RESUMO
Chemoreception through odorant receptors (ORs), ionotropic receptors (IRs) and gustatory receptors (GRs) represents the functions of key proteins in the chemical ecology of insects. Recent studies have identified chemoreceptors in coleopterans, facilitating the evolutionary analysis of not only ORs but also IRs and GRs. Thus, Cerambycidae, Tenebrionidae and Curculionidae have received increased attention. However, knowledge of the chemoreceptors from Scarabaeidae is still limited, particularly for those that are sympatric. Considering the roles of chemoreceptors, this analysis could shed light on evolutionary processes in the context of sympatry. Therefore, the aim of this study was to identify and compare the repertoires of ORs, GRs and IRs between two sympatric scarab beetles, Hylamorpha elegans and Brachysternus prasinus. Here, construction of the antennal transcriptomes of both scarab beetle species and analyses of their phylogeny, molecular evolution and relative expression were performed. Thus, 119 new candidate chemoreceptors were identified for the first time, including 17 transcripts for B. prasinus (1 GR, 3 IRs and 13 ORs) and 102 for H. elegans (22 GRs, 14 IRs and 66 ORs). Orthologs between the two scarab beetle species were found, revealing specific expansions as well as absence in some clades. Purifying selection appears to have occurred on H. elegans and B. prasinus ORs. Further efforts will be focused on target identification to characterize kairomone and/or pheromone receptors.
Assuntos
Besouros , Receptores Odorantes , Gorgulhos , Animais , Transcriptoma , Simpatria , Perfilação da Expressão Gênica , Besouros/genética , Besouros/metabolismo , Gorgulhos/genética , Filogenia , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Antenas de Artrópodes/metabolismoRESUMO
Odorant receptors (ORs) belong to a large family of G protein-coupled receptors (GPCRs) that are highly expressed by olfactory sensory neurons of the nose. Accumulating evidence indicates that they are also expressed in a variety of nonolfactory tissues, which makes them new potential drug targets. Here we discuss the challenges and strategies to target these receptors.
Assuntos
Neurônios Receptores Olfatórios , Receptores Odorantes , Humanos , Receptores Acoplados a Proteínas GRESUMO
This study aimed to identify ORs (odorant receptors) and Orco (odorant receptor coreceptor) genes in Sitophilus zeamais Motschulsky (Coleoptera: Curculionoidea), to explore the relative expression levels of these genes in different adult tissues and obtain information on highly expressed receptor proteins. Putative OR and Orco genes were identified from transcriptomic data previously obtained for S. zeamais using bioinformatics methods. Quantitative real-time PCR was used to compare the differences in expression in seven adult tissues (male antennae, female antennae, heads, thoraxes, abdomens, wings, and legs). The candidate OR and Orco gene sequences were analyzed, and the protein physicochemical properties were predicted. We identified 64 OR genes including the Orco gene. Forty-seven OR genes, including Orco, were over expressed in male or female antennae. Seventeen OR genes appeared to be expressed at elevated levels in male antennae. Twenty-nine genes were expressed at significantly elevated levels in female antennae. In total, 11 OR genes were selected for further sequence analysis. The selected proteins were structurally characterized, and bioinformatics analysis was performed. Overall, in this study, candidate ORs of S. zeamais have been identified for the first time, and these ORs could be molecular targets for interference in the insect olfactory system.
Assuntos
Besouros/genética , Proteínas de Insetos/genética , Receptores Odorantes/genética , Animais , Antenas de Artrópodes , Feminino , Masculino , Estrutura Terciária de Proteína , Reação em Cadeia da Polimerase em Tempo Real , TranscriptomaRESUMO
The mouse olfactory epithelium is composed of a heterogeneous population of olfactory sensory neurons, where each neuron expresses one single type of odorant receptor gene, out of a repertoire of ~1000 different genes. Fluorescent-activated cell sorting (FACS) is a powerful technique, which can be used to isolate a cellular subpopulation from a heterogeneous tissue. The sorted neurons can then be used in gene expression studies, or analyzed for the presence of different DNA epigenetic modification marks. Here we describe a method to separate a subpopulation of olfactory sensory neurons expressing the odorant receptor Olfr17. In this method, the main olfactory epithelium from transgenic Olfr17-IRES-GFP mice is dissociated into single cells, followed by separation of the GFP positive cells by FACS.
Assuntos
Citometria de Fluxo/métodos , Mucosa Olfatória/citologia , Receptores Odorantes , Células Receptoras Sensoriais/citologia , Animais , Camundongos , Camundongos Transgênicos , Mucosa Olfatória/metabolismo , Células Receptoras Sensoriais/metabolismoRESUMO
Olfactory perception plays an important role in food flavor. Humans have around 400 odorant receptors (ORs), which can be activated by an enormous number of odorants in a combinatorial fashion. To date, only a few odorant receptors have been linked to their respective odorants, due to the difficulties in expressing these receptor proteins in heterologous cell systems. In vivo approaches allow for the analysis of odorant-receptor interactions in their native environment and have the advantage that the complete OR repertoire is simultaneously tested. Once mouse odorant-receptor pairs are defined, one can search for the corresponding human orthologues, which can be validated against the odorants in heterologous cells. Thus, the combination of in vivo and in vitro methods should contribute to the identification of human ORs that recognize odorants of interest, such as key food odorants.
Assuntos
Odorantes/análise , Percepção Olfatória , Receptores Odorantes/metabolismo , Animais , Análise de Alimentos , Humanos , Camundongos , Receptores Odorantes/genética , OlfatoRESUMO
The odorant receptor (OR) genes constitute the largest gene family among vertebrates. While over 800 loci are present in the human genome, their allele diversity is still poorly characterized. It has been hypothesized that the products of OR genes can be relevant in the reproductive context, thereby interacting with products of genes of the major histocompatibility complex (MHC). Here we investigated the genetic diversity of the OR2W6P, OR2B8P, OR1F12 and OR12D2 genes, in order to define haplotypes and haplotype frequencies. We measured levels of linkage disequilibrium (LD) between these OR genes and the MHC genes HLA-A, HLA-B and HLA-DRB1. This was accomplished through the assessment of 30 single nucleotide polymorphisms (SNPs) in samples from 61 family trios. We characterized 26 alleles among the four OR genes and identified three SNPs that had not yet been reported. Based on our haplotype analysis, LD spanning the OR-HLA region is not very strong, and therefore not enough to enable selection regarding specific HLA-OR haplotypes.
Assuntos
Alelos , Desequilíbrio de Ligação , Complexo Principal de Histocompatibilidade/genética , Receptores Odorantes/genética , Brasil , Família , Feminino , Frequência do Gene , Haplótipos , Humanos , Masculino , Filogenia , Polimorfismo de Nucleotídeo Único , Receptores Odorantes/classificaçãoRESUMO
Through the sense of smell mammals can obtain information about food, danger, sexual partners and predators. Two main different types of signals can be recognized by the olfactory system: volatile odorants, which are detected by the olfactory sensory neurons of the nose; and pheromones, which are detected by the vomeronasal neurons of the accessory olfactory system, or vomeronasal organ. These sensory neurons express respectively hundreds of odorant and pheromone receptors, which belong to the superfamily of G protein-coupled receptors. We review the general organization of the main and accessory olfactory systems, the structures of the receptor families in each of these organs and their signaling pathways.