Abstract
Entamoeba dispar andEntamoeba histolytica are now recognized as two distinct species-the former being nonpathogenic to humans. We had earlier studied the organization of ribosomal RNA genes inE. histolytica. Here we report the analysis of ribosomal RNA genes inE. dispar. The rRNA genes ofE. dispar, like their counterpart inE. histolytica are located on a circular rDNA molecule. From restriction map analysis, the size ofE. dispar rDNA circle was estimated to be 24·4 kb. The size was also confirmed by linearizing the circle withBsaHI, and by limited DNAseI digestion. The restriction map of theE. dispar rDNA circle showed close similarity to EhR1, the rDNA circle ofE. histolytica strain HM-1:IMSS which has two rDNA units per circle. The various families of short tandem repeats found in the upstream and downstream intergenic spacers (IGS) of EhR1 were also present inE. dispar. Partial sequencing of the cloned fragments ofE. dispar rDNA and comparison with EhR1 revealed only 2·6% to 3·8% sequence divergence in the IGS. The region Tr and the adjoiningPvuI repeats in the IGS of EhR1, which are missing in thoseE. histolytica strains that have one rDNA unit per circle, were present in theE. dispar rDNA circle. Such close similarity in the overall organization and sequence of the IGS of rDNAs of two different species is uncommon. In fact the spacer sequences were only slightly more divergent than the 18S rRNA gene sequence which differs by 1·6% in the two species. The most divergent sequence betweenE. histolytica andE. dispar was the internal transcribed spacer, ITS2. Therefore, it was concluded that probes derived from the ITS1 and ITS 2 sequences would be more reliable and reproducible than probes from the IGS regions used earlier for identifying these species.
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References
Bhattacharya S, Bhattacharya A, Diamond L S and Sodo A T 1989 Circular DNA ofE. histolytica encodes ribosomal RNA;J. Protozool. 36 455–458
Bhattacharya S, Som I and Bhattacharya A 1998 The ribosomal DNA plasmids of Entamoeba;Parasitol. Today 14 181–185
Britten D, Wilson S M, McNerney R, Moody A H, Chiodini P L and Ackers J P 1997 An improved colorimetric PCR-based method for detection and differentiation ofEntamoeba histo-lytica andEntamoeba dispar in feces;J. Clin. Microbiol. 35 1108–1111
Bruchhaus I, Jacobs T, Leippe M and Tannich E 1996Enta-moeba histolytica andEntamoeba dispar: differences in numbers and expression of cysteine proteinase genes;Mol. Microbiol. 22 255–263
Chen C A, Miller D J, Wei N V, Dai C F and Yang H P 2000 The ETS/IGS region in a lower animal, the seawhip,Junceella fragilis (Cindaria; Anthozoa: Octocorallia): Compactness, low variation and apparent conservation of a pre-rRNA proces-sing signal with fungi;Zoologic. St. 39 136–143
Chomczynski P and Sacchi N 1987 Single step method of RNA isolation by guanidinium thiocyanate-phenol-chloroform extraction;Anal. Biochem. 162 156–159
Clark C G and Diamond L S 1997 Intraspecific variation and phylogenetic relationships in the genus Entamoeba as revealed by riboprinting;J. Euk. Microbiol. 44 142–154
Diamond L S 1978 A new medium for axenic cultivation ofEntamoeba histolytica and other Entamoeba;Trans. R. Soc. Trop. Med. Hyg. 72 431–432
Diamond L S 1982 A new liquid medium for xenic cultivation ofEntamoeba histolytica and other lumen dwelling protozoa;J. Parasitol. 68 958–959
Dietrich P, Soares M B, Affonso M H T and Floeter-Winter L M 1993 TheTrypanosoma cruzi ribosomal RNA-encoding gene: analysis of promoter and upstream intergenic spacer sequences;Gene 125 103–107
Dover G A, Linares A R, Bowen T and Hancock J M 1993 Detection and quantification of concerted evolution and molecular drive;Methods Enzymol. 224 525–541
