Document Detail


Organization of repeated sequences in the region downstream to rRNA genes in the rDNA episome of Entamoeba histolytica.
MedLine Citation:
PMID:  1364100     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The E. histolytica rDNA episome consists of a 3.7 kb HindIII fragment located downstream of the rDNA inverted repeats. We have determined the complete nucleotide sequence of this fragment and have shown that it is comprised of two families of short tandem repeats, the 170 bp DraI repeat and the 144 bp ScaI repeat. Each DraI repeat unit consists of 12-mer sequences with near complete homology to yeast consensus autonomously replicating sequence. In addition, a 21-mer subrepeat structure is also present in each unit. The sequence of the ScaI repeat is about 90% homologous with the sequence of another family of 145 bp tandem repeats, the PvuI repeats reported to be present upstream of the rRNA genes (3). Compared with most other parts of the rDNA episome, the downstream region showed frequent restriction fragment length polymorphism. This was due to changes in the number of tandem DraI repeat units. The loss of these repeats might explain how rDNA length heterogeneity observed in the clones of HM1:IMSS could have arisen. On the other hand, the number of ScaI repeat units in these clones remained unchanged. The repeat units found in the 3.7 kb HindIII fragment show superficial resemblance to equivalent regions of the intergenic spacers of higher eukaryotes. Moreover, these repeated sequences seem to be specific for the pathogenic strain of E. histolytica.
Authors:
V Mittal; A Bhattacharya; S Bhattacharya
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Archives of medical research     Volume:  23     ISSN:  0188-4409     ISO Abbreviation:  Arch. Med. Res.     Publication Date:  1992  
Date Detail:
Created Date:  1993-12-20     Completed Date:  1993-12-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9312706     Medline TA:  Arch Med Res     Country:  MEXICO    
Other Details:
Languages:  eng     Pagination:  17-8     Citation Subset:  IM    
Affiliation:
School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
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MeSH Terms
Descriptor/Qualifier:
Animals
Base Sequence
Consensus Sequence
DNA, Circular / genetics*
DNA, Protozoan / genetics*
DNA, Ribosomal / genetics
Entamoeba histolytica / genetics*
Molecular Sequence Data
Plasmids / genetics*
Polymorphism, Restriction Fragment Length
RNA, Protozoan / genetics
RNA, Ribosomal / genetics
Repetitive Sequences, Nucleic Acid*
Sequence Homology, Nucleic Acid
Chemical
Reg. No./Substance:
0/DNA, Circular; 0/DNA, Protozoan; 0/DNA, Ribosomal; 0/RNA, Protozoan; 0/RNA, Ribosomal

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