Molecular Mechanisms Of Phototransduction And Rhythm Regulation In Photoperiod Diapause Of Aedes Albopictus

Background:Aedes albopictus,also known as the "Asian tiger mosquito",originated in Asia,is one of the 100 most invasive species in the world,which is a vector of various arboviruses including dengue virus,Chikungunya virus,Zika virus and so on.One key to their ability to invade diverse ecological spaces is the capacity of diapause in Ae.albopictus which allow them to exploit seasonal resources and bridge harsh winters or other seasonally inimical conditions.Therefore,it is of great scientific and practical significance to study the molecular mechanism of photoperiodic diapause of Ae.albopictus and to explore new vector control methods based on diapause genetic or chemical means,so as to effectively suppress the population of Ae.albopictus.Methods:Establish a diapause induction system and RNA-seq sampling protocol for Ae.albopictus.A high-quality transcriptome database was assemblied using genome-based combined with De novo methodology.The potential diapause relative molecules and pathways were screened by RNA-seq.LW-opsin,SW-opsin and UV-opsin sequences were identified using RT-PCR.The expression profile of opsin genes and core circadian clock genes of Ae.albopictus under short day(SD)diapause-inducing and long day(LD)non-diapause-inducing conditions were analyzed by qRT-PCR.Results:1.From the results of RNA-seq,211,237 high-quality transcripts were assembled.A total of 3498 differential expression transcripts(DETs)were obtained,of which the number of potential diapause relative DETs,namely Dark,Light,Oscillation and Dark-Light,were 310,243,183 and 5 respectively.2.We found that the potential diapause relative DETs were enriched in the Phototransduction-fly and Circadian rhythm pathways.3.Six LW-opsin transpcripts,1 SW-opsin and 1 UV-opsin of Ae.albopictus were amplified.While LW-opsin and SW-opsin had multiple copies.4.The LW-opsin genes represented a different expressional profile both in different stages of Ae.albopictus,and different time points of its adults under SD and LD conditions.5.The potential diapause relative circadian genes were found with several alternative isoforms,such as the pdf-receptor gene presented different isoforms in different groups.6.Under the SD and LD conditions,different expressional profiles of 10 core circadian clock genes of Ae.albopictus including per,tim,cry2,cry1,clk,cyc,pdf,vri,pdp1 and sr were observed using qRT-PCR.Among them,the cyc and clk showed a similar expressional trend under LD condition but separate under SD,while the pdf transcriptional level obviously decreased under SD condition.Conclusion:1.The potential photoperiodic diapause relative genes and pathways of Ae.albopictus were found mainly enriched in Phototransduction-fly and Circadian rhythm pathways,et al.2.Ae.albopictus contains 6 LW-opsins,1 SW-opsin and 1 UV-opsin,and there are multiple copies of LW-opsin and SW-opsin.3.The LW-opsin genes may be involved in the regulation of photoperiodic diapause of Ae.albopictus.4.The potential diapause relative genes might spatiotemporally participate in molecular regulation of Ae.albopictus diapause in different alternative isoforms.5.Under the SD and LD conditions,different expressional profiles of circadian genes were found,the cyc and clk might co-regulate under LD condition but separate under SD,while the pdf transcriptional level obviously decreased under SD condition.