title: Evolution of Chemosensory Gene Families in Arthropods: Insight from the First Inclusive Comparative Transcriptome Analysis across Spider Appendages.
abstract: Unlike hexapods and vertebrates, in chelicerates, knowledge of the specific molecules involved in chemoreception comes exclusively from the comparative analysis of genome sequences. Indeed, the genomes of mites, ticks and spiders contain several genes encoding homologs of some insect membrane receptors and small soluble chemosensory proteins. Here, we conducted for the first time a comprehensive comparative RNA-Seq analysis across different body structures of a chelicerate: the nocturnal wandering hunter spider Dysdera silvatica Schmidt 1981. Specifically, we obtained the complete transcriptome of this species as well as the specific expression profile in the first pair of legs and the palps, which are thought to be the specific olfactory appendages in spiders, and in the remaining legs, which also have hairs that have been morphologically identified as chemosensory. We identified several ionotropic (Ir) and gustatory (Gr) receptor family members exclusively or differentially expressed across transcriptomes, some exhibiting a distinctive pattern in the putative olfactory appendages. Furthermore, these IRs were the only known olfactory receptors identified in such structures. These results, integrated with an extensive phylogenetic analysis across arthropods, uncover a specialization of the chemosensory gene repertoire across the body of D. silvatica and suggest that some IRs likely mediate olfactory signaling in chelicerates. Noticeably, we detected the expression of a gene family distantly related to insect odorant-binding proteins (OBPs), suggesting that this gene family is more ancient than previously believed, as well as the expression of an uncharacterized gene family encoding small globular secreted proteins, which appears to be a good chemosensory gene family candidate.
authors.affiliation: Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Spain.
authors.forename: Joel
authors.initials: J
authors.lastname: Vizueta
authors.affiliation: Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Frías-López
authors.affiliation: Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Macías-Hernández
authors.affiliation: Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Spain.
authors.forename: Miquel A
authors.initials: MA
authors.lastname: Arnedo
authors.affiliation: Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sánchez-Gracia
authors.affiliation: Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Rozas
mesh_terms: D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D016678:Genome; D005810:Multigene Family; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013112:Spiders / Q000145:classification / Q000235:genetics*
chemical_list: D060829:Arthropod Proteins
keywords: arthropods; chelicerates; chemosensory gene families; de novo transcriptome assembly; functional annotation; specific RNA-Seq