Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada.
Gen Comp Endocrinol. 2013 Jul 1;188:85-93. doi: 10.1016/j.ygcen.2013.04.018. Epub 2013 May 1.
The Pacific beetle cockroach, Diploptera punctata, has proven to be a valuable model insect in the study of the dynamics regulating juvenile hormone (JH) biosynthesis and metabolism, particularly during late nymphal development and reproduction. This stems in part from its unusual mode of reproduction, adenotrophic viviparity, in which females give birth to live young that have been nourished throughout embryonic development by a protein-rich 'milk' secreted by the wall of the brood sac or uterus. In this animal, as in most insects, JH regulates both vitellogenin production and its uptake by developing oocytes. However, JH has an antagonistic effect on embryonic development and following oviposition of the fertilized oocytes into the brood sac, JH production halts, in part through the action of a peptide family, the FGLa allatostatins. JH production remains at a low level throughout pregnancy and is only reinstated at the end of gestation, at which time, the next wave of oocytes begins to develop and enter vitellogenesis. Thus, JH production in this species is precisely regulated, since the appearance of JH at inappropriate times would result in abortion of the embryos. Numerous factors are responsible for the regulation of JH biosynthesis, including peptides, biogenic amines, neurotransmitters, ecdysteroids and second messenger effectors. In this review, we discuss these factors and highlight potentially fruitful areas of future research. Although several of the enzymes of the biosynthetic pathway have been cloned, the precise points of rate limitation remain uncertain. The dissection of the biosynthetic pathway and its control awaits the completion of the genome and transcriptome of this important model insect.
太平洋蟑螂，双翅目 punctata，已被证明是研究调控保幼激素（JH）生物合成和代谢的有价值的模式昆虫，特别是在晚期若虫发育和繁殖期间。这部分源于其不寻常的繁殖方式，腺营养胎生，其中雌性产下已通过卵囊或子宫壁分泌的富含蛋白质的“乳汁”滋养整个胚胎发育的活幼体。在这种动物中，与大多数昆虫一样，JH 调节卵黄蛋白原的产生及其被发育中的卵母细胞摄取。然而，JH 对胚胎发育有拮抗作用，并且在受精卵被产卵到卵囊中之后，JH 的产生停止，部分是通过一种肽家族，即 FGLa 脑激素抑制素的作用。在怀孕期间，JH 产生一直处于低水平，只有在妊娠末期才重新开始，此时，下一波卵母细胞开始发育并进入卵黄生成期。因此，这种物种的 JH 产生受到精确调节，因为在不合适的时间出现 JH 会导致胚胎流产。许多因素负责 JH 生物合成的调节，包括肽、生物胺、神经递质、蜕皮激素和第二信使效应物。在这篇综述中，我们讨论了这些因素，并强调了未来研究的有前途的领域。尽管已经克隆了生物合成途径的几种酶，但限速的确切点仍不确定。该生物合成途径及其控制的剖析有待于这种重要模式昆虫的基因组和转录组的完成。
