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Analysis of the ITS region and partial ssu and lsu rRNA genes of Blastocystis and Proteromonas lacertae

  • J. D. HOEVERS (a1) and K. F. SNOWDEN (a1)

Blastocystis is a common single-celled enteric parasite found in a large variety of hosts. Recent molecular analysis supports the concept that this eukaryotic organism is a stramenopile most closely related to Proteromonas lacertae, a parasite of reptiles. In this study, the internal transcribed spacer region, partial small subunit rRNA and large subunit rRNA genes from 7 Blastocystis isolates (5 human, 1 pig and 1 sheep), and a Proteromonas lacertae isolate were amplified by PCR, cloned and sequenced. Blastocystis was found to be a typical eukaryote with both ITS1 and ITS2 regions present. Phylogenetic analysis based on the entire PCR amplicon revealed that the Blastocystis isolates did not segregate according to host or geographic origin. The highest sequence identities with the conserved Blastocystis 5·8S rDNA sequence were with the stramenopiles Fibrocapsa japonica, Chattonella marina, Cylindrotheca closterium and Hyphochytrium catenoides. The most parsimonious tree based on the 5·8S rDNA sequence from P. lacertae, 11 other stramenopiles, 2 fungi, 3 algae and 3 alveolates showed Blastocystis positioned within the stramenopiles, with P. lacertae as its closest relative. This work therefore supports the hypothesis that Blastocystis is most closely related to P. lacertae, and that it should be regarded as an unusual stramenopile.

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ABE, N. ( 2004). Molecular and phylogenetic analysis of Blastocystis isolates from various hosts. Veterinary Parasitology 120, 235242.
ABE, N., NAGOSHI, M., TAKAMI, K., SAWANO, Y. & YOSHIKAWA, H. ( 2002). A survey of Blastocystis sp. in livestock, pets, and zoo animals in Japan. Veterinary Parasitology 106, 203212.
ABE, N., WU, Z. & YOSHIKAWA, H. ( 2003). Zoonotic genotypes of Blastocystis hominis detected in cattle and pigs by PCR with diagnostic primers and restriction fragment length polymorphism analysis of the small subunit ribosomal RNA gene. Parasitology Research 90, 124128.
ARISUE, N., HASHIMOTO, T. & YOSHIKAWA, H. ( 2003). Sequence heterogeneity of the small subunit ribosomal RNA genes among Blastocystis isolates. Parasitology 126, 19.
ARISUE, N., HASHIMOTO, T., YOSHIKAWA, H., NAKAMURA, Y., NAKAMURA, G., NAKAMURA, F., YANO, T. & HASEGAWA, M. ( 2002). Phylogenetic position of Blastocystis hominis and of stramenopiles inferred from multiple molecular sequence data. Journal of Eukaryotic Microbiology 49, 4253.
ALLARD, M. W. & HONEYCUTT, R. L. ( 1991). Ribosomal DNA variation within and between species of rodents, with emphasis on the genus Onychomys. Molecular and Biochemical Evolution 8, 7184.
ALTSCHUL, S. F., GISH, W., MILLER, W., MYERS, E. W. & LIPMAN, D. J. ( 1990). Basic local alignment search tool. Journal of Molecular Biology 215, 403410.
ASHFORD, R. W. & ATKINSON, E. A. ( 1992). Epidemiology of Blastocystis hominis infection in Papua New Guinea: age-prevalence and associations with other parasites. Annals of Tropical Medicine and Parasitology 86, 129136.
BALDWIN, B. G. ( 1992). Phylogenetic utility of the internal transcribed spacers of ribosomal DNA in plants. Molecular and Phylogenetic Evolution 1, 316.
BARNARD, S. M. & UPTON, S. J. ( 1994). A Veterinary Guide to the Parasites of Reptiles: Protozoa, 1st Edn. Krieger Publishing Company, Melbourne, Florida.
BOREHAM, P. F. L. & STENZEL, D. J. ( 1998). Blastocystis. In Zoonoses: Biology, Clinical Practice, and Public Health Control (ed. Palmer, S. R., Soulsby, L. & Simpson, D. I. H.), pp. 625632. Oxford University Press, Oxford.
CAVALIER-SMITH, T. ( 1998). A revised six-kingdom system of life. Biological Reviews of the Cambridge Philosophical Society 73, 203266.
