Cloning of ribosomal RNA genes from an Indian isolate of Giardia lamblia and the use of intergenic nontranscribing spacer regions in the differentiation of Giardia from other enteric pathogens.
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1998-12
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Abstract
The ribosomal RNA genes from an Indian isolate of Giardia lamblia have been cloned and characterized
with respect to size, composition and copy number. Southern blotting and rDNA cloning of Giardia lamblia
revealed that genes coding for ribosomal RNA (rRNA) are exceptionally small and are encoded within a
5.6 kb genome fragment repeat. The rDNA repeat unit of this isolate was found to be highly G-C rich like
other human isolates and the physical map showed several SmaI sites. There are 132 copies of the rDNA
repeat unit per cell in a head to tail arrangement. Two fragments corresponding to intergenic (0.2 kb and
0.3 kb) region and one (0.8 kb) containing both an intergenic region and a small part of the small subunit
ribosomal RNA (SS rRNA) have been identified within the rDNA. These were used in heterogeneity studies
of Giardia isolated from two geographic locations as well as in the analysis of cross reactivity with other
enteric organisms. In Southern blots, all the three fragments were found to be highly specific for the
differential diagnosis of Giardia spp. from the other enteric pathogens. These findings should help in
developing a sensitive and more specific method for the diagnosis of giardiasis over currently available
techniques.
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Sil A K, Das P, Bhattacharyya S, Ghosh S, Chattopadhyay D J. Cloning of ribosomal RNA genes from an Indian isolate of Giardia lamblia and the use of intergenic nontranscribing spacer regions in the differentiation of Giardia from other enteric pathogens. Journal of Biosciences. 1998 Dec; 23(5): 557-564.