An rRNA variable region has an evolutionarily conserved essential role despite sequence divergence.

Regions extremely variable in size and sequence occur at conserved locations in eukaryotic rRNAs. The functional importance of one such region was determined by gene reconstruction and replacement in Tetrahymena thermophila. Deletion of the D8 region of the large-subunit rRNA inactivates T. thermophila rRNA genes (rDNA): transformants containing only this type of rDNA are unable to grow. Replacement with an unrelated sequence of similar size or a variable region from a different position in the rRNA also inactivated the rDNA. Mutant rRNAs resulting from such constructs were present only in precursor forms, suggesting that these rRNAs are deficient in either processing or stabilization of the mature form. Replacement with D8 regions from three other organisms restored function, even though the sequences are very different. Thus, these D8 regions share an essential functional feature that is not reflected in their primary sequences. Similar tertiary structures may be the quality these sequences share that allows them to function interchangeably.

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Sequence data for two large-subunit rRNA genes from an Asian strain of Alexandrium catenella.

Applied and Environmental Microbiology ◽

10.1128/aem.62.11.4199-4201.1996 ◽

1996 ◽

Vol 62 (11) ◽

pp. 4199-4201 ◽

Cited By ~ 27

Author(s):

P K Yeung ◽

K F Kong ◽

F T Wong ◽

J T Wong

Keyword(s):

Sequence Data ◽

Large Subunit ◽

Rrna Genes ◽

Alexandrium Catenella ◽

Asian Strain ◽

Large Subunit Rrna

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Nucleotide sequence of the 5.8S and large subunit rRNA genes and the internal transcribed spacer and part of the external spacer fromGiardia ardeae

Nucleic Acids Research ◽

10.1093/nar/19.21.6050 ◽

1991 ◽

Vol 19 (21) ◽

pp. 6050-6050 ◽

Cited By ~ 9

Author(s):

Harry van Keulen ◽

Simon Horvat ◽

Stanley L. Erlandsen ◽

Edward L. Jarroll

Keyword(s):

Nucleotide Sequence ◽

Internal Transcribed Spacer ◽

Large Subunit ◽

Rrna Genes ◽

Large Subunit Rrna

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Sequence and organization of large subunit rRNA genes from the extrachromosomal 35 kb circular DNA of the malaria parasitePlasmodium falciparum

Nucleic Acids Research ◽

10.1093/nar/21.5.1067 ◽

1993 ◽

Vol 21 (5) ◽

pp. 1067-1071 ◽

Cited By ~ 41

Author(s):

M.J. Gardner ◽

J.E. Feagin ◽

D.J. Moore ◽

K. Rangachari ◽

D.H. Williamson ◽

...

Keyword(s):

Large Subunit ◽

Rrna Genes ◽

Circular Dna ◽

Large Subunit Rrna

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Candida ficus sp. nov., a novel yeast species from the gut of Apriona germari larvae

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijs.0.044214-0 ◽

2012 ◽

Vol 62 (Pt_11) ◽

pp. 2805-2809 ◽

Cited By ~ 5

Author(s):

Feng-Li Hui ◽

Qiu-Hong Niu ◽

Tao Ke ◽

Zheng Liu

Keyword(s):

Type Strain ◽

Yeast Species ◽

Large Subunit ◽

Sequence Divergence ◽

Central China ◽

Rrna Gene ◽

The Novel ◽

Ascomycetous Yeasts ◽

Large Subunit Rrna ◽

Wood Boring

A novel yeast species is described based on three strains from the gut of wood-boring larvae collected in a tree trunk of Ficus carica cultivated in parks near Nanyang, central China. Phylogenetic analysis based on sequences of the D1/D2 domains of the large subunit rRNA gene showed that these strains occurred in a separate clade that was genetically distinct from all known ascomycetous yeasts. In terms of pairwise sequence divergence, the novel strains differed by 15.3 % divergence from the type strain of Pichia terricola, and by 15.8 % divergence from the type strains of Pichia exigua and Candida rugopelliculosa in the D1/D2 domains. All three are ascomycetous yeasts in the Pichia clade. Unlike P. terricola, P. exigua and C. rugopelliculosa, the novel isolates did not ferment glucose. The name Candida ficus sp. nov. is proposed to accommodate these highly divergent organisms, with STN-8T ( = CICC 1980T = CBS 12638T) as the type strain.

