TY - JOUR
T1 - Microevolutionary changes in Candida albicans identified by the complex Ca3 fingerprinting probe involve insertions and deletions of the full-length repetitive sequence RPS at specific genomic sites
AU - Pujol, Claude
AU - Joly, Sophie
AU - Nolan, Bridgid
AU - Srikantha, Thyagarajan
AU - Soll, David R.
PY - 1999/10
Y1 - 1999/10
N2 - The 11 kb complex DNA fingerprinting probe Ca3 is effective both in cluster analyses of Candida albicans isolates and in identifying microevolutionary changes in the size of hypervariable genomic fragments. A 2.6 kb EcoRI fragment of Ca3, the C fragment, retains the capacity to identify these microevolutionary changes, and when the C fragment is cleaved with Sacl, the capacity is retained exclusively by a 1 kb subfragment, C1, which contains a partial RPS repeat element. The microevolutionary changes identified by Ca3, therefore, may involve reorganization of RPS elements dispersed throughout the genome. To test this possibility, hypervariable fragments from several strains of C. albicans were sequenced and compared. The results demonstrate that the microevolutionary changes identified by Ca3 are due to the insertion and deletion of full-length tandem RPS elements at specific genomic sites dispersed throughout the C. albicans genome. The RPS elements at these dispersed sites are bordered by the same upstream and downstream sequences. The frequency of recombination was estimated to be one recombination per 1000 cell divisions by following RPS reorganization in vitro. The results are inconsistent with unequal recombination between homologous or heterologous chromosomes, but consistent with intrachromosomal recombination. Two alternative models of intrachromosomal recombination are proposed: unequal sister-chromatid exchange and slipped misalignment at the replication fork.
AB - The 11 kb complex DNA fingerprinting probe Ca3 is effective both in cluster analyses of Candida albicans isolates and in identifying microevolutionary changes in the size of hypervariable genomic fragments. A 2.6 kb EcoRI fragment of Ca3, the C fragment, retains the capacity to identify these microevolutionary changes, and when the C fragment is cleaved with Sacl, the capacity is retained exclusively by a 1 kb subfragment, C1, which contains a partial RPS repeat element. The microevolutionary changes identified by Ca3, therefore, may involve reorganization of RPS elements dispersed throughout the genome. To test this possibility, hypervariable fragments from several strains of C. albicans were sequenced and compared. The results demonstrate that the microevolutionary changes identified by Ca3 are due to the insertion and deletion of full-length tandem RPS elements at specific genomic sites dispersed throughout the C. albicans genome. The RPS elements at these dispersed sites are bordered by the same upstream and downstream sequences. The frequency of recombination was estimated to be one recombination per 1000 cell divisions by following RPS reorganization in vitro. The results are inconsistent with unequal recombination between homologous or heterologous chromosomes, but consistent with intrachromosomal recombination. Two alternative models of intrachromosomal recombination are proposed: unequal sister-chromatid exchange and slipped misalignment at the replication fork.
KW - Ca3 fingerprinting
KW - Candida albicans
KW - Microevolution
KW - RPS repetitive units
UR - http://www.scopus.com/inward/record.url?scp=0032823296&partnerID=8YFLogxK
U2 - 10.1099/00221287-145-10-2635
DO - 10.1099/00221287-145-10-2635
M3 - Article
C2 - 10537185
AN - SCOPUS:0032823296
SN - 1350-0872
VL - 145
SP - 2635
EP - 2646
JO - Microbiology
JF - Microbiology
IS - 10
ER -