title: Diversity and Universality of EndosymbioticRickettsiain the Fish ParasiteIchthyophthirius multifiliis.
abstract: Although the presence of endosymbiotic rickettsial bacteria, specificallyCandidatusMegaira, has been reported in diverse habitats and a wide range of eukaryotic hosts, it remains unclear how broadlyCa.Megaira are distributed in a single host species. In this study we seek to address whetherCa.Megaira are present in most, if not all isolates, of the parasitic ciliateIchthyophthirius multifiliis. Conserved regions of bacterial 16S rRNA genes were either PCR amplified, or assembled from deep sequencing data, from 18 isolates/populations ofI. multifiliissampled worldwide (Brazil, Taiwan, and USA). We found that rickettsial rRNA sequences belonging to three out of fourCa.Megaira subclades could be consistently detected in allI. multifiliissamples.I. multifiliiscollected from local fish farms tend to be inhabited by the same subclade ofCa.Megaira, whereas those derived from pet fish are often inhabited by more than one subclade ofCa.Megaira. Distributions ofCa.Megaira inI. multifiliisthus better reflect the travel history, but not the phylogeny, ofI. multifiliis. In summary, our results suggest thatI. multifiliismay be dependent on this endosymbiotic relationship, and the association betweenCa.Megaira andI. multifiliisis more diverse than previously thought.
authors.affiliation: Department of Biology, Hamilton College, Clinton NY, USA.
authors.forename: Kassandra E
authors.initials: KE
authors.lastname: Zaila
authors.affiliation: Department of Biology, Indiana University, BloomingtonIN, USA; National Center for Genome Analysis Support, Indiana University, BloomingtonIN, USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Doak
authors.affiliation: Department of Biology, Hamilton College, Clinton NY, USA.
authors.forename: Hannah
authors.initials: H
authors.lastname: Ellerbrock
authors.affiliation: Department of Aquatic Biosciences, National Chyai University Chyai City, Taiwan.
authors.forename: Che-Huang
authors.initials: CH
authors.lastname: Tung
authors.affiliation: Departamento de Aquicultura, Centro de Ciências Agrárias, Universidade Federal de Santa Catarina Florianópolis, Brazil.
authors.forename: Mauricio L
authors.initials: ML
authors.lastname: Martins
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca NY, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kolbin
authors.affiliation: Institute of Molecular Biology, Academia Sinica Taipei, Taiwan.
authors.forename: Meng-Chao
authors.initials: MC
authors.lastname: Yao
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca NY, USA.
authors.forename: Donna M
authors.initials: DM
authors.lastname: Cassidy-Hanley
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca NY, USA.
authors.forename: Theodore G
authors.initials: TG
authors.lastname: Clark
authors.affiliation: Department of Biology, Hamilton College, ClintonNY, USA; Institute of Molecular Biology, Academia SinicaTaipei, Taiwan.
authors.forename: Wei-Jen
authors.initials: WJ
authors.lastname: Chang
keywords: Ciliophora; Sphingobacteria; alphaproteobacteria; hyperparasitism; phagocytosis; symbiosis