【摘要】 尿素循环在生物体氮化合物代谢和调节控制中起着极为重要的作用。昆虫排出的尿素是否由于存在尿素循环而形成,尚未定论。我们对各种蚕体组织所作的研究表明,不存在尿素全循环,但脂肪体中精氨酸酶活力甚高,该酶与蚕的变态密切相关,并受保幼激素类似物(JHA)的调控。家蚕、蓖麻蚕和柞蚕脂肪体中,除精氨酸酶具有明显活力外,氨基甲酰磷酸合成酶,鸟氨酸转氨甲酰磷酸酶和精氨酸合成酶均无可检出的活力。在蚕幼虫期,尤其在五龄中后期,精氨酸酶活力最高;眠期和蛹期,该酶活力很低;蛹化蛾后,该酶活力又明显增高。用不同剂量的JHAZR515处理家蚕,观察到在适当剂量时,精氨酸酶活力明显地高于对照组,提高范围从30%到110%;当用高剂量ZR515处理蚕后,引起不结茧蚕,精氨酸酶活力先低于对照组,以后再逐步回升并高于对照组,而且持续增高的时间也较长。这表明蚕的变态和精氨酸酶活力的变化与JHA的量密切相关联并受JHA的调节控制。更多还原

【Abstract】 In the present paper it was shown that in the fat body cells of Bombyx mori L. we have been unable to demonstrate the activities of carbamyl phosphate synthetase, ornithine transcarbamylase and argininosuccinate synthetase, but arginase activity can be detected. It was suggested that the urea cycle may be absent. It is indicated from nutri tional studies that insects in general are unable to synthesize arginine for their needs, and we have also demonstrated in our other paper that the fat body cells of Bombyx mori L. can form ornithine, urea, glutamate and proline at the expense of arginine and ketoglutarate. Thus, arginase may play an important role in the metabolism of amino acids in the silkworm. The activity of arginase was found to be the highest in the fat body of fifth instar larvae and adult silkworms and to be lowest in the embryo and pupae.The juvenile hormone analogue ZR515 was applied in adequate doses onto the body surface of the 5th instar larvae of the silkworm Bombyx mori L. It was observed that the activity of arginase in the fat body cells increased, the 5th stadium was prolonged, the weights of the cocoon and cocoon shell also increased.A major effect of juvenile hormone is to control sequential polymorphism, i. e. it is involved in the switching on and off of successive batches of genetic information. Its regulation role on enzyme activity may shed further light on the mechanism of action of the hormone.更多还原