Dataset Information

Molecular evidence for multiple host-specific strains in the genus Rhinosporidium.

ABSTRACT: The taxonomic relationship of Rhinosporidium seeberi with other organisms remained controversial for over a century. Recently, molecular studies have shown R. seeberi to be a protistal microbe in the newly described class Mesomycetozoea at the animal-fungal boundary. Phylogenetic analyses of R. seeberi using 18S small-subunit (SSU) rRNA genes from several hosts suggested Rhinosporidium as a monotypic genus. To test this hypothesis, the internal transcribed spacer 1 (ITS1), 5.8S, and ITS2 from eight humans, two swans, and a dog with rhinosporidiosis were sequenced. The ITS regions were amplified by PCR using a primer designed from a unique region of R. seeberi's 18S SSU rRNA genes in combination with the ITS4 universal primer. In addition, the universal ITS4 and ITS5 primers were also used. R. seeberi's ITS sequences showed differences in the numbers of nucleotides among strains. For instance, the eight human ITS sequences were uniformly similar with only a few mismatches and approximately 1,060 bp long. In contrast, sequences from one of the swans and the dog were 1,356 bp and approximately 1,147 bp long, respectively. Clustal analysis of all of the ITS sequences showed multiple 50- to 60-bp gaps and several mismatches among them. Parsimony analysis placed the Rhinosporidium ITS sequences in three well-supported sister groups according to the hosts' identities. This analysis strongly suggests that the genus Rhinosporidium may possess multiple host-specific strains. No correlation was found between this finding and the phenotypic features of R. seeberi in the studied samples.

SUBMITTER: Silva V

PROVIDER: S-EPMC1081358 | biostudies-literature | 2005 Apr

REPOSITORIES: biostudies-literature

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Molecular evidence for multiple host-specific strains in the genus Rhinosporidium.

Silva Victor V Pereira Cristiane N CN Ajello Libero L Mendoza Leonel L

Journal of clinical microbiology 20050401 4

The taxonomic relationship of Rhinosporidium seeberi with other organisms remained controversial for over a century. Recently, molecular studies have shown R. seeberi to be a protistal microbe in the newly described class Mesomycetozoea at the animal-fungal boundary. Phylogenetic analyses of R. seeberi using 18S small-subunit (SSU) rRNA genes from several hosts suggested Rhinosporidium as a monotypic genus. To test this hypothesis, the internal transcribed spacer 1 (ITS1), 5.8S, and ITS2 from ei ...[more]

PMID: 15815010

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Project description:BACKGROUND:Natural hybridization is prevalent in ferns, and plays an important role in fern evolution and speciation. In the Indo West-Pacific region, the mangrove fern genus Acrostichum consists of two largely sympatric species, A. aureum and A. speciosum. Although there has been no report of interspecific hybridization before, we found some individuals morphologically intermediate between them in Guangdong and Hainan, China, for the first time, which were suspected to be hybrids. In this study, we aimed to test the hypothesis of natural hybridization between A. aureum and A. speciosum in Guangdong and Hainan using three low-copy nuclear genes. A chloroplast intergenic spacer was used to infer the hybridization direction once the hybrid status was confirmed. In addition, we examined spore shapes and germination for these taxa. RESULTS:Both A. aureum and A. speciosum showed a low level of polymorphism at all three nuclear genes; however, they were well separated at these loci. At both locations, each individual of the putative hybrid showed additivity in chromatograms at all sites where the two species showed fixed differences. Haplotype analysis at all three nuclear genes indicated that each individual of the putative hybrid possessed two haplotypes, matching with those of A. aureum and A. speciosum, respectively. Sequencing of the chloroplast trnV-trnM regions showed that A. aureum differed from A. speciosum by eleven nucleotide substitutions and three indels (insertions/deletions), and all sampled individuals of the putative hybrid had the identical sequences with A. speciosum. Compared with A. aureum and A. speciosum, the putative hybrid had much reduced spore germination rate. CONCLUSIONS:Sequence data of the three nuclear genes provide compelling evidence for natural hybridization between A. aureum and A. speciosum, and all the hybrid individuals are likely F1s. The hybridization is unidirectional and A. speciosum is the maternal parent of the hybrid based on the assumption of maternal inheritance of chloroplast DNA. Human disturbance on mangrove habitats may facilitate the establishment of hybrids of Acrostichum.

Dataset Information

Molecular evidence for multiple host-specific strains in the genus Rhinosporidium.

Publications

Molecular evidence for multiple host-specific strains in the genus Rhinosporidium.

Similar Datasets

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