Putative Chemosensory Proteins Research Articles

Identification and expression characteristics of putative chemosensory proteins in the peach fruit borer Carposina sasakii Matsumura (Lepidoptera: Carposinidae)

Chemosensory proteins (CSPs) are important for insect chemoreception, which bind, solubilize and transport hydrophobic chemical molecules from external environment to dendrite membrane of chemosensory neurons. Moreover, CSPs are also involved in non-sensory physiological activities. The peach fruit borers Carposina sasakii Matsumura (Lepidoptera: Carposinidae) seriously damage fruit trees and their chemoreception mainly occurs in the adult stage. We identified 10 putative CSPs (CsasCSP1 ~ CsasCSP10) from head transcriptomes of C. sasakii adult males and females, all of which are classic CSPs that have 4 conserved cysteines with a spacing pattern C1–X6–C2–X17–18–C3–X2–C4. Their phylogenetic characteristics were also described. An analysis using fluorescence quantitative PCR showed CsasCSP2 has the highest level of expression in the heads, so it is more likely to be involved in C. sasakii chemoreception than the other C. sasakii CSPs. CsasCSP1, CsasCSP3, CsasCSP4, CsasCSP6, CsasCSP7 and CsasCSP8 are expressed dominantly in the wings; CsasCSP5 and CsasCSP10 have the highest expression level in the thoraxes; CsasCSP9 is dominantly and equally expressed in the thoraxes and abdomens. This study contributes to understanding physiological functions of C. sasakii CSPs and chemosensory mechanism at C. sasakii molecular level.

Identification of putative olfactory genes in newly hatched larvae of a Coleopteran ectoparasitoid Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) by transcriptome analysis

AbstractDastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is an effective ectoparasitoid of pine sawyer beetle Monochamus alternatus Hope (Coleoptera: Cerambycidae) which is the major median insect for transmission of pine wood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle (Aphelenchida: Parasitaphelenchidae). A sensitive and acute olfactory system is extremely essential for newly hatched larva of D. helophoroides to forage for a host. Therefore, we established the transcriptome of newly hatched D. helophoroides larvae and characterized the expression profiles of olfactory genes. We identified 20 transcripts encoding putative odorant binding proteins (OBPs), 11 putative chemosensory proteins (CSPs), 9 putative odorant receptors (ORs), 11 putative ionotropic receptors (IRs), 7 putative gustatory receptors (GRs) and 4 putative sensory neuron membrane proteins (SNMPs) olfactory genes from the transcriptome of newly hatched D. helophoroides larvae. According to the phylogenetic analysis, 3 OBPs (DhelOBP6, DhelOBP14 and DhelOBP19), 1 CSP (DhelCSP11), 1 OR (DhelOrco1), 3 IRs (DhelIR3, DhelIR6 and DhelIR8), 3 GRs (DhelGR2, DhelGR4 and DhelGR5) and 2 SNMPs (DhelSNMP1 and DhelSNMP3) had high similarities with reported Coleopteran species. The highest expressed olfactory gene was DhelCSP3, followed by DhelOBP8 and DhelCSP2. The expression levels of the majority of OR, IR, GR and SNMP genes were low. These results indicate that CSPs and OBPs may play important roles in the olfactory recognition process in newly hatched D. helophoroides larvae. The findings from the present study are helpful in unraveling the profound mystery between D. helophoroides and M. alternatus, as well as improving the parasitism efficiency of D. helophoroides larvae.

Identification of Leg Chemosensory Genes and Sensilla in the Apolygus lucorum.

