metamorphosis were studied with electron microscope.Activities of their esterases were also analysed with biochemical methods.The results are summarized as follows:1.The external morphology of Malpighian tubules remained unchanged during prepupal and pupal stages,but that part of the tubule within the crytonephridial segment was dissociated owing to cryptohephridal membrane degeneration.2.On the other hand,the cells of the Malpighian tubules changed dramatially in the late 6th instar.As revealed by electron micrographes the changes were as follows:electron density of cytoplasm increased,the basal infold disappeared,and microvilli shortened where the mitochondria retracted to cytoplasm.Cells of the larval Malpighian tubule degenerated during the prepupal and the early pupal stage:base infolds,microvilli,mitochondria and other orga-nelles almost disappeared;autophagocytosis took place and the cytoplasm contained only various vesicles.But the basal lamina of Malpighian tubules persisted unchanged;therefore,the Malpighian tubules appeared intact.When the late pupal stage began,the adult Malpighian tubule cells were reconstructed at their original position;base infolds deepened;the length of microvilli increased;and mitochondria reappeared.3.The esterase activities in Malpighian tubule were quite different at various periords during metamorphosis,and the activity sequence could be arranged as follows:6th instar larvae>prepupae>pupae.