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Insulin receptors (InR) are an integral component of the insulin/insulin‐like growth factor signaling pathway, which plays a vital role in insect development, lifespan, reproduction, and olfactory sensitivity. However, whether InR participate in the peripheral olfactory system of insects remains unclear. Recently, we found that 2‐heptanone (2‐HT) affects AcerInR expression, the gene for an InR protein, in Apis cerana cerana. We then examined the spatiotemporal expression profile of the gene in A. cerana cerana. The mRNA of AcerInR was primarily expressed in the antennae, wings, and legs of forager bees, which are probable chemosensory tissues. The results of fluorescence competitive binding assays, combined with site‐directed mutagenesis, demonstrated that AcerOBP6 and AcerOBP14 exhibit strong binding affinities to 2‐HT. Furthermore, after foragers were fed with double‐stranded AcerInR, the expression levels of AcerOBP6 and AcerOBP14 decreased significantly, as did the electroantennogram responsiveness to 2‐HT and some other odorants. In conclusion, our findings provide a foundation for understanding the involvement of AcerInR in the odor perception of A. cerana cerana. Moreover, they offer novel insights into the olfactory recognition mechanism in insects. [ABSTRACT FROM AUTHOR]

Background : Baryscapus dioryctriae (Chalcidodea: Eulophidae) is a parasitic wasp that parasitizes the pupae of many Pyralidae members and has been used as a biological control agent against Dioryctria pests of pinecones. Results: This B. dioryctriae assembly has a genome size of 485.5 Mb with a contig N50 of 2.17 Mb, and scaffolds were assembled onto six chromosomes using Hi-C analysis, significantly increasing the scaffold N50 to 91.17 Mb, with more than 96.13% of the assembled bases located on chromosomes, and an analysis revealed that 94.73% of the BUSCO gene set. A total of 54.82% (279.27 Mb) of the assembly was composed of repetitive sequences and 24,778 protein-coding genes were identified. Comparative genomic analysis demonstrated that the chemosensory perception, genetic material synthesis, and immune response pathways were primarily enriched in the expanded genes. Moreover, the functional characteristics of an odorant-binding protein (BdioOBP45) with ovipositor-biased expression identified from the expanded olfactory gene families were investigated by the fluorescence competitive binding and RNAi assays, revealing that BdioOBP45 primarily binds to the D. abietella-induced volatile compounds, suggesting that this expanded OBP is likely involved in locating female wasp hosts and highlighting a direction for future research. Conclusions: Taken together, this work not only provides new genomic sequences for the Hymenoptera systematics, but also the high-quality chromosome-level genome of B. dioryctriae offers a valuable foundation for studying the molecular, evolutionary, and parasitic processes of parasitic wasps. [ABSTRACT FROM AUTHOR]

The identification of odorant-binding proteins (OBPs) involved in host location by Oides leucomelaena (O. leucomelaena Weise, 1922, Coleoptera, Galerucinae) is significant for its biological control. Tools in the NCBI database were used to compare and analyze the transcriptome sequences of O. leucomelaena with OBP and other chemosensory-related proteins of other Coleoptera insects. Subsequently, MEGA7 was utilized for OBP sequence alignment and the construction of a phylogenetic tree, combined with expression profiling to screen for candidate antennae-specific OBPs. In addition, fumigation experiments with star anise volatiles were conducted to assess the antennae specificity of the candidate OBPs. Finally, molecular docking was employed to speculate on the binding potential of antennae-specific OBPs with star anise volatiles. The study identified 42 candidate OBPs, 8 chemosensory proteins and 27 receptors. OleuOBP3, OleuOBP5, and OleuOBP6 were identified as classic OBP family members specific to the antennae, which was confirmed by volatile fumigation experiments. Molecular docking ultimately clarified that OleuOBP3, OleuOBP5, and OleuOBP6 all exhibit a high affinity for β-caryophyllene among the star anise volatiles. We successfully obtained three antennae-specific OBPs from O. leucomelaena and determined their high-affinity volatiles, providing a theoretical basis for the development of attractants in subsequent stages. [ABSTRACT FROM AUTHOR]

Abstract Background Baryscapus dioryctriae (Chalcidodea: Eulophidae) is a parasitic wasp that parasitizes the pupae of many Pyralidae members and has been used as a biological control agent against Dioryctria pests of pinecones. Results This B. dioryctriae assembly has a genome size of 485.5 Mb with a contig N50 of 2.17 Mb, and scaffolds were assembled onto six chromosomes using Hi-C analysis, significantly increasing the scaffold N50 to 91.17 Mb, with more than 96.13% of the assembled bases located on chromosomes, and an analysis revealed that 94.73% of the BUSCO gene set. A total of 54.82% (279.27 Mb) of the assembly was composed of repetitive sequences and 24,778 protein-coding genes were identified. Comparative genomic analysis demonstrated that the chemosensory perception, genetic material synthesis, and immune response pathways were primarily enriched in the expanded genes. Moreover, the functional characteristics of an odorant-binding protein (BdioOBP45) with ovipositor-biased expression identified from the expanded olfactory gene families were investigated by the fluorescence competitive binding and RNAi assays, revealing that BdioOBP45 primarily binds to the D. abietella-induced volatile compounds, suggesting that this expanded OBP is likely involved in locating female wasp hosts and highlighting a direction for future research. Conclusions Taken together, this work not only provides new genomic sequences for the Hymenoptera systematics, but also the high-quality chromosome-level genome of B. dioryctriae offers a valuable foundation for studying the molecular, evolutionary, and parasitic processes of parasitic wasps.

Worldwide, pine forests have been threatened by a devastating pine wood disease caused by Bursaphelenchus xylophilus, with Monochamus saltuarius being a newly recorded vector of the disease in Northeast China. The olfactory system plays important roles in both feeding and oviposition during the adult stage of M. saltuarius, and olfactory gene function research is essential for gaining an understanding of the olfactory mechanisms of this pest. However, there is limited information available regarding olfactory gene functions in this pest. In the present study, we selected 7 olfactory genes, including 2 chemosensory proteins, 2 odorant‐binding proteins, the odorant co‐receptor and 2 odorant receptors, which were relatively highly expressed during the adult stage. We silenced these genes by RNA interference (RNAi), and real‐time quantitative PCR was used to detect their expression levels after double‐stranded RNA (dsRNA) injection. The results indicate that these genes were significantly downregulated at 2 d post‐dsRNA injection, and this was sustained until 5 d post‐injection. Electroantennography tests indicated that the knockdown of MsalOBP14 and MsalOrco impaired the olfactory response of M. saltuarius to 11 host volatiles and 1 sex pheromone compound. Y‐tube experiments further confirmed that downregulated MsalOBP14 and MsalOrco expression led to olfactory dysfunction in M. saltuarius, which significantly lost selectivity. The results indicate that MsalOBP14 and MsalOrco play critical roles in sex communication and host volatile detection in M. saltuarius, and possibly represent 2 effective targets for controlling this forest pest through olfactory disruption. [ABSTRACT FROM AUTHOR]

The oriental fruit fly (Bactrocera dorsalis) is an exceptionally hazardous pest that can cause up to 100% loss. Male annihilation using male attractant methyl eugenol (ME) is the most adopted control measure of this insect. The molecular process underlying this perception of insects remains unexplored. In this study, we focus on gene functionality of odorant‐binding protein 13 (OBP13) in ME perception by knockout using CRISPR/Cas9 mediated embryonic editing through microinjection. The electrophysiological study of mutant flies through electroantennogram has shown highly depressed ME perception and further the genetic‐level mutational confirmation stating that OBP13 is a major OBP involved in ME perception. The molecular docking of OBP13 with ME revealed the predicted key interactions involved, thus providing more scope in targeting gene editing and in engineering ME substitutes. [ABSTRACT FROM AUTHOR]