Feinberg A P and Vogelstein B 1983 A technique for radio-labelling DNA restriction endonuclease fragments to high specific activity;Anal. Biochem. 132 6–13
Ghosh S, Zaki M, Clark C G and Bhattacharya S 2001 Recom-binational loss of a ribosomal DNA unit from the circular episome ofEntamoeba histolytica HM-1:IMSS;Mol. Bio-chem. Parasitol. 116 105–108
Gonzalez I L and Sylvester J E 2001 Human rDNA: Evolutionary patterns within the genes and tandem arrays derived from multiple chromosomes;Genomics 73 255–263
Haque R, Ali I K M, Akther S and Petri W A Jr 1998 Comparison of PCR, Isoenzyme analysis and antigen detection for diagnosis ofEntamoeba histolytica infection;J. Clin. Microbiol. 36 449–452
Jackson T F H G and Ravdin J I 1996 Differentiation ofEntamoeba histolytica andEntamoeba dispar infections;Parasitol. Today 12 406–409
Mirelman D, Nuchamowitz Y and Stolarsky T 1997 Comparison of use of Enzyme linked Immunoabsorbent assay-based kits and PCR amplification of rRNA genes for simultaneous detection ofEntamoeba histolytica andEntamoeba dispar;J. Clin. Microbiol. 35 2405–2407
Nickel R, Otto C, Dandekar T and Leippe M 1999 Pore forming peptides ofEntamoeba dispar. Similarity and divergence to amoebapores in structure, expression and activity;Eur. J. Biochem. 265 1002–1007
Novati S, Sironi M, Granata S, Scaglia and Bandi C 1996 Direct sequencing of the PCR amplified ssu rRNA gene ofEntamoeba dispar and the design of primers for rapid differentiation fromEntamoeba histolytica;Parasitology 112 363–369
Petri W A Jr, Jackson T F H G, Gathiram V, Kress K, Saffer L D, Snodgrass T L, Chapman M D and Mirelman D 1990 Pathogenic and non pathogenic strains ofEntamoeba histolytica can be differentiated by monoclonal antibodies to the galactose-specific adherence lectin;Infect. Immun. 58 1802–1806
Ramachandran S 1993Organization and characterisation of Ribosomal Nucleic Acid genes in Entamoeba histolytica, Ph.D. thesis, Jawaharlal Nehru University, New Delhi
Rogers S A and Bendich A J 1987 Ribosomal RNA genes in plants: variability in copy number and in the intergenic spacer;Plant Mol. Biol. 9 509–520
Sambrook J, Fritsch E F and Maniatis T 1989Molecular cloning. A laboratory manual Vol. 1–3 (New York: Cold Spring Harbor Press)
Samuelson J, Acuna-soto R, Reed S, Biagi F and Wirth D 1989 DNA hybridization probe for clinical diagnosis ofEntamoeba histolytic;J. Clin. Microbiol. 27 671–676
Sanger F, Nicklen D and Coulson A R 1977 DNA sequencing with chain terminating inhibitors;Proc. Natl. Acad. Sci. USA 74 5463–5467
Sehgal D, Mittal V, Ramachandran S, Dhar S K, Bhattacharya, Bhattacharya S 1994 Nucleotide sequence organization and analysis of the ribosomal DNA circle of the protozoan parasiteEntamoeba histolytica;Mol. Biochem. Parasitol. 67 205–214
Som I, Azam A, Bhattacharya A and Bhattacharya S 2000 Inter and intra-strain variation in the 5.8S ribosomal RNA and internal transcribed spacer sequences ofEntamoeba histolytica and comparison withEntamoeba dispar, Entamoeba moshkovskii andEntamoeba invadens;Int. J. Parasitol. 30 723–728
Uliana S R, Fischer W, Stemplink V A and Floeter-Winter L M 1996 Structural and functional characterisation of theLeishmania amazonensis ribosomal RNA promoter;Mol. Biochem. Parasitol. 76 245–255
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Paul, J., Bhattacharya, A. & Bhattacharya, S. Close sequence identity between ribosomal DNA episomes of the non-pathogenicEntamoeba dispar and pathogenicEntamoeba histolytica . J Biosci 27, 619–627 (2002). https://doi.org/10.1007/BF02704857
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DOI: https://doi.org/10.1007/BF02704857