Apolygus lucorum (Hemiptera: Miridae), one of the main insect pests, causes severe damage in cotton and many other economic crops. As is well-known, legs play important roles in the chemoreception of insects. In this study, the putative chemosensory proteins in legs of A. lucorum involved in close or contact chemical communication of adult bugs were investigated using RNA transcriptome sequencing and qPCR methods. Transcriptome data of forelegs, middle legs and hind legs of adult bugs demonstrated that 20 odorant binding protein (OBP) genes, eight chemosensory protein (CSP) genes, one odorant receptor (OR) gene, one ionotropic receptor (IR) gene and one sensory neuron membrane protein (SNMP) gene were identified in legs of A. lucorum. Compared to the previous antennae transcriptome data, five CSPs, IR21a and SNMP2a were newly identified in legs. Results of qPCR analysis indicated that all these putative chemosensory genes were ubiquitously expressed in forelegs, middle legs and hind legs of bugs. Furthermore, four types of sensilla on legs of A. lucorum including sensilla trichodea (subtypes: long straight sensilla trichodea, Str1; long curved sensilla trichodea, Str2), sensilla chaetica (subtypes: sensilla chaetica 1, Sch1; sensilla chaetica 2, Sch2; and sensilla chaetica 3, Sch3), sensilla basiconca (subtypes: medium-long sensilla basiconca, Sba1; short sensilla basiconca, Sba2) and Böhm bristles (BB) were found using scanning electron microscopy. Additionally, the largest number of sensilla was observed on hind legs, while the forelegs had the smallest number of sensilla. Our data provide valuable insights into understanding the chemoreception of legs in A. lucorum.

Varroa chemosensory proteins: some are conserved across Arthropoda but others are arachnid specific

The tight synchronization between the life cycle of the obligatory parasitic mite Varroa destructor (Varroa) and its host, the honeybee, is mediated by honeybee chemical stimuli. These stimuli are mainly perceived by a pit organ located on the distal part of the mite's foreleg. In the present study, we searched for Varroa chemosensory molecular components by comparing transcriptomic and proteomic profiles between forelegs from different physiological stages, and rear legs. In general, a comparative transcriptomic analysis showed a clear separation of the expression profiles between the rear legs and the three groups of forelegs (phoretic, reproductive and tray-collected mites). Most of the differentially expressed transcripts and proteins in the mite's foreleg were previously uncharacterized. Using a conserved domain approach, we identified 45 transcripts with known chemosensory domains belonging to seven chemosensory protein families, of which 14 were significantly upregulated in the mite's forelegs when compared to rear legs. These are soluble and membrane bound proteins, including the somewhat ignored receptors of degenerin/epithelial Na+ channels and transient receptor potentials. Phylogenetic clustering and expression profiles of the putative chemosensory proteins suggest their role in chemosensation and shed light on the evolution of these proteins in Chelicerata.

Antennal transcriptome analysis of the chemosensory gene families in Carposina sasakii (Lepidoptera: Carposinidae)

BackgroundThe peach fruit moth, Carposina sasakii Matsumura (Lepidoptera: Carposinidae), poses a serious threat to a variety of fruits and causes significant economic loss owing to difficulties in its prevention and control. The olfactory sense is generally acknowledged to be a novel target for pest control. However, a systematic study of the olfactory genes expressed in C. sasakii has not been reported yet. Here, we reported the antennal transcriptome of C. sasakii using high-throughput sequencing and annotated the main chemosensory multi-gene families.ResultsIn the chemosensory gene families, 29 odorant-binding proteins, 13 chemosensory proteins, 1 sensory neuron membrane protein, 52 odorant receptors, 8 ionotropic receptors and 11 gustatory receptors were annotated in the C. sasakii antennal transcriptome. The number of olfactory genes obtained in our transcriptome was consistent with that identified in other lepidopteran insects, confirming that we basically accomplished the annotation of the chemosensory genes of C. sasakii in the adult antennal transcriptome. All sequences were annotated and analyzed by BLAST (basic local alignment search tool), and some chemosensory genes with specific functions were named according to the BLAST results and phylogenetic trees. Based on the expression profile in the transcriptome and phylogenetic analysis, differentially expressed genes (DEGs) were analyzed in both male and female adults. Finally, fluorescence quantitative real-time PCR was used to identify the male-specific or female-specific chemosensory genes that were putatively related to odor detection and recognition. Moreover, expression levels of OR33 and PBP2 were significantly higher in males than in females, indicating that these genes may interact with sex pheromones. We found some conserved antennal IRs and GRs involved in detecting sugar compounds (GR2, GR5, GR6, GR8) and carbon dioxide (GR1), which were also identified based on phylogenetic analysis.ConclusionsThere are 114 putative chemosensory proteins expressed in C. sasakii identified in this study. The identification of these proteins will make the molecular mechanism of odor recognition accessible.

