Two genomes of highly polyphagous lepidopteran pests (Spodoptera frugiperda, Noctuidae) with different host-plant ranges.

Emergence of polyphagous herbivorous insects entails significant adaptation to recognize, detoxify and digest a variety of host-plants. Despite of its biological and practical importance - since insects eat 20% of crops - no exhaustive analysis of gene repertoires required for adaptations in generalist insect herbivores has previously been performed. The noctuid moth Spodoptera frugiperda ranks as one of the world's worst agricultural pests.

Identification of candidate odorant degrading gene/enzyme systems in the antennal transcriptome of Drosophila melanogaster.

The metabolism of volatile signal molecules by odorant degrading enzymes (ODEs) is crucial to the ongoing sensitivity and specificity of chemoreception in various insects, and a few specific esterases, cytochrome P450s, glutathione S-transferases (GSTs) and UDP-glycosyltransferases (UGTs) have previously been implicated in this process. Significant progress has been made in characterizing ODEs in Lepidoptera but very little is known about them in Diptera, including in Drosophila melanogaster, a major insect model. We have therefore carried out a transcriptomic analysis of the antennae of D.

Antennal uridine diphosphate (UDP)-glycosyltransferases in a pest insect: diversity and putative function in odorant and xenobiotics clearance.

Uridine diphosphate UDP-glycosyltransferases (UGTs) are detoxification enzymes widely distributed within living organisms. They are involved in the biotransformation of various lipophilic endogenous compounds and xenobiotics, including odorants. Several UGTs have been reported in the olfactory organs of mammals and involved in olfactory processing and detoxification within the olfactory mucosa but, in insects, this enzyme family is still poorly studied.

Cytochrome P450s and cytochrome P450 reductase in the olfactory organ of the cotton leafworm Spodoptera littoralis.

Cytochrome P450 enzymes (P450s) are involved in many physiological functions in insects, such as the metabolism of signal molecules, adaptation to host plants and insecticide resistance. Several P450s have been reported in the olfactory organs of insects, the antennae, and have been proposed to play a role in odorant processing and/or xenobiotic metabolism. Despite recent transcriptomic analyses in several species, the diversity of antennal P450s in insects has not yet been investigated.

Antennal carboxylesterases in a moth, structural and functional diversity.

Pheromone-degrading enzymes (PDEs) are supposed to be involved in the signal inactivation step within the olfactory sensilla of insects by quickly degrading pheromone molecules. Because esters are widespread insect pheromone components, PDEs belonging to the carboxylesterase (CCE) family have been the most studied. However, only two CCEs were both identified at the molecular level and functionally characterized as PDEs until recently.

Characterization of maspardin, responsible for human Mast syndrome, in an insect species and analysis of its evolution in metazoans.

Mast syndrome is a complicated form of human hereditary spastic paraplegias, caused by a mutation in the gene acid cluster protein 33, which encodes a protein designated as "maspardin." Maspardin presents similarity to the α/β-hydrolase superfamily, but might lack enzymatic activity and rather be involved in protein-protein interactions. Association with the vesicles of the endosomal network also suggested that maspardin may be involved in the sorting and/or trafficking of molecules in the endosomal pathway, a crucial process for maintenance of neuron health.

A carboxylesterase, Esterase-6, modulates sensory physiological and behavioral response dynamics to pheromone in Drosophila.

Background: Insects respond to the spatial and temporal dynamics of a pheromone plume, which implies not only a strong response to 'odor on', but also to 'odor off'. This requires mechanisms geared toward a fast signal termination. Several mechanisms may contribute to signal termination, among which odorant-degrading enzymes.

Degradation of pheromone and plant volatile components by a same odorant-degrading enzyme in the cotton leafworm, Spodoptera littoralis.

Background: Odorant-Degrading Enzymes (ODEs) are supposed to be involved in the signal inactivation step within the olfactory sensilla of insects by quickly removing odorant molecules from the vicinity of the olfactory receptors. Only three ODEs have been both identified at the molecular level and functionally characterized: two were specialized in the degradation of pheromone compounds and the last one was shown to degrade a plant odorant.

Methodology: Previous work has shown that the antennae of the cotton leafworm Spodoptera littoralis, a worldwide pest of agricultural crops, express numerous candidate ODEs.

An Expressed Sequence Tag collection from the male antennae of the Noctuid moth Spodoptera littoralis: a resource for olfactory and pheromone detection research.