Personal protection from mosquito bites is essential for preventing mosquito‐borne diseases. Mosquito repellents are effective methods for preventing mosquito bites. Due to their ease of use and indirect skin contact, mosquito‐repellent stickers loaded with essential oils (EOs) have recently become favoured as novel spatial repellents. To discover active EOs with high spatial repellency, 64 commercial EOs were screened using a modified arm‐in‐cage assay. Four EOs, including nutmeg, melissa, eucalyptus and cinnamon, displayed longer complete protection times (CPTs) of about 60 min. Ten main constituents from the four active EOs were identified by gas chromatography–mass spectrometry (GC–MS), and their spatial repellent activities were further evaluated. 1,8‐Cineole, cinnamaldehyde and citral showed potent repellent activity, with average CPTs of 67.5, 63.8 and 60 min respectively. The interactions of 1,8‐cineole and citral with odorant‐binding protein‐3 (OBP‐3) were studied via molecular docking. Both compounds are docked well in the high hydrophobic pocket and interacted with AealOBP3 through Van der Waals interactions with Phe105, Phe112, Leu114, Met48 and Val50. These natural products provide promising lead fragments for the further development of botanical spatial repellents. [ABSTRACT FROM AUTHOR]

The primary function of odorant‐binding proteins (OBPs) is thought to be binding and transporting odorants molecules. The research on the molecular mechanisms of SfruOBPs binding with sex pheromones is beneficial to the prevention and control of Spodoptera frugiperda (S. frugiperda). Herein, two screened SfruOBPs (Sfru10933 and Sfru21187) were knocked down by RNA interference, and then the changes in electroantennogram (EAG) and behavioral responses of male mutants to their main sex pheromone components were recorded. Upon interfering with Sfru10933, the EAG response and behavioural preferences of males to sex pheromones were significantly reduced or eliminated. The interference with Sfru21187 resulted in a weakening of the behavioural preference, while the EAG response remained unchanged. However, the co‐interference of Sfru10933/Sfru21187 led to a significant reduction in the EAG activity of male to sex pheromones. These results reveal that Sfru10933 and Sfru21187 play a crucial role in sex pheromone recognition, and there may be a synergistic effect between them. Furthermore, these results will help clarify the perception of sex pheromones by S. frugiperda, which may provide new targets for the development of mating inhibitors in the future. [ABSTRACT FROM AUTHOR]

A highly sensitive olfactory system allows insects to precisely identify and position volatile compounds from different sources in their habitats, and plays a crucial role in their foraging, mating, and oviposition activities. During evolution, insects have successfully developed a large and complex olfactory system to adapt to heterogeneous environments, enabling the maintenance of inset population. A comprehensive examination of the olfactory system of insects may therefore yield novel insights into the development of innovative pest control and prevention strategies, as well as the study of olfactory mechanisms in vertebrates and even humans. This paper outlines the current state of research into the signal transduction mechanism by which insects perceive the olfactory molecules of their habitats. The aim of this review is to provide a reference point for future studies into the olfactory perception mechanism and its potential applications in pest management. [ABSTRACT FROM AUTHOR]

Molecular studies on odorant receptors (ORs), odorant‐binding proteins (OBPs) and the functioning of the receptor and pheromone signal transduction in fruit fly Bactrocera species have expanded exponentially during the past few decades. OBPs contribute to the sensing of the olfactory system (OS) via the transduction of odorants through the sensillum lymph. However, ORs, a family of G‐protein‐coupled receptors in Bactrocera and various other species, exhibit heightened responsiveness to multiple chemical odours such as hormones, sensory stimuli and neurotransmitters. The apparent mechanism involves a combinatorial code encompassing both peripheral and antennal lobe processing, facilitating the reception of sexual pheromones and environmental cues. The OS is specifically designed to recognize and process information from volatile chemical signals, and these chemical signals play an important function in various flies. Insects rely on these chemicals to navigate and comprehend their surroundings. A mature insect OS is composed of two pairs of sensillae‐covered palps, antennae and two primary pairs of olfactory appendages on the anterior head. It has been shown that chemosensory gene families contribute in odour perception. These include various neuroreceptor families, such as OBPs, chemosensory proteins and sensory neuron membrane proteins. Additionally, there are three divergent chemoreceptors, namely ORs, ionotropic receptors and gustatory receptors. Methods based on systematic biology, molecular biology and bioinformatics tools have rapidly emerged to investigate the insect communication systems and provide new insights for the management of many agricultural pest. Several aromatic compounds, including semiochemicals and pheromones, have been employed to defend crops and animals from destructive fruit flies and other invasive and frugivorous species. To promote the expansion of the cropping system, the utilization of phytochemical lures can be convenient for sustainable agriculture production and enhance food security. Hence, this review examined the state of the art in chemical communication of insects with a focus on fruit fly pest species to identify OS and their semiochemical receptors, protein receptors and chemosensory receptors (CSRs), as well as their practical applications for biological control and integrated pest management are highlighted. [ABSTRACT FROM AUTHOR]

Olfactory is the main sense for the survival and reproduction of honey bees, providing important information for honey bees to forage, mate, escape from natural enemies, and other behaviors. Odorant-binding proteins (OBPs) play a crucial role in bees' olfactory perception. Therefore, exploring the interaction between honey bee OBPs and various chemicals in the environment is of significant importance for elucidating the binding characteristics and mechanisms of honey bee OBPs towards different exogenous compounds, including semiochemicals, pheromones, plant volatiles, and insecticides. On one hand, the binding of semiochemicals with bee OBPs plays a crucial role in maintaining bee colony stability, reproduction, foraging, pollination, and other physiological functions. On the other hand, the binding of insecticides with OBPs may pose a threat to the bee's olfactory system, affecting the bee’s ability to recognize environmental odor molecules. In this review, we summarize the research progress on the types, and functions of bee OBPs, as well as the research progress on their interaction mechanisms with exogenous compounds. The aim is to offer a reference basis for further exploration of the physiological functions of bee OBPs and for protecting bees from the harm of pesticides and other chemicals. [ABSTRACT FROM AUTHOR]

Bemisia tabaci (Gennadius) is an important invasive pest transmitting plant viruses that are maintained through a plant–insect–plant cycle. Tomato yellow leaf curl virus (TYLCV) can be transmitted in a persistent manner by B. tabaci, which causes great losses to global agricultural production. From an environmentally friendly, sustainable, and efficient point of view, in this study, we explored the function of d-limonene in reducing the acquisition and transmission of TYLCV by B. tabaci as a repellent volatile. D-limonene increased the duration of non-feeding waves and reduced the duration of phloem feeding in non-viruliferous and viruliferous whiteflies by the Electrical Penetration Graph technique (EPG). Additionally, after treatment with d-limonene, the acquisition and transmission rate of TYLCV was reduced. Furthermore, BtabOBP3 was determined as the molecular target for recognizing d-limonene by real-time quantitative PCR (RT-qPCR), fluorescence competitive binding assays, and molecular docking. These results confirmed that d-limonene is an important functional volatile which showed a potential contribution against viral infections with potential implications for developing effective TYLCV control strategies. [ABSTRACT FROM AUTHOR]

Odorant binding protein(OBP) is an important protein in the process of insect olfactory communication. OBPs are involved in the first step of insect odor recognition, and play an important role in insect activities such as foraging, aggregation, courtship, and looking for spawning places. In order to determine the expression characteristics of OBP genes in Agasicles hygrophila and to preliminarily understand its functions, in this study, three OBP genes were cloned and analyzed using bioinformatics. The relative expression levels of OBPs in different tissues were analyzed by quantitative real-time PCR. The results showed that the open reading frame of AhygOBP27, AhygOBP32, and AhygOBP44 were 351, 408, 423 bp, respectively. The proteins encoded by the three OBPs were acidic soluble proteins with small molecular weight. AhygOBP27 was mainly expressed in the antennae, head, feet and wings of both sexes. AhygOBP32 was expressed in antennae, head, leg and wings of the male and in antennae, feet and wings of the female. AhygOBP44 was expressed in the antennae, heads and feet of both sexes. The expression levels of above three genes in the antennae of male and female were significantly higher than that of other tissues. The expression level of AhygOBP27 and AhygOBP44 in female antennae were significantly higher than that in male antennae, and the expression level of AhygOBP32 in the antennae of males was significantly higher than that of females. The three genes might play an important role in the olfactory recognition of Agasicles hygrophila, AhypOBP27, and AhygOBP44 might be related to the recognition of host plant volatiles and the search for spawning ground; AhygOBP32 might be involved in the recognition of sex pheromone emitted by females. [ABSTRACT FROM AUTHOR]