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Rearranged Subtelomeric rRNA Genes in Giardia duodenalis

Eukaryotic Cell ◽

10.1128/ec.4.2.484-486.2005 ◽

2005 ◽

Vol 4 (2) ◽

pp. 484-486 ◽

Cited By ~ 15

Author(s):

Jacqueline A. Upcroft ◽

Mahin Abedinia ◽

Peter Upcroft

Keyword(s):

Large Subunit ◽

Giardia Duodenalis ◽

Rrna Genes ◽

Rrna Gene ◽

Two Dimensional ◽

Linear Chromosomes ◽

Large Subunit Rrna

ABSTRACT Giardia duodenalis has linear chromosomes capped with typical eukaryotic repeats [(TAGGG) n ], subtelomeric rRNA genes, and telomere gene units. The absence of two closely associated NotI sites in the large-subunit rRNA gene was used as an indicator in hybridizations of one- and two-dimensional NotI-cleaved Giardia chromosome separations that some chromosomes carry only rearranged and, by deduction, nonfunctional rRNA genes.

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Zygotorulaspora cariocana sp. nov., a yeast species isolated from tree bark in Brazil

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijsem.0.004089 ◽

2020 ◽

Vol 70 (4) ◽

pp. 2677-2681

Author(s):

Juliana D. Moreira ◽

Ana Raquel O. Santos ◽

Fernanda L. C. Oliveira ◽

Raquel M. Cadete ◽

Ana Luiza Freire ◽

...

Keyword(s):

Yeast Species ◽

Novel Species ◽

Large Subunit ◽

Sequence Divergence ◽

Amazon Rainforest ◽

Tree Bark ◽

Rrna Gene ◽

The Novel ◽

Nucleotide Substitutions ◽

Large Subunit Rrna

Six strains of a novel yeast species were isolated from tree bark collected in the Atlantic Forest and the Amazon Rainforest in Brazil. Analyses of the sequences of D1/D2 domains of the large subunit rRNA gene showed that the strains belong to a species in the genus Zygotorulaspora. The species differed by 5.54 % sequence divergence (25 substitutions and five indels out of 542 bp) in the D1/D2 sequences from Zygotorulaspora mrakii, its closest relative. The ITS sequence of the type strain of the novel species differs by 27–69 nucleotide substitutions/indels from the other Zygotorulaspora species. The novel species is able to grow on trehalose, maltose, l-sorbose, inulin and at 37 °C, which are negative in Z. mrakii. The name Zygotorulaspora cariocana sp. nov. is proposed. The holotype of Z. cariocana sp. nov. is CBS 16118T. The MycoBank number is MB 833702.

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Genomic Analysis Reveals Chromosomal Variation in Natural Populations of the Uncultured Psychrophilic ArchaeonCenarchaeum symbiosum

Journal of Bacteriology ◽

10.1128/jb.180.19.5003-5009.1998 ◽

1998 ◽

Vol 180 (19) ◽

pp. 5003-5009 ◽

Cited By ~ 114

Author(s):

Christa Schleper ◽

Edward F. DeLong ◽

Christina M. Preston ◽

Robert A. Feldman ◽

Ke-Ying Wu ◽

...

Keyword(s):

Large Subunit ◽

Natural Populations ◽

Genomic Analysis ◽

Rrna Genes ◽

Homologous Protein ◽

Dna Libraries ◽

Ribosomal Operon ◽

Molecular Phylogenetic ◽

Large Subunit Rrna ◽

Genotypic Characteristics

ABSTRACT Molecular phylogenetic surveys have recently revealed an ecologically widespread crenarchaeal group that inhabits cold and temperate terrestrial and marine environments. To date these organisms have resisted isolation in pure culture, and so their phenotypic and genotypic characteristics remain largely unknown. To characterize these archaea, and to extend methodological approaches for characterizing uncultivated microorganisms, we initiated genomic analyses of the nonthermophilic crenarchaeoteCenarchaeum symbiosum found living in association with a marine sponge, Axinella mexicana. Complex DNA libraries derived from the host-symbiont population yielded several large clones containing the ribosomal operon from C. symbiosum. Unexpectedly, cloning and sequence analysis revealed the presence of two closely related variants that were consistently found in the majority of host individuals analyzed. Homologous regions from the two variants were sequenced and compared in detail. The variants exhibit >99.2% sequence identity in both small- and large-subunit rRNA genes and they contain homologous protein-encoding genes in identical order and orientation over a 28-kbp overlapping region. Our study not only indicates the potential for characterizing uncultivated prokaryotes by genome sequencing but also identifies the primary complication inherent in the approach: the widespread genomic microheterogeneity in naturally occurring prokaryotic populations.

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