BACKGROUND Insulin/insulin-like growth peptide signaling (IIS) down-regulates hemolymph sugar level and facilitates larval growth in the soybean pod borer, Maruca vitrata. The objective of this study is to determine whether IIS of M. vitrata can mediate ovarian development of adult females. RESULTS A pair of ovaries consists of 8 ovarioles, each of which is separated into distal germarium and proximal vitellarium in M. vitrata. In the germarium, oocyte development occurred with active mitotic activity which was visible by incorporating bromodeoxyribose uridine. Previtellogenic development and subsequent vitellogenesis began soon after adult emergence. They continued with increase of female age. Oocyte development was facilitated by up-regulation of vitellogenin (Vg) and Vg receptor (VgR) gene expression. Larval diets significantly influenced on ovarian development of M. vitrata because oocyte development varied with pupal size derived from larvae treated with different nutritional diets. Its ovarian development was dependent on endocrine signal(s) from the head because decapitation soon after adult emergence prevented oogenesis and subsequent vitellogenesis along with marked reduction of Vg and VgR expression. Topical application of juvenile hormone (JH) significantly recovered its ovarian development whereas farnesoic acid (a precursor of JH biosynthesis) or 20-hydroxyecdysone treatment did not. JH stimulated vitellogenesis and choriogenesis, but not previtellogenic development. In contrast, insulin injection to decapitated females stimulated oocyte differentiation and vitellogenesis along with increase of Vg and VgR expression. To further analyze the effect of insulin on ovarian development, expression of four IIS components (InR, FOXO, Akt, and TOR) genes was manipulated by RNA interference. Hemocoelic injection of gene-specific double stranded RNAs significantly reduced their target gene mRNA levels and interfered with ovarian development. An addition of insulin to JH treatment against decapitated females enhanced the gonadotropic effect of JH by stimulating oogenesis. CONCLUSIONS IIS plays crucial role in mediating previtellogenic development of M. vitrata in response to nutrient signal. It also enhances the gonadotropic effect of JH II on vitellogenesis.

中文翻译：

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胰岛素信号传导介导前玻璃体形成，并增强鳞翅目昆虫马卢卡（Maruca vitrata）的幼体激素介导的卵黄发生。

背景技术胰岛素/胰岛素样生长肽信号传导（IIS）下调血淋巴糖水平并促进大豆荚bore（Maruca vitrata）中的幼虫生长。这项研究的目的是确定玻璃体分枝杆菌的IIS是否可以介导成年女性的卵巢发育。结果一对卵巢由8个卵巢组成，每个卵在M. vitrata中被分离为远侧菌群和近侧vi骨。在生殖器中，卵母细胞的发育具有活跃的有丝分裂活性，通过掺入溴脱氧核糖尿苷可以看出。成年后不久，玻璃体前发育和随后的卵黄发生开始。随着女性年龄的增加，她们继续。卵黄蛋白原（Vg）和Vg受体（VgR）基因表达的上调促进了卵母细胞的发育。幼虫饮食对卵形支原体的卵巢发育有显着影响，因为卵母细胞的发育随衍生自不同营养饮食的幼虫的p大小而变化。它的卵巢发育依赖于头部的内分泌信号，因为成年后不久的断头会阻止卵子发生和随后的卵黄发生，同时显着降低Vg和VgR表达。局部应用少年激素（JH）可以显着恢复其卵巢发育，而法呢酸（JH生物合成的前体）或20-羟基蜕皮酮治疗则不能。JH刺激卵黄发生和绒毛膜形成，但不能促进玻璃体形成。相反，向断头的女性注射胰岛素刺激卵母细胞分化和卵黄形成，同时增加Vg和VgR表达。为了进一步分析胰岛素对卵巢发育的影响，四个IIS组件（InR，FOXO，Akt和TOR）基因的表达受到RNA干扰的操纵。特定基因双链RNA的血红素注射显着降低了它们的靶基因mRNA水平，并干扰了卵巢的发育。在JH治疗中，针对头部丧失的雌性添加胰岛素可以通过刺激卵子形成来增强JH的促性腺激素作用。结论IIS在响应营养信号而介导玻璃体分枝杆菌的玻璃体前发育中起着至关重要的作用。它还增强了JH II对卵黄发生的促性腺作用。特定基因双链RNA的血红素注射显着降低了它们的靶基因mRNA水平，并干扰了卵巢的发育。在JH治疗中，针对头部丧失的雌性添加胰岛素可以通过刺激卵子形成来增强JH的促性腺激素作用。结论IIS在响应营养信号而介导玻璃体分枝杆菌的玻璃体前发育中起着至关重要的作用。它还增强了JH II对卵黄发生的促性腺作用。特定基因双链RNA的血红素注射显着降低了它们的靶基因mRNA水平，并干扰了卵巢的发育。在JH治疗中，针对头部丧失的雌性添加胰岛素可以通过刺激卵子形成来增强JH的促性腺激素作用。结论IIS在响应营养信号而介导玻璃体分枝杆菌的玻璃体前发育中起着至关重要的作用。它还增强了JH II对卵黄发生的促性腺作用。