The remarkable biological and evolutionary adaptations of insects to plants are largely attributed to the powerful chemosensory systems of insects. The tomato leaf miner (Tuta absoluta) is a destructive invasive pest with a global distribution that poses a serious threat to the production of nightshade crops, especially tomatoes. Functional plants can attract or repel insect pests by releasing volatiles that interact with the olfactory system of insects, thereby reducing the damage of insect pests to target crops. However, there is limited research on the interaction between T. absoluta olfactory genes and functional plants. In this study, 97 members of the putative odorant-binding protein (OBP) family have been identified in the whole genome of T. absoluta. Phylogenetic analysis involving various Lepidopteran and Dipteran species, including D. melanogaster, revealed that OBP gene families present conserved clustering patterns. Furthermore, the Plus-C subfamily of OBP showed extremely significant expansion. Moreover, the expression levels of the OBP genes varied significantly between different developmental stages; that is, the highest number of OBP genes were expressed in the adult stage, followed by the larval stage, and fewer genes were expressed in high abundance in the egg stage. On the other hand, through a Y-tube olfactometer, we identified a functional plant—Plectranthus tomentosa—that significantly repels adult and larval T. absoluta. Finally, we screened the OBP genes in response to tomato and P. tomentosa volatiles at the genomic level of T. absoluta using RT-qPCR. These results laid a good foundation for controlling T. absoluta with functional plants and further studying olfactory genes. [ABSTRACT FROM AUTHOR]

The identification of odorant-binding proteins (OBPs) involved in host location by Oides leucomelaena (O. leucomelaena Weise, 1922, Coleoptera, Galerucinae) is significant for its biological control. Tools in the NCBI database were used to compare and analyze the transcriptome sequences of O. leucomelaena with OBP and other chemosensory-related proteins of other Coleoptera insects. Subsequently, MEGA7 was utilized for OBP sequence alignment and the construction of a phylogenetic tree, combined with expression profiling to screen for candidate antennae-specific OBPs. In addition, fumigation experiments with star anise volatiles were conducted to assess the antennae specificity of the candidate OBPs. Finally, molecular docking was employed to speculate on the binding potential of antennae-specific OBPs with star anise volatiles. The study identified 42 candidate OBPs, 8 chemosensory proteins and 27 receptors. OleuOBP3, OleuOBP5, and OleuOBP6 were identified as classic OBP family members specific to the antennae, which was confirmed by volatile fumigation experiments. Molecular docking ultimately clarified that OleuOBP3, OleuOBP5, and OleuOBP6 all exhibit a high affinity for β-caryophyllene among the star anise volatiles. We successfully obtained three antennae-specific OBPs from O. leucomelaena and determined their high-affinity volatiles, providing a theoretical basis for the development of attractants in subsequent stages.

BACKGROUND: Rhynchophorus ferrugineus, the red palm weevil (RPW), is a key pest that attacks many economically important palm species and that has evolved a sensitive and specific olfactory system to seek palm hosts. Odorant‐binding proteins (OBPs) not only play crucial roles in its olfactory perception process but are also important molecular targets for the development of new approaches for pest management. RESULTS: Analysis of the tissue expression profiles of RferOBP8 and RferOBP11 revealed that these two Rhynchophorus ferrugineus odorant binding proteins (RferOBPs) exhibited high expression in the antennae and showed sexual dimorphism. We analyzed the volatiles of seven host plants by gas chromatography–mass spectrometry and screened 13 potential ligands by molecular docking. The binding affinity of two recombinant OBPs to aggregation pheromones and 13 palm odorants was tested by fluorescence competitive binding assays. The results revealed that eight tested palm volatiles and ferrugineol have high binding affinities with RferOBP8 or RferOBP11. Behavioral trials showed that these eight odor compounds could elicit an attraction response in adult RPW. RNA interference analysis indicated that the reduction in the expression levels of the two RferOBPs led to a decrease in behavioral responses to these volatiles. CONCLUSION: These results suggest that RferOBP8 and RferOBP11 are involved in mediating the responses of RPW to palm volatiles and to aggregation pheromones and may play important roles in RPW host‐seeking. This study also provides a theoretical foundation for the promising application of novel molecular targets in the development of new behavioral interference strategies for RPW management in the future. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The transcriptomes of Agasicles hygrophila eggs and first instar larvae were analyzed to explore the olfactory mechanism of larval behavior. The analysis resulted in 135,359 unigenes and the identification of 38 odorant-binding proteins (OBPs), including 23 Minus-C OBPs, 8 Plus-C OBPs, and 7 Classic OBPs. Further analysis of differentially expressed genes (DEGs) revealed 10 DEG OBPs, with 5 (AhygOBP5 , AhygOBP9 , AhygOBP12 , AhygOBP15 and AhygOBP36) up-regulated in first instar larvae. Verification of expression patterns of these 5 AhygOBPs using qPCR showed that AhygOBP9 and AhygOBP36 were mainly expressed in the adult stage with gradually increasing expression in the larval stage. AhygOBP5 , AhygOBP12 , and AhygOBP15 were not expressed in eggs and pupae, and their expression in larvae and adults showed no clear pattern. These 5 AhygOBPs may play an olfactory role in larval behavior, providing a basis for further investigation of their specific functions and clarifying the olfactory mechanism of A. hygrophila. [ABSTRACT FROM AUTHOR]

Background We were curious if the urinary proteome could reflect the effects of e-cigarettes on the organism. Methods Urine samples were collected from a rat e-cigarette model before, during, and after two weeks of e-cigarette smoking. Urine proteomes before and after smoking of each rat were compared individually, while the control group was set up to rule out differences caused by rat growth and development. Results Fetuin-B, a biomarker of chronic obstructive pulmonary disease (COPD), and annexin A2, which is recognized as a multiple tumour marker, were identified as differential proteins in five out of six smoking rats on day 3. To our surprise, odourant-binding proteins expressed in the olfactory epithelium were also found and were significantly upregulated. Pathways enriched by the differential proteins include the apelin signalling pathway, folate biosynthesis pathway, arachidonic acid metabolism, chemical carcinogenesis-DNA adducts and chemical carcinogenesis-reactive oxygen species. They have been reported to be associated with immune system, cardiovascular system, respiratory system, etc. Conclusions Urinary proteome could reflect the effects of e-cigarettes in rats.

The brown‐winged green bug, Plautia stali Scott (Hemiptera: Pentatomidae), is a major pest in orchards in Japan and Korea. Large numbers of adults are attracted by aggregation pheromone [methyl (E,E,Z)‐2,4,6‐decatrienoate] and cause extensive damage to the fruit. To identify olfactory‐related genes in P. stali, we performed RNA sequencing (RNA‐seq) of adult antennae. Among the 27299 contigs, 16 putative odorant‐binding protein (OBP) genes were identified and designated as PstaOBP1–16, including 10 classic (i.e., containing six conserved cysteines) and six Plus‐C (i.e., containing more than six cysteines) OBP genes. Quantitative reverse‐transcription polymerase chain reaction (qRT‐PCR) revealed that four genes (PstaOBP1, 3, 6, and 7) were strongly expressed in the antennae. PstaOBP2 was detected throughout the insect body, with higher expression in the antennae, stylet, and tarsus. The remaining OBP genes were expressed in very small amounts. PstaOBP1, which showed the highest expression in adult antennae, was expressed in Escherichia coli (Migula) Castellani & Chalmers cells and the recombinant protein was subjected to a ligand‐binding competitive assay. PstaOBP1 bound to methyl (E,E,Z)‐2,4,6‐decatrienoate with high affinity. Of the other 26 compounds tested, hinokitiol and tropolone bound strongly to PstaOBP1. Hinokitiol is an odor component of hinoki cypress, a host tree of P. stali. Electrophysiological responses to methyl (E,E,Z)‐2,4,6‐decatrienoate and hinokitiol were detected using adult P. stali antennae. Combined, these results suggest that PstaOBP1 is involved in P. stali responses to pheromone and host plant volatiles. [ABSTRACT FROM AUTHOR]

