Structural basis of karyotype heterogeneity in Giardia lamblia

Blancq, S Le; Adam, RodneyD.

doi:10.1016/s0166-6851(98)00150-9

Cited by 38 publications

(28 citation statements)

References 37 publications

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“…PFGE separations of chromosomal DNA have been used to demonstrate that G. lamblia trophozoites have five chromosome linkage groups ranging in size from approximately 1.6 to 3.8 Mb (7,177) (Fig 12). The initial report of PFGE separations of G. lamblia chromosomes identified four intensely staining ethidium bromide-stained chromosomal bands for most isolates (including ISR and WB) and five bands for JH (7).…”

Section: Genetics and Molecular Biology Genome Structurementioning

confidence: 99%

“…A PFGE separation of JH (genotype A-2) chromosomes demonstrates five distinct bands, while a PFGE separation of ISR (genotype A-1) chromosomes demonstrates four intensely staining and two more faintly staining bands. A series of chromosome-specific probes have been used to identify five distinct linkage groups corresponding to the five bands of the JH isolate (7,177). The fainter bands of the ISR isolate represent size variants of chromosome 1, as demonstrated by a set of chromosomespecific probes (7) as well as by detailed mapping of chromosome 1 (139).…”

Section: Genetics and Molecular Biology Genome Structurementioning

confidence: 99%

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Biology ofGiardia lamblia

2001

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Giardia lamblia is a common cause of diarrhea in humans and other mammals throughout the world. It can be distinguished from other Giardia species by light or electron microscopy. The two major genotypes of G. lamblia that infect humans are so different genetically and biologically that they may warrant separate species or subspecies designations. Trophozoites have nuclei and a well-developed cytoskeleton but lack mitochondria, peroxisomes, and the components of oxidative phosphorylation. They have an endomembrane system with at least some characteristics of the Golgi complex and encoplasmic reticulum, which becomes more extensive in encysting organisms. The primitive nature of the organelles and metabolism, as well as small-subunit rRNA phylogeny, has led to the proposal that Giardia spp. are among the most primitive eukaryotes. G. lamblia probably has a ploidy of 4 and a genome size of approximately 10 to 12 Mb divided among five chromosomes. Most genes have short 5′ and 3′ untranslated regions and promoter regions that are near the initiation codon. Trophozoites exhibit antigenic variation of an extensive repertoire of cysteine-rich variant-specific surface proteins. Expression is allele specific, and changes in expression from one vsp gene to another have not been associated with sequence alterations or gene rearrangements. The Giardia genome project promises to greatly increase our understanding of this interesting and enigmatic organism

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Section: Genetics and Molecular Biology Genome Structurementioning

confidence: 99%

Section: Genetics and Molecular Biology Genome Structurementioning

confidence: 99%

Biology ofGiardia lamblia

2001

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“…Therefore, it can be deduced that such rearrangements in the highly conserved G. duodenalis LS rRNA genes (14) will result in nonfunctional LS rRNA genes and rRNA gene units (7). The precise function of the rRNA gene unit fragments embedded in the telomere regions remains unknown, but the telomere regions of Giardia chromosomes are highly plastic (9,16), and they appear to be indicative of the plasticity and rearrangements typical of this region of eukaryotic chromosomes.…”

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confidence: 99%

Rearranged Subtelomeric rRNA Genes in Giardia duodenalis

2005

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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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“…Generally, the central core of protozoan chromosomes remains stable while the subtelomeric regions vary. Variability in these regions is responsible for a major part of the large polymorphisms observed between chromosome homologues in parasitic protozoa (72,73,113,129,179). Because of this variability, DNA elements positioned at chromosomal margins are apt to live short lives unless they can expand rapidly enough to offset the high rate of casualties.…”

Section: Life On the Edge: Subtelomeric Repeatsmentioning

confidence: 99%

“…A subset of subtelomeres of G. lamblia contain tandem repeats of rRNA genes which show extensive polymorphisms (1,92,115) and also apparently jump from telomere to telomere (113,187), providing an interesting genic parallel to the mobility of the subtelomeric satellites of other species. However, most G. lamblia subtelomeres consist of tandem copies of active LINE retroposons (either GilM or GilT elements), which directly abut the telomeric repeats and are oriented such that reverse transcription would have run toward the chromosome end (15,37).…”

Section: Life On the Edge: Subtelomeric Repeatsmentioning

confidence: 99%

Repetitive Elements in Genomes of Parasitic Protozoa

Wickstead

Ersfeld

Gull

2003

Microbiol Mol Biol Rev

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Repetitive DNA elements have been a part of the genomic fauna of eukaryotes perhaps since their very beginnings. Millions of years of coevolution have given repeats central roles in chromosome maintenance and genetic modulation. Here we review the genomes of parasitic protozoa in the context of the current understanding of repetitive elements. Particular reference is made to repeats in five medically important species with ongoing or completed genome sequencing projects: Plasmodium falciparum, Leishmania major, Trypanosoma brucei, Trypanosoma cruzi, and Giardia lamblia. These organisms are used to illustrate five thematic classes of repeats with different structures and genomic locations. We discuss how these repeat classes may interact with parasitic life-style and also how they can be used as experimental tools. The story which emerges is one of opportunism and upheaval which have been employed to add genetic diversity and genomic flexibility

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Structural basis of karyotype heterogeneity in Giardia lamblia

Cited by 38 publications

References 37 publications

Biology ofGiardia lamblia

Biology ofGiardia lamblia

Rearranged Subtelomeric rRNA Genes in Giardia duodenalis

Repetitive Elements in Genomes of Parasitic Protozoa

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