Molecular characterization and developmental expression of the gene encoding the prothoracicotropic hormone in the beet armyworm, Spodoptera exigua

Abstract

Prothoracicotropic hormone (PTTH), a neuropeptide hormone stimulating the prothoracic glands to synthesize ecdysone, plays an important role in regulating postembryonic development in insects. The cDNA encoding PTTH was isolated and sequenced from the beet armyworm, Spodoptera exigua (Spe). The deduced amino acid sequence is composed of a signal peptide, a peptide (65 amino acids) of unknown function, and a mature PTTH molecule (111 amino acids). The Spe-PTTH shows similarities (45.5%-70.3%) to other known PTTHs reported in Lepidoptera species, but 7 cysteine residues and the hydrophobic regions were conserved. Whole-mount immunocytochemistry by using an antiserum against recombinant Helicoverpa armigera PTTH showed that Spe-PTTH was synthesized in two pairs of neurosecretory cells in the S. exigua brain. Northern blot analysis demonstrates the presence of a 1.2-kb transcript in the brain. The Spe-PTTH mRNA is detectable at high levels at the wandering larval stage, early pupal stage, and pharate adult stage, suggesting that the Spe-PTTH gene might be correlated with molting, metamorphosis, and reproduction.

The effect of silencing 20E biosynthesis relative genes by feeding bacterially expressed dsRNA on the larval development of Chilo suppressalis

“…These peaks were clearly reduced in the newly-molted 2 nd and 3 rd instar larvae. This expression pattern is similar to those reported in other insects 23 34 38 39 40 . In addition, it has been reported that the expression pattern of a gene which has an inerratic change around ecdysis, is almost synchronized with that ecdysone titer in insects 41 .…”

Molecular structure of the prothoracicotropic hormone gene in the northern house mosquito, Culex pipiens, and its expression analysis in association with diapause and blood feeding

“…Sequence alignment indicates a huge variation in PTTH at the primary structure level, suggesting that the PTTH molecule evolved rapidly from a common ancestral gene. Following the first report on the cDNA structure of PTTH in B. mori (Kawakami et al ., 1990), the structures of quite a few PTTH cDNAs have been described, including Samia cynthia (Ishizaki & Suzuki, 1994), Antheraea pernyi (Sauman & Reppert, 1996), Hyalophora cecropia (Sehnal et al ., 2002), M. sexta (Shionoya et al ., 2003), and several noctuids including Heliothis virescens (Xu & Denlinger, 2003), Helicoverpa zea (Xu et al ., 2003), Helicoverpa armigera (Wei et al ., 2005), and Spodoptera exigua (Xu et al ., 2007). These PTTHs are exclusively from Lepidoptera.…”

“…The homology drops dramatically when PTTH from Drosophila is compared with that from C. pipiens , though both are Diptera, but PTTH sequences are still well conserved at the family level. For example, among the four PTTHs known from Saturniidae, the lowest identity of mature PTTH is 71% between S. cynthia and Antheraea pernyi ; among the five PTTHs known from Noctuidae, the lowest identity of mature PTTH is 68%, between H. zea and S. exigua (Xu et al ., 2007). In the four Culicidae compared in the present study the lowest identity of mature PTTH is 84%, between C. pipiens and An.…”

Genetic approaches to sustainable pest management in sugar beet (Beta vulgaris)

“…Thomas (1991) suggested the introduction of phytoecdysteroid (plant chemicals similar to insect hormones) to prevent insect development. Several genes have been isolated from armyworms including chitinase (Bolognesi et al, 2005), pheromone (Xu et al, 2007a) and prothoracicotropic hormone (Xu et al, 2007b). Transgenic corn plants engineered to express the western corn rootworm (Diabrotica virgifera virgifera) double-stranded RNAs show a significant reduction in pest feeding damage in a growth chamber assay (Baum et al, 2007).…”