Functional analysis of the SGNP I in the pupal diapause of the oriental tobacco budworm, Helicoverpa assulta (Lepidoptera: Noctuidae).
Helicoverpa assulta suboesophageal ganglion neuropeptide I (Has-SGNP I) is a 24-amino acids peptide amide, which shows 62.5% similarity with the diapause hormone of Bombyx mori (Bom-DH). It has been demonstrated that embryonic diapause is induced by DH in B. mori. Injection of synthetic amidated Has-SGNP I terminated pupal diapause in a dose-dependent manner. Therefore, Has-SGNP I might be referred to a "diapause termination hormone" in H. assulta (Has-DTH). The maximal dose of Has-DTH for diapause termination was 1.0 microg and the half-maximal dose 0.4 microg. The time required for diapause termination of Has-DTH was 2-3 days longer than that of 20-hydroxyecdysone. During the pupal stage, DTH mRNA content in the SGs of nondiapausing pupae was always higher than in diapausing pupae using the combined method of quantitative RT-PCR and Southern blot. DTH gene also expressed at a low level while diapausing pupae were chilled at 4 degrees C, but increased rapidly and largely after being transferred to 25 degrees C. Using a competitive ELISA, Has-DTH-like immunoreactivity in the haemolymph showed the same pattern as that of Has-DTH gene expression. Those results indicated that Has-DTH gene expression was related to diapause development and could be activated by low temperature. Has-DTH might be useful to elucidate the mechanism of diapause termination in pupal diapause species.
Zhao
Jing-Ya
JY
State Key Lab of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Science, 19 Zhongguancun Road, Haidian District, Beijing 100080, China.
Xu
Wei-Hua
WH
Kang
Le
L
D000595:Amino Acid Sequence; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004441:Ecdysterone / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D007301:Insect Hormones / Q000032:analysis / Q000494:pharmacology / Q000502:physiology*; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000032:analysis / Q000494:pharmacology / Q000502:physiology*; D011679:Pupa / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013696:Temperature
D007301:Insect Hormones; D009479:Neuropeptides; D012333:RNA, Messenger; D004441:Ecdysterone; C075027:diapause hormone