Rearranged Subtelomeric rRNA Genes in
            <i>Giardia duodenalis</i>

Upcroft, Jacqueline; Abedinia, Mahin; Upcroft, Peter

doi:10.1128/ec.4.2.484-486.2005

Cited by 17 publications

(30 citation statements)

References 17 publications

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“…Different Giardia isolates demonstrate substantial differences in the chromosomal locations of the rDNA repeats (Adam et al, 1991), even for different cloned lines of the same isolate (Adam and Prabhu, unpublished observations). In addition to being present as repeating units, the rRNA genes may be present in subtelomeric regions as rearranged or incomplete genes (Upcroft et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Characterisation of the subtelomeric regions of Giardia lamblia genome isolate WBC6

Prabhu

Morrison

Martínez

et al. 2007

International Journal for Parasitology

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Giardia trophozoites are polyploid and have five chromosomes. The chromosome homologues demonstrate considerable size heterogeneity due to variation in the subtelomeric regions. We used clones from the genome project with telomeric sequence at one end to identify six subtelomeric regions in addition to previously identified subtelomeric regions, to study the telomeric arrangement of the chromosomes. The subtelomeric regions included two retroposons, one retroposon pseudogene, and two vsp genes, in addition to the previously identified subtelomeric regions that include ribosomal DNA repeats. The presence of vsp genes in a subtelomeric region suggests that telomeric rearrangements may contribute to the generation of vsp diversity. These studies of the subtelomeric regions of Giardia may contribute to our understanding of the factors that maintain stability, while allowing diversity in chromosome structure.

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Section: Introductionmentioning

confidence: 99%

Characterisation of the subtelomeric regions of Giardia lamblia genome isolate WBC6

Prabhu

Morrison

Martínez

et al. 2007

International Journal for Parasitology

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“…Whole G. duodenalis chromosomes and NotI (New England Biolabs)-cleaved chromosomes were prepared and electrophoretically separated as previously described (Chen et al 1994;Upcroft et al 1996a;Upcroft et al 2005). I-PpoI (Promega) chromosome cleavage was according to the manufacturer's instructions (Upcroft et al 2005).…”

Section: Whole and Cleaved Chromosome Separationsmentioning

confidence: 99%

“…I-PpoI (Promega) chromosome cleavage was according to the manufacturer's instructions (Upcroft et al 2005).…”

Section: Whole and Cleaved Chromosome Separationsmentioning

confidence: 99%

“…What we originally called chromosome 1 is likely to be an accessory chromosome and not present uniformly in all isolates (Adam et al 1988;Upcroft and Upcroft 1999;Le Blancq 1994). Other accessory chromosomes and partial duplications, particularly a feature of lines induced in the laboratory to be drug-resistant, have also complicated efforts to determine the number and identity of G. duodenalis chromosomes (Chen et al 1994;Upcroft et al 2005). Figure 1 provides a reference for this study with chromosome names and sizes the same as those historically used in our previous publications (Chen et al 1994;Upcroft et al 1996aUpcroft et al , 2005 compared with the numbering system used by Adam et al (1988).…”

Section: Introductionmentioning

confidence: 99%

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Sequence map of the 3-Mb Giardia duodenalis assemblage A chromosome

et al. 2009

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The genome of the gut protozoan parasite Giardia duodenalis (assemblage A) has been sequenced and compiled as contigs and scaffolds (GiardiaDB- http://GiardiaDB.org ), but specific chromosome location of all scaffolds is unknown. To determine which scaffolds belong to the 3-Mb chromosome, a library of probes specific for this chromosome was constructed. The probes were hybridised to NotI-cleaved whole chromosomes, and the combined size of different NotI segments identified by the probes was 2,225 kb indicating the probes were well distributed along the 3-Mb chromosome. Six scaffolds (CH991814, CH991779, CH991793, CH991763, CH991764, and CH991761) were identified as belonging to the 3-Mb chromosome, and these scaffolds were ordered and oriented according to scaffold features including I-PpoI sites and hybridisation pattern. However, the combined size of scaffolds was more than 4 Mb. Approximately, 1 Mb of scaffold CH991763 carrying previously identified sequences specific for the 1.5-Mb chromosome(s) including subtelomeric sequence was reassigned, and several other anomalies were addressed such that the final size of the apparently 3-Mb chromosome is estimated to be 2,885 kb. This work addresses erroneous computer-based assignment of a number of contigs and emphasises the need for alternative and confirmatory methods of scaffold construction.

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“…The results of PFGE and sequence analysis indicate that chromosomes of Giardia are dynamic; frequent rearrangements and recombinations have been reported from telomeric arrays of rDNA genes and from subtelomeric repeats. Inner parts of chromosomes seem to be more stable (Adam 1992;Upcroft and Upcroft 1999;Upcroft et al 2005). A common consensus is that there are five chromosome linkage groups defined by using chromosome-specific probes (Adam et al 1988;Le Blancq and Adam 1998), that homologous chromosomes are present in several copies, and that their size variability is a hallmark of heterogeneity of molecular karyotypes of Giardia isolates (Le Blancq and Adam 1998).…”

Section: Introductionmentioning

confidence: 99%

Cytogenetic evidence for diversity of two nuclei within a single diplomonad cell of Giardia

et al. 2006

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Giardia intestinalis is an ancient protist that causes the most commonly reported human diarrheal disease of parasitic origin worldwide. An intriguing feature of the Giardia cell is the presence of two morphologically similar nuclei, generally considered equivalent, in spite of the fact that their karyotypes are unknown. We found that within a single cell, the two nuclei differ both in the number and the size of chromosomes and that representatives of two major genetic groups of G. intestinalis possess different karyotypes. Odd chromosome numbers indicate aneuploidy of Giardia nuclei, and their stable occurrence is suggestive of a long-term asexuality. A semi-open type of Giardia mitosis excludes a chromosome interfusion between the nuclei. Differences in karyotype and DNA content, and cell cycle-dependent asynchrony are indicative of diversity of the two Giardia nuclei.

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Rearranged Subtelomeric rRNA Genes in Giardia duodenalis

Cited by 17 publications

References 17 publications

Characterisation of the subtelomeric regions of Giardia lamblia genome isolate WBC6

Characterisation of the subtelomeric regions of Giardia lamblia genome isolate WBC6

Sequence map of the 3-Mb Giardia duodenalis assemblage A chromosome

Cytogenetic evidence for diversity of two nuclei within a single diplomonad cell of Giardia

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