粘虫蛾飞行肌的发育：超微结构特征分析

应用电子显微镜对正常条件下饲养的0-16日龄粘虫Mythimna separata (Walker)雌蛾飞行肌超微结构的研究结果表明：肌原纤维直径。线粒体和横管的体积分量均随蛾龄的增加而增加，到7日龄达到最大值以后又随蛾龄的增加而下降；但是，肌节长度则随蛾龄的增加而缩短，到7日龄达到最短后又随蛾龄的增加而延长，从而使整条发育曲线呈“V”字形；肌原纤维和肌质网体积分量变化不大或无规律可寻；二位体在发育初期和未期的比例较高，而三位体在4和7口龄比例较高；肌丝排列从0～7日龄均是有序的，肌动蛋白丝(细丝)和肌球蛋白丝(粗丝)的数量比为3：1，粗丝的数量变化也不大，每根肌原纤维约有600根。但从10日龄开始肌丝排列出现紊乱，细丝全部消失，粗丝降解、数量减少了30%，从而使肌原纤维留下一片片的空白。根据这些结果，把7日龄前的飞行肌发育过程视为生长过程，而把10日龄后的视作降解过程。最后对粘虫蛾飞行肌与卵巢发育及其飞行能力变化的关系进行了讨论。

AN ULTRASTRUCTURAL STUDY ON THE DEVELOPMENT OF FLIGHT MUSCLE IN ADULT ORIENTAL ARMYWORM,MYTHIMNA SEPARATA(WALKER)

The development of thoracic dorsolongitudinal muscle in the female adult Oriental armyworm, Mythimna separata (Walker) reared at 23℃ , aged from emergence to sixteenth day of the adult life was studied through quantitative and qualitative analysis of elecron micrographs. Myofibrillar diameter, mitochondria and T-system volume fractions of the muscle fiber increased from 0.7μm, 35% and 2.5% at emergence or 1-day-old to 1μm, 45% and 8.5%, respectively by day 7 of the adult life, while sarcomere length short- ened from 3.0μm to 2.2μm during this period, but the hexagonaI organization of myoffiaments and the number of thick filaments per myofibril remained unchanged.Thereafter, the myofibrillar diameter, mitochondria and T-system volume fractions become decreased and the sarcomere length increased gradually. Thin filaments and the hexagonal arrangement of myofilaments disappeared and the number of thick filaments per myofibril reduced from about 600 to 450 by day 10 of the moth life; they are indicative of muscle degeneration. Developmental changes of the dyads and triads in volume fraction of T-system of the muscle varied: the ratio of dyads was high when the volume fraction ofT-system was low while the ratio of triads was high when that of T-system was high. These results indicate that ultrastructural changes do occur in flight muscle development of the moth, even though variation in volume fractions of myofibrillar and sarcoplasmicreticulum of the muscle fiber shows no obvious trend. Flight muscle development seems to be related to flight performance and ovarian development in female moth of M. separata when their relationship is investigated in light of published findings. The moth's flight muscle grows and flight capacity increases as its ovary develops, but its flight muscle degenerates and flight capacity decreases after the moth begins laying eggs.