Publications by authors named "Stephane Fraichard"

Artificial sweeteners are highly sweet, non-nutritive compounds that have become increasingly popular over recent decades despite research suggesting that their consumption has unintended consequences. Specifically, there is evidence suggesting that some of these chemicals interact with bitter taste receptors, implying that sweeteners likely generate complex chemosensory signals. Here, we report the basic sensory characteristics of sweeteners in Drosophila, a common model system used to study the impacts of diet, and find that all noncaloric sweeteners inhibited appetitive feeding responses at higher concentrations.

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Article Synopsis
  • • A study investigated how a sex pheromone (cis-vaccenyl acetate or cVa) transferred to eggs by female flies affected male behavior and pheromone release, depending on whether the eggs were exposed to maternal factors 1 day or 5 days after mating.
  • • By observing these effects over 40 generations, the research found significant differences in reproductive traits, survival, and gene expression between flies exposed to maternal factors at different times, suggesting these maternal influences can shape adult characteristics.
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Odorant metabolizing enzymes, considered as critical olfactory perireceptor actors, control the odor molecules reaching the olfactory epithelium by biotransforming them. As an odorant, the mammary pheromone, i.e.

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Article Synopsis
  • - Glutathione transferases (GSTs) are important enzymes that detoxify harmful compounds and are found in the chemosensory organs, which are crucial for detecting chemicals like tastants and odors.
  • - They help protect the body by breaking down these chemicals before they interact with receptors, thus modulating how we perceive smells and tastes.
  • - The review will explore the roles of GSTs in both insects and mammals, highlighting their contributions to chemosensory systems and the evolutionary benefits of linking detoxification and chemosensory processes.
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Glutathione transferases (GSTs) are ubiquitous enzymes that catalyze the conjugation of glutathione to various molecules. Among the 42 GSTs identified in , Delta and Epsilon are the largest classes, with 25 members. The Delta and Epsilon classes are involved in different functions, such as insecticide resistance and ecdysone biosynthesis.

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The detection and processing of chemical stimuli involve coordinated neuronal networks that process sensory information. This allows animals, such as the model species , to detect food sources and to choose a potential mate. In peripheral olfactory tissues, several classes of proteins are acting to modulate the detection of chemosensory signals.

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Animals need to detect in the food essential amino acids that they cannot synthesize. We found that the odorant binding protein OBP19b, which is highly expressed in taste sensilla, is necessary for the detection of several amino acids including the essential l-phenylalanine. The recombinant OBP19b protein was produced and characterized for its binding properties: it stereoselectively binds to several amino acids.

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Odorant-binding proteins (OBPs) are small soluble proteins that are thought to transport hydrophobic odorants across the aqueous sensillar lymph to olfactory receptors. A recent study revealed that OBP28a, one of the most abundant Drosophila OBPs, is not required for odorant transport, but acts in buffering rapid odour variation in the odorant environment. To further unravel and decipher its functional role, we expressed recombinant OBP28a and characterized its binding specificity.

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The data presented in this article are related to the research article entitled "Characterization of a Drosophila glutathione transferase involved in isothiocyanate detoxification." (Gonzalez et al., 2018) [1].

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Glutathione transferases (GSTs) are ubiquitous key enzymes that catalyse the conjugation of glutathione to xenobiotic compounds in the detoxification process. GSTs have been proposed to play a dual role in the signal termination of insect chemodetection by modifying odorant and tasting molecules and by protecting the chemosensory system. Among the 40 GSTs identified in Drosophila melanogaster, the Delta and Epsilon groups are insect-specific.

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The flying ability of insects has coevolved with the development of organs necessary to take-off from the ground, generate, and modulate lift during flight in complex environments. Flight orientation to the appropriate food source and mating partner depends on the perception and integration of multiple chemical signals. We used a wind tunnel-based assay to investigate the natural and molecular evolution of free flight odor tracking in Drosophila.

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Caffeine (1, 3, 7-trimethylxanthine), an alkaloid produced by plants, has antioxidant and insecticide properties that can affect metabolism and cognition. In vertebrates, the metabolites derived from caffeine have been identified, and their functions have been characterized. However, the metabolites of caffeine in insects remain unknown.

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Mate choice is based on the comparison of the sensory quality of potential mating partners, and sex pheromones play an important role in this process. In Drosophila melanogaster, contact pheromones differ between male and female in their content and in their effects on male courtship, both inhibitory and stimulatory. To investigate the genetic basis of sex pheromone discrimination, we experimentally selected males showing either a higher or lower ability to discriminate sex pheromones over 20 generations.

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Morphogenesis of the adult structures of holometabolous insects is regulated by ecdysteroids and juvenile hormones and involves cell-cell interactions mediated in part by the cell surface integrin receptors and their extracellular matrix (ECM) ligands. These adhesion molecules and their regulation by hormones are not well characterized. We describe the gene structure of a newly described ECM molecule, tenectin, and demonstrate that it is a hormonally regulated ECM protein required for proper morphogenesis of the adult wing and male genitalia.

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Adaptive animal behaviors depend upon the precise development of the nervous system that underlies them. In Drosophila melanogaster, the pan-neural prospero gene (pros), is involved in various aspects of neurogenesis including cell cycle control, axonal outgrowth, neuronal and glial cell differentiation. As these results have been generally obtained with null pros mutants inducing embryonic lethality, the role of pros during later development remains poorly known.

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During Drosophila embryonic development, various morphogenetic processes require the remodeling of the extracellular matrix. In a previous study, we have identified and characterized a cDNA encoding a novel putative extracellular matrix protein named tenebrin, in the beetle Tenebrio molitor. Here, we examine the expression of the Drosophila ortholog, referred to as Tenectin (Tnc), during embryonic development.

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We used differential display to isolate epidermis cDNAs corresponding to juvenile-hormone analog-regulated mRNA from the beetle Tenebrio molitor. One of them encodes a putative extracellular matrix (ECM) protein, named Tenebrin. Indeed, the deduced protein sequence contains ECM typical features like the presence of a signal peptide, internal repeats, a RGD tripeptide sequence motif known to bind integrins and von Willebrand factor type c domains involved in protein-protein interactions.

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We have used differential display to identify genes that are regulated by juvenile hormone in the epidermis of the beetle Tenebrio molitor. One of the genes encodes T. molitor chitinase 5 (TmChit5), a chitinase possessing an unusual structure.

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