Molecular characterization of prothoracicotropic hormone and diapause hormone in Heliothis virescens during diapause, and a new role for diapause hormone

Authors

  • W.-H. Xu,

    1. *Department of Entomology, Ohio State University, Columbus, Ohio, USA; and †Department of Molecular and Cellular Biology, University of Science and Technology of China, Hefei, China
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  • and * D. L. Denlinger *

    Corresponding author
    1. *Department of Entomology, Ohio State University, Columbus, Ohio, USA; and †Department of Molecular and Cellular Biology, University of Science and Technology of China, Hefei, China
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Dr David L. Denlinger, Department of Entomology, Ohio State University, 1735 Neil Avenue, Columbus, OH 43210, USA. Tel.: +1 614 292 6425; fax: +1 614 292 2180; e-mail: denlinger.1@osu.edu

Abstract

cDNAs encoding prothoracicotropic hormone (PTTH) and diapause hormone (DH) were isolated from the tobacco budworm, Heliothis virescens (Hvi). Hvi-PTTH cDNA reveals key structural features known from other PTTHs, yet there is a > 30% amino acid difference between the PTTH sequences found in this noctuid when compared with the PTTHs known from Bombycoidea. Hvi-DH-PBAN cDNA encodes a precursor protein including a DH-like peptide, pheromone biosynthesis-activating neuropeptide (PBAN) and three additional neuropeptides with an FXPRL sequence at the C terminus. PTTH and DH-PBAN transcripts are most highly expressed in the brain and subesophageal ganglion (SG), respectively. Expression of both the PTTH and the DH-PBAN transcripts is high in larvae and remains high in nondiapausing pupae, but in larvae programmed for pupal diapause, expression declines sharply at the onset of larval wandering behaviour and remains low during pupal diapause. This pattern implies that both of these genes are shut down during diapause. These results are not consistent with a role for DH in promoting the entry into diapause as noted in Bombyx mori. Instead, the higher expression of DH in nondiapausing pupae suggests a possible role for DH in promoting continuous development. The injection of DH into diapausing pupae did indeed successfully terminate diapause, thus suggesting a possible new role for this neuropeptide.

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