- The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. - The Asian tiger mosquito, Aedes albopictus, is one of the most invasive species in the world and is increasingly becoming an important vector of virus-induced diseases (chikungunya, dengue, Zika) [1]. - Human activities also create new breeding and trophic niches of adaptation in the vicinity of dwellings, strengthening their association with humans [13, 14].. - As a result, a great deal of intra-population variability has been de- tected in both Southeast Asian populations and in the globally distributed adventive populations [19]. - The antennae are implicated in the sensory reception of stimuli such as sound, heat, and odours [24] that are of vital importance to mosquitoes for mate location, the detection of suitable blood meal hosts, nectar sources, resting and oviposition sites [25]. - We extended our analyses to determine the presence and na- ture of single nucleotide polymorphisms (SNPs) in the transcripts present in the considered populations. - We also identified variability related to viral replication in the populations. - Both sexes were maintained together in the same cage with 20%. - The results of these analyses were then piped into a hyperlinked Excel report, as de- scribed in the dCAS software tool [37]. - The coding se- quences (CDS) that encoded putative polypeptides of at least 40 amino acids (aa) were extracted according to i) matches to proteins in the NCBI nr database. - The predicted effects of the SNP variants (synonymous/nonsynonymous) on the putative amino acid product were determined manually using CLC Main Workbench 6 (Qiagen) and MEGA 6.0.6. - albopictus that had been maintained together in the same cage since emergence. - Pools of each of the following were used: antennae. - Differential transcription in the antennae of mosquitoes from different geographic populations. - This differentiation of the populations was evident as. - 7418 of the transcripts displayed differential abundances in the four population samples with a False Detection Rate (FDR) of 0.05. - Significantly more abundant transcripts in the different population samples and those shared between the differ- ent samples are shown in the Venn diagram (Fig. - Lower numbers of unique more abundant tran- scripts were present in the two Italian Arco and Trento. - The number of transcripts with differential abun- dances varied greatly in the different population pairwise comparisons (Fig. - The terms that were enriched in the different comparisons are summarised in Table 1. - Functional categories of antennal transcripts that are differentially abundant in the four populations Sensory perception of smell. - Functional categories related to odorant perception and sensory perception of smell were found to be overrepre- sented in the pairwise population antennal comparisons.. - No members of the Two-domain subfamily were identified. - it is transcribed in the an- tennae, head and tarsi of both sexes but also in the female maxillary palps and proboscis. - 3 Differential abundances of transcripts in the different population samples. - a Venn diagram illustrating the number of more abundant transcripts shared in the different population samples. - b Numbers of transcripts that displayed differential abundances in the pairwise comparisons between the population samples. - Arrows indicate that transcript abundance was greater in the respective population sample. - Table 1 Enriched Gene Ontology categories in the different Ae. - The abundances of the OR transcripts differed enormously. - The over-representation of viral infection terms in the antennae of the north Italian populations, Arco and Trento compared to Athens and Ban Rai involved nine up-regulated sequences: Aalb-11,736, Aalb-24,050, Aalb- 24,228, Aalb-50,498, Aalb-52,817, Aalb-67,423, Aalb-71, 556, Aalb-77,037 and Aalb-82,640 which display very high identities (99–100%) with parts of the polyprotein gene of Aedes flavivirus (AeFV) (GenBank acc.. - These AeFV transcripts were abundant in the two Italian popu- lations (average FPKM = 6.7 and 9.7 in Arco and Trento, respectively) and practically absent in the Athens (FPKM = 0.005) and Ban Rai (FPKM = 0.103) populations.. - Transcripts associated with the perception of sound were enriched in Athens and Ban Rai in the comparisons with Arco. - The mean SNP densities (sites with at least one alternative allele/kb) were significantly different in the population samples (Ban Rai 10.35. - The poly- morphic site densities were not correlated with read depth (FPKM) in the population samples (Pearson’s product-moment correlation: Arco, r = 0.0053, P = 0.237. - However, as 25 of the non-synonymous substitutions are in the signal-peptide encoding sequences, just under 13% (60) of the SNPs would result in amino acid substitutions in the mature OBPs (Additional file 12:. - A total of 1900 SNP loci (including clustered loci) are present in the 78 OR transcripts, 16 of which are trialle- lic. - 4 Odorant binding protein transcript abundances (Log 2 FPKM) in the four wild population samples. - In both these ORs, a non- synonymous substitution was present in the extracellular loop 2 (ECL2) region that has been shown to determine odorant specificity [69, 70] (Fig. - Of