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

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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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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Schistonchus hirtus n. sp. (Nematoda: Aphelenchoididae), an associate of Ficus hirta in China

Nematology ◽

10.1163/138855409x12571623969727 ◽

2010 ◽

Vol 12 (4) ◽

pp. 543-556 ◽

Cited By ~ 7

Author(s):

Yongsan Zeng ◽

Weimin Ye ◽

Robin M. Giblin-Davis ◽

Changhui Li ◽

Zhijian Du ◽

...

Keyword(s):

Sequence Data ◽

Large Subunit ◽

Morphological Characters ◽

Small Subunit ◽

Rrna Gene ◽

Small Subunit Rrna ◽

Wasp Species ◽

Dna Sequence Data ◽

Ficus Hirta ◽

Large Subunit Rrna

Abstract A nematode recovered from syconia of Ficus hirta from Guangzhou, P. R. China, during a survey of nematode biodiversity from 2007 to 2009, is described herein as Schistonchus hirtus n. sp. and is differentiated by a combination of morphological characters, including excretory pore (EP) located near the metacorpus, a short post-uterine sac (PUS) (0.5 vulval body diam. (VBD) long), rose thorn-shaped spicules, amoeboid sperm, absence of gubernaculum, three pairs of subventral papillae on the male tail, host-Ficus and host-wasp species and DNA sequence data. Morphologically, S. hirtus n. sp. is close to S. centerae, S. altermacrophylla, S. aureus, S. laevigatus and S. virens based upon the length of the PUS (about 0.5 VBD long). However, the relative position of the EP in S. hirtus n. sp. is very different from these species (near metacorpus vs near head). With regard to the EP character, S. hirtus n. sp. is very similar to S. macrophylla, S. guangzhouensis and S. caprifici where the EP is at metacorpus level. However, S. hirtus n. sp. differs from S. macrophylla and S. guangzhouensis by possessing a shorter PUS and smaller spicules, and differs from S. caprifici by a shorter female stylet and smaller spicules. Schistonchus hirtus n. sp. was easily differentiated from other sequenced species by the proportion of parsimony informative changes in the partial small subunit rRNA gene (SSU) and D2/D3 expansion segments of the large subunit rRNA gene (LSU). Phylogenetic analysis with SSU sequences suggests that S. hirtus n. sp. is in a highly supported monophyletic clade with Aphelenchoides and Laimaphelenchus and is polyphyletic to other sequenced Schistonchus species. With LSU sequence data, it forms a clade with S. caprifici and they appear polyphyletic relative to S. guangzhouensis, S. centerae, S. aureus, S. laevigatus and S. virens.

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

Molecular and Cellular Biology ◽

10.1128/mcb.14.6.4203 ◽

1994 ◽

Vol 14 (6) ◽

pp. 4203-4215 ◽

Cited By ~ 57

Author(s):

R Sweeney ◽

L Chen ◽

M C Yao

Keyword(s):

Large Subunit ◽

Sequence Divergence ◽

Variable Region ◽

Rrna Genes ◽

Functional Importance ◽

Functional Feature ◽

Tertiary Structures ◽

Unrelated Sequence ◽

Evolutionarily Conserved ◽

Large Subunit Rrna

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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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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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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Occurrence and Morpho-Molecular Identification of Botryosphaeriales Species from Guizhou Province, China

Journal of Fungi ◽

10.3390/jof7110893 ◽

2021 ◽

Vol 7 (11) ◽

pp. 893

Author(s):

Asha J. Dissanayake ◽

Ya-Ya Chen ◽

Ratchadawan Cheewangkoon ◽

Jian-Kui Liu

Keyword(s):

Fungal Pathogens ◽

Sequence Data ◽

Phylogenetic Analyses ◽

Large Subunit ◽

Elongation Factor ◽

Morphological Characteristics ◽

Guizhou Province ◽

Southwestern China ◽

Rrna Gene ◽

Large Subunit Rrna

Botryosphaeriales is an important order of diverse fungal pathogens, saprobes, and endophytes distributed worldwide. Recent studies of Botryosphaeriales in China have discovered a broad range of species, some of which have not been formerly described. In this study, 60 saprobic isolates were obtained from decaying woody hosts in southwestern China. The isolates were compared with other species using morphological characteristics, and available DNA sequence data was used to infer phylogenetic analyses based on the internal transcribed spacer (ITS), large subunit rRNA gene (LSU), and translation elongation factor 1-α (tef) loci. Three novel species were illustrated and described as Botryobambusa guizhouensis, Sardiniella elliptica, and Sphaeropsis guizhouensis, which belong to rarely identified genera within Botryosphaeriaceae. Botryobambusa guizhouensis is the second species identified from the respective monotypic genus. The previously known species were identified as Aplosporella hesperidica, Barriopsis tectonae, Botryosphaeria dothidea, Diplodia mutila, Di. neojuniperi, Di. pseudoseriata, Di. sapinea, Di. seriata, Dothiorella sarmentorum, Do. yunnana, Lasiodiplodia pseudotheobromae, Neofusicoccum parvum, Sardiniella celtidis, Sa. guizhouensis, and Sphaeropsis citrigena. The results of this study indicate that numerous species of Botryosphaeriales are yet to be revealed in southwestern China.

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