Gené's Organ Transcriptome of the Southern Cattle Fever Tick, Rhipicephalus microplus

The southern cattle fever tick (SCFT), Rhipicephalus microplus, is considered the most economically important ectoparasite of livestock worldwide and ranks sixth among the most pesticide resistant arthropods globally. This single-host hard tick is a vector of the infectious agents causing bovine babesiosis and anaplasmosis. The estimated impact of these SCFT-borne diseases on the livestock industry in the world is $7 billion annually. This project focuses on the Gené’s organ and addresses the need to identify novel targets that can serve as the basis for sustainable SCFT control strategies. Wax secreted by the Gené’s organ during oviposition protects the eggs from desiccation, bacterial and fungal infections, inorganic chemicals, and pesticides.  Full development of the Gené’s organ occurs until the female tick is close to full engorgement.  RNA was purified from undeveloped and developed Gené’s organs. The transcriptome of each Gené’s organ set was sequenced using next generation sequencing with de novo assembly. A total of 22,199 putative unigenes with 17,531 singletons were identified for the undeveloped Gené’s organ. For the developed Gené’s organ, 15,374 putative unigenes with 12,242 singletons were detected. A comparison of the two transcriptomes through quantitative RNA-seq analysis revealed 5,454 differentially expressed transcripts. The altered expression levels of the genes were confirmed by quantitative RT-PCR. This is the first transcriptome analysis of the Gené’s organ in R. microplus. Functional genomic studies are planned to evaluate the Gené’s organ as a target to disrupt SCFT biology.