The Food and Environment Research Agency, Sand Hutton, York YO41 1LZ, UK.
Insect Biochem Mol Biol. 2013 Jan;43(1):65-74. doi: 10.1016/j.ibmb.2012.09.007. Epub 2012 Oct 17.
The insect PISCF/allatostatins (ASTs) are pleiotropic peptides that are involved in the regulation of juvenile hormone biosynthesis, are myoinhibitory on the gut and the heart, and suppress feeding in various insects, but their roles in beetles are poorly understood. To provide further insight into the significance of PISCF/ASTs in beetles, the PISCF/AST receptor from Tribolium castaneum has been characterised and its tissue distribution determined. The biological activity of the T. castaneum PISCF/AST (Trica-AS) was also investigated. The Trica-AS receptor shows high sequence homology to other insect PISCF/AST receptors, which are related to the mammalian somatostatin/opioid receptors, a family of G protein-coupled receptors. The Trica-AS receptor was activated in a dose-dependent manner by both Trica-AS and T. castaneum allatostatin double C (Trica-ASTCC) as well as Manduca sexta-allatostatin (Manse-AS). Other allatoregulatory peptides (a FLG/AST, a MIP/AST and an allatotropin) and somatostatin(14) were inactive on this receptor. Receptor transcript levels in tissues, determined by qRT-PCR, were highest in the head and the gut, with variable amounts in the fat body and reproductive organs. There were measurable differences in receptor levels of the head, fat body and reproductive organs between males and females. There was also a widespread distribution of Trica-AS in various tissues of T. castaneum. The Trica-AS peptide precursor was most abundant in the head and there was a significant difference between levels in the heads and reproductive organs of males and females. Whole mount immunocytochemistry localised Trica-AS in the median and lateral neurosecretory cells of the brain, in the corpus cardiacum and throughout the ventral nerve cord. The peptide was also present in midgut neurosecretory cells, but no immunostaining was detected in the reproductive organs or Malpighian tubules. The widespread distribution of both Trica-AS and its receptor suggest this peptide may have multiple roles in beetles. However, Trica-AS had no effect on the spontaneous contractions of the gut or ovaries of T. castaneum but this peptide did stimulate the release of proteases from the anterior midgut of another beetle, Tenebrio molitor. The activation of the Trica-AS receptor by Trica-ASTCC implies a physiological role for this peptide in beetles, which remains to be identified.
昆虫 PISCF/ 孤雌生殖抑制素（ASTs）是一种多功能肽，参与了保幼激素生物合成的调控，对肠道和心脏具有肌抑制作用，并抑制各种昆虫的摄食，但它们在甲虫中的作用还知之甚少。为了进一步了解 PISCF/AST 在甲虫中的意义，已对来自赤拟谷盗的 PISCF/AST 受体进行了特征描述，并确定了其组织分布。还研究了赤拟谷盗 PISCF/AST（Trica-AS）的生物学活性。Trica-AS 受体与其他昆虫 PISCF/AST 受体具有很高的序列同源性，这些受体与哺乳动物生长抑素/阿片受体有关，是一类 G 蛋白偶联受体。Trica-AS 受体以剂量依赖的方式被 Trica-AS 和赤拟谷盗孤雌生殖抑制素双 C（Trica-ASTCC）以及烟青虫孤雌生殖抑制素（Manse-AS）激活。其他孤雌生殖调节肽（a FLG/AST、a MIP/AST 和 an allatotropin）和生长抑素（14）对该受体没有活性。通过 qRT-PCR 确定的组织中转录本水平，在头部和肠道中最高，在脂肪体和生殖器官中则有所不同。在雄性和雌性之间，头部、脂肪体和生殖器官的受体水平存在可测量的差异。在赤拟谷盗的各种组织中也广泛分布着 Trica-AS。Trica-AS 肽前体在头部最为丰富，雄性头部和生殖器官之间的水平存在显著差异。整体免疫细胞化学将 Trica-AS 定位于脑的中脑和侧神经分泌细胞、心体和腹神经索。该肽也存在于中肠神经分泌细胞中，但在生殖器官或马氏管中未检测到免疫染色。Trica-AS 及其受体的广泛分布表明，该肽可能在甲虫中具有多种作用。然而，Trica-AS 对赤拟谷盗肠道或卵巢的自发收缩没有影响，但这种肽确实刺激了另一种甲虫黄粉虫前肠的蛋白酶释放。Trica-ASTCC 对 Trica-AS 受体的激活表明该肽在甲虫中具有生理作用，但其作用仍有待确定。