COLLINS, N. E. & ALLSOPP, B. A. ( 1999). Theileria parva ribosomal internal transcribed spacer sequences exhibit extensive polymorphism and mosaic evolution: application to the characterization of parasites from cattle and buffalo. Parasitology 118, 541551.
FAITH, D. P. ( 1991). Cladistic permutation tests for monophyly and non-monophyly. Cladistics 40, 366375.
FELSENSTEIN, J. ( 1985). Confidence limits on phylogenies: an approach using the bootstrap. Evolution 39, 783791.
HO, L. C., ARMIUGAM, A., JEYASEELAN, K., YAP, E. H. & SINGH, M. ( 2000). Blastocystis elongation factor-1 alpha: genomic organization, taxonomy and phylogenetic relationships. Parasitology 121, 135144.
HOEVERS, J., HOLMAN, P., LOGAN, K., HOMMEL, M., ASHFORD, R. & SNOWDEN, K. ( 2000). Restriction fragment length polymorphism analysis of small subunit rRNA genes of Blastocystis hominis isolates from geographically diverse human hosts. Parasitology Research 86, 5761.
JOHNSON, A. M., THANOU, A., BOREHAM, P. F. L. & BAVERSTOCK, P. R. ( 1989). Blastocystis hominis: phylogenetic affinities determined by rRNA sequence comparison. Experimental Parasitology 68, 283288.
KATIYAR, S. K., VISVESVARA, G. S. & EDLIND, T. D. ( 1995). Comparisons of ribosomal RNA sequences from amitochondrial protozoa: implications for processing, mRNA binding and paromomycin susceptibility. Gene 152, 2733.
LEIPE, D. D., TONG, S. M., GOGGIN, C. L., SLEMENDA, S. B., PIENIAZEK, N. J. & SOGIN, M. L. ( 1996). 16S-like rDNA sequences from Developayella elegans, Labyrinthuloides haliotidis, and Proteromonas lacertae confirm that the stramenopiles are a primarily heterotrophic group. European Journal of Protistology 32, 449459.
MCLAUGHLIN, G. L., HOWE, D. K., BIGGS, D. R., SMITH, A. R., LUDWINSKI, P., FOX, B. C., TRIPATHY, N., FRASCH, C. E., WENGER, J. D., CAREY, R. B., HASSEN-KING, M. & VODKIN, H. ( 1993). Amplification of rDNA loci to detect and type Neisseria meningitidis and other eubacteria. Molecular and Cellular Probes 7, 717.
MOE, K., SINGH, T. M., HOWE, J., HO, L. C., TAN, S. W., CHEN, X. Q., NG, G. C. & YAP, E. H. ( 1997). Experimental Blastocystis hominis infection in laboratory mice. Parasitology Research 83, 319325.
NAKAMURA, Y., HASHIMOTO, T., YOSHIKAWA, H., KAMAISHI, T., NAKAMURA, F., OKAMOTO, K. & HASEGAWA, M. ( 1996). Phylogenic position of Blastocystis hominis that contains cytochrome-free mitochondria, inferred from the protein phylogeny of elongation factor –?1. Molecular and Biochemical Parasitology 77, 241245.
NICKRENT, D. & SARGENT, M. ( 1991). An overview of the secondary structure of the V4 region of the eukaryotic small subunit ribosomal RNA. Nucleic Acids Research 19, 227235.
NOËL, C., DUFERNEZ, F., GERBOD, D., EDGCOMB, V. P., DELGADO-VISCOGLIOSI, P., HO, L. C., SINGH, M., WINTJENS, R., SOGIN, M. L., CAPRON, M., PIERCE, R., ZENNER, L. & VISCOGOGLIOSI, E. ( 2005). Molecular phylogenies of Blastocystis isolates from different hosts: implications for genetic diversity, identification of species, and zoonosis. Journal of Clinical Microbiology 43, 348355.
NOËL, C., PEYRONNET, C., GERBOD, D., EDGCOMB, V., DELGADO-VISCOGLIOSI, P., SOGIN, M., CAPRON, M., VISCOGLIOSI, E. & ZENNER, L. ( 2003). Phylogenetic analysis of Blastocystis isolates from different hosts based on the comparison of small-subunit rRNA gene sequences. Molecular and Biochemical Parasitology 126, 119123.
