Extensive chromosome translocation in a clinical isolate showing the distinctive carbohydrate assimilation profile from a candidiasis patient

Abstract

Variation of the electrophoretic karyotype is common among clinical strains of Candida albicans and chromosome translocation is considered one of the causes of karyotypic variation. Such chromosome translocations may be a mechanism to confer phenotypic diversity on the imperfect fungus C. albicans. A clinical strain, TCH23, from a vaginal candidiasis patient shows distinct carbohydrate assimilation profile, serotype B, no chlamydospore formation and an atypical karyotype (Asakura et al., 1991). To examine the taxonomic relationship among C. albicans, Candida dubliniensis and this strain, we sequenced the internal transcribed spacer 1 (ITS1) of nuclear ribosomal DNA. The ITS1 sequence of TCH23 was identical with that of C. albicans but not of C. dubliniensis. Thus, strain TCH23 was classified as a variant of C. albicans with an atypical phenotype. The chromosomal DNAs of this strain were resolved into 13 bands on pulse-field gel electrophoresis (PFGE). Using DNA probes located at or near both ends of each chromosome of C. albicans, we investigated the chromosome organization of this strain. Referring to the SfiI map of C. albicans 1006 (Chu et al., 1993), we found that seven chromosomal DNA bands in strain TCH23 were reciprocal chromosome translocations. One homologue from chromosomes 1, 2 and 6 and both homologues from chromosomes 4 and 7 participated in these events. One translocation product was composed of three SfiI fragments, one each from chromosomes 2, 4 and 7. We deduced the breakpoints of chromosome translocation from the physical map of this strain; between 1J and 1J1, between 2A and 2U, both ends of 4F2, between 6C and 6O and both ends of 7F.

Chromosome translocation induced by the insertion of the URA blaster into the major repeat sequence (MRS) in Candida albicans

“…To investigate the possibility of chromosome translocation in transformants containing extra chromosome DNA bands, we selected 19 DNA probes that are located at or near at one end of each chromosome in strain 1006 (Table 2). We reported previously that these probes helped us to identify chromosome translocation products (Iwaguchi et al, 2001). Probes from chromosomes R, 1, 5 and 7 hybridized to extrachromosomal DNA bands in five of the transformants.…”

“…Five transformants (tRB6, tRB16, tRB26, tRB29 and tRB41) contained extra chromosome DNA bands. Extrachromosomal DNA bands are usually considered to be the products of chromosome translocation (Chu et al, 1993;Navarro-Garcia et al, 1995;Iwaguchi et al, 2000Iwaguchi et al, , 2001. In the case of the RUS blaster, we obtained 36 transformants and the insertion events occurred on all of the chromosomes except for 3 and 4.…”

“…Other strains of this organism, 1001 and STN21, also contained translocation products, between chromosomes 2 and 7 and between chromosomes 4 and 7, respectively (Navarro-Garcia et al, 1995;Iwaguchi et al, 2000). Strain TCH23 of this organism, isolated from a vaginal candidiasis patient, contains 13 chromosomal DNA bands (Iwaguchi et al, 2001). Using DNA probes located at or near both ends of each chromosome of C. albicans, it was found that seven of the chromosomal DNA bands in strain TCH23 were the products of reciprocal chromosome translocations.…”

“…There are several reports of chromosome translocation involving chromosome 7 (Chu et al, 1993;Iwaguchi et al, 2000;Navarro-Garcia et al, 1995;Iwaguchi et al, 2001;Chibana et al, 2000). Both ends of the SfiI fragment 7F have been shown to be active sites for recombination, and each is flanked by major repeat sequences (MRSs).…”

Candida africana and its closest relatives

“…These karyotypes were rather similar to those of C. stellatoidea type I but the authors discarded the hypothesis that their seven isolates belonged to the latter species on the basis of positive assimilation of sucrose. 30 Ten years later, Iwanughi et al [76] analysed the chromosome structure of the TCH23 strain (one of the seven atypical strains isolated by Asakura et al [30]) and found that seven chromosomal DNA bands in this strain were reciprocal chromosome translocations. Therefore, it is possible that the inability to assimilate some carbon sources and to produce chlamydospore by C. africana is due to these genetic rearrangements that occurred within its genome.…”