title: Physiological effect of mild thermal stress and its induction of gene expression in the common cutworm, Spodoptera litura.
abstract: Heat shock protein (Hsp) and its cognate protein (Hsc) play important roles in helping insects survive extreme temperatures. However, high level of Hsp expression usually brings negative physiological effects on organisms. The mechanism of this trade-off is unclear. In this study, a lepidopteran insect, the common cutworm Spodoptera litura, was stressed at different temperatures, and the impact on both thermotolerance and fecundity was examined. The mRNA levels of four Hsp/Hscs (Hsp90, Hsc90, Hsp70 and Hsc70) and two ecdysone receptors (EcRs, EcRA and EcRB1) in different stresses and during the larval-pupal metamorphosis were determined. The results revealed that the pre-acclamation at mild stress increased the thermotolerance but decreased the egg production in adults. During the stress process, the mRNA levels of all the Hsp/Hsc and ecdysone receptor genes were significantly up-regulated. The two Hsp/Hsc70s and EcRs revealed consistent expression profiles with each other during the larval-pupal metamorphosis. Co-immunoprecipitation and Western blotting analysis indicated that Hsp/Hsc70 interacted with EcRs. RNAi of Hsc70 decreased the mRNA levels of two 20E-induced genes such as E74B and E75. Hsp70 transferred from the cytoplasm to nucleus in response to cold stress. These data together suggest that Hsp/Hsc70 might be involved in the regulation of 20E signaling, and the protein-protein interaction between Hsp/Hsc70 and EcRs probably act as a bridge mediating the trade-off between high thermotolerance and physiological defects.
authors.affiliation: Laboratory of Molecular and Developmental Entomology, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Laboratory of Molecular and Developmental Entomology, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Yan-Jun
authors.initials: YJ
authors.lastname: Gong
authors.affiliation: Laboratory of Molecular and Developmental Entomology, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Gu
authors.affiliation: Laboratory of Molecular and Developmental Entomology, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China. Electronic address: huanglh@scnu.edu.cn.
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Huang
authors.affiliation: Laboratory of Molecular and Developmental Entomology, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Qi-Li
authors.initials: QL
authors.lastname: Feng
mesh_terms: D000818:Animals; D015153:Blotting, Western; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D018869:Heat-Shock Response; D047468:Immunoprecipitation; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000235:genetics / Q000502:physiology; D008675:Metamorphosis, Biological; D011679:Pupa / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D011987:Receptors, Steroid / Q000235:genetics* / Q000378:metabolism; D012098:Reproduction; D018411:Spodoptera / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
chemical_list: D006360:Heat-Shock Proteins; D019476:Insect Proteins; D012333:RNA, Messenger; D011987:Receptors, Steroid; C055469:ecdysone receptor
keywords: Co-immunoprecipitation; EcR; Heat shock protein; Subcellular localization; Trade-off