Background: Nocturnal insects such as moths are ideal models to study the molecular bases of olfaction that they use, among examples, for the detection of mating partners and host plants. Knowing how an odour generates a neuronal signal in insect antennae is crucial for understanding the physiological bases of olfaction, and also could lead to the identification of original targets for the development of olfactory-based control strategies against herbivorous moth pests. Here, we describe an Expressed Sequence Tag (EST) project to characterize the antennal transcriptome of the noctuid pest model, Spodoptera littoralis, and to identify candidate genes involved in odour/pheromone detection.

Characterization of an antennal carboxylesterase from the pest moth Spodoptera littoralis degrading a host plant odorant.

Background: Carboxyl/cholinesterases (CCEs) are highly diversified in insects. These enzymes have a broad range of proposed functions, in neuro/developmental processes, dietary detoxification, insecticide resistance or hormone/pheromone degradation. As few functional data are available on purified or recombinant CCEs, the physiological role of most of these enzymes is unknown.

Molecular characterization of a phospholipase C beta potentially involved in moth olfactory transduction.

To clarify the role of phospholipase C (PLC) in insect olfactory transduction, we have undertaken its molecular identification in the moth Spodoptera littoralis. From the analysis of a male antennal expressed sequence tag library, we succeeded in cloning a full-length cDNA encoding a PLC that belongs to the cluster of PLC-beta subtypes. In adult males, the PLC-beta transcript was located predominantly in brain and antennae where its presence was detected in the olfactory sensilla trichodea.

A diversity of putative carboxylesterases are expressed in the antennae of the noctuid moth Spodoptera littoralis.

Recent studies have suggested that pheromone-degrading enzymes belonging to the carboxylesterase family could play a role in the dynamics of the olfactory response to acetate sex pheromones in insects. Bioinformatic analyses of a male antennal expressed sequence tag library allowed the identification of 19 putative esterase genes expressed in the antennae of the moth Spodoptera littoralis. Phylogenetic analysis revealed that these genes belong to different insect esterase clades, defined by their putative cellular localization and substrate preferences.

A TRP channel is expressed in Spodoptera littoralis antennae and is potentially involved in insect olfactory transduction.

The molecular characterization of post-receptor actors involved in insect olfactory transduction has yet to be understood. We have investigated the presence of a Transient Receptor Potential (TRP) channel in the peripheral olfactory system of the moth Spodoptera littoralis. A cDNA encoding a Lepidopteran TRP channel (TRPgamma) was identified by analysis of a male-antennal EST database and subsequently cloned by RACE PCR.

An antennal circadian clock and circadian rhythms in peripheral pheromone reception in the moth Spodoptera littoralis.

Circadian rhythms are observed in mating behaviors in moths: females emit sex pheromones and males are attracted by these pheromones in rhythmic fashions. In the moth Spodoptera littoralis, we demonstrated the occurrence of a circadian oscillator in the antenna, the peripheral olfactory organ. We identified different clock genes, period (per), cryptochrome1 (cry1) and cryptochrome2 (cry2), in this organ.

Identification of candidate aldehyde oxidases from the silkworm Bombyx mori potentially involved in antennal pheromone degradation.

Signal inactivation is a crucial step in the dynamic of olfactory process and involves various Odorant-Degrading Enzymes. In the silkworm Bombyx mori, one of the best models for studying olfaction in insects, the involvement of an antennal-specific aldehyde oxidase in the degradation of the sex pheromone component bombykal has been demonstrated over the three past decades by biochemical studies. However, the corresponding enzyme has never been characterized at the molecular level.

Antennal esterase cDNAs from two pest moths, Spodoptera littoralis and Sesamia nonagrioides, potentially involved in odourant degradation.

Rapid degradation of odours after interaction with olfactory receptors is a critical step of the signal reception process. However, the implied mechanisms are still largely unknown in vertebrates as well as in insects. Involvement of odourant-degrading enzymes in odourant degradation within the antennae has been shown in some insect species and, in particular, esterases could play a key role in degradation of sex pheromones from Lepidoptera.

Molecular cloning and in Situ expression patterns of two new pheromone-binding proteins from the corn stemborer Sesamia nonagrioides.

We describe the identification and characterization of two new cDNAs encoding pheromone-binding proteins (PBPs) from the male antennae of Sesamia nonagrioides, a species where no PBPs have been identified to date. Because PBPs are thought to participate in the first step of odor detection in a specific manner, we focused our investigation on this olfactory protein family using reverse transcription-polymerase chain reaction strategies. The deduced amino acid sequences of SnonPBP1 and SnonPBP2 revealed mature proteins of 142 and 143 amino acids, respectively, with six cysteine residues in conserved positions relative to other known PBPs.