the other 32 OR proteins, for which it was possible to derive the seven transmembrane domain structure, ten contained from one to two non-synonymous substitutions in the ECL2 region. - Only one of the SNP loci, in arrestin-1, was non-synonymous resulting in the substitution of a non-polar Phenylalanine with a polar Tyrosine. - Evaluation of the ratios of fixed or polymorphic, non- synonymous/synonymous sites in the differentially tran- scribed OBP and OR genes, AalbOBP17, AalbOBP75, AalbOBP62, AalbOR47-N2 and AalbOR100, compared with their Ae. - Here we provide an overview of the vast reservoir of transcribed genes coding for sensory related functions in the antennae of wild mature adult mosquitoes collected in different ecogeographic areas. - Given the public health impact of this mosquito, the information that we provide may prove important in the implementation of control methods such as the Sterile Insect Technique (SIT).. - Enrichment of transcripts of genes associated with the perception of sound was evident in the Greek Athens and Thai Ban Rai samples in the comparisons with the Italian Arco sample. - 5 Transcriptional profiles of the three differentially transcribed Ae. - 6 Odorant receptor transcript abundances (Log 2 FPKM) in the four wild population samples. - In the mosquito, the Johnston’s organs are especially well developed in the male [76], where they are acutely sensitive to the wing-beat frequency of the female mosquito – a cue that is essential for mating success [77]. - Arrestins are involved in the desensitization of both visual and olfactory transduction pathways where they regulate G protein-coupled recep- tors [79, 80]. - These included homologues of the sensory neuron membrane protein 1 (SNMP1), a member of a family of SNMPs originally identified in Lepidoptera where they are antennal- specific and are associated with pheromone specific sen- silla [81]. - Among the identified OBP transcripts, three were sig- nificantly up-regulated in the Arco population sample in the comparisons with both the Athens and Ban Rai samples (AalbOBP17, AalbOBP75) or with Athens (Aal- bOBP62). - AAEL004339 is mainly transcribed in the antennae of fe- males and, to a lesser extent, in males [84]. - The Plus-C OBP, AalbOBP75, appears to be transcribed only in the antennae of both sexes, whereas its Ae. - Furthermore, AaegOBP75 is enriched in the saliv- ary glands of virally nạve females [85]. - At least 83 ORs are transcribed in the antennae of Ae.. - aegypti orthologues of these ORs are enriched in female compared to male antennae [84] and are upregulated in domestic forms that prefer to bite humans compared to forest forms that prefer guinea pigs [88], suggesting that they may be in- volved in the perception of odours related to host detection.. - The identification of the highly conserved gustatory receptor GR1 orthologue (98% identity with AaegGR1) in the antennae is noteworthy, as in Ae. - aegypti, this gene is expressed exclusively in the maxillary palps [89], where it acts as a CO 2 receptor. - Numerous cytochrome P450 transcripts were more abundant in the Athens sample. - Cytochrome P450s are one of the largest and oldest gene superfamilies in in- sects and are involved in the metabolism of many en- dogenous and xenobiotic compounds including the detoxification of insecticides [94]. - Why this term should be enriched in the Athens and Ban Rai samples compared to the two Italian samples is not clear. - The enrichment of viral infection terms in the two geo- graphically close northern Italian populations related to the polyprotein gene of an Aedes flavivirus (AeFV). - Whether these transcripts represent viral integrations in the mosquito genome or infections needs additional study. - A vast repertoire of SNPs is in present in the antennal transcriptomes of wild populations. - The SNP densities in the four population samples ranged from 7.30 SNPs per kilo- base in Arco to 10.35 in Ban Rai. - SNP loci were abundant in the OBP and OR transcripts with numerous non-synonymous variants that may, depending on their position and the properties of the amino acids involved, change the affinity of the protein for its ligand.. - This is evident in the analysis of SNP frequencies in the four considered populations where the relationships between the native Thai population, the adventive Athens and Italian populations was supported. - Molecular function (level 3) Gene Ontology classification of the transcripts that were differentially abundant in the different population libraries.. - Comparison of the odorant binding protein transcripts identified against the Lombardo (2017) transcripts.. - Comparison of the odorant receptor transcripts identified against the Lombardo (2017) transcripts.. - Tren- dlines are plotted on each of the graphs.. - Frequencies of synonymous and non- synonymous SNP variants in the OBP transcripts.. - Frequencies of synonymous and non- synonymous SNP variants in the OR transcripts.. - The funding bodies played no role in the design of the study and collection, analysis and inter- pretation of the data and in writing the manuscript.. - No ethics approval is required for experimentation of the study organism, Aedes albopictus. - 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