Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China.
Department of Entomology, Texas A&M University, College Station, TX, USA.
Insect Sci. 2020 Apr;27(2):292-303. doi: 10.1111/1744-7917.12638. Epub 2018 Sep 25.
Juvenile hormone (JH), a growth regulator, inhibits ecdysteroid-induced metamorphosis and controls insect development and diapause. Methoprene-tolerant (Met) and Krüppel homolog 1 (Kr-h1) are two proteins involved in JH action. To gain some insight into their function in development of Sitodiplosis mosellana, an insect pest undergoing obligatory larval diapause at the mature 3rd instar stage, we cloned full-length complementary DNAs of Met and Kr-h1 from this species. SmMet encoded a putative protein, which contained three domains typical of the bHLH-PAS family and eight conserved amino acid residues important for JH binding. SmKr-h1 encoded a protein showing high sequence homology to its counterparts in other species, and contained all eight highly conserved Zn-finger motifs for DNA-binding. Expression patterns of SmMet and SmKr-h1 were developmentally regulated and JH III responsive as well. Their mRNA abundance increased as larvae entered early 3rd instar, pre-diapause and maintenance stages, and peaked during post-diapause quiescence, a pattern correlated with JH titers in this species. Different from reduced expression of SmMet, SmKr-h1 mRNA increased at mid-to-late period of post-diapause development. Topical application of JH III on diapausing larvae also induced the two genes in a dose-dependent manner. Expression of SmMet and SmKr-h1 clearly declined in the pre-pupal phase, and was significantly higher in female adults than male adults. These results suggest that JH-responsive SmMet and SmKr-h1 might play key roles in diapause induction and maintenance as well as in post-diapause quiescence and adult reproduction, whereas metamorphosis from larvae to pupae might be correlated with their reduced expression.
保幼激素（JH）是一种生长调节剂，抑制蜕皮甾类激素诱导的变态，并控制昆虫的发育和滞育。对灭幼脲敏感（Met）和 Krüppel 同源物 1（Kr-h1）是两种参与 JH 作用的蛋白质。为了深入了解它们在经历强制性幼虫滞育的鳞翅目昆虫枣实蝇发育中的功能，我们从该物种中克隆了 Met 和 Kr-h1 的全长 cDNA。SmMet 编码一个假定的蛋白质，该蛋白质包含三个典型的 bHLH-PAS 家族结构域和八个对 JH 结合很重要的保守氨基酸残基。SmKr-h1 编码的蛋白质与其他物种的同源物具有很高的序列同源性，并且包含所有八个高度保守的用于 DNA 结合的 Zn 指模体。SmMet 和 SmKr-h1 的表达模式受发育调控和 JH III 反应的影响。随着幼虫进入早期 3 龄期、预滞育和维持阶段，其 mRNA 丰度增加，并在滞育后静止期达到峰值，这与该物种中 JH 浓度的模式相关。与 SmMet 的表达减少不同，SmKr-h1 的 mRNA 在滞育后发育的中晚期增加。JH III 对滞育幼虫的局部处理也以剂量依赖的方式诱导这两个基因。SmMet 和 SmKr-h1 的表达在预蛹期明显下降，并且在雌性成虫中显著高于雄性成虫。这些结果表明，JH 反应性的 SmMet 和 SmKr-h1 可能在滞育诱导和维持以及滞育后静止和成虫生殖中发挥关键作用，而从幼虫到蛹的变态可能与它们的表达减少有关。
