Neuron Membrane Proteins Research Articles

Structural and functional mechanisms of anti-NMDAR autoimmune encephalitis.

Autoantibodies against neuronal membrane proteins can manifest in autoimmune encephalitis, inducing seizures, cognitive dysfunction and psychosis. Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most dominant autoimmune encephalitis; however, insights into how autoantibodies recognize and alter receptor functions remain limited. Here we determined structures of human and rat NMDARs bound to three distinct patient-derived antibodies using single-particle electron cryo-microscopy. These antibodies bind different regions within the amino-terminal domain of the GluN1 subunit. Through electrophysiology, we show that all three autoantibodies acutely and directly reduced NMDAR channel functions in primary neurons. Antibodies show different stoichiometry of binding and antibody-receptor complex formation, which in one antibody, 003-102, also results in reduced synaptic localization of NMDARs. These studies demonstrate mechanisms of diverse epitope recognition and direct channel regulation of anti-NMDAR autoantibodies underlying autoimmune encephalitis.

Antennal Transcriptome Screening and Identification of Chemosensory Proteins in the Double-Spine European Spruce Bark Beetle, Ips duplicatus (Coleoptera: Scolytinae).

The northern bark beetle, Ips duplicatus, is an emerging economic pest, reportedly infesting various species of spruce (Picea spp.), pine (Pinus spp.), and larch (Larix spp.) in Central Europe. Recent climate changes and inconsistent forest management practices have led to the rapid spread of this species, leaving the current monitoring strategies inefficient. As understanding the molecular components of pheromone detection is key to developing novel control strategies, we generated antennal transcriptomes from males and females of this species and annotated the chemosensory proteins. We identified putative candidates for 69 odorant receptors (ORs), 50 ionotropic receptors (IRs), 25 gustatory receptors (GRs), 27 odorant-binding proteins (OBPs), including a tetramer-OBP, 9 chemosensory proteins (CSPs), and 6 sensory neuron membrane proteins (SNMPs). However, no sex-specific chemosensory genes were detected. The phylogenetic analysis revealed conserved orthology in bark beetle chemosensory proteins, especially with a major forest pest and co-habitant, Ips typographus. Recent large-scale functional studies in I. typographus chemoreceptors add greater significance to the orthologous sequences reported here. Nevertheless, identifying chemosensory genes in I. duplicatus is valuable to understanding the chemosensory system and its evolution in bark beetles (Coleoptera) and, generally, insects.

Sex Differences in Antennal Transcriptome of Hyphantria cunea and Analysis of Odorant Receptor Expression Profiles.

Insects rely on olfaction for mating, finding oviposition sites, and locating hosts. Hyphantria cunea is a serious pest that severely damages forests. Differential expression analysis of olfactory-related genes between males and females is the basis for elucidating the functions of olfactory-related proteins in H. cunea. In this study, Illumina HiSeqTM 4000 high-throughput sequencing technology was used to perform transcriptome sequencing of the antennal tissues of adult male and female H. cunea. Functional annotation was conducted using the NR, Swiss-Prot, KOG, KEGG, and GO databases, and the results showed that the antennal transcriptome of adult H. cunea contained 50,158 unigenes. Differential expression analysis identified 3923 genes that were significantly differentially expressed between male and female antennae. A total of 221 olfactory-related genes were annotated, and 96 sex-biased genes were identified, including 13 odorant receptors (ORs), 48 odorant binding proteins (OBPs), 7 chemosensory proteins (CSPs), 10 ionotropic receptors (IRs), 10 sensory neuron membrane proteins (SNMPs), 2 gustatory receptors (GRs), and 6 odorant-degrading enzymes (ODEs), indicating that there were differences in olfaction between male and female H. cunea. Quantitative real-time PCR was used to verify the expression levels of 21 putative general odorant receptor genes in male and female antennae. HcunOR4 and HcunOR5 showed female-biased expression; HcunOR48, HcunOR49 and HcunOR50 showed male-biased expression. The results were consistent with the transcriptome differential analysis. The screening of male-biased odorant receptor genes might provide a theoretical basis for the functional characterization of odorant receptors for recognizing sex pheromones in H. cunea.

