Comparative Profiling of MicroRNAs in Male and Female Rhipicephalus sanguineus

Rhipicephalus sanguineus is an ectoparasite of medical and veterinary significance, which can transmit a number of pathogens including Babesia canis, Ehrlichia canis, and Rickettsia conorii. MicroRNAs (miRNAs) are recognized as regulators in sex differentiation in dioecious species. We here investigated and compared the miRNA profiles of male and female adults of R. sanguineus by combining Solexa deep sequencing with bioinformatics platform and quantitative real-time PCR. A total of 11.88 and 16.09 million raw reads were obtained from male and female R. sanguineus, respectively. By mapping to the reference genome, 59 and 76 miRNA candidates from the female and male parasite were obtained, with 19 of each consistent with known Ixodes scapularis miRNAs deposited in the miRBase database. Besides, 51 miRNAs were shared by the two genders, and 8 and 25 were female and male specific, respectively. The number of predicted targets of the identified miRNAs ranged from 1 to 383 with an average of 176. Functional analysis showed that a number of predicted targets corresponded to transcription, splicing, and translation factors, elongation factors, and growth factors which were essential for the development of the parasite. Enrichment analysis revealed that some functions of the predicted targets were higher in female than in male, such as antioxidant and electron carrier. The present study firstly described the global profiling of miRNAs in male and female R. sanguineus and identified a number of gender-specific miRNAs, which are likely to participate in the sex differentiation/maintenance process and provide novel resources for better understanding of the biology of the parasite, and may further lead to effective control of the parasite and diseases it causes.