Antennal transcriptome analysis and expression profiles of odorant binding proteins in Eogystia hippophaecolus (Lepidoptera: Cossidae).

BackgroundEogystia hippophaecolus (Hua et al.) (Lepidoptera: Cossidae) is the major threat to seabuckthorn plantations in China. Specific and highly efficient artificial sex pheromone traps was developed and used to control it. However, the molecular basis for the pheromone recognition is not known. So we established the antennal transcriptome of E. hippophaecolus and characterized the expression profiles of odorant binding proteins. These results establish and improve the basis knowledge of the olfactory receptive system, furthermore provide a theoretical basis for the development of new pest control method.ResultsWe identified 29 transcripts encoding putative odorant-binding proteins (OBPs), 18 putative chemosensory proteins (CSPs), 63 odorant receptors (ORs), 13 gustatory receptors (GRs), 12 ionotropic receptors (IRs), and two sensory neuron membrane proteins (SNMPs). Based on phylogenetic analysis, we found one Orco and three pheromone receptors of E. hippophaecolus and found that EhipGR13 detects sugar, EhipGR11 and EhipGR3 detect bitter. Nine OBPs expression profile indicated that most were the highest expression in antennae, consistent with functions of OBPs in binding and transporting odors during the antennal recognition process. OBP6 was external expressed in male genital-biased in, and this locus may be responsible for pheromone binding and recognition as well as mating. OBP1 was the highest and biased expressed in the foot and may function as identification of host plant volatiles.ConclusionsOne hundred thirty-seven chemosensory proteins were identified and the accurate functions and groups of part proteins were obtained by phylogenetic analysis. The most OBPs were antenna-biased expressed, which are involved in antennal recognition. However, few OBP was detected biased expression in the foot and external genitalia, and these loci may function in pheromone recognition, mating, and the recognition of plant volatiles.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3008-4) contains supplementary material, which is available to authorized users.

Identification and tissue distribution of chemosensory protein and odorant binding protein genes in Athetis dissimilis (Lepidoptera: Noctuidae)

Insect olfactory and gustatory systems play important roles in communication with the external environment. Two families of small soluble proteins, the chemosensory proteins (CSPs) and odorant binding proteins (OBPs), are believed to mediate chemoreception in insects. In this study, we identified ten putative CSP and five classic OBP genes by sequencing transcripts from the antennae of Athetis dissimilis Hampson, an emerging lepidopteran crop pest. The results of real-time quantitative PCR revealed that CSP genes were expressed broadly in A. dissimilis: six of the ten CSP genes were highly expressed in the antennae, including three that exhibited male-biased expression and three that exhibited female-biased expression. In addition to the antennae, CSP genes were also highly expressed in the proboscis, labial palpi, abdomen, legs, and wings of A. dissimilis. All OBP genes were primarily expressed in the female and male antennae of A. dissimilis. Three OBP genes exhibited female-biased expression patterns, while one was male-biased in the antennae. Surprisingly, the expression of AdisOBP6 was very high in the testes of A. dissimilis. This study is the first characterization of CSPs and OBPs in A. dissimilis and provides the foundation for a better understanding of the molecular mechanisms of chemoreception in A. dissimilis.

Chemosensory proteins involved in host recognition in the stored-food mite Tyrophagus putrescentiae.

