Expression Characteristics And Biological Functions Analysis Of 5-HT Receptor Gene Bmu-ser-1 In Bursaphelenchus Mucronatus

Bursaphelenchus mucronatus,a native species,and Bursaphelenchus xylophilus,an alien species,have a close phylogenetic relationship.Under the conditions of mixed culture,there is fierce interspecific competition and population displacement between them.The foundations for population colonization in nematodes are quick and vigorous development,frequent as well as efficient copulation,which is strongly linked to the signal transduction pathways involved in G Protein-Coupled Receptors(GPCRs).This thesis started with the G protein-coupled five-hydroxy tryptamine receptor gene Bmu-ser-1,which is associated to nematode development and reproduction.Based on the bioinformatics analysis,RT-qPCR and in situ hybridization were utilized to investigate its spatio-temporal dynamic expression characteristics.RNAi was used to partially suppress Bmu-ser-1 expression in order to examine its important roles in B.mucronatus.The following are the results:(1)Bioinformatics analysis: the results indicated that Bmu-ser-1 gene encoded a G protein-coupled serotonin receptor with a typical 7 transmembrane helix structure.It shared high homology with ser-1 in B.xylophilus and Caenorhabditis elegans.(2)Gene expression levels: the RT-qPCR data revealed that Bmu-ser-1 was expressed in all stages,with dynamic expression pattern.The highest levels of expression were found in the second and fourth stages of juveniles,followed by the adult stage,embryonic stage,and the third stage.Intriguingly,in the fourth and adult stages,the gene was significantly differently expressed,with male expressing significantly higher than females.(3)Gene expression sites: the results of in situ hybridization demonstrated that Bmu-ser-1 was expressed in different stages with distinct expression locations.During the late embryonic stage,it was discovered in the lip,pharynx,and esophagus.It was manifested throughout the body in the second stage.It was expressed in the terminal gonadal primordium in the third stage.It was found in female vulvas and male gonads in the fourth stage.It was discovered in mature male spermatogonia,primordial spermatocytes,and female vulvas.(4)Biological functions analysis: the RNAi results demonstrated that Bmu-ser-1 had a beneficial effect on B.mucronatus development and copulation.By using RNAi,the hatching rates of embryos were attenuated,and the embryos were arrested in the first stage.The locomotion of the second stage juveniles was impaired by RNAi,and they also displayed aberrant esophageal and intestine expansion,as well as shorter length and slower development.Males with RNAi exhibited a shorter mating duration,poorer vulva localization ability,and lower reproductive potential,whereas females with RNAi only had negative fertility and defective ovulation.According to the above research results,the expression level of Bmu-ser-1 gene is high in the second,fourth,and adult stages.It may have a significant role in B.mucronatus locomotion,digestion,ontogeny,mating behavior,and reproductive ability.Meanwhile,there are disparities in expression levels and sites between female and male.The findings of this study can be used as a foundation for research into the growth and development,mating and reproduction mechanisms of B.mucronatus,as well as a reference for further research into the homologous gene in B.xylophilus and the analysis of interspecific competition between the two nematodes.