Elsevier

Gene

Volume 44, Issue 1, 1986, Pages 63-70
Gene

Length variation in eukaryotic rRNAs: small subunit rRNAs from the protists Acanthamoeba castellanii and Euglena gracilis

https://doi.org/10.1016/0378-1119(86)90043-0Get rights and content

Abstract

We have sequenced the region of the Acanthamoeba castellanii ribosomal RNA transcription unit which encodes the mature small subunit ribosomal RNA (SSU rRNA). It, like the SSU rRNA coding regions of Euglena gracilis and kinetoplastids, is approx. 30% larger than those reported from other eukaryotes. The extra nucleotides are present in highly variable regions of the rRNA genes. Direct sequence analysis of the corresponding variable regions in the rRNA of A. castellanii and E. gracilis demonstrates that the extra nucleotides are present in the mature rRNA; no post-transcriptional modification of the rRNAs occurs to reduce them to a size more typical of eukaryotes. The extra elements present in the rRNAs of these two organisms are not homologous; they have independent evolutionary origins.

References (19)

There are more references available in the full text version of this article.

Cited by (73)

  • Report of rare genotypes of Acanthamoeba from soil source of the Payeh Maga Highland forest, North-eastern Sarawak, Malaysia

    2022, Acta Tropica
    Citation Excerpt :

    Morphological-based classification of Acanthamoeba sp. is becoming less popular nowadays mainly due to challenges such as polymorphism of cyst features within a clonal isolate, alteration of cyst shape by different growth conditions, and the technique requires intensive skill to perform. With the advent of PCR and sequencing techniques, the first complete 18S rRNA gene sequence of the Acanthamoeba genus was published in the mid-1980s (Gunderson et al.,1986). When more isolates were sequenced, scientists started to explore 18S rRNA gene sequences as a molecular marker for the taxonomic classification of Acanthamoeba sp. (Gast et al., 1996).

  • Isolates from ancient permafrost help to elucidate species boundaries in Acanthamoeba castellanii complex (Amoebozoa: Discosea)

    2020, European Journal of Protistology
    Citation Excerpt :

    Due to a well-established method of axenic cultivation, it has become a popular model in biochemical and cell structure studies (Siddiqui and Khan 2012). Acanthamoeba was among the first organisms whose nuclear small subunit ribosomal RNA gene sequence (18S rDNA) was determined (Gunderson and Sogin 1986). The genome of one strain is assembled and annotated (Clarke et al. 2013), and several other draft genomes are available in GenBank.

  • Insights from the DNA databases: Approaches to the phylogenetic structure of Acanthamoeba

    2014, Experimental Parasitology
    Citation Excerpt :

    However, that did not seem to be the case for “species” of Acanthamoeba. It quickly became obvious that the extra sequence regions discovered by Gunderson and Sogin (1986) were probably subjected to much weaker purifying natural selection, and thus were able to vary much more extensively than the majority of nucleotide sites within the gene. These regions would provide the necessary information for an extensive analysis of phylogenetic relationships among isolates of Acanthamoeba.

  • Complete modification maps for the cytosolic small and large subunit rRNAs of euglena gracilis: Functional and evolutionary implications of contrasting patterns between the two rRNA components

    2011, Journal of Molecular Biology
    Citation Excerpt :

    For RNase protection experiments, updated secondary structure models allowed us to define complementary PCR products that: (i) are not adjacent to stable RNA structural elements, (ii) would direct RNase T1 cleavage to single-stranded or weakly structured sites, and (iii) would disrupt highly structured domains and protect only one strand of very stable hairpins (a strategy that eliminated band compressions occurring in sequencing gels due to hairpin formation). The E. gracilis SSU rRNA sequence3,10 was first folded (Fig. 1a) to fit the highly conserved central core that is shared between the Saccharomyces cerevisiae SSU rRNA secondary structure model and the Escherichia coli SSU rRNA secondary structure model available at the Comparative RNA Web site.11 Where possible, we used the variable region structures proposed by Wuyts et al.12,13 for E. gracilis, but we found that those structures required extensive revisions when they were tested by a comparative analysis11 of SSU rRNA sequences from a large number of Euglena species.14

View all citing articles on Scopus
View full text