Suppression of the amyloidogenic metabolism of APP and the accumulation of Aβ by alcadein α in the brain during aging

Generation and accumulation of amyloid-β (Aβ) protein in the brain are the primary causes of Alzheimer’s disease (AD). Alcadeins (Alcs composed of Alcα, Alcβ and Alcγ family) are a neuronal membrane protein that is subject to proteolytic processing, as is Aβ protein precursor (APP), by APP secretases. Previous observations suggest that Alcs are involved in the pathophysiology of Alzheimer’s disease (AD). Here, we generated new mouse AppNL-F (APP-KI) lines with either Alcα- or Alcβ-deficient background and analyzed APP processing and Aβ accumulation through the aging process. The Alcα-deficient APP-KI (APP-KI/Alcα-KO) mice enhanced brain Aβ accumulation along with increased amyloidogenic β-site cleavage of APP through the aging process whereas Alcβ-deficient APP-KI (APP-KI/Alcβ-KO) mice neither affected APP metabolism nor Aβ accumulation at any age. More colocalization of APP and BACE1 was observed in the endolysosomal pathway in neurons of APP-KI/Alcα-KO mice compared to APP-KI and APP-KI/Alcβ-KO mice. These results indicate that Alcα plays an important role in the neuroprotective function by suppressing the amyloidogenic cleavage of APP by BACE1 in the brain, which is distinct from the neuroprotective function of Alcβ, in which p3-Alcβ peptides derived from Alcβ restores the viability in neurons impaired by toxic Aβ.

Identification and expression profiles of olfactory-related genes in the antennal transcriptome of Graphosoma rubrolineatum (Hemiptera: Pentatomidae).

Graphosoma rubrolineatum (Hemiptera: Pentatomidae) is an important pest of vegetables and herbs (e.g., Umbelliferae and Cruciferae) in China, Siberia, Korea, and Japan. Insects are highly dependent on their olfactory system to detect odorants. However, no molecular-mediated olfactory genes in G. rubrolineatum have yet been identified. In this study, we first established the antennal transcriptome of G. rubrolineatum and identified 189 candidate olfactory genes, including 31 odorant-binding proteins (OBPs), 15 chemosensory proteins (CSPs), four sensory neuron membrane proteins (SNMPs),94 odorant receptors (ORs), 23 ionotropic receptors (IRs), and 22 gustatory receptors (GRs). Additionally, phylogenetic trees were constructed for olfactory genes between G. rubrolineatum and other hemipteran insects. We also detected the expression profiles of ten OBPs, five CSPs, two SNMPs, five ORs, four IRs, and four GRs by real-time quantitative PCR. The results revealed that most genes (GrubOBP1/11/31, GrubCSP3/8, GrubSNMP1a/1b, GrubOrco/OR9/11/13, GrubGR1/4/22, GrubIR25/75h/76b/GluR1) were highly expressed in the antennae, GrubOBP13/31 and GrubCSP4/11/12 were highly expressed in the legs, while GrubOBP20 and GrubGR19 were highly expressed in the wings. Our results will enrich the gene inventory of G. rubrolineatum and provide further insight into the molecular chemosensory mechanisms of G. rubrolineatum.

Antennal transcriptome analysis reveals sensory receptors potentially associated with host detection in the livestock pest Lucilia cuprina

BackgroundLucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae) is the main causative agent of flystrike of sheep in Australia and New Zealand. Female flies lay eggs in an open wound or natural orifice, and the developing larvae eat the host’s tissues, a condition called myiasis. To improve our understanding of host-seeking behavior, we quantified gene expression in male and female antennae based on their behavior.MethodsA spatial olfactometer was used to evaluate the olfactory response of L. cuprina mated males and gravid females to fresh or rotting beef. Antennal RNA-Seq analysis was used to identify sensory receptors differentially expressed between groups.ResultsLucilia cuprina females were more attracted to rotten compared to fresh beef (> fivefold increase). However, males and some females did not respond to either type of beef. RNA-Seq analysis was performed on antennae dissected from attracted females, non-attracted females and males. Transcripts encoding sensory receptors from 11 gene families were identified above a threshold (≥ 5 transcript per million) including 49 ATP-binding cassette transporters (ABCs), two ammonium transporters (AMTs), 37 odorant receptors (ORs), 16 ionotropic receptors (IRs), 5 gustatory receptors (GRs), 22 odorant-binding proteins (OBPs), 9 CD36-sensory neuron membrane proteins (CD36/SNMPs), 4 chemosensory proteins (CSPs), 4 myeloid lipid-recognition (ML) and Niemann-Pick C2 disease proteins (ML/NPC2), 2 pickpocket receptors (PPKs) and 3 transient receptor potential channels (TRPs). Differential expression analyses identified sex-biased sensory receptors.ConclusionsWe identified sensory receptors that were differentially expressed between the antennae of both sexes and hence may be associated with host detection by female flies. The most promising for future investigations were as follows: an odorant receptor (LcupOR46) which is female-biased in L. cuprina and Cochliomyia hominivorax Coquerel, 1858; an ABC transporter (ABC G23.1) that was the sole sensory receptor upregulated in the antennae of females attracted to rotting beef compared to non-attracted females; a female-biased ammonia transporter (AMT_Rh50), which was previously associated with ammonium detection in Drosophila melanogaster Meigen, 1830. This is the first report suggesting a possible role for ABC transporters in L. cuprina olfaction and potentially in other insects.Graphical

Silencing sensory neuron membrane protein RferSNMPu1 impairs pheromone detection in the invasive Asian Palm Weevil

The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier), also known as the Asian palm weevil, is an invasive pest that causes widespread damage to palm trees around the globe. As pheromone communication is crucial for their mass attack and survival on palm trees, the olfactory concept of pest control strategies has been widely explored recently. We aim to understand the molecular basis of olfaction in RPW by studying one of the key olfactory proteins in insect pheromone communication, sensory neuron membrane proteins (SNMPs). SNMPs belong to the CD36 (cluster of differentiation 36) family that perform two distinct olfactory roles in insects, either in pheromone (odorant) transfer to the odorant receptors (SNMP1) or in the pheromone clearing process (SNMP2). In this study, we performed antennal transcriptomic screening and identified six SNMPs, mapping them on the R. ferrugineus genome, and confirmed four distinct SNMPs. Both SNMP1 proteins in RPW, viz., RferSNMPu1 and RferSNMPu2, were mapped onto the same scaffold in different loci in the RPW genome. To further understand the function of these proteins, we first classified them using phylogenetic analysis and checked their tissue-specific expression patterns. Further, we measured the relative transcript abundance of SNMPs in laboratory-reared, field-collected adults and pheromone-exposure experiments, ultimately identifying RferSNMPu1 as a potential candidate for functional analysis. We mapped RferSNMPu1 expression in the antennae and found that expression patterns were similar in both sexes. We used RNAi-based gene silencing to knockdown RferSNMPu1 and tested the changes in the RPW responses to aggregation pheromone compounds, 4-methyl-5-nonanol (ferrugineol) and 4-methyl-5-nonanone (ferrugineone), and a kairomone, ethyl acetate using electroantennogram (EAG) recordings. We found a significant reduction in the EAG recordings in the RferSNMPu1 knockdown strain of adult RPWs, confirming its potential role in pheromone detection. The structural modelling revealed the key domains in the RferSNMPu1 structure, which could likely be involved in pheromone detection based on the identified ectodomain tunnels. Our studies on RferSNMPu1 with a putative role in pheromone detection provide valuable insight into understanding the olfaction in R. ferrugineus as well as in other Curculionids, as SNMPs are under-explored in terms of its functional role in insect olfaction. Most importantly, RferSNMPu1 can be used as a potential target for the olfactory communication disruption in the R. ferrugineus control strategies.