Pachyrhinus yasumatsui Kono et Morimoto is a major pest of Chinese jujube, which is widespread in northern China and causes severe economic losses in the jujube industry. Chemosensory genes play crucial roles in insect behaviors. Currently, little is known about chemosensory genes in P. yasumatsui. In the present study, antennal transcriptomes of female and male adult P. yasumatsui were annotated. In total, 113 genes involved in chemosensory functions were identified, including 41 odorant receptors, 28 odorant-binding proteins, 16 ionotropic receptors, 15 chemosensory proteins, 9 gustatory receptors, and 4 sensory neuron membrane proteins. Subsequently, the phylogenetic analyses of these olfactory-related proteins in P. yasumatsui were conducted using multiple sequence alignment. Furthermore, sex-specific expression levels of 113 genes were analyzed based on fragments per kilobase of transcript per million mapped reads (FPKM). Then, the quantitative real-time PCR (RT-qPCR) was used to quantify gene expression profiles of 28 P. yasumatsui OBPs (PyasOBPs) and 15 CSPs (PyasCSPs). The results revealed that 20 PyasOBPs and 13 PyasCSPs exhibited significantly higher expression in the antennae than in the bodies, suggesting that they might have functions in olfaction. Moreover, some OBPs and CSPs (PyasOBP6 , PyasOBP7 , PyasOBP16 , PyasOBP21 , and PyasCSP4) exhibited female-biased expression, indicating that they might take part in several female-specific behaviors. This study will promote the understanding of olfactory mechanism in P. yasumatsui , and our findings lay the groundwork for developing environmentally friendly pest management measures. [ABSTRACT FROM AUTHOR]

Bemisia tabaci (Gennadius) is an important invasive pest transmitting plant viruses that are maintained through a plant–insect–plant cycle. Tomato yellow leaf curl virus (TYLCV) can be transmitted in a persistent manner by B. tabaci, which causes great losses to global agricultural production. From an environmentally friendly, sustainable, and efficient point of view, in this study, we explored the function of d-limonene in reducing the acquisition and transmission of TYLCV by B. tabaci as a repellent volatile. D-limonene increased the duration of non-feeding waves and reduced the duration of phloem feeding in non-viruliferous and viruliferous whiteflies by the Electrical Penetration Graph technique (EPG). Additionally, after treatment with d-limonene, the acquisition and transmission rate of TYLCV was reduced. Furthermore, BtabOBP3 was determined as the molecular target for recognizing d-limonene by real-time quantitative PCR (RT-qPCR), fluorescence competitive binding assays, and molecular docking. These results confirmed that d-limonene is an important functional volatile which showed a potential contribution against viral infections with potential implications for developing effective TYLCV control strategies.

The remarkable biological and evolutionary adaptations of insects to plants are largely attributed to the powerful chemosensory systems of insects. The tomato leaf miner (Tuta absoluta) is a destructive invasive pest with a global distribution that poses a serious threat to the production of nightshade crops, especially tomatoes. Functional plants can attract or repel insect pests by releasing volatiles that interact with the olfactory system of insects, thereby reducing the damage of insect pests to target crops. However, there is limited research on the interaction between T. absoluta olfactory genes and functional plants. In this study, 97 members of the putative odorant-binding protein (OBP) family have been identified in the whole genome of T. absoluta. Phylogenetic analysis involving various Lepidopteran and Dipteran species, including D. melanogaster, revealed that OBP gene families present conserved clustering patterns. Furthermore, the Plus-C subfamily of OBP showed extremely significant expansion. Moreover, the expression levels of the OBP genes varied significantly between different developmental stages; that is, the highest number of OBP genes were expressed in the adult stage, followed by the larval stage, and fewer genes were expressed in high abundance in the egg stage. On the other hand, through a Y-tube olfactometer, we identified a functional plant—Plectranthus tomentosa—that significantly repels adult and larval T. absoluta. Finally, we screened the OBP genes in response to tomato and P. tomentosa volatiles at the genomic level of T. absoluta using RT-qPCR. These results laid a good foundation for controlling T. absoluta with functional plants and further studying olfactory genes.

Pheromone cues released from hosts or prey are of crucial importance to natural enemies for prey and habitat location. The use of herbivorous insect sex pheromones has long been considered as a potential pest control alternative that is non-toxic and harmless to beneficials. We hypothesized that Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), a major predatory coccinellid beetle of the devastating migratory pest Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), could perceive and use the sex pheromone of S. frugiperda to locate its habitat. Here we tested the electrophysiological and behavioral responses of H. axyridis to the two components Z7-12:Ac and Z9-14:Ac of S. frugiperda sex pheromone by using electroantennography (EAG) and Y-tube bioassay. The 3D modeling of H. axyridis odorant-binding proteins (HaxyOBPs) and molecular docking were also performed. The results showed that both female and male H. axyridis exhibited significantly higher electrophysiological and behavioral responses to Z9-14:Ac at the concentrations of 0.001, 0.01, and 0.1 μg/μL, while no significant electrophysiological and behavioral responses of H. axyridis were observed to Z7-12:Ac. The blend of Z7-12:Ac and Z9-14:Ac at the ratio of 1:100 had a significant attraction to both male and female H. axyridis at the concentrations of 0.01 and 0.1 μg/μL based on electrophysiological and behavioral assays, but no significant behavioral responses were observed at the ratios of 1:9. According to the 3D modeling of HaxyOBPs and molecular docking, HaxyOBP12 has a good affinity with Z9-14:Ac. Z9-14:Ac is bound to the HaxyOBP12 by hydrogen bonding and hydrophobic interactions. However, there were no credible docking results between HaxyOBPs and Z7-12:Ac. Our findings revealed that H. axyridis can perceive Z9-14:Ac and could use it as a chemical cue to locate prey habitat. We speculated that Z7-12:Ac, which showed some antagonistic effect toward the response of H. axyridis to Z9-14:Ac, could improve the adaptability of S. frugiperda in the presence of predators. This study provides new insights into the application of pheromones to manipulate natural enemy behavior for pest control.

Simple Summary: Odorant-binding proteins are soluble proteins abundantly secreted in the nasal mucus of vertebrates. Although their physiological functions are not known, these proteins are suspected to have a carrier role in solubilizing and carrying hydrophobic odorant molecules to the olfactory receptors. Here, we describe the expression of functional mouse mOBP5. The protein produced using bacteria was purified and characterized. We investigated its binding properties using a fluorescent competitive assay and microcalorimetry. Molecular docking experiments revealed hydrophobic residues in the binding cavity potentially involved in the stabilization of the odorant, thus explaining its binding properties. Odorant-binding proteins (OBPs) are abundant soluble proteins secreted in the nasal mucus of a variety of species that are believed to be involved in the transport of odorants toward olfactory receptors. In this study, we report the functional characterization of mouse OBP5 (mOBP5). mOBP5 was recombinantly expressed as a hexahistidine-tagged protein in bacteria and purified using metal affinity chromatography. The oligomeric state and secondary structure composition of mOBP5 were investigated using gel filtration and circular dichroism spectroscopy. Fluorescent experiments revealed that mOBP5 interacts with the fluorescent probe N-phenyl naphthylamine (NPN) with micromolar affinity. Competitive binding experiments with 40 odorants indicated that mOBP5 binds a restricted number of odorants with good affinity. Isothermal titration calorimetry (ITC) confirmed that mOBP5 binds these compounds with association constants in the low micromolar range. Finally, protein homology modeling and molecular docking analysis indicated the amino acid residues of mOBP5 that determine its binding properties. [ABSTRACT FROM AUTHOR]

