Molecular cloning, transcriptional regulation, and differential expression profiling of vitellogenin in two wing‐morphs of the brown planthopper, Nilaparvata lugens Stål (Hemiptera: Delphacidae)

Abstract

The brown planthopper, Nilaparvata lugens, is a serious pest of rice crops throughout Asia and exhibits wing dimorphism, with brachypterous adults having reduced wings and macropterous adults possessing fully developed wings. To understand the reproductive strategies in two wing-morphs of this insect, the transcript encoding the major yolk protein precursor, vitellogenin (Vg), was cloned. The complete mRNA transcript was 6314 bp, which encodes a protein of 2063 residues including an 18-residue putative signal peptide. Analysis of the mature protein revealed two vitellogenin-N (or lipoprotein amino-terminal) domains near the N-terminus and a von Willebrand factor type D domain near the C-terminus. In addition, a highly conserved motif GL/ICG, and a number of cysteine residues were identified near the C-terminus. Northern blot analysis identified a ∼6.8 kb Vg gene transcript that was expressed exclusively in the adult female fat body cells. The expression profile revealed that the Vg gene starts to be expressed earlier (on day 3) in brachypters as compared to macropters where the mRNA transcript was observed on day 4. However, in both morphs, the amount of Vg mRNA increased to reach high levels during vitellogenic periods [from day 4 (in brachypters) and day 5 (in macropters) and onwards]. Reflecting the RNA transcription pattern, the Vg signal was detected by immunoblotting on day 3 and day 4 in haemolymph of brachypterous and macropterous females, respectively, and that was increased every day and remained high during the vitellogenic periods. Furthermore, the topical application of juvenile hormone (JH) III had up-regulated the Vg gene expression suggesting that the Vg gene is regulated by JH in N. lugens. In addition, it was demonstrated by Southern blot analysis that there exists a single copy of the gene in the N. lugens genome. A delayed trend in expression (of both the transcript and the protein) demonstrated by macropterous females in the present studies supports the hypothesis of prereproductive long distance migration in this wing-dimorphic species.

Genetic variations in the pre-feeding and pre-oviposition periods among four pure lines in the brown planthopper, Nilaparvata lugens (Hemiptera: Auchenorrhyncha:Delphacidae)

“…5, 6). Our results confirmed the recent findings that vitellogenin gene expression in N. lugens is triggered by JH III, and the transcript first appears 1 day after adult emergence in the brachypters and 2 days in the macropter in none-selected lines (Tufail et al 2010).…”

“…These findings support the involvement of JH in the regulation of ovarian development. Recently, the vitellogenin gene was cloned in N. lugens, and its expression was found to be enhanced by exogenous JH III and to occur earlier in the brachypters than macropters (Tufail et al 2010). Since vitellogenin is the yolk protein precursor, it is used as a predictor of fecundity in many species, including the soldier bug, Podisus maculiventris Say (Shapiro et al 2000).…”

Molecular characterization and immunohistochemical localization of a mitogen-activated protein kinase, Accp38b, from Apis cerana cerana

“…The expression and purification of the fusion protein were performed as described previously (25). Western blot was performed according to the procedure of Tufail et al (26) with minor modifications. Briefly, the purified protein was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) (12%).…”

Differential expression of vitellogenin mRNA and protein in response to rice resistance genes in two strains of Nilaparvata lugens (Hemiptera: Delphacidae) with different levels of virulence

“…BPH Vg (NlVg) was first identified as a 175 kDa female specific yolk protein after an electrophoretic comparison of hemolymphs and homogenates of whole bodies and ovaries from reproducing females, males and fifth-instar BPH nymphs (Cheng and Hou 2005). We have cloned a complete cDNA sequence of NlVg mRNA and shown that NlVg has two subunit polypeptides of 175 and 50 kDa that are originated after the proteolitic cleavage of a single primary NlVg precursor (Tufail et al 2010). Because of the prime role of Vg proteins in BPH reproduction, characterizing NlVg gene expression and the accumulation of NlVg protein after the infestation of BPH strains on resistant rice lines should aid our understanding of the interaction between BPH strains and rice resistance genes.…”