SNMP1 is critical for sensitive detection of the desert locust aromatic courtship inhibition pheromone phenylacetonitrile

BackgroundAccurate detection of pheromones is crucial for chemical communication and reproduction in insects. In holometabolous flies and moths, the sensory neuron membrane protein 1 (SNMP1) is essential for detecting long-chain aliphatic pheromones by olfactory neurons. However, its function in hemimetabolous insects and its role for detecting pheromones of a different chemical nature remain elusive. Therefore, we investigated the relevance of SNMP1 for pheromone detection in a hemimetabolous insect pest of considerable economic importance, the desert locust Schistocerca gregaria, which moreover employs the aromatic pheromone phenylacetonitrile (PAN) to govern reproductive behaviors.ResultsEmploying CRISPR/Cas-mediated gene editing, a mutant locust line lacking functional SNMP1 was established. In electroantennography experiments and single sensillum recordings, we found significantly decreased electrical responses to PAN in SNMP1-deficient (SNMP1−/−) locusts. Moreover, calcium imaging in the antennal lobe of the brain revealed a substantially reduced activation of projection neurons in SNMP1−/− individuals upon exposure to PAN, indicating that the diminished antennal responsiveness to PAN in mutants affects pheromone-evoked neuronal activity in the brain. Furthermore, in behavioral experiments, PAN-induced effects on pairing and mate choice were altered in SNMP1−/− locusts.ConclusionsOur findings emphasize the importance of SNMP1 for chemical communication in a hemimetabolous insect pest. Moreover, they show that SNMP1 plays a crucial role in pheromone detection that goes beyond long-chain aliphatic substances and includes aromatic compounds controlling reproductive behaviors.

Transcriptome and differential expression analysis of chemosensory genes in the antennae and heads of Apis cerana cerana drones

The olfactory system plays a critical role in honey bee adaptation to complex and constantly changing environments, as well as in the maintenance of social cohesion. Honey bees have evolved a sophisticated chemical communication system to regulate their intricate social interactions. Despite there is a preliminary understanding of the components, cells, and physiological pathways involved in pheromone response, the molecular mechanisms underlying honey bee drones’ mating behavior and pheromone communication remain largely unknown. This study presented the first comprehensive transcriptome analysis of the antennae and heads of Apis cerana cerana drones in response to 9-ODA. Based on gene ontology and KEGG pathway, we found the majority of differentially expressed genes associated with molecular functions and signal transduction. Additionally, we identified 153 genes closely related to olfaction in the transcriptome datasets, including 111 odorant receptors (ORs), 16 odorant-binding proteins (OBPs), nine ionotropic receptors (IRs), 10 gustatory receptors (GRs), five chemosensory proteins (CSPs), and two sensory neuron membrane proteins (SNMPs), and most of them showed relatively high expression levels in the drone antennae. The reliability of these differential genes was validated using RT-qPCR. Our results will contribute to detect the molecular mechanisms of odorant and investigate olfactory functions in the Asian honey bees.

Identification of chemosensory genes and antennal sensilla in Nassophasis sp. (Coleoptera: Rhynchophorinae)

Phytophagous insects rely on plant volatiles to select and locate hosts for feeding or reproduction and their olfactory system is essential for detecting plant volatiles. The stem-boring pest, Nassophasis sp. damages Dendrobium and causes economic losses. Currently, there are no effective methods for its control. However, understanding the morphological and molecular basis of its olfactory system may identify new pathways for their management and control. In this study, we observed the stemborer's antennal sensilla using scanning electron microscopy, and transcriptome sequencing was undertaken to annotate and analyze its chemosensory genes. Results showed that the antennal morphology is similar between males and females, with five types of antennal sensilla observed: sensilla chaetica (SC), sensilla trichodea (ST), sensilla brush (SB), sensilla basiconica (SBA) and sensilla gemmiformium (SG). Sexual dimorphism was not observed in sensilla type, but in the length of SBA and SG. A total of 70 olfactory-related genes were annotated, including 16 odorant binding proteins (OBP), 5 chemosensory proteins (CSPs), 26 olfactory receptors (ORs), 9 gustatory receptors (GRs), 10 ionotropic receptors (IRs), and 4 sensory neuron membrane proteins (SNMPs). Most genes were highly expressed and 14 of these genes were only expressed in the head, and 7 genes in the abdomen. This study provides a theoretical basis for the olfactory perception of Nassophasis sp. and a scientific basis for developing new pest control strategies.

Real-time imaging of axonal membrane protein life cycles.

