Discovery and functional analysis of small RNAs (miRNA/siRNA) of livestock ectoparasites

Parasitic arthropods remain an impediment for livestock production systems worldwide with tremendous economic impact. Current ectoparasite control largely relies on chemical pesticides and resistance to available ectoparasiticides is a major concern.  Continued discovery research is required to find innovative and effective technologies for sustainable tick and biting fly control. Small noncoding RNAs (e.g., miRNAs and siRNAs) are key regulators of gene expression and possess utility for analysis of gene function as well as potential for external manipulation of gene expression. Ongoing research efforts by our group aim to: 1) identify miRNAs present in flies and ticks; 2) determine the role of miRNAs in key metabolic/physiologic processes of flies and ticks; and 3) evaluate miRNA potential to disrupt key processes (e.g., development and reproduction). We discovered miRNAs expressed in the stable fly Stomoxys calcitrans (Linnaeus) by RNA sequencing. Sequence reads were mapped against known arthropod miRNAs and the Drosophila melanogaster genome. The majority of miRNAs identified in S. calcitrans are conserved among arthropod species. Candidates for novel miRNAs were also discovered. A dual luciferase assay was developed to facilitate miRNA target validation and quantitative analysis of RNA interference (RNAi) molecules. The reporter system was initially developed for the embryonic tick cell line BME26, derived from the southern cattle tick Boophilus microplus (Canestrini). In addition to furthering our understanding of arthropod physiology, elucidating the miRNome of ectoparasites has potential to aid in the discovery of novel targets and/or approaches for livestock pest control.

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