Transcriptome Profiling Of Chemosensory Genes In Different Chemosensory Organs Of The Malaria Vector Anopheles Sinensis

Mosquitoes not only bite and harass people,but also transmit a variety of diseases,such as malaria,dengue fever,filariasis,Zika fever and Japanese encephalitis.Aamong them,malaria is the most severe disease mainly caused by Anopheles mosquitoes.In China,Anopheles sinensis is the most widely distributed species and thought to be the main vector for Plasmodium vivax.Recently,the prevalence of P.vivax tends to increase in some places of China.Therefore,controlling the An.sinensis is one of the key measures.Female mosquitoes hunt the host,select a mate and find the spawning place depend on the scent or CO₂ released by the host,as well as the chemical signals in the surrounding environments.These chemical clues are mainly detected by the chemoreceptor system.The antennae,proboscis and maxillary palps are important parts of the chemosensory system of mosquitoes,and there are various sensilla on the surfaces,in which there are many protein factors that can sense the odor molecules.Through the protein-odor interactions,mosquitoes can complete the sensation and signal transmission of chemical substances,and then produce behavioral responses.Therefore,it is very important to explore the molecular mechanism of the mosquito chemosensory system.So far,the transcriptomes of female antennae and maxillary palps of Anopheles gambiae,Aedes albopictus,Culex quinquefasciatus,Anopheles quadriann?latus and Anopheles c?licifacies have been sequenced and many chemosensory genes have been identified based on bioinformatic analysis.Among them,more detailed analysis has been conducted for An.gambiae.However,the differential expressions of chemosensory genes in different tissues of An.sinensis have not been reported.In this study,to investigate gene expression patterns of chemosensory genes of An.sinensis,the transcriptomes for the antennae,proboscis,and maxillary palps of female and male were analyzed.The results provided a basis for further studies on the regulatory mechanisms of chemosensory in behaviors of An.sinensis.The main results were as follows:?1?Number of chemosensory genes expressed in chemosensory tissuesTotally,109 chemosensory genes were annotated.Among them,78,58,41 and 43genes were identified from the female antennae?FA?,female proboscis?FP?,female maxillary palps?FM?and the whole female body?FB?,respectively.79,55,27 and 34genes were from the male antennae?MA?,male proboscis?MP?,male maxillary palps?MM?and the whole male bodies?FB?,respectively.No significant difference of gene numbers was found in the antennae,proboscis and the whole body of the female and male,but more genes were found in the maxillary palps of the female than in the male.?2?Expression profile of chemosensory genesThe expression patterns of chemosensory genes of An.sinensis showed a distinct tissue specificity.67 differentially expression genes were enriched in chemosensory tissues,while 14 genes were expressed in both chemosensory and non-chemosensory tissues.Forty-three genes were uniquely expressed in females,while 21 gene were uniquely expressed in males.Thirty-one genes were uniquely expressed in antennae,including AsOBP62,AsOR1,AsOR22,AsOR30,etc.Nine genes were found in the proboscis,including AsOR4,AsGR6,AsGR7,AsIR7x,AsGR26,AsGR36,AsGR60,AsGR63 and AsGR71.Five genes were expressed in the maxillary palps,including AsOBP58,AsOR8,AsOR28,AsGR1 and AsGR30.Higher expression genes were identified in the antennae with the cutoff value of FPKM more than 15.In the antennae of females,7 genes were found,including AsOBP1,AsOBP2,AsOBP4,AsOBP7,AsOBP20b,AsOBP72 and AsOR11.However,only AsOBP2 was highly expressed in the antennae of males.Compared among the antenna,proboscis and maxillary palps,most differentially expressed chemosensory genes were found in the antennae of females.For males,most differentially expressed genes were found in the proboscis.Antennae are important sensory organs for perceiving external information.GO annotation analysis showed that most differentially expressed genes in the antennae of females were enriched in the category of olfactory perception,while the enriched genes in the antennae of males was clustered into taste perceptions.At the same time,one or more proteins in the antennae of males may replace the odor binding proteins functioning in carrying odor molecules.?3?Possible function of differentially expressed chemosensory genesBased on gene expression profiles and comparisons with other mosquito species,possible functions of some genes were predicted and the result showed that gene AsOR1,AsOBP1,AsOBP2,AsOBP4,AsOBP7,AsOBP20b,AsOBP72 and AsOR11 may play an important role for females in hunting and identifying hosts.Gene AsOBP1 and AsOBP4probably function in searching spawning sites.While,gene AsOBP33 and AsOBP42might lost the olfactory functions.Gene AsOR37,AsOR40,AsOR52,and AsOR58 may be crucial for larvae.Gene AsGR58,AsGR46,and AsGR3 may be involved in sensing airflow.However,their specific function needs to be further studied.