The construction of neuronal membranes is a dynamic process involving the biogenesis, vesicular packaging, transport, insertion and recycling of membrane proteins. Optical imaging is well suited for the study of protein spatial organization and transport. However, various shortcomings of existing imaging techniques have prevented the study of specific types of proteins and cellular processes. Here we describe strategies for protein tagging and labeling, cell culture and microscopy that enable the real-time imaging of axonal membrane protein trafficking and subcellular distribution as they progress through some stages of their life cycle. First, we describe a process for engineering membrane proteins with extracellular self-labeling tags (either HaloTag or SNAPTag), which can be labeled with fluorescent ligands of various colors and cell permeability, providing flexibility for investigating the trafficking and spatiotemporal regulation of multiple membrane proteins in neuronal compartments. Next, we detail the dissection, transfection and culture of dorsal root ganglion sensory neurons in microfluidic chambers, which physically compartmentalizes cell bodies and distal axons. Finally, we describe four labeling and imaging procedures that utilize these enzymatically tagged proteins, flexible fluorescent labels and compartmentalized neuronal cultures to study axonal membrane protein anterograde and retrograde transport, the cotransport of multiple proteins, protein subcellular localization, exocytosis and endocytosis. Additionally, we generated open-source software for analyzing the imaging data in a high throughput manner. The experimental and analysis workflows provide an approach for studying the dynamics of neuronal membrane protein homeostasis, addressing longstanding challenges in this area. The protocol requires 5-7 days and expertise in cell culture and microscopy.

Candidate membrane protein gene families related to chemoreception in a wood-boring beetle, Pharsalia antennata Gahan (Coleoptera: Cerambycidae)

The longhorned beetles are key players for the maintenance of biodiversity in the terrestrial ecosystem. As xylophagous cerambycid insects in Coleoptera, the beetles have evolved specialized olfactory and gustatory systems to recognize chemical cues in the surrounding habitats. Despite over 36,000 described species in the Cerambycidae family including a wood-boring pest Pharsalia antennata, only a limited number of them (<1 %) have been characterized regarding their chemical ecology at the molecular level. Here, we surveyed four membrane protein gene families in P. antennata related to chemoreception through transcriptomics, phylogenetics and expression profiling analyses. In total, 144 genes encoding 72 odorant receptors (ORs), 33 gustatory receptors (GRs), 23 ionotropic receptors (IRs), four sensory neuron membrane proteins (SNMPs) and 12 ionotropic glutamate receptors (iGluRs) were harvested from the transcriptome of multiple tissues including antennae and legs of both sexes. The lineage-specific expansion of PantORs possibly implied a diverse range of host plants in this beetle, supporting this correlation between the host range and olfactory receptor repertoire sizes across cerambycid species. Further phylogenetic analysis revealed that Group 2 was contributed mainly to the large OR gene repertoire in P. antennata, representing 18 genes in Group 2A and eight in Group 2B. On the other hand, some key chemosensory genes were identified by applying a phylogenetics approach, such as PantOR21 close to the 2-phenylethanol receptor in Megacyllene caryae, three carbon dioxide GRs and seven Antennal IRs (A-IRs) clades. We also determined sex- and tissue-specific expression profiles of 69 chemosensory genes, revealing the high expression of most PantORs in antennae. Noticeably, 10 sex-biased genes (six PantORs, three PantIRs and PantSNMP1a) were presented in antennae, five sex-biased PantGRs in legs and 39 sex-biased genes (15 PantORs, 13 PantGRs, eight PantIRs and three PantSNMPs) in abdomens. These findings have greatly enhanced our knowledge about the chemical ecology of P. antennata and identify candidate molecular targets for mediating smell and taste of this beetle.

The Neurotranscriptome of Monochamus alternatus.