Chemosensory proteins (CSPs) have been proposed to transport a range of aliphatic compounds, esters and other long-chain compounds. A large number of CSPs from different gene subfamilies have been identified and annotated in arthropods; however, the CSP genes in mites remain unknown. Tyrophagus putrescentiae Schrank is an important stored-product and house-dust pest. By analysing the transcriptome, two putative CSPs were identified, namely TputCSP1 and TputCSP2 (14.9 kDa and 12.1 kDa respectively). The phylogenetic tree showed that the two TputCSPs shared most homology with CSPs in Ixodes scapularis and partially with Diptera, including Anopheles gambiae, Drosophila melanogaster, D. pseudoobscura, D. simulans, Delia antiqua and Culex quinquefasciatus. Additionally, they had similar secondary structure. The 3D models revealed that there are six α-helices enclosing the hydrophobic ligand binding pocket. Based on a docking study, we found that three ligands, (-)-alloaromadendrene, 2-methylnaphthalene and cyclopentadecane, had high binding affinities for TputCSP1. Moreover, the TputCSP2 protein had a higher inhibition constant with different affinities to all test ligands from host volatile substances. The two CSPs have distinct physiological functions. TputCSP1 may mediate host recognition. © 2015 Society of Chemical Industry.

Identification and expression profiling of putative chemosensory protein genes in two rice planthoppers, Laodelphax striatellus (Fallén) and Sogatella furcifera (Horváth)

Chemosensory proteins (CSP) afford insects the ability to recognize complicated environmental cues and are involved in diverse physiological processes. The planthoppers Laodelphax striatellus and Sogatella furcifera are serious specialist pests of rice throughout eastern Asia. In this study, we identified 21 putative CSP genes (namely LsCSP1–12 and SfCSP1–9) in the two planthoppers L. striatellus and S. furcifera, and profiled their transcript accumulation in different developmental stages and body parts by real-time quantitative PCR (qPCR). All CSPs had the characteristic typical features of the CSP family, with the exception of LsCSP10 and SfCSP2, which lacked the predicted signal peptide sequence. Among these putative CSP genes, only two (LsCSP9 and SfCSP5) were more highly expressed in the antennae, indicating that they might be involved in olfaction. On the contrary, eleven genes (LsCSP2, 3, 4, 6, 8, 12; SfCSP1, 4, 6, 7, 8) and one gene (SfCSP9) were more highly expressed in the legs and heads (without antennae), respectively. The remainders of the genes were ubiquitously expressed in the heads (without antennae) and the bodies (without the legs and heads). The broad expression patterns in different body parts indicate that the CSPs of these two delphacid species may be involved in diverse functions besides chemosensation. These findings increase the understanding of the chemosensory protein system of Hemiptera species.

Identification and expression profiles of putative chemosensory protein genes in Cnaphalocrocis medinalis (Lepidoptera: Pyralidae)

Insect chemosensory proteins (CSPs) are small, water-soluble proteins which can bind and transport hydrophobic odorants through sensillum lymph to activate odorant receptors, thus play important roles in the olfactory recognition. In the present study, by searching the transcriptome data sets, a total of 22 candidate CSP genes were identified from Cnaphalocrocis medinalis, a serious lepidopteran rice pest in Asia. CSP proteins encoded by these genes showed typical characteristics: an N-terminal signal peptide, four conserved cysteine residues and the pattern of cysteine spacing. The expression profiles of these putative CSP genes were investigated using real-time quantitative PCR. The results showed that five genes (CmedCSP4, CmedCSP8, CmedCSP11, CmedCSP18 and CmedCSP21) were expressed primarily in antennae, suggesting their involvement in olfactory processes; whilst other genes are mainly expressed in non-olfactory tissues, such as abdomen and legs, indicating a broader physiological function for these CSPs. The findings will lead to a better understanding of the molecular mechanisms of chemoreception in C. medinalis.

Application of Cydia pomonella expressed sequence tags: Identification and expression of three general odorant binding proteins in codling moth

The codling moth, Cydia pomonella, is one of the most important pests of pome fruits in the world, yet the molecular genetics and the physiology of this insect remain poorly understood. A combined assembly of 8 341 expressed sequence tags was generated from Roche 454 GS-FLX sequencing of eight tissue-specific cDNA libraries. Putative chemosensory proteins (12) and odorant binding proteins (OBPs) (18) were annotated, which included three putative general OBP (GOBP), one more than typically reported for other Lepidoptera. To further characterize CpomGOBPs, we cloned cDNA copies of their transcripts and determined their expression patterns in various tissues. Cloning and sequencing of the 698 nt transcript for CpomGOBP1 resulted in the prediction of a 163 amino acid coding region, and subsequent RT-PCR indicated that the transcripts were mainly expressed in antennae and mouthparts. The 1 289 nt (160 amino acid) CpomGOBP2 and the novel 702 nt (169 amino acid) CpomGOBP3 transcripts are mainly expressed in antennae, mouthparts, and female abdomen tips. These results indicate that next generation sequencing is useful for the identification of novel transcripts of interest, and that codling moth expresses a transcript encoding for a new member of the GOBP subfamily.