The bean bug Riptortus pedestris is a notorious insect pest that can damage various crops, especially soybean, in East Asia. In insects, the olfactory system plays a crucial role in host finding and feeding behaviour in which the odorant‐binding proteins (OBPs) are believed to be involved in initial step in this system. In this study, we produced the R. pedestris adult antennae‐expressed RpedOBP4 protein using a recombinant expression system in E. coli. Fluorescence competitive binding confirmed that RpedOBP4 has binding affinities to 7 of 20 soybean volatiles (ligands), and that a neutral condition is the best environment for it. The binding property of RpedOBP4 to these ligands was further revealed by integrating data from molecular docking, site‐directed mutagenesis and ligand binding assays. This demonstrated that five amino acid residues (I30, L33, Y47, I57 and Y121) are involved in the binding process of RpedOBP4 to corresponding ligands. These findings will not only help us to more thoroughly explore the olfactory mechanism of R. pedestris during feeding on soybean, but also lead to the identification of key candidate targets for developing environmental and efficient behaviour inhibitors to prevent population expansion of R. pedestris in the future. [ABSTRACT FROM AUTHOR]

Chemical communication between sexes in the elephants has been well studied at the chemical and behavioural levels, but little is known about the proteins mediating the exchange of chemical signals. Two sex pheromones have been identified in Asian elephants: (Z)-7-dodecenyl acetate and frontalin, and their effects on the elephants’ behaviour have been described in detail. The genomes of both the Asian (Elephas maximus) and the African elephant (Loxodonta africana) have been poorly annotated. In particular, the complete sequences of two odorant-binding proteins and a VEG protein are available for the African elephant, together with isoforms and other members of the same families, which however are incomplete or unreliable. In a previous study, we have expressed the OBP1 of both elephant species, and investigated their binding properties. We showed that OBP1 is tuned to the pheromone (Z)-7-dodecenyl acetate and few structurally related linear esters, but also binds (E)-β-farnesene and farnesol with good affinity. In this work we have explored the characteristics of the second OBP of the African elephant (LafrOBP2). This protein, which was not found in the trunk wash, does not bind any of the above listed semiochemicals. Instead, it shows selected affinity to unsaturated linear aldehydes of 16 carbon atoms, specifically (Z)-9-hexadecenal, (Z)-11-hexadecenal and (10E,12Z)-hexadecadienal (bombykal). Fourteen and 18 carbon orthologues show only much reduced binding affinity. Some linear alcohols, fatty acids and esters also weakly bind this protein with dissociation constants about one order of magnitude higher.

Peptides are promising molecular-binding elements and have attracted great interest in novel biosensor development. In this study, a series of peptides derived from odorant-binding proteins (OBPs) were rationally designed for recognition of SARS-CoV-2-related volatile organic compounds (VOCs). Ethanol, nonanal, benzaldehyde, acetic acid, and acetone were selected as representative VOCs in the exhaled breath during the COVID-19 infection. Computational docking and prediction tools were utilized for OBPs peptide characterization and analysis. Multiple parameters, including the docking model, binding affinity, sequence specification, and structural folding, were investigated. The results demonstrated a rational, rapid, and efficient approach for designing breath-borne VOC-recognition peptides, which could further improve the biosensor performance for pioneering COVID-19 screening and many other applications. [ABSTRACT FROM AUTHOR]

Malaria vector mosquito species rely on a handful of specific pheromones for mating; one of them, sulcatone (6-methyl-5-hepten-2-one), is also found in human exudation. Therefore, a complete understanding of the insect's olfaction, and rapid real-time methods for odorant detection, are required. Here, we mimic the odorant recognition of the nerve cells of an insect's antenna with a synthetic graphene-based bio-electro-interfacial odorant receptor. By this means, we obtain the kinetics of the genuine odorant recognition reaction and compare them to electro-antennogram data that represent the more complex scenario of a living insect. The odorant-binding proteins OBP 9A and 9B only associate with their ligands weakly, showing KDs of between 2.1 mM and 3 mM, while the binding kinetics of OBP proteins depend on the structural feature of a cystine knot and are modulated by the local milieu within a protein-aided enhancement zone. [ABSTRACT FROM AUTHOR]

Cotesia ruficrus presents a promising local natural enemy for controlling the invasive fall armyworm Spodoptera frugiperda in China. However, the mechanisms underlying how C. ruficrus locates its target pest remain unclear. In this study, we analyzed the expression patterns of 18 CrufOBPs across different developmental stages of C. ruficrus , and found that CrufOBP1 exhibited consistent and high expression levels in female adults. CrufOBP1 transcript was predominantly localized in sensilla placodea and sensilla trichodea on the antennae. Additionally, we confirmed the binding properties of CrufOBP1 protein to various cuticular compounds of S. frugiperda larvae. Subsequent electroantennogram and behavioral assays revealed that 1-(2-hydroxy-5-methylphenyl)-ethanone attracted female C. ruficrus , consequently increased the parasitism rate. However, upon silencing CrufOBP1 , females exhibited reduced attraction towards 1-(2-hydroxy-5-methylphenyl)-ethanone, indicating the crucial role of CrufOBP1 in the chemoreception of C. ruficrus. These findings shed light on the kairomone-based mechanism employed by C. ruficrus to locate S. frugiperda larvae and hold a promise for the development of environmentally friendly pest management strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

Odorant-binding proteins (OBPs) play key roles in host plant location by insects, and can accordingly serve as important targets for the development of attractants. In this study, we detected the high expression of SlitOBP34 in male antennae of Spodoptera litura. Subsequently, the fluorescence competitive binding experiments displayed that the SlitOBP34 protein has binding affinity for different ligands. Then, protein-ligand interaction analyses found the presence of six amino acid residues may serve as key recognition sites. Further electroantennographic and biobehavioral assessments revealed that the electrophysiological responses of male antennae were evoked in response to stimulation with the six identified host volatiles, and that these volatiles attracted male moths to varying extents. Notably, low concentrations of benzaldehyde, 1-hexanol, and cis -3-hexenyl acetate were found to have significant attractant effects on male moths, thereby identifying these three host volatiles as potential candidates for the development of male attractants. These findings advance our current understanding of the olfactory-encoded mechanisms of host plants selection in S. litura and have enabled us to develop novel adult attractants for controlling the pest in the future. [Display omitted] • The expression of SlitOBP34 was antenna-predominant and male-biased. • SlitOBP34 had binding affinity to three sex pheromones and six host volatiles. • Six residues participate in the interaction between SlitOBP34 and different ligands. • The six host volatiles could elicit electrophysiological response in male. • Three host volatiles have great potential for the development of male attractants. [ABSTRACT FROM AUTHOR]

Chemosensory genes play important roles in insect behaviors and have thus become potential molecular targets for pest control based on the manipulation of chemoreception-driven behaviors. The great gray weevil Sympiezomias velatus (Chevrolat) (Coleoptera: Curculionidae) is an important agricultural pest that causes serious economic losses to many crops in China, but its chemosensory genes have not been reported. Here we assembled the antennal transcriptomes of female and male adult S. velatus and revealed the major chemosensory genes necessary for olfaction. A total of 138 candidate chemosensory genes in six families were identified, including 41 encoding odorant-binding proteins (OBPs), 11 encoding chemosensory proteins (CSPs), 62 encoding odorant receptors (ORs), 15 encoding gustatory receptors (GRs), six encoding ionotropic receptors (IRs), and three encoding sensory neuron membrane proteins (SNMPs). We analyzed their phylogenetic relationship based on the amino acid sequences of these chemosensory-related protein families in S. velatus and other insects, and the expression profiles based on their antennal transcriptomes. Chemosensory genes that show antenna-abundant/specific or sex-biased expression were observed, suggesting that these genes might have functions in olfaction. Furthermore, we chose an antenna-abundant OBP belonging to ABPX subfamily, SvelOBP15, to investigate its binding property. The results showed that among 33 tested compounds, SvelOBP15 displayed high binding affinities (Ki = 7.36–12.94 μmol/L) with farnesol, nerolidol, limonene and diisobutyl phthalate, indicating that SvelOBP15 plays olfactory roles by binding and transporting specific plant volatiles. These findings will help us better understand the olfactory systems of S. velatus , and provide a basis for functional elucidation of these chemosensory genes. [ABSTRACT FROM AUTHOR]