The Japanese pine sawyer Monochamus alternatus serves as the primary vector for pine wilt disease, a devastating pine disease that poses a significant threat to the sustainable development of forestry in the Eurasian region. Currently, trap devices based on informational compounds have played a crucial role in monitoring and controlling the M. alternatus population. However, the specific proteins within M. alternatus involved in recognizing the aforementioned informational compounds remain largely unclear. To elucidate the spatiotemporal distribution of M. alternatus chemosensory-related genes, this study conducted neural transcriptome analyses to investigate gene expression patterns in different body parts during the feeding and mating stages of both male and female beetles. The results revealed that 15 genes in the gustatory receptor (GR) gene family exhibited high expression in the mouthparts, most genes in the odorant binding protein (OBP) gene family exhibited high expression across all body parts, 22 genes in the odorant receptor (OR) gene family exhibited high expression in the antennae, a significant number of genes in the chemosensory protein (CSP) and sensory neuron membrane protein (SNMP) gene families exhibited high expression in both the mouthparts and antennae, and 30 genes in the ionotropic receptors (IR) gene family were expressed in the antennae. Through co-expression analyses, it was observed that 34 genes in the IR gene family were co-expressed across the four developmental stages. The Antenna IR subfamily and IR8a/Ir25a subfamily exhibited relatively high expression levels in the antennae, while the Kainate subfamily, NMDA subfamily, and Divergent subfamily exhibited predominantly high expression in the facial region. MalIR33 is expressed only during the feeding stage of M. alternatus, the MalIR37 gene exhibits specific expression in male beetles, the MalIR34 gene exhibits specific expression during the feeding stage in male beetles, the MalIR8 and MalIR39 genes exhibit specific expression during the feeding stage in female beetles, and MalIR8 is expressed only during two developmental stages in male beetles and during the mating stage in female beetles. The IR gene family exhibits gene-specific expression in different spatiotemporal contexts, laying the foundation for the subsequent selection of functional genes and facilitating the full utilization of host plant volatiles and insect sex pheromones, thereby enabling the development of more efficient attractants.

Contactin 5 and Apolipoproteins Interplay in Alzheimer's Disease.

Apolipoproteins and contactin 5 are proteins associated with Alzheimer's disease (AD) pathophysiology. Apolipoproteins act on transport and clearance of cholesterol and phospholipids during synaptic turnover and terminal proliferation. Contactin 5 is a neuronal membrane protein involved in key processes of neurodevelopment. To investigate the interactions between contactin 5 and apolipoproteins in AD, and the role of these proteins in response to neuronal damage. Apolipoproteins (measured by Luminex), contactin 5 (measured by Olink's proximity extension assay), and cholesterol (measured by liquid chromatography mass spectrometry) were assessed in the cerebrospinal fluid (CSF) and plasma of cognitively unimpaired participants (n = 93). Gene expression was measured using polymerase chain reaction in the frontal cortex of autopsied-confirmed AD (n = 57) and control subjects (n = 31) and in the hippocampi of mice following entorhinal cortex lesions. Contactin 5 positively correlated with apolipoproteins B (p = 5.4×10-8), D (p = 1.86×10-4), E (p = 2.92×10-9), J (p = 2.65×10-9), and with cholesterol (p = 0.0096) in the CSF, and with cholesterol (p = 0.02), HDL (p = 0.0143), and LDL (p = 0.0121) in the plasma. Negative correlations were seen between CNTN5, APOB (p = 0.034) and APOE (p = 0.015) mRNA levels in the brains of control subjects. In the mouse model, apoe and apoj gene expression increased during the reinnervation phase (p < 0.05), while apob (p = 0.023) and apod (p = 0.006) increased in the deafferentation stage. Extensive interactions were observed between contactin 5 and apolipoproteins and cholesterol, possibly due to neuronal damage. The alterations in gene expression of apolipoproteins suggest a role in axonal, terminal, and synaptic remodeling in response to entorhinal cortex damage.

(Z, Z, Z)-3,6,9-Nonadecadiene, a potential inhibitor of sex pheromone of Grey Tea Geometrid (Lepidoptera: Geometridae): electroantennogram test, wind tunnel, and in silico study.

