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ARS Home » Plains Area » Kerrville, Texas » Knipling-Bushland U.S. Livestock Insects Research Laboratory » Cattle Fever Tick Research Unit » Research » Publications at this Location » Publication #415767
Research Project: Integrated Pest Management of Cattle Fever Ticks

Location: Cattle Fever Tick Research Unit

Title: Identifying the sex chromosome and sex determination genes in the cattle tick, Rhipicephalus (Boophilus) microplus

Author
item Tidwell, Jason
item Bendele, Kylie
item Bodine, Deanna
item HOLMES, V. RENEE - Texas A&M University
item JOHNSTON, J. SPENCER - Texas A&M University
item Saelao, Perot
item Lohmeyer, Kimberly - Kim
item TEEL, PETE - Texas A&M University
item TARONE, AARON - Texas A&M University

Submitted to: Genes, Genomes, Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: The southern cattle tick is one of the most economically important vector of disease in cattle costing the worldwide agriculture industry billions of dollars annually. Recent control methods in human and other animal vectors have utilized sex determination research to manipulate sex ratios, which has shown promising results with mosquitoes. Our study will provide foundational research that will allow similar avenues of investigation in ticks. Through several different molecular and computational analyses, as well as generating a new southern cattle tick genome, the sex chromosome was identified. This is the first time that the sex chromosome has been identified within a tick genome assembly.

Technical Abstract: The cattle tick, Rhipicephalus (Boophilus) microplus, is one of the most economically important veterinary vectors in the world, costing the agriculture industry billions of dollars annually. Recent control methods in human and other animal vectors have utilized sex determination research to manipulate sex ratios, which has shown promising results with mosquitoes such as Aedes aegypti and Anopheles stephensi. Our study will provide foundational research that will allow similar avenues of investigation in ticks using R. (B.) microplus as a model. Karyotypes for R. (B.) microplus have shown that the largest chromosome is the sex chromosome, and has an XX:XO sex determining system. With flow cytometry, the sex chromosome was estimated at 528.5 Mb. Sequencing coverage ratio of mixed sex and male samples against a female reference genome identified two chromosomes with coverages similar to a sex chromosome. SNP density, repeat sequence enrichment, and gene copy number variation analyses corroborated these results identifying chromosomes 2 and 8 as putative sex chromosomes. A new genome assembly of R. (B.) microplus was created and assembled to the chromosome level from an individual adult male. The two genomes were compared. Chromosomes 2 and 8 of the old R. (B.) microplus reference genome were confirmed to be part of the X chromosome, thus merging the karyotype and biology of the species with sequencing data. This is the first time that the sex chromosome has been identified within an Ixodid genome assembly.