Developmental expression, synthesis, and secretion of insecticyanin by the epidermis of the tobacco hornworm, Manduca sexta.
Developmental expression, synthesis, and secretion of insecticyanin by the epidermis of the tobacco hornworm, Manduca sexta.
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烟草天蛾（Manduca sexta）表皮昆虫青素的发育表达、合成和分泌。
DOI：
10.1002/arch.940140305
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发表时间：
1990
影响因子：
2.2
通讯作者：
Webb,BA
中科院分区：
文献类型：
--
作者：
Riddiford,LM;Palli,SR;Hiruma,K;Li,W;Green,J;Hice,RH;Wolfgang,WJ;Webb,BA
昆虫花青素被发现以几种等电形式合成，并储存在表皮的色素颗粒中。两种主要的表皮形态(Ins-a，pl5.5；Ins-b，pl5.7)都存在于角质层中，但只有最基本的Ins-b存在于血淋巴中。在体外，表皮合成并分泌这两种形式到角质层和介质中。分离到两个昆虫花青素的cDNA克隆，然后与表皮mRNA杂交，发现只有一个1.1kb的mRNA，但转录出一个产生Ins-a而不产生Ins-b的RNA。昆虫花青素在4龄和5龄幼虫的蜕皮间取食期存在，在幼虫蜕皮和变态开始后不存在。用20-羟基蜕皮酮(20HE)处理4龄幼虫2天或5龄幼虫1天，均可引起该mRNA的剂量依赖性下降，但JH的同时作用并不能阻止这一作用。当蜕皮前恢复合成时，Ins-b出现在Ins-a之前；然后在摄食的最后一天，Ins-a的合成停止，Ins-b的合成停止。
Insecticyanin was found to be synthesized in several isoelectric forms and stored in the pigment granules in the epidermis. Both major epidermal forms (INS‐a, pl5.5; INS‐b, pl5.7) were found in the cuticle, but only the most basic form, INS‐b, was present in the hemolymph. In vitro the epidermis synthesized and secreted both forms into both the cuticle and the medium. Isolation of two cDNA clones for insecticyanin followed by hybridization to epidermal mRNA showed the presence of only one 1.1 kb mRNA, but transcription of the longer cDNA yielded a RNA which produced INS‐a but no INS‐b. Insecticyanin mRNA was present during the intermolt feeding stages of the 4th and 5th instars and absent during the larval molt and after the onset of metamorphosis. Exposure of either day 2 4th‐instar or day 1 5th‐instar larval epidermis to 20‐hydroxyecdysone (20HE) in vitro caused a dose‐dependent decline in this mRNA that was not prevented by simultaneous exposure to JH. When synthesis resumes just before ecdysis, INS‐b appears before INS‐a; then on the final day of feeding, synthesis of INS‐a ceases before that of INS‐b.