Sex pheromone analogs have high structural similarity to sex pheromone components. They also play a role in studying many agricultural pests. In our study, (Z, Z, Z)-3,6,9-nonadecadiene (Z3Z6Z9-19:Hy) was successfully synthesized, which is an analogue to 1 of 2 sex pheromone components of Ectropis grisescens Warren (Z, Z, Z)-3,6,9-octadecatriene (Z3Z6Z9-18:Hy), and it showed potential inhibition in experiments. In the electroantennogram test, Z3Z6Z9-19:Hy showed a dose-dependent response, and only measured half the response of Z3Z9-6,7-epo-18:Hy. However, the compound significantly reduced positive response of E. grisescens males by up to 70% in the Y-tube olfactometer. Furthermore, in the wind tunnel, it significantly inhibited all types of behavioral responses. The percentage of moths contacting the pheromone odor source was reduced even at the lowest dose tested. In silico study afterward, molecular docking results showed affinity between Z3Z6Z9-19:Hy and sensory neuron membrane protein 1. Our study revealed the potential of Z3Z6Z9-19:Hy as a sex pheromone inhibitor, which would provide new tools for monitoring and mating disruption of E. grisescens.

Identification and functional characterization of chemosensory genes in olfactory and taste organs of Spodoptera litura (Lepidoptera: Noctuidae).

The tobacco cutworm Spodoptera litura is one of the most destructive polyphagous crop pests. Olfaction and taste play a crucial role in its host plant selection and sexual communication, but the expression profile of chemosensory genes remains unclear. In this study, we identified 185 chemosensory genes from 7 organs in S. litura by transcriptome sequencing, of which 72 genes were published for the first time, including 27 odorant receptors (ORs), 26 gustatory receptors (GRs), 1 ionotropic receptor (IR), 16 odorant-binding proteins (OBPs), and 2 chemosensory proteins (CSPs). Phylogenetic analyses revealed that ORs, IRs, OBPs, and sensory neuron membrane proteins (SNMPs) were mainly expressed in antennae and sequence-conserved among Noctuidae species. The most differentially expressed genes (DEGs) between sexes were ORs and OBPs, and no DEGs were found in GRs. GR transcripts were enriched in proboscis, and the expression of sugar receptors was the highest. Carbon dioxide receptors, sugar receptor-SliuGR6, and bitter GRs-SlituGR43 and SlituGR66 had higher sequence identities between Noctuidae species. CSPs were broadly expressed in various organs, and SlituCSP13 was a DEG in adult antennae. The functional analysis in the Drosophila OR67d expression system found that SlituOR50, a receptor highly expressed in female antennae, is selectively tuned to farnesyl acetate. The results provide a solid foundation for understanding the molecular mechanisms by which chemosensory genes operate to elicit behavioral responses in polyphagous insects.

The CHD Protein Kismet Restricts the Synaptic Localization of Cell Adhesion Molecules at the Drosophila Neuromuscular Junction.

The appropriate expression and localization of cell surface cell adhesion molecules must be tightly regulated for optimal synaptic growth and function. How neuronal plasma membrane proteins, including cell adhesion molecules, cycle between early endosomes and the plasma membrane is poorly understood. Here we show that the Drosophila homolog of the chromatin remodeling enzymes CHD7 and CHD8, Kismet, represses the synaptic levels of several cell adhesion molecules. Neuroligins 1 and 3 and the integrins αPS2 and βPS are increased at kismet mutant synapses but Kismet only directly regulates transcription of neuroligin 2. Kismet may therefore regulate synaptic CAMs indirectly by activating transcription of gene products that promote intracellular vesicle trafficking including endophilin B (endoB) and/or rab11. Knock down of EndoB in all tissues or neurons increases synaptic FasII while knock down of EndoB in kis mutants does not produce an additive increase in FasII. In contrast, neuronal expression of Rab11, which is deficient in kis mutants, leads to a further increase in synaptic FasII in kis mutants. These data support the hypothesis that Kis influences the synaptic localization of FasII by promoting intracellular vesicle trafficking through the early endosome.

