Bacterial endosymbionts of Placobdella (Annelida: Hirudinea: Glossiphoniidae): phylogeny, genetic distance, and vertical transmission
Blood-feeding leeches of the genus Placobdella have acquired intracellular alphaproteobacterial endosymbionts of the genus Reichenowia that potentially aid in the production of B vitamins, thereby ameliorating the lack of these essential nutrients in the diet of the hosts. For Placobdella associates, little is still known about the diversity, genetic makeup, and the mode of transmission of bacteria between leeches. We aimed to (i) place the bacterial symbionts in a phylogenetic context, (ii) compare patterns of cladogenesis between the bacteria and hosts to search for evidence of co-speciation, and (iii) explore the mode of bacterial transmission between leech parent and offspring. DNA sequencing of the bacterial 16S rDNA and 23S rDNA loci suggests that, whereas Reichenowia forms a monophyletic group within the alphaproteobacterial family Rhizobiaceae, no evidence for co-speciation between hosts and bacteria can be traced. Attempts at DNA amplification for ovarial tissues were negative for a range of species, but two 16S rDNA sequences retrieved from the testisacs of P. rugosa showed very high similarity with Reichenowia. Although we cannot rule out that this may be a contamination, or a different, potentially free-living species of bacteria, our results may indicate that Reichenowia is transferred from leech parent to offspring via the testisacs.
KeywordsPlacobdella Reichenowia Rhizobiaceae Intracellular symbiosis Bacteriomes Phylogeny Co-phylogeny Species diversity
We thank Steven Doyle for aiding with imaging, Michael Tessler for creating the script used to run TNT, and the Willi Hennig Society for making TNT freely available. Danielle de Carle and Rafael Iwama provided much input during analyses and interpretation of the results, which greatly benefitted the paper. We thank the Saskatchewan ministry of Parks, Culture, and Sports, the Ontario Ministry of the Environment, Conservation, and Parks, as well as Manitoba Parks for help with permitting. This research was funded by a NSERC Discovery grant and an Olle Engkvist Byggmästare stipend to SK.
- Bhuvaneswari, G. (2013). Molecular Characterization of camphor utilizing bacterial isolates from refinery sludge and detection of target loci-Cytochrome P-450 cam mono oxygenase (cam C gene) by PCR and gene probe. SpringerPlus, 2(1)Google Scholar
- Boyd, B. M., J. M. Allen, N. P. Nguyen, P. Vachaspati, Z. S. Quicksall, T. Warnow, L. Mugisha, K. P. Johnson & D. L. Reed, 2017. Primates, lice and bacteria: speciation and genome evolution in the symbionts of hominid lice. Molecular Biology and Evolution 34: 1743–1757.PubMedPubMedCentralCrossRefGoogle Scholar
- Farikou, O., F. Njiokou, J. A. Mbida Mbida, G. R. Njitchouang, H. N. Djeunga, T. Asonganyi, P. P. Simarro, G. Cuny & A. Geiger, 2010. Tripartite interactions between tsetse flies, Sodalis glossinidius and trypanosomes-an epidemiological approach in two historical human African trypanosomiasis foci in Cameroon. Infection, Genetics and Evolution 10: 115–121.PubMedCrossRefPubMedCentralGoogle Scholar
- Kearse, M., R. Moir, A. Wilson, S. Stones-Havas, M. Cheung, S. Sturrock, S. Buxton, A. Cooper, S. Markowitz, C. Duran, et al., 2012. Geneious basic: an integrated and extendable desktop software platform for the organization and analysis of sequence data. Bioinformatics 28: 1647–1649.PubMedPubMedCentralGoogle Scholar
- Klemm, D. J., 1985. A Guide to the Freshwater Annelida (Polychaeta, Naidid and Tubificid Oligochaeta, and Hirudinea) of North America. Kendall-Hunt Publishing Company, Dubuque.Google Scholar
- Manzano-Marín, A., A. Oceguera-Figueroa, A. Latorre, L. F. Jiménez-García & A. Moya, 2015. Solving a bloody mess: B-vitamin independent metabolic convergence among gammaproteobacterial obligate endosymbionts from blood-feeding arthropods and the leech Haementeria officinalis. Genome Biology and Evolution 7: 2871–2884.PubMedPubMedCentralCrossRefGoogle Scholar
- Miller, M. A., W. Pfeiffer, & T. Schwartz, 2010. Creating the CIPRES Science Gateway for inference of large phylogenetic trees. Gateway Computing Environments Workshop (GCE) 1–8.Google Scholar
- Nogge, G., 1981. Significance of symbionts for the maintenance of an optimal nutritional state for successful reproduction in hematophagous arthoropods. Parasitology 82: 101–104.Google Scholar
- Ronquist, F., M. Teslenko, P. Van Der Mark, D. L. Ayres, A. Darling, S. Höhna, B. Larget, L. Liu, M. A. Suchard & J. P. Huelsenbeck, 2012. MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic Biology 61: 539–542.PubMedPubMedCentralCrossRefGoogle Scholar
- Sambrook, J., E. F. Fritsch & T. Maniatis, 1989. Molecular Cloning: A Laboratory Manual. Cold Spring Harbor Laboratory Press, New York.Google Scholar
- Sawyer, R. T., 1986. Leech Biology and Behaviour. Oxford University Press, New York: 419–793.Google Scholar