Evidence for a putative antennal clock in Mamestra brassicae: molecular cloning and characterization of two clock genes--period and cryptochrome-- in antennae.

Circadian rhythms are generated by endogenous circadian clocks, organized in central and peripheral clocks. An antennal peripheral clock has been demonstrated to be necessary and sufficient to generate Drosophila olfactory rhythms in response to food odours. As moth pheromonal communication has been demonstrated to follow daily rhythms, we thus investigated the occurence of a putative antennal clock in the noctuid Mamestra brassicae.

A new aldehyde oxidase selectively expressed in chemosensory organs of insects.

Signal termination is a crucial step in the dynamic of the olfactory process. It involves different classes of odorant-degrading enzymes. Whereas aldehyde oxidase enzymatic activities have been demonstrated in insect antennae by previous biochemical studies, the corresponding enzymes have never been characterized at the molecular level.

P450 and P450 reductase cDNAs from the moth Mamestra brassicae: cloning and expression patterns in male antennae.

The involvement of cytochrome P450 (CYP) enzymes in olfaction has been demonstrated in vertebrates over the past decade. In insects, these enzymes are well known for their role in biosynthesis of endogenous compounds as well as xenobiotic metabolism, but the presence of olfactory cytochrome P450s was poorly investigated. Using a PCR-based strategy, we have isolated cDNAs of two new microsomal P450s from the antennae of the cabbage armyworm Mamestra brassicae, CYP9A13 and CYP4G20 of two new microsomal P450s, as well as their red-ox partner, the cytochrome P450 reductase (CPR).

Pheromone anosmia in a scarab beetle induced by in vivo inhibition of a pheromone-degrading enzyme.

Previous biochemical evidence suggests that a cytochrome P450 specific to male antennae of the pale-brown chafer, Phyllopertha diversa, has evolved as a pheromone-degrading enzyme. By using a bioinformatics approach, we have now cloned three P450 cDNAs: CYP4AW1, CYP4AW2, and CYP6AT1. RT-PCR indicated that CYP4AW2 is expressed in all tissues examined, that CYP6AT1 is antennae-rich, and that CYP4AW1 is antennae-specific.

Putative odorant-degrading esterase cDNA from the moth Mamestra brassicae: cloning and expression patterns in male and female antennae.

An esterase cDNA was isolated from the cabbage armyworm Mamestra brassicae antennae by PCR strategy. The full-length cDNA, designated as Mbra-EST, contains a 1638 bp open reading frame encoding a predicted protein of 546 amino acids. This predicted protein presents the structural characteristics of known insect carboxyl-esterases, in particular the Ser-His-Glu catalytic triad.

cDNA cloning of biotransformation enzymes belonging to the cytochrome P450 family in the antennae of the noctuid moth Mamestra brassicae.

The involvement of cytochrome P450 enzymes in olfaction was demonstrated in vertebrates some time ago. In insects these enzymes are well known for their role in insecticide resistance, but the involvement of P450 in pheromone degradation was only recently demonstrated. Using a PCR strategy, we have isolated two cDNAs from the antennae of the cabbage armyworm Mamestra brassicae - CYP4L4 and CYP4S4 - which encode microsomal P450s.

Molecular cloning of a novel crustacean member of the aldoketoreductase superfamily, differentially expressed in the antennal glands.

Biochemical studies on ecdysteroid metabolism in arthropods suggest that aldoketoreductase enzymes (AKRs) may be involved in this pathway, but very few molecular data are available on these oxidoreductases in invertebrates. Looking for such enzymes in the crayfish Orconectes limosus, we have used a PCR strategy with primers deduced from a recent insect 3beta-reductase sequence, and from mammalian 5beta-reductase sequences. A full-length cDNA, corresponding to a putative AKR, was isolated from crayfish antennal gland.

A new cytochrome P450 from Drosophila melanogaster, CYP4G15, expressed in the nervous system.

A novel cytochrome P450 was isolated from Drosophila melanogaster by PCR strategy with primers deduced from the crayfish Orconectes limosus CYP4C15 sequence, which is supposed to be involved in ecdysteroid biosynthesis. The full-length cDNA contains a 1980 bp open reading frame encoding a predicted protein of 574 amino acids and was designated CYP4G15. The corresponding gene is located at 10C1 on the X chromosome.