Comparative genomics of insect juvenile hormone biosynthesis☆

Abstract

The biosynthesis of insect juvenile hormone (JH) and its neuroendocrine control are attractive targets for chemical control of insect pests and vectors of disease. To facilitate the molecular study of JH biosynthesis, we analyzed ESTs from the glands producing JH, the corpora allata (CA) in the cockroach Diploptera punctata, an insect long used as a physiological model species and compared them with ESTs from the CA of the mosquitoes Aedes aegypti and Anopheles albimanus. The predicted genes were analyzed according to their probable functions with the Gene Ontology classification, and compared to Drosophila and Anopheles gambiae genes. A large number of reciprocal matches in the cDNA libraries of cockroach and mosquito CA were found. These matches defined known and suspected enzymes of the JH biosynthetic pathway, but also several proteins associated with signal transduction that might play a role in the modulation of JH synthesis by neuropeptides. The identification in both cockroach and mosquito CA of homologs of the small ligand binding proteins from insects, Takeout/JH binding protein and retinol-binding protein highlights a hitherto unsuspected complexity of metabolite trafficking, perhaps JH precursor trafficking, in these endocrine glands. Furthermore, many reciprocal matches for genes of unknown function may provide a fertile ground for an in-depth study of allatal-specific cell physiology.

NADP + -dependent farnesol dehydrogenase, a corpora allata enzyme involved in juvenile hormone synthesis

“…Sequencing of an A. aegypti CA ϩ CC (corpora cardiaca) cDNA library revealed one EST encoding a full length ORF for a 245-amino acid short chain dehydrogenase that could be responsible for the oxidation of farnesol into farnesal (14). In addition, an EST encoding a segment of an ortholog of this gene was isolated from a CA ϩ CC cDNA library of the cockroach Diploptera punctata (GenBank acc: DV017939) (14). Screening the A. aegypti genome using this EST revealed an almost identical nonannotated sequence (AaSDR-1) and 4 additional sequences with a high degree of similarity (72-83%) (AaSDR-2 to AaSDR-5) (Fig.…”

“…One EST was found in a CA library of A. aegypti encoding AaSDR-1 and its ortholog was also present in a CA library of the cockroach D. punctata (14). Short-chain dehydrogenases/reductases constitute a large family of NAD(P)(H)-dependent oxidoreductases, sharing sequence motifs and displaying similar mechanisms (16).…”

DPP-mediated TGFβ signaling regulates juvenile hormone biosynthesis by activating the expression of juvenile hormone acid methyltransferase

“…We first compared mRNA levels for these genes between wild-type and Mad mutant larvae at the 2nd instar using quantitative real-time PCR. Six enzymes, including JHAMT, farnesyl diphosphate synthase (FPPS), farnesol oxidase (FARox), farnesol dehydrogenase (FARD), cytochrome P450 6g2 (Cyp 6g2) and farnesoic acid O-methyltransferase (Famet), were chosen because they catalyze the key steps of JH biosynthesis and are predominantly expressed in the CA (Belles et al, 2005;Noriega et al, 2006). We found that in the Mad k00237 larvae, the mRNA levels of jhamt were decreased to less than half of that in wild type.…”

Insecticide Susceptibility of Aedes Aegypti Larvae to Bacillus Thuringiensis Israelensis and Juvenile Hormone in Dengue Epidemic Areas of Samutsongkhram, Thailand

“…Bti is a gram-positive bacterium present in regular soil that can form endospores that produce the insecticidal Delta endotoxin, which is a toxic protein to the gut epithelium of mosquito larvae [8]. An additional agent is juvenile hormone, which can halt mosquito larval and pupal growth [9]. In foreign countries, there is a report that Bti can effectively reduce a number of mosquito larvae in a short period [10] and that juvenile hormone can efficiently eradicate Ae.…”