@article{ruark-seward_davis_sit_2020, title={Localization of viral and host RNA within soybean cyst nematode via fluorescence in situ hybridization}, volume={211}, ISSN={["1090-2449"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85082019323&partnerID=MN8TOARS}, DOI={10.1016/j.exppara.2020.107866}, abstractNote={Nematode-infecting RNA viruses have recently been discovered via transcriptome sequencing. In soybean cyst nematode (SCN; Heterodera glycines), seven single-stranded RNA viruses have been identified from transcriptome data and experimentally confirmed with qRT-PCR and Sanger sequencing. Presently, there is still much unknown about the relationship between these viruses and the nematode host. In this study, we localize three viruses within the soybean cyst nematode: SCN socyvirus-1 (SbCNV-1), SCN nyami-like virus (NLV), and SCN bunya-like virus (BLV). To visually locate the viruses, whole-mount fluorescence in situ hybridization (FISH) methodology was developed for SCN pre-parasitic second-stage juveniles (ppJ2s). Two SCN populations with differing viral titers (LY1 and MM21) were used as a comparison for viral probe fluorescence intensity. Viral RNAs for all three viruses were abundant in cells throughout the SCN ppJ2 body of the high titer (LY1) population but absent within the majority of the intestinal tract. A significant reduction in viral fluorescence intensity was observed in a similar body pattern in ppJ2 of the low-titer (MM21) SCN, highlighting the specificity of the FISH method. As controls, viral RNAs were colocalized with host mRNA glyceraldehyde 3-phosphate dehydrogenase (GAPDH) for full body localization and a secretory ubiquitin protein (4G06) expressed specifically within the subventral esophageal glands. In addition, viral replication was confirmed in SCN eggs and ppJ2s via qRT-PCR detection of the anti-genomic RNA strands.}, journal={EXPERIMENTAL PARASITOLOGY}, publisher={Elsevier BV}, author={Ruark-Seward, Casey L. and Davis, Eric L. and Sit, Tim L.}, year={2020}, month={Apr} }
 @article{ruark_gardner_mitchum_davis_sit_2018, title={Novel RNA viruses within plant parasitic cyst nematodes}, volume={13}, ISSN={["1932-6203"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042946067&partnerID=MN8TOARS}, DOI={10.1371/journal.pone.0193881}, abstractNote={The study of invertebrate–and particularly nematode–viruses is emerging with the advancement of transcriptome sequencing. Five single-stranded RNA viruses have now been confirmed within the economically important soybean cyst nematode (SCN; Heterodera glycines). From previous research, we know these viruses to be widespread in greenhouse and field populations of SCN. Several of the SCN viruses were also confirmed within clover (H. trifolii) and beet (H. schachtii) cyst nematodes. In the presented study, we sequenced the transcriptomes of several inbred SCN populations and identified two previously undiscovered viral-like genomes. Both of these proposed viruses are negative-sense RNA viruses and have been named SCN nyami-like virus (NLV) and SCN bunya-like virus (BLV). Finally, we analyzed publicly available transcriptome data of two potato cyst nematode (PCN) species, Globodera pallida and G. rostochiensis. From these data, a third potential virus was discovered and called PCN picorna-like virus (PLV). PCN PLV is a positive-sense RNA virus, and to the best of our knowledge, is the first virus described within PCN. The presence of these novel viruses was confirmed via qRT-PCR, endpoint PCR, and Sanger sequencing with the exception of PCN PLV due to quarantine restrictions on the nematode host. While much work needs to be done to understand the biological and evolutionary significance of these viruses, they offer insight into nematode ecology and the possibility of novel nematode management strategies.}, number={3}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Ruark, Casey L. and Gardner, Michael and Mitchum, Melissa G. and Davis, Eric L. and Sit, Tim L.}, editor={Melcher, UlrichEditor}, year={2018}, month={Mar} }
 @article{ruark_koenning_davis_opperman_lommel_mitchum_sit_2017, title={Soybean cyst nematode culture collections and field populations from North Carolina and Missouri reveal high incidences of infection by viruses}, volume={12}, ISSN={["1932-6203"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85011268632&partnerID=MN8TOARS}, DOI={10.1371/journal.pone.0171514}, abstractNote={Five viruses were previously discovered infecting soybean cyst nematodes (SCN; Heterodera glycines) from greenhouse cultures maintained in Illinois. In this study, the five viruses [ScNV, ScPV, ScRV, ScTV, and SbCNV-5] were detected within SCN greenhouse and field populations from North Carolina (NC) and Missouri (MO). The prevalence and titers of viruses in SCN from 43 greenhouse cultures and 25 field populations were analyzed using qRT-PCR. Viral titers within SCN greenhouse cultures were similar throughout juvenile development, and the presence of viral anti-genomic RNAs within egg, second-stage juvenile (J2), and pooled J3 and J4 stages suggests active viral replication within the nematode. Viruses were found at similar or lower levels within field populations of SCN compared with greenhouse cultures of North Carolina populations. Five greenhouse cultures harbored all five known viruses whereas in most populations a mixture of fewer viruses was detected. In contrast, three greenhouse cultures of similar descent to one another did not possess any detectable viruses and primarily differed in location of the cultures (NC versus MO). Several of these SCN viruses were also detected in Heterodera trifolii (clover cyst) and Heterodera schachtii (beet cyst), but not the other cyst, root-knot, or reniform nematode species tested. Viruses were not detected within soybean host plant tissue. If nematode infection with viruses is truly more common than first considered, the potential influence on nematode biology, pathogenicity, ecology, and control warrants continued investigation.}, number={1}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Ruark, Casey L. and Koenning, Stephen R. and Davis, Eric L. and Opperman, Charles H. and Lommel, Steven A. and Mitchum, Melissa G. and Sit, Tim L.}, editor={Rao, A.L.N.Editor}, year={2017}, month={Jan} }