title: Under-Expression of Chemosensory Genes in Domiciliary Bugs of the Chagas Disease Vector Triatoma brasiliensis.
abstract: BACKGROUND
  In Latin America, the bloodsucking bugs Triatominae are vectors of Trypanosoma cruzi, the parasite that causes Chagas disease. Chemical elimination programs have been launched to control Chagas disease vectors. However, the disease persists because native vectors from sylvatic habitats are able to (re)colonize houses-a process called domiciliation. Triatoma brasiliensis is one example. Because the chemosensory system allows insects to interact with their environment and plays a key role in insect adaption, we conducted a descriptive and comparative study of the chemosensory transcriptome of T. brasiliensis samples from different ecotopes.
  
  
  RESULTS
  In a reference transcriptome built using de novo assembly, we found transcripts encoding 27 odorant-binding proteins (OBPs), 17 chemosensory proteins (CSPs), 3 odorant receptors (ORs), 5 transient receptor potential channel (TRPs), 1 sensory neuron membrane protein (SNMPs), 25 takeout proteins, 72 cytochrome P450s, 5 gluthatione S-transferases, and 49 cuticular proteins. Using protein phylogenies, we showed that most of the OBPs and CSPs for T. brasiliensis had well supported orthologs in the kissing bug Rhodnius prolixus. We also showed a higher number of these genes within the bloodsucking bugs and more generally within all Hemipterans compared to the other species in the super-order Paraneoptera. Using both DESeq2 and EdgeR software, we performed differential expression analyses between samples of T. brasiliensis, taking into account their environment (sylvatic, peridomiciliary and domiciliary) and sex. We also searched clusters of co-expressed contigs using HTSCluster. Among differentially expressed (DE) contigs, most were under-expressed in the chemosensory organs of the domiciliary bugs compared to the other samples and in females compared to males. We clearly identified DE genes that play a role in the chemosensory system.
  
  
  CONCLUSIONS
  Chemosensory genes could be good candidates for genes that contribute to adaptation or plastic rearrangement to an anthropogenic system. The domiciliary environment probably includes less diversity of xenobiotics and probably has more stable abiotic parameters than do sylvatic and peridomiciliary environments. This could explain why both detoxification and cuticle protein genes are less expressed in domiciliary bugs. Understanding the molecular basis for how vectors adapt to human dwellings may reveal new tools to control disease vectors; for example, by disrupting chemical communication.
authors: UMR Evolution, Génomes, Comportement, Ecologie, CNRS-IRD- Univ. Paris-Sud, Université Paris Saclay, Campus CNRS, Gif-sur-Yvette - France.|UFR Sciences, Université Paris Sud, Orsay, France.
authors: Axelle
authors: A
authors: Marchant
authors: UMR Evolution, Génomes, Comportement, Ecologie, CNRS-IRD- Univ. Paris-Sud, Université Paris Saclay, Campus CNRS, Gif-sur-Yvette - France.|UFR Sciences, Université Paris Sud, Orsay, France.
authors: Florence
authors: F
authors: Mougel
authors: INRA, UMR 1392, Institut d'Ecologie et des Sciences de l'Environnement de Paris, Route de Saint Cyr, Versailles, France.
authors: Emmanuelle
authors: E
authors: Jacquin-Joly
authors: Laboratório de Biodiversidade Entomológica; Instituto Oswaldo Cruz - Fiocruz; Rio de Janeiro; Brasil Instituto Oswaldo Cruz, Fiocruz - Brazil.
authors: Jane
authors: J
authors: Costa
authors: Universidade Estadual de Campinas (Uncamp), Campinas São Paulo - Brazil.|Universidade Federal da Paraíba (UFPB), Paraíba - Brazil.
authors: Carlos Eduardo
authors: CE
authors: Almeida
authors: UMR Evolution, Génomes, Comportement, Ecologie, CNRS-IRD- Univ. Paris-Sud, Université Paris Saclay, Campus CNRS, Gif-sur-Yvette - France.|UFR Sciences, Université Paris Sud, Orsay, France.
authors: Myriam
authors: M
authors: Harry
mesh_terms: D000818:Animals; D014355:Chagas Disease / Q000469:parasitology / Q000635:transmission*; D017753:Ecosystem; D006801:Humans; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007303:Insect Vectors / Q000235:genetics* / Q000378:metabolism / Q000469:parasitology; D010802:Phylogeny; D018035:Receptors, Odorant / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome; D014224:Triatoma / Q000235:genetics* / Q000378:metabolism / Q000469:parasitology; D014349:Trypanosoma cruzi / Q000502:physiology
chemical_list: D019476:Insect Proteins; D018035:Receptors, Odorant; C045648:odorant-binding protein