Functional characterization of sensory neuron membrane protein 1a involved in sex pheromone detection of Apolygus lucorum (Hemiptera: Miridae)

The mirid bug Apolygus lucorum (Hemiptera: Miridae) is a polyphagous pest that affects a wide range of host plants. Its control remains challenging mainly due to its rapid reproduction, necessitating an understanding of sex pheromone communication. The recognition of sex pheromones is vital for courtship and mating behaviors, and is mediated by various chemosensory-associated proteins. Among these, sensory neuron membrane protein (SNMP), a CD36-related protein, is suggested to play crucial roles in detecting sex pheromones. In this study, we employed transcriptomic and genomic data from A. lucorum and phylogenetic approaches, and identified four putative SNMP genes (AlucSNMP1a, AlucSNMP1b, AlucSNMP2a, and AlucSNMP2b) with full open reading frames. Expression analysis revealed the ubiquitous presence of AlucSNMP transcripts in multiple tissues, with only AlucSNMP1a exhibiting male-biased expression in the antennae, suggesting its potential role in male chemosensation. Functional analysis using the Xenopus oocyte expression system, coupled with two-electrode voltage clamp recording, demonstrated that the co-expression of AlucSNMP1a with specific pheromone receptors (PRs) and the co-receptor (Orco) significantly enhanced electrophysiological responses to sex pheromones compared to the co-expression of PRs and Orco alone. Moreover, the results indicated that the presence of AlucSNMP1a not only affected the responsiveness to sex pheromones but also influenced the kinetics (activation and inactivation) of the induced signals. In contrast, the co-expression of AlucSNMP1b with AlucPR/Orco complexes had no impact on the inward currents induced by two pheromone compounds. An examination of the selective pressures on SNMP1 genes across 20 species indicated strong purifying selection, implying potential functional conservation in various insects. These findings highlight the crucial role of AlucSNMP1a in the response to sex pheromones.

Antennal transcriptome analysis of Psyttalia incisi (silvestri) (Hymenoptera: Braconidae): identification and tissue expression profiling of candidate odorant-binding protein genes.

Olfaction plays an important role in host-seeking by parasitoids, as they can sense chemical signals using sensitive chemosensory systems. Psyttalia incisi (Silvestri) (Hymenoptera: Braconidae) is the dominant parasitoid of Bactrocera dorsalis (Hendel) in fruit-producing regions of southern China. The olfactory behavior of P. incisi has been extensively studied; however, the chemosensory mechanisms of this species are not fully understood. Bioinformatics analysis of 64,515 unigenes from the antennal transcriptome of both male and female adults P. incisi identified 87 candidate chemosensory genes. These included 13 odorant-binding proteins (OBPs), seven gustatory receptors (GRs), 55 odorant receptors (ORs), 10 ionotropic receptors (IRs), and two sensory neuron membrane proteins (SNMPs). Phylogenetic trees were constructed to predict evolutionary relationships between these chemosensory genes in hymenopterans. Moreover, the tissue expression profiles of 13 OBPs were analyzed by quantitative real-time PCR, revealing high expression of seven OBPs (1, 3, 6, 7, 8, 12, and 13) in the antennae. This study represents the first identification of chemosensory genes and the determination of their expression patterns in different tissues of P. incisi. These results contribute to a better understanding of the function of the chemosensory system of this parasitoid species.

Identification of candidate chemosensory genes in Bactrocera cucurbitae based on antennal transcriptome analysis.

The melon fly, Bactrocera cucurbitae (Coquillett) (Tephritidae: Diptera), is an invasive pest that poses a significant threat to agriculture in Africa and other regions. Flies are known to use their olfactory systems to recognise environmental chemical cues. However, the molecular components of the chemosensory system of B. cucurbitae are poorly characterised. To address this knowledge gap, we have used next-generation sequencing to analyse the antenna transcriptomes of sexually immature B. cucurbitae adults. The results have identified 160 potential chemosensory genes, including 35 odourant-binding proteins (OBPs), one chemosensory protein (CSP), three sensory neuron membrane proteins (SNMPs), 70 odourant receptors (ORs), 30 ionotropic receptors (IRs), and 21 gustatory receptors (GRs). Quantitative real-time polymerase chain reaction quantitative polymerase chain reaction was used to validate the results by assessing the expression profiles of 25 ORs and 15 OBPs. Notably, high expression levels for BcucOBP5/9/10/18/21/23/26 were observed in both the female and male antennae. Furthermore, BcucOROrco/6/7/9/13/15/25/27/28/42/62 exhibited biased expression in the male antennae, whereas BcucOR55 showed biased expression in the female antennae. This comprehensive investigation provides valuable insights into insect olfaction at the molecular level and will, thus, help to facilitate the development of enhanced pest management strategies in the future.