Chemosensory protein genes of batocera horsfieldi (hope): identification and expression pattern

AbstractChemoreception is an essential feature for selection of host plants by insects. Chemosensory proteins (CSPs) are a group of small proteins (approximately 13 kDa) that are expressed widely in various insect sensory appendages. Batocera horsfieldi (Hope) is a major pest of Popolus and utilizes a variety of semiochemicals for its mating and oviposition. However, no CSP gene has been identified in B. horsfieldi. Here, to obtain the DNA sequences of B. horsfieldi CSPs, we used both bioinformatics and experimental approaches to analyse the antennal expressed sequence tags (ESTs). Among 649 EST clones, three unique CSP sequences (BhorCSP1, 2 and 3) were identified and characterized from B. horsfieldi (Hope) antennal cDNA libraries based on their four conserved cysteine residues, which have a characteristic spacing pattern. A phylogenetic tree of BhorCSPs and other insect CSPs showed that BhorCSP1 and BhorCSP2 are more similar to CSPs of Tribolium castaneum than BhorCSP3. BhorCSP3 is closely related to CSPs of the Dipteran, Culex quinquefasciatus. Using reverse transcription polymerase chain reaction (RT‐PCR) and real‐time Q‐PCR strategies, we examined the expression patterns of these three putative CSP genes in different tissues, sexes and developmental stages. Our analysis shows that all three genes were expressed in all tissues examined, including the antennae, labial palps, maxillary palps, legs, abdomen and wings but not in the head. Real‐time Q‐PCR results revealed that these CSP genes were expressed throughout the life of the adults, and the transcription levels of these genes depended on the sex, age and mating status of adults.

Genome and EST Analyses and Expression of a Gene Family with Putative Functions in Insect Chemoreception

Odorant-binding proteins (OBPs) are thought to be responsible for the transport of semiochemicals across hydrophobic interfaces to olfactory receptors. In insects, a second class of OBPs with four conserved cysteines has been variously named as sensory appendage proteins, olfactory segment-D proteins, and chemosensory proteins (CSPs). The physiological functions of these proteins have remained elusive. Here we report a comprehensive survey of both genome and expressed sequence tags (EST) databases. This showed that CSPs are apparently only present in the phylum, Arthropoda, and in two subphyla, Crustacea and Uniramia. This is the first report of a putative CSP in Crustacea and suggests that the origin of these genes predates the divergence of Uniramia and Crustacea. For the Uniramia, we identified 74 new genes encoding putative CSPs of insect species from 10 different orders. Using tissue-specific EST libraries, we have examined the relative expression of putative CSP genes in many tissues from 22 insect species suggesting that the genes are expressed widely. One Drosophila CSPs is expressed sixfold higher in head than other CSPs. One Bombyx mori CSPs was found at a very high level in pheromone gland, and for the first time, six CSPs were identified in B. mori compound eyes. The different frequencies of CSP transcripts were observed between solitary and gregarious EST libraries of Locusta migratoria.

Bioinformatics-Based Identification of Chemosensory Proteins in African Malaria Mosquito, Anopheles gambiae

Chemosensory proteins (CSPs) are identifiable by four spatially conserved Cysteine residues in their primary structure or by two disulfide bridges in their tertiary structure according to the previously identified olfactory specific-D related proteins. A genomics- and bioinformatics-based approach is taken in the present study to identify the putative CSPs in the malaria-carrying mosquito, Anopheles gambiae. The results show that five out of the nine annotated candidates are the most possible Anopheles CSPs of A. gambiae. This study lays the foundation for further functional identification of Anopheles CSPs, though all of these candidates need additional experimental verification.