Odorant-binding proteins (OBPs) play essential roles in the functioning of insect peripheral olfactory systems. To fully understand the olfactory roles of OBPs in Halyomorpha halys , an important invasive pest found worldwide, we studied the expression and functional characterization of five OBP-associated genes from H. halys that are clustered in the genome. The tissue distribution of the OBP gene cluster suggests that these genes were enriched in nymph and adult antennae, indicating their possible involvement in the chemosensory process. The different expression levels of the five OBPs in nymph and adult antennae suggest that this gene cluster is regulated independently. Ligand-binding experiments have shown similar specificities of these five OBPs towards several organic compounds, including the alarm pheromone of H. halys (trans -2-decenal), the aggregation pheromone of Plautia stali (methyl (2 E , 4 E , 6 Z)-decatrienoate), and plant volatile compounds (e.g., cis -3-hexenyl benzoate and β-ionone). In particular, trans -2-dodecenal, an alarm pheromone analog, exhibited high affinity to the five OBP proteins and alarm pheromone activity towards H. halys. Thus, this OBP cluster may mediate the response of stink bugs to the both the alarm pheromone and host-related volatiles and could be an interesting target to design novel olfactory regulators for the management of H. halys infestations. • The five clustered HhalOBPs were abundantly expressed in the antennae of Halyomorpha halys. • All five clustered HhalOBPs showed similar binding specificities. • The five HhalOBPs displayed high bindings to both the alarm pheromone and host-related volatiles. • trans -2-Dodecenal exhibited alarm pheromone activity towards H. halys. [ABSTRACT FROM AUTHOR]

As a quarantine pest of conifer, Sirex noctilio has caused widespread harm around the world. It is expected that the molecular mechanism of protein–ligand binding can be elucidated to carry out the pest control. Through studies of SnocOBP12–ligand hydrophobic binding and dynamics and responsible amino acid residues identification, we got some promising results. SnocOBP12 had a general and excellent affinity for host plant volatiles, and may be a key protein for S. noctilio to find host plants. Among the many odor molecules that are bound to SnocOBP12, (−)-α-cedrene and (E)-β-farnesene from host plants and (−)-globuol from the symbiotic fungi of Sirex noctilio stood out and formed highly stable complexes with SnocOBP12. By the molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) method, the calculated free binding energy of the three complexes was −30.572 ± 0.101 kcal/mol, −28.349 ± 0.119 kcal/mol and −25.244 ± 0.152 kcal/mol, respectively. It was found that the van der Waals energy contributed to the stability of the complexes. Some key amino acid residues were also found: LEU74 and TYR109 were very important for SnocOBP12 to stably bind (−)-α-cedrene, while for (E)-β-farnesene, ILE6, MET10, and LEU74 were very important for the stable binding system. We discovered three potential ligands and analyzed the interaction pattern of the protein with them, this paper provides a favorable molecular basis for optimizing the attractant formulation. Investigation of the binding characteristics in the olfactory system at the molecular level is helpful to understand the behavior of S. noctilio and develop new methods for more effective and environmentally friendly pest control. [ABSTRACT FROM AUTHOR]

Iseropus (Gregopimpla) kuwanae Vlereck (Hymenoptera: Ichneumonidae) is an ectoparasitoid wasp that attacks the larvae of Rondotia menciana Moore (Lepidoptera: Bombycidae), which is a major pest harming mulberry trees in China. In this study, we obtained the antennal transcriptome dataset of I. kuwanae using RNA‐Seq technology. A total of 22,090,144 clean reads were generated, and 21,802 unigenes were assembled. Among them, 11,546 (52.96%) unigenes were matched in the NCBI non‐redundant protein database (E‐value of 10−5). Moreover, a total of 9,229 (42.33%) and 5,305 (24.33%) unigenes were annotated by Gene Ontology and Clusters of Orthologous Groups of the proteins database respectively. By antennal transcriptome analysis, a total of 122 candidate chemosensory genes were identified, including 11 odorant‐binding protein (OBP) genes, 6 chemosensory protein (CSP) genes, 87 olfactory receptor (OR) genes (including one odorant co‐receptor, Orco), 16 ionotropic receptor genes and two sensory neuron membrane protein genes. RT‐qPCR assays revealed that seven of the 11 IkuwOBPs were predominantly expressed in the antennae of I. kuwanae adults. IkuwOBP4 was highly expressed in the head. IkuwOBP7 and IkuwOBP8 had higher expression levels in the legs. Interestingly, IkuwOBP6 was significantly expressed in both female antennae and ovipositor. The present findings can provide the basis for the subsequent in‐depth exploration of chemosensory mechanisms in I. kuwanae. [ABSTRACT FROM AUTHOR]

Chemosensory genes play important roles in insect behaviors and have thus become potential molecular targets for pest control based on the manipulation of chemoreception-driven behaviors. The great gray weevil Sympiezomias velatus (Chevrolat) (Coleoptera: Curculionidae) is an important agricultural pest that causes serious economic losses to many crops in China, but its chemosensory genes have not been reported. Here we assembled the antennal transcriptomes of female and male adult S. velatus and revealed the major chemosensory genes necessary for olfaction. A total of 138 candidate chemosensory genes in six families were identified, including 41 encoding odorant-binding proteins (OBPs), 11 encoding chemosensory proteins (CSPs), 62 encoding odorant receptors (ORs), 15 encoding gustatory receptors (GRs), six encoding ionotropic receptors (IRs), and three encoding sensory neuron membrane proteins (SNMPs). We analyzed their phylogenetic relationship based on the amino acid sequences of these chemosensory-related protein families in S. velatus and other insects, and the expression profiles based on their antennal transcriptomes. Chemosensory genes that show antenna-abundant/specific or sex-biased expression were observed, suggesting that these genes might have functions in olfaction. Furthermore, we chose an antenna-abundant OBP belonging to ABPX subfamily, SvelOBP15, to investigate its binding property. The results showed that among 33 tested compounds, SvelOBP15 displayed high binding affinities (Ki = 7.36–12.94 μmol/L) with farnesol, nerolidol, limonene and diisobutyl phthalate, indicating that SvelOBP15 plays olfactory roles by binding and transporting specific plant volatiles. These findings will help us better understand the olfactory systems of S. velatus, and provide a basis for functional elucidation of these chemosensory genes.

[Objective] The dorant-binding protein (OBP) and chemosensoiy protein (CSP) in mustard aphid ( including Myzus persicae, Brevicoryne brassicae and l.ipaphis erysimi) are compared and analyzed from gene sequences and structure, which provides reference for relative research and application of odor recognition and chemosensoiy of mustard aphid. [Method] Based on the public transcriptome data, OBP genes and CSP genes of B. brassicae and L. erysimi were identified using local BLAST, multiple sequence alignment, analysis of conserved cysteine sequences, phylogenetic tree analysis and homology modeling of protein 3 D structures. [Result] 12 OBP genes and 8 CSP genes were identified from B. brassicae, 12 OBP genes and 12 CSP genes are identified from L. erysimi. By sequences comparison and phylogenetic tree, the similarity of orthologous gene in mustard aphid (including M. persicae, B. brassicae and L. erysimi) was high, but differentiation of OBP gene and CSP gene was obvious. By onserved cysteine sequences,the OBP14,0BP7-12 and OBP14-17 in mustard aphid all belong to Classic OBP subfamily, while OBPS and OBP6 belong to Plus-C OBP subfamily, and the cysteine sequences of aphid CSPs were much conserved. Analysis of motif patterns also show that the aphids CSPs were much more conserved than the aphids OBPs. Homology modeling showed that 3D structures of OBP3 proteins of Acyrthosiphon pisum and three mustard aphids were much similar. [Conclusion] The present study find that there are some differences in the number and sequence characteristics between the OBP genes and CSP genes of the three mustard aphids, but the orthologous gene represents conservative. [ABSTRACT FROM AUTHOR]

