The Ribosomal DNA Plasmids of Entamoeba

Bhattacharya, Sudha; Som, Indrani; Bhattacharya, Alok

doi:10.1016/s0169-4758(98)01222-8

Cited by 59 publications

(35 citation statements)

References 38 publications

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“…A complete sequence map of the ribosomal DNA (rDNA) episome has been successfully completed (23,201). Sehgal et al (201) and Bhattacharya et al (23) found that E. histolytica circular DNA is 24.5 kb.…”

Section: Life Cycle and Biologymentioning

confidence: 99%

Laboratory Diagnosis of Amebiasis

2003

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The detection of Entamoeba histolytica, the causative agent of amebiasis, is an important goal of the clinical microbiology laboratory. To assess the scope of E. histolytica infection, it is necessary to utilize accurate diagnostic tools. As more is discovered about the molecular and cell biology of E. histolytica, there is great potential for further understanding the pathogenesis of amebiasis. Molecular biology-based diagnosis may become the technique of choice in the future because establishment of these protozoa in culture is still not a routine clinical laboratory process. In all cases, combination of serologic tests with detection of the parasite (by antigen detection or PCR) offers the best approach to diagnosis, while PCR techniques remain impractical in many developing country settings. The detection of amebic markers in serum in patients with amebic colitis and liver abscess appears promising but is still only a research tool. On the other hand, stool antigen detection tests offer a practical, sensitive, and specific way for the clinical laboratory to detect intestinal E. histolytica. All the current tests suffer from the fact that the antigens detected are denatured by fixation of the stool specimen, limiting testing to fresh or frozen samples

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Section: Life Cycle and Biologymentioning

confidence: 99%

Laboratory Diagnosis of Amebiasis

2003

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“…Most of them target either the small-subunit rRNA (18S rRNA) gene (5,10,15,18) or species-specific episomal repeats (1,19,21). These targets are present on multicopy, extrachromosomal plasmids in the amebas (3). The sensitivity and specificity of PCR assays exceed what can be accomplished with microscopy and are comparable to those of the antigen test (13,16,17,20,23).…”

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confidence: 99%

Comparison of Real-Time PCR Protocols for Differential Laboratory Diagnosis of Amebiasis

et al. 2005

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Specific identification of Entamoeba spp. in clinical specimens is an important confirmatory diagnostic step in the management of patients who may be infected with Entamoeba histolytica, the species that causes clinical amebiasis. Distinct real-time PCR protocols have recently been published for identification of E. histolytica and differentiation from the morphologically identical nonpathogenic Entamoeba dispar. In this study, we compared three E. histolytica real-time PCR techniques published by December 2004. The limits of detection and efficiency of each real-time PCR assay were determined using DNA extracted from stool samples spiked with serially diluted cultured E. histolytica trophozoites. The ability of each assay to correctly distinguish E. histolytica from E. dispar was evaluated with DNA extracted from patients' stools and liver aspirates submitted for confirmatory diagnosis. Real-time PCR allowed quantitative analysis of the spiked stool samples, but major differences in detection limits and assay performance were observed among the evaluated tests. These results illustrate the usefulness of comparative evaluations of diagnostic assays.

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“…In addition to these, a chromosomal copy of the rDNA exists in Dictyostelium (9) that likely is the source of the extrachromosomal elements. Extrachromosomal rDNA is also found in other amoebae like Physarum (10) or the ciliate Tetrahymena (11,12), whereas Entamoeba features circular rDNA templates (13).…”

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confidence: 99%

Sequence and Generation of Mature Ribosomal RNA Transcripts in Dictyostelium discoideum

Boesler

Kruse

Söderbom

et al. 2011

Journal of Biological Chemistry

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The amoeba Dictyostelium discoideum is a well established model organism for studying numerous aspects of cellular and developmental functions. Its ribosomal RNA (rRNA) is encoded in an extrachromosomal palindrome that exists in ϳ100 copies in the cell. In this study, we have set out to investigate the sequence of the expressed rRNA. For this, we have ligated the rRNA ends and performed RT-PCR on these circular RNAs. Sequencing revealed that the mature 26 S, 17 S, 5.8 S, and 5 S rRNAs have sizes of 3741, 1871, 162, and 112 nucleotides, respectively. Unlike the published data, all mature rRNAs of the same type uniformly display the same start and end nucleotides in the analyzed AX2 strain. We show the existence of a short lived primary transcript covering the rRNA transcription unit of 17 S, 5.8 S, and 26 S rRNA. Northern blots and RT-PCR reveal that from this primary transcript two precursor molecules of the 17 S and two precursors of the 26 S rRNA are generated. We have also determined the sequences of these precursor molecules, and based on these data, we propose a model for the maturation of the rRNAs in Dictyostelium discoideum that we compare with the processing of the rRNA transcription unit of Saccharomyces cerevisiae.Ribosomes belong to the most important molecular machines in the cell. As the sites of protein biosynthesis, they are highly conserved, and the analysis of their RNA constituents allows the determination of phylogenetic relationships over large evolutionary distances. Within the last decade, beautiful crystallographic work has confirmed that the catalytic activity resides with the RNA and that the

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The Ribosomal DNA Plasmids of Entamoeba

Cited by 59 publications

References 38 publications

Laboratory Diagnosis of Amebiasis

Laboratory Diagnosis of Amebiasis

Comparison of Real-Time PCR Protocols for Differential Laboratory Diagnosis of Amebiasis

Sequence and Generation of Mature Ribosomal RNA Transcripts in Dictyostelium discoideum

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