Comparative Studies On Mitochondrial Genome And Ovarian Development Related Genes In The Bisexual And Parthenogenetic Populations Of Haemaphysalis Longicornis

The tick Haemaphysalis longicornis is an obligate blood-sucking ectoparasite,which is widely distributed in Australia,New Zealand and eastern Asia,and notorious as vector for many pathogens.In China,H.longicornis is one of the dominant species in north China with excellent reproductive ability and great potential to eapand,this species exhibits two reproductive strategies,the bisexual population(HLBP)and parthenogenetic population(HLPP).Comparative researches on the reproductive mechanism and population characteristics of the two reproductive populations are of medical and epidemiological significance for subsequent control of H.longicornis.In this study,the mitochondrial genomes of HLBP and HLPP were sequenced and compared,results showed that the gene structure,number and position of the two reproductive populations did not change.Phylogenetic analysis indicated that the HLBP and HLPP had low differentiation with a close relationship and less genetic distance than between the subspecies.Quantitative analysis of mitochondrial protein-coding genes showed that there were significant differences in the transcription patterns of mitochondrial genes in the HLBP and HLPP at different development stages,but the results of genetic sequence still supported the classification that the two reproductive populations belonged to the same species.In order to understand the molecular function of genes associated with H.longicornis ovarian development,transcriptome sequencing was carried out on the HLBP and HLPP ovary in the different feeding stages.Results showed that the differentil expression genes in ovarian development were mainly enriched in the signal transduction,cell differentiation,organization development,translation modified,lipid metabolism,catalytic activity and biological metabolism pathway.In different feeding stages of H.longicornis,the differentially expressed genes in oxidative phosphorylation,MAPK signaling pathway,ubiquitin proteasome pathway,mitogen activated protein kinase,and cell differentiation genes involved in protein degradation and organ development were significantly upregulated,and these genes may be involved in the important physiological processes of early ovarian development in H.longicornis.In comparison of differentially expressed genes between two reproductive populations,ABC transporter,PI3K-Akt signaling pathway and cAMP signaling pathway were found obvious differences between the transcriptional regulation,suggesting that the function of some signal transduction mechanisms may have changed during ovarian development in the HLBP and HLPP.The two reproductive patterns showed heritable transcriptional differences in key biological processes such as ovarian development and oogenesis.The results are useful to preliminarily understand the HLBP and HLPP in reproductive regulation related genetic background and molecular mechanism.Based on transcriptome database,the ovarian proteins of H.longicornis were identified using quantitative proteomics,results showed that the functional and pathway of proteins involved in ovarian development were strongly correlated with transcriptome genes,which provided a theoretical basis for the functional study of genes related to ovarian development in ticks.QPCR was used to verify the differentially expressed genes identified by both transcriptome and proteome analysis,and results showed that the expression trend of screened genes was more reliable.In the HLBP ovary,the cathepsin L,secreted proteins and glycosidase protein expression were significantly upregulated in the feeding stages.In the HLPP,the lysozyme,yolk proteins,heat shock protein,glutathione S transferase,myosin and ATP synthase protein were found upregulated,suggesting that these genes may play important function in early ovarian development,material transport,energy metabolism,and oxidative stress during the feeding stages of H.longicornis.The results of this study provide an important scientific basis for revealing the molecular mechanism of ovarian development and exploring the functions of ovarian genes in the different reproductive populations of H.longicornis.