【摘要】 本文用脂肪体体外培养方法,研究了取食天然食物和基础人工饲料的七星瓢虫雌虫中卵黄原蛋白、其他分泌蛋白和RNA合成的发育期变化,以及保幼激素类似物ZR-512的调节作用。结果表明:(1)取食蚜虫的雌虫脂肪体羽化后3天即开始合成卵黄原蛋白。11天时合成急剧上升,13天到达最高峰。脂肪体RNA的合成随发育天数而逐渐上升,第9天出现高峰。(2)取食基础人工饲料的雌虫脂肪体合成卵黄原蛋白的能力很弱;在羽化后20天内一直停留在极低的水平,所合成的卵黄原蛋白仅为取食蚜虫时合成高峰的3％。其他分泌蛋白的合成被抑制的程度小得多。脂肪体的RNA合成也一直比较低。(3)取食基础人工饲料的雌虫点滴或喂食ZR-512后,卵黄原蛋白的合成在高峰期比对照组分别增加44倍和67倍。而其他分泌蛋白的合成仅比对照组提高近3倍,表明保幼激素对卵黄原蛋白合成有特别明显的促进作用。激素处理后脂肪体RNA的合成比对照组提高6—7倍,证明保幼激素作用于转录水平。更多还原

【Abstract】 Syntheses of vitellogenin (Vg), other secretory proteins and ENA were investigated in the fat body from adult female Coccinella septempunctata at different stages of development by incubation in vitro with [3H] leucine and [3H] uridine. The capacity for Vg synthesis was assayed by radioactive Vg secreted into the medium after specific antibody precipitation. In females feeding on aphids, Vg synthesis began at day 3 after emergence and reached a small peak at day 5, when Vg constituted 26% of the total secreted proteins. Bate of Vg synthesis increased sharply after day 11, and became maximal at day 13. At the maximum, 34% of the total proteins secreted was Vg. In females reared on a basic artificial diet, synthesis of Vg by the fat body was greatly suppressed. [3H] leucine incorporation into Vg was first detected at day 3 as it was in normal development, but with a much lower rate. Vg synthesis remain at a very low steady-state level during adult development; the amount of Vg synthesized was only about 5% of the total secretory proteins. Vg produced in females on artificial diet was less than 3% of that in aphid-feeding females at the peak of Vg synthesis. Synt.hsis of other secretory proteis in females on artificial diet was reduced to a lesser extent.The incorporation of [3H] uridine into fat body UNA increased with time after emergence in females on aphids, and rose to a maximum at day 9, which preceded the major rise in Vg synthesis. In females on artificial diet, incorporation into ENA kept at a relatively low level throughout the adult development.Stimulation of Vg and ENA synthesis by a juvenile hormone analog ZE-512 was studied in fat body from females peared on artificial diet. When ZE-512 was applied topically at a dosage of 100 g/insect to females at day 3, a more than 40-fold sitmula-tion in Vg synthesis over the control was observed at the stage of maximal synthesis. At this time, newly synthesized Vg made up 56% of the total secretory proteins, being 12 times higher than in the control. When females were kept on an artificial diet containing ZE-512 after emergence, Vg synthesis was stimulated to a greater extent than after a single treatment. These results confirmed the involvement of JH in the regulation of Vg synthesis and secretion in Coccinella septempunctata. Hormone treatment produced only a 3-fold increase in the synthesis of other secretory proteins, showing the specificity of JH effect. The incorporation into ENA increased 6-7 times in hormone-treated females. This is consistent with action of JH at the transcriptional level.更多还原