OLIVIER, C., VAN DE PAS, C., LEPP, P., YODER, K. & RELMAN, D. A. ( 2001). Sequence variability in the first internal transcribed spacer region within and among Cyclospora species is consistent with polymorphism. International Journal for Parasitology 31, 14751487.
PAKANDL, M. ( 1992). An experimental transmission of porcine strains of Blastocystis sp. in mice and gerbils. Folia Parasitology 39, 383386.
PATTERSON, D. J. ( 1989). Stramenopiles: chromophytes from a protistan perspective. In The Chromophyte Algae: Problems and Perspectives (ed. Green, J. C., Leadbeater, B. S. C. & Diver, W. L.), pp. 357379. Clarendon Press, Oxford.
PEARSON, W. R. ( 1997). Effective protein sequence comparison. Methods in Enzymology 266, 227258.
PÉLANDAKIS, M., SERRE, S. & PERNIN, P. ( 2000). Analysis of the 5·8S rRNA gene and the internal transcribed spacers in Naegleria spp. and in N. fowleri. Journal of Eukaryotic Microbiology 47, 116121.
POSADA, D. & CRANDALL, K. L. ( 1998). Model test: testing the model of DNA substitution. Bioinformatics 14, 817818.
SILBERMAN, J. D., SOGIN, M. L., LEIPE, D. D. & CLARK, C. G. ( 1996). Human parasite finds taxonomic home. Nature, London 380, 398.
SNOWDEN, K., LOGAN, K., BLOZINSKI, C., HOEVERS, J. & HOLMAN, P. ( 2000). Restriction fragment length polymorphism analysis of small subunit rRNA genes of Blastocystis isolates from animal hosts. Parasitology Research 86, 6266.
SOM, I., AZAM, A. & BHATTACHARYA, A. ( 2000). Inter and intra-strain variation in the 5·8S ribosomal RNA and ITS sequences of Entamoeba histolytica and comparison with Entamoeba dispar, Entamoeba moshkovskii and Entamoeba invadens. International Journal for Parasitology 30, 723728.
STENZEL, D. J. & BOREHAM, P. F. L. ( 1996). Blastocystis hominis revisited. Clinical Microbiology Reviews 9, 563584.
SWOFFORD, D. L. ( 1996). PAUP: phylogenetic analysis using parsimony, version 4.0. Sinauer Associates, Sunderland, Massachusetts.
TAN, K., SINGH, M. & YAP, E. ( 2002). Recent advances in Blastocystis hominis research: hot spots in terra incognita. International Journal for Parasitology 32, 789804.
THATHAISONG, U., WORAPONG, J., MUNGTHIN, M., TAN-ARIYA, P., VIPUTTIGUL, K., SUDATIS, A., NOONAI, A. & LEELAYOOVA, S. ( 2003). Blastocystis isolates from a pig and a horse are closely related to Blastocystis hominis. Journal of Clinical Microbiology 41, 967975.
VAN DE PEER, Y., DE RIJK, P., WUYTS, J., WINKELMANS, T. & DE WACHTER, R. ( 2000). The European Small Subunit Ribosomal RNA database. Nucleic Acids Research 28, 175176.
VAN DER AUWERA, G. & DE WACHTER, R. ( 1998). Structure of the large subunit rDNA from a diatom, and comparison between small and large subunit ribosomal RNA for studying stramenopile evolution. Journal of Eukaryotic Microbiology 6, 521527.
WHITE, T. J., BRUNS, T., LEE, S. & TAYLOR, J. ( 1990). Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In PCR Protocols: a Guide to Methods and Applications (ed. Innis, M. A., Gelfand, D. H., Sninsky, J. J. & White, T. J.), pp. 315322. Academic Press, San Diego, California.
YOSHIKAWA, H., MORIMOTO, K., WU, Z., SINGH, M. & HASHIMOTO, T. ( 2004). Problems in speciation in the genus Blastocystis. Trends in Parasitology 20, 251255.
YOSHIKAWA, H., NAGANO, I., WU, Z., YAP, E. H., SINGH, M. & TAKAHASHI, Y. ( 1998). Genomic polymorphism among Blastocystis hominis strains and development of subtype-specific diagnostic primers. Molecular and Cellular Probes 12, 153159.
ZIERDT, C. H. ( 1991). Blastocystis hominis – past and future. Clinical Microbiology Reviews 4, 6179.
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