title: Regulation of hemolymph trehalose level by an insulin-like peptide through diel feeding rhythm of the beet armyworm, Spodoptera exigua.
abstract: Like vertebrate insulins, some insect insulin-like peptides (ILPs) play crucial roles in controlling immature growth, adult lifespan, and hemolymph sugar level. An ILP gene (SeILP1) was predicted from a transcriptome database of Spodoptera exigua. SeILP1 encodes 95 amino acid sequence and shares sequence homologies (33-83%) with other insect ILPs, in which six conserved cysteine residues are found in the predicted B-A chains. SeILP1 was expressed in all developmental stages of S. exigua. However, SeILP1 expression was tissue-specific because the transcript was detected in fat body and epidermis, but not in hemocytes and gut. Its expression increased with feeding activity. Hemolymph trehalose levels of the fifth instar larvae maintained a relatively constant level at 2.31±0.62mM. However, starvation induced a significant increase of the hemolymph trehalose level by more than twofold in 48h, at which few SeILP1 was transcribed. RNA interference of SeILP1 using its specific double-stranded RNA induced a significant increase of hemolymph trehalose level. Interestingly, a bovine insulin decreased hemolymph trehalose level in a dose-dependent manner. These results indicate that SeILP1 plays a role in suppressing hemolymph trehalose level in S. exigua.
authors.affiliation: Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea. Electronic address: hosanna@andong.ac.kr.
authors.forename: Yonggyun
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea.
authors.forename: Youkyeong
authors.initials: Y
authors.lastname: Hong
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D005247:Feeding Behavior; D005260:Female; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D006458:Hemolymph / Q000201:enzymology; D019476:Insect Proteins / Q000097:blood* / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D013002:Somatomedins / Q000502:physiology*; D018411:Spodoptera; D014199:Trehalose / Q000097:blood* / Q000235:genetics
chemical_list: D019476:Insect Proteins; D013002:Somatomedins; D014199:Trehalose
keywords: Feeding rhythm; Insulin-like peptide; Spodoptera exigua; Trehalose