Structure of a frequently rearranged rRNA-encoding chromosome inGiardia lamblia

Characterisation of the subtelomeric regions of Giardia lamblia genome isolate WBC6

“…This would also fit with previous reports describing p4E at one end (Hou et al, 1995) and rDNA (Adam, 1992;Hou et al, 1995) at the other end of chromosome 1a on other isolates from the same genotype as WB. The four NotI telomeric fragments are the expected results for two co-migrating chromosomes (Fig.…”

“…The portion of STR6 that was used as a probe had no identified BLAST hit, but had an rDNA sequence located between the unknown sequence and the telomere. In addition to the six STRs we identified, two other STRs have been identified in previous reports from other Genotype A-1 isolates by the identification of clones with telomeric repeats at one end and nontelomeric sequence at the other end ((rDNA; STR7 (Adam et al, 1991)) or (p4e; STR8 (Hou et al, 1995)). STRs 7 and 8 co-localized with telomeric fragments on restriction digests of chromosomal DNA and are discussed below.…”

“…Previous studies of the Giardia chromosomes have demonstrated substantial size variation of chromosome 1 (Adam et al, , 1991Adam, 1992;Le Blancq et al, 1991a, 1992, 1991bHou et al, 1995). These analyses of chromosome 1 demonstrated a core region that was highly similar for all copies of the chromosome and substantial variation in the subtelomeric regions (STRs).…”

“…These analyses of chromosome 1 demonstrated a core region that was highly similar for all copies of the chromosome and substantial variation in the subtelomeric regions (STRs). Ribosomal DNA (rDNA) repeats were found adjacent to the TAGGG telomeric repeat at one end of chromosome 1 and accounted for a substantial portion of the size heterogeneity for the different chromosome 1 homologues (Adam, 1992;Hou et al, 1995). 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locations of the rDNA repeats (Adam et al, 1991), even for different cloned lines of the same isolate (Adam and Prabhu, unpublished observations).…”

“…A chromosome 1 STR (p4e) was cloned on the basis of having the telomeric repeat at one end (Hou et al, 1995). Clones have been identified that have telomeric repeats at one end and a retroposon sequence at the other (Arkhipova and Morrison, 2001).…”