七星瓢虫的卵黄发生:脂肪体与卵巢中卵黄原蛋白的合成与分泌

本文利用³H]亮氨酸参入及特异性抗体沉淀等方法,研究了七星瓢虫体外培养的脂肪体中卵黄原蛋白合成与分泌的动力学,以及不同发育期脂肪体与卵巢中卵黄原蛋白合成的定量变化。脂肪体中卵黄原蛋白的合成与分泌在培养1—4小时内直线上升,到6小时稍下降。保留在脂肪体内的卵黄原蛋白缓慢积累,但一直水平很低。卵黄原蛋白合成的最初30分钟,分泌速率较慢,60%以上的卵黄原蛋白保留在脂肪体内。1小时后分泌速率加快,70%以上的卵黄原蛋白被分泌,保留的卵黄原蛋白在4小时中逐渐被释放。在4小时,被分泌的卵黄原蛋白超过80%,最高可达92%。 在雌虫发育过程中,脂肪体中卵黄原蛋白合成的高峰在羽化后11—15天,所合成的卵黄原蛋白占整个发育期合成总量的80%。在合成高峰期分泌的卵黄原蛋白高达90%以上,但在发育的早期和晚期分泌的卵黄原蛋白仅占30%或稍多。 卵黄发生前的卵巢就开始合成卵黄原蛋白,但卵巢中卵黄原蛋白的合成高峰期与脂肪体中大致相同。与脂肪体相反,卵巢合成的卵黄原蛋白大部分保留在卵巢内。在卵黄发生盛期,卵巢合成的卵黄原蛋白为脂肪体合成的卵黄原蛋白的20%。

ON THE VITELLOGENESIS OF COCC/NELLA SEPTEMPUNCTATA: SYNTHESIS AND SECRETION OF VITELLOGENIN BY THE FAT BODY AND THE OVARY

The kinetics of vitellogenin (Vg) synthesis and secretion by the fat body and the quantitative changes of Vg synthesis in the fat body and the ovary during adult development of the female lady beetle Coccinella septempunctate have been studied by measuring the 3H] leucine incorporation in vitro after specific antibody precipitation. In vitellogenic females, Vg synthesis and secretion by the fat body showed a quick linear increase for 4 hr, whereas the Vg retained in the tissue accumulated slowly and remained at a low level. The percentage of Vg secreted by the fat body was less than 40% at 30 min and increased to a maximum of about 90% by 4 hr. Most of the Vg retained in the fat body was secreted during a chase of 4 hr.In normal development, Vg synthesis by the fat body was maximal at 11-15 days after adult emergence. The Vg synthesized in this period accounted for 80% of the total Vg synthesized during adult life. At the time of maximal Vg synthesis, more than 90% of the newly synthesized Vg was secreted. In the early and later stages of development, only 30% or more Vg was secreted after synthesis.Ovaries of previtellogenic stages can synthesize Vg, but the maximal level of Vg synthesis occurred in ovaries of the active vitellogenic stages. Contrary to the fat body, the ovaries retained most of the Vg synthesized. In active vitellogenic females, the Vg synthesized in the ovary was about 20% of that made in the fat body. Thus the ovary is a minor site of Vg syntheis in this species.