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Pheromonal communication is widespread among living organisms, but in apes and particularly in humans there is currently no strong evidence for such phenomenon. Among primates, lemurs use pheromones to communicate within members of the same species, whereas in some monkeys such capabilities seem to be lost. Chemical communication in humans appears to be impaired by the lack or malfunctioning of biochemical tools and anatomical structures mediating detection of pheromones. Here, we report on a pheromone-carrier protein (SAL) adopting a "reverse chemical ecology" approach to get insights on the structures of potential pheromones in a representative species of lemurs (Microcebus murinus) known to use pheromones, Old-World monkeys (Cercocebus atys) for which chemical communication has been observed, and humans (Homo sapiens), where pheromones and chemical communication are still questioned. We have expressed the SAL orthologous proteins of these primate species, after reconstructing the gene encoding the human SAL, which is disrupted due to a single base mutation preventing its translation into RNA. Ligand-binding experiments with the recombinant SALs revealed macrocyclic ketones and lactones as the best ligands for all three proteins, suggesting cyclopentadecanone, pentadecanolide, and closely related compounds as the best candidates for potential pheromones. Such hypothesis agrees with the presence of a chemical very similar to hexadecanolide in the gland secretions of Mandrillus sphinx , a species closely related to C. atys. Our results indicate that the function of this carrier protein has not changed much during evolution from lemurs to humans, although its physiological role has been certainly impaired in humans. [ABSTRACT FROM AUTHOR]

BACKGROUND Athetis lepigone, a noctuid moth feeding on more than 30 different crops worldwide, has evolved a sophisticated, sensitive, and specific chemosensory system to detect and discriminate exogenous chemicals. Odorant‐binding proteins (OBPs) are the most important agent in insect chemosensory systems to be explored as an alternative target for environmentally friendly approaches to pest management. RESULTS: To investigate the olfactory function of A. lepigone OBPs (AlepOBPs), AlepOBP6 was identified and expressed in Escherichia coli. The binding affinity of the recombinant OBP to 20 different ligands was then examined using a competitive binding approach. The results revealed that AlepOBP6 can bind to two sex pheromones and ten maize volatiles, and its conformation stability is pH dependent. We also carried out a structure–function study using different molecular approaches, including structure modeling, molecular docking, and a mutation functional assay to identify amino acid residues (M39, V68, W106, Q107, and Y114) involved in the binding of AlepOBP6 to both sex pheromones and maize volatiles in A. lepigone. CONCLUSION: These results suggest that AlepOBP6 is likely involved in mediating the responses of A. lepigone to sex pheromones and maize volatiles, which may play a pivotal function in mating, feeding, and oviposition behaviors. This study not only provides new insight into the binding mechanism of OBPs to sex pheromones and host volatiles in moths, but also contributes to the discovery of novel target candidates for developing efficient behavior disruptors to control A. lepigone in the future. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Odorant-binding proteins (OBPs) are small, water-soluble, globular, and ligand-specific proteins found in the sensillar lymph in insects and mucus layer in vertebrates. They function as a carrier for transferring odorants to their respective olfactory receptors. However, the functionality and expression of OBPs are not limited to olfaction mechanism and olfactory organs. OBPs are involved in various other functions like measuring odorant concentration and deactivating odorants. They are found in insect taste organs, venom glands, and sex hormone glands. To gain more insight into the functioning and expression pattern of OBPs, it has become essential to identify OBP sequences. The available OBP prediction methods are primarily based on sequence similarity, which seems inefficient since OBPs share low interspecies and intraspecies sequence similarities. Effective representation of protein sequence-based features is essential for the development of predictive models. Single feature representation like physicochemical properties and secondary structure content (PCSS), amino acid composition (AAC), and sequence graph transform may be insufficient. Therefore, we propose two feature combination schemes: feature fusion and feature concatenation, for OBP prediction. The role of conventional machine learning algorithms and deep learning algorithms have not been explored much for identifying OBP sequences. The performance metrics suggest the feature fusion scheme enhances the overall performance of the OBP prediction classifiers. Deep networks yield better accuracy as compared to traditional Machine learning algorithms. The performance of the deep neural network and one-dimensional convolution neural network was found to be comparative. Among all feature representation schemes, the feature fusion scheme with AAC + PCSS gave the best performance. The accuracy of deep neural network and convolutional neural network-1D for AAC + PCSS representation was found to be 98.6% and 96.5%, respectively. We propose OBPred, a deep neural network model with the fused ACC + PCSS feature set, for OBP identification. The current study is the first attempt, to our knowledge, to predict OBPs using deep neural networks. [ABSTRACT FROM AUTHOR]

Olfaction is of great significance for insect mate-seeking and host-locating behaviors. Insect odorant-binding proteins (OBPs), especially those antenna-enriched OBPs, are thought to discriminate, capture and transport odorant molecules to olfactory receptors, but this has not been fully clarified in Bactrocera minax (Enderlein), an economically important pest of citrus crops. Our previous studies showed that seven OBP genes (BminOBP1 - 7) were identified from B. minax adults via a head transcriptome analysis, of which only BminOBP3 and 6 were highly expressed in antennae, suggesting an olfactory role. To confirm their functions, here, BminOBP3 and 6 were cloned, expressed in Escherichia coli cells. Binding properties of the recombinant BminOBPs with 13 volatiles, most of which can elicit a significant behavioral response from B. minax adults, were determined by fluorescent competitive binding assays. The results showed that Both BminOBP3 and 6 exhibited a remarkable selectivity towards the 13 ligands tested. BminOBP3 displayed strong binding affinity only with undecanol. BminOBP6 demonstrated strong binding affinity with undecanol and limonene among 13 ligands tested. Undecanol is believed to be main sex pheromone component of B. minax. Limonene is an important volatile compound enriched in citrus fruits. Taken together, we concluded that BminOBP3 and 6 may play a prominent role in the process of B. minax mate-seeking and host-locating behaviors through recognizing and transporting these volatiles. It is conceivable that this study will increase our molecular understanding of B. minax olfaction, facilitating the development of OBP-based behavioral interference that is potentially useful for the integrated management of B. minax. [ABSTRACT FROM AUTHOR]

Odorant-binding proteins (OBPs) are abundant soluble proteins secreted in the nasal mucus of a variety of species that are believed to be involved in the transport of odorants toward olfactory receptors. In this study, we report the functional characterization of mouse OBP5 (mOBP5). mOBP5 was recombinantly expressed as a hexahistidine-tagged protein in bacteria and purified using metal affinity chromatography. The oligomeric state and secondary structure composition of mOBP5 were investigated using gel filtration and circular dichroism spectroscopy. Fluorescent experiments revealed that mOBP5 interacts with the fluorescent probe N-phenyl naphthylamine (NPN) with micromolar affinity. Competitive binding experiments with 40 odorants indicated that mOBP5 binds a restricted number of odorants with good affinity. Isothermal titration calorimetry (ITC) confirmed that mOBP5 binds these compounds with association constants in the low micromolar range. Finally, protein homology modeling and molecular docking analysis indicated the amino acid residues of mOBP5 that determine its binding properties.

The greater wax moth, Galleria mellonella (Linnaeus, 1758), is a notorious pest of honey bee colonies that has negatively affected the global apicultural industry. Olfactory cues influence the behavior of wax moth, where males attract females, making them an ideal candidate for pheromone studies. However, the molecular mechanism of chemoreception in G. mellonella pertaining to sex pheromone recognition has not been elucidated. In this study, transcriptome sequencing was conducted on the antennae of male and female greater wax moths to assess the differential expression patterns of chemosensory genes and better understand the underlying olfactory mechanism. In the results, a total of 121 chemosensory gene transcripts were identified, including 37 odorant-binding proteins, 35 chemosensory proteins, 33 olfactory receptors, 14 ionotropic receptors and 2 sensory neuron membrane proteins. The expression patterns of these genes were determined using the estimated fragments per kilobase of transcript per million fragments mapped. Among the 114 DEGs, 66 were expressed exclusively in the female antennae, whereas the remaining were expressed predominantly in the male antennae. Additionally, five chemosensory-related genes (OBP69alike, OBP72-like, CSP7, CSP10 and OR29) were differentially expressed between the two samples. In conclusion, the study lay a foundation for understanding the olfactory functions of chemosensory genes in G. mellonella, which can help to control and prevent the damage caused by this pest. [ABSTRACT FROM AUTHOR]

Major evolutionary transitions were always accompanied by genetic remodelling of phenotypic traits. For example, the vertebrate transition from water to land was accompanied by rapid evolution of olfactory receptors and by the expansion of genes encoding lipocalins, which – due to their transporting functions – represent an important interface between the external and internal organic world of an individual and also within an individual. Similarly, some lipocalin genes were lost along other genes when this transition went in the opposite direction leading, for example, to cetaceans. In terrestrial vertebrates, lipocalins are involved in the transport of lipophilic substances, chemical signalling, odour reception, antimicrobial defence and background odour clearance during ventilation. Many ancestral lipocalins have clear physiological functions across the vertebrate taxa while many other have – due to pleiotropic effects of their genes – multiple or complementary functions within the body homeostasis and development. The aim of this review is to deconstruct the physiological functions of lipocalins in light of current OMICs techniques. We concentrated on major findings in the house mouse in comparison to other model taxa (e.g., voles, humans, and birds) in which all or most coding genes within their genomes were repeatedly sequenced and their annotations are sufficiently informative. [ABSTRACT FROM AUTHOR]

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As potential molecular targets for developing novel pest management strategies, odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) have been considered to initiate odor recognition in insects. Herein, we investigated the OBPs and CSPs in a major global crop pest (Spodoptera exempta). Using transcriptome analysis, we identified 40 OBPs and 33 CSPs in S. exempta, among which 35 OBPs and 29 CSPs had intact open reading frames. Sequence alignment indicated that 30 OBPs and 23 CSPs completely contained the conserved cysteines. OBPs of lepidopteran insects usually belonged to classical, minus-C, and plus-C groups. However, phylogenetic analyses indicated that we only identified 28 classical and seven minus-C OBPs in S. exempta, suggesting that we might have missed some typical OBPs in lepidopteran insects, probably due to their low expression levels. All of the CSPs from S. exempta clustered with the orthologs of other moths. The identification and expression of the OBPs and CSPs were well studied in insect adults by transcriptional analyses, and herein we used samples at different stages to determine the expression of OBPs and CSPs in S. exempta. Interestingly, our data indicated that several OBPs and CSPs were especially or more highly expressed in larvae or pupae than other stages, including three exclusively (SexeOBP13, SexeOBP16 and SexeCSP23) and six more highly (SexeOBP15, SexeOBP37, SexeCSP4, SexeCSP8, SexeCSP19, and SexeCSP33) expressed in larvae, two exclusively (SexeCSP6 and SexeCSP20) and three more highly (SexeOBP18, SexeCSP17, and SexeCSP26) expressed in pupae. Usually, OBPs and CSPs had both male- and female-biased expression patterns in adult antennae. However, our whole-body data indicated that all highly expressed OBPs and CSPs in adults were male-biased or did not differ, suggesting diverse OBP and CSP functions in insect adults. Besides identifying OBPs and CSPs as well as their expression patterns, these results provide a molecular basis to facilitate functional studies of OBPs and CSPs for exploring novel management strategies to control S. exempta. [ABSTRACT FROM AUTHOR]

Major evolutionary transitions were always accompanied by genetic remodelling of phenotypic traits. For example, the vertebrate transition from water to land was accompanied by rapid evolution of olfactory receptors and by the expansion of genes encoding lipocalins, which – due to their transporting functions – represent an important interface between the external and internal organic world of an individual and also within an individual. Similarly, some lipocalin genes were lost along other genes when this transition went in the opposite direction leading, for example, to cetaceans. In terrestrial vertebrates, lipocalins are involved in the transport of lipophilic substances, chemical signalling, odour reception, antimicrobial defence and background odour clearance during ventilation. Many ancestral lipocalins have clear physiological functions across the vertebrate taxa while many other have – due to pleiotropic effects of their genes – multiple or complementary functions within the body homeostasis and development. The aim of this review is to deconstruct the physiological functions of lipocalins in light of current OMICs techniques. We concentrated on major findings in the house mouse in comparison to other model taxa (e.g., voles, humans, and birds) in which all or most coding genes within their genomes were repeatedly sequenced and their annotations are sufficiently informative.

Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) play a fundamental role in insect olfaction. Galeruca daurica (Joannis) is a new pest with outbreak status in the Inner Mongolia grasslands, northern China. In this study, six olfactory protein genes (GdauOBP1, GdauOBP6, GdauOBP10, GdauOBP15, GdauCSP4, and GdauCSP5) were cloned by RACE and expressed by constructing a prokaryotic expression system. Their binding affinities to 13 compounds from host volatiles (Allium mongolicum) were determined by fluorescence-binding assay. In order to further explore the olfactory functions of GdauOBP15 and GdauCSP5, RNA interference (RNAi) and electroantennogram (EAG) experiments were conducted. Ligand-binding assays showed that the binding properties of the six recombinant proteins to the tested volatiles were different. GdauOBP6, GdauOBP15, GdauCSP4, and GdauCSP5 could bind several tested ligands of host plants. It was suspected that GdauOBP6, GdauOBP15, GdauCSP4, and GdauCSP5 were related to the host location in G. daurica. We also found that there were different EAG responses between males and females when the GdauOBP15 and GdauCSP5 genes were silenced by RNAi. The EAG response of G. daurica females to 2-hexenal was significantly decreased in dsRNA-OBP15-injected treatment compared to the control, and the dsRNA-CSP5-treated females significantly reduced EAG response to eight tested host volatiles (1,3-dithiane, 2-hexenal, methyl benzoate, dimethyl trisulfide, myrcene, hexanal, 1,3,5-cycloheptatriene, and p-xylene). However, the EAG response had no significant difference in males. Both GdauOBP15 and GdauCSP5 may have different functions between males and females in G. daurica and may play more important roles in females searching for host plants.

Odorant-binding proteins (OBPs) capture and transport semiochemicals to olfactory receptors (OR) and function in the first step in insect olfaction. In the present study, we cloned a full-length cDNA sequence of BodoOBP5 from the insect pest Bradysia odoriphaga (Diptera: Sciaridae). Real-time PCR (qRT-PCR) analysis revealed that BodoOBP5 was expressed at higher levels in female adults than in other developmental stages. In the different tissues, BodoOBP5 was highly expressed in the female antennae, whereas low levels were expressed in the head and the male antennae, expression was negligible in other tissues. The recombinant protein of BodoOBP5 was successfully expressed with a bacterial system. Competitive binding assays with nine host plant volatiles and a putative sex pheromone revealed that purified BodoOBP5 strongly bound to two sulfur compounds (methyl allyl disulfide and diallyl disulfide); the corresponding dissolution constants (Ki) were 10.38 and 9.23 μM, respectively. Molecular docking indicated that Leu99, Leu103, Ala143, Tyr107, Phe142, and Trp144 in the hydrophobic cavity of BodoOBP5 are the key residues mediating the interaction of BodoOBP5 with methyl allyl disulfide and diallyl disulfide. RNAi-based Y-tube olfactometer assay indicated that there is no significant difference in methyl allyl disulfide and diallyl disulfide. The results of this study increase our understanding of the binding of BodoOBP5 with plant volatiles, facilitating the development of novel ways to control B. odoriphaga. [ABSTRACT FROM AUTHOR]