Cells of Different Ploidy Are Often Present Together in Cryptococcus neoformans Strains.

Hata, Kunihiko; Ohkusu, Misako; Aoki, Shigeji; Ito‐Kuwa, Shoko; Pienthaweechai, Keskaew; Takeo, Kanji

doi:10.3314/jjmm.41.161

Cited by 9 publications

(9 citation statements)

References 9 publications

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“…However, one should take into account that our analysis of genome size and ploidy was based on the uninucleated cell subpopulation presenting the lowest DNA content (R 1 ), within a total population of 30,000 cells. In this sense, it is not possible to discard the presence of a small number of cells with distinct ploidy levels within the total cell population, a phenomenon that has already been reported for the pathogenic fungus Cryptococcus neoformans (Hata et al, 2000). This study provides information that addresses fundamental questions of P. brasiliensis biology, namely genome size and ploidy, an important asset for the development/ design of molecular techniques (e.g., gene disruption and/or over-expression) and the future genetic manipulation of this human dimorphic pathogen.…”

Section: Discussionmentioning

confidence: 92%

Genome size and ploidy of Paracoccidioides brasiliensis reveals a haploid DNA content: Flow cytometry and GP43 sequence analysis

Almeida¹,

Matute²,

Carmona³

et al. 2007

Fungal Genetics and Biology

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The aim of this study was to evaluate genome size and ploidy of the dimorphic pathogenic fungus Paracoccidioides brasiliensis. The cell cycle analysis of 10 P. brasiliensis isolates by flow cytometry (FCM) revealed a genome size ranging from 26.3+/-0.1Mb (26.9+/-0.1fg) to 35.5+/-0.2Mb (36.3+/-0.2fg) per uninucleated yeast cell. The DNA content of conidia from P. brasiliensis ATCC 60855-30.2+/-0.8Mb (30.9+/-0.8fg) -showed no significant differences with the yeast form, possibly excluding the occurrence of ploidy shift during morphogenesis. The ploidy of several P. brasiliensis isolates was assessed by comparing genome sizing by FCM with the previously described average haploid size obtained from electrophoretic karyotyping. The analysis of intra-individual variability of a highly polymorphic P. brasiliensis gene, GP43, indicated that only one allele seems to be present. Overall, the results showed that all analysed isolates presented a haploid, or at least aneuploid, DNA content and no association was detected between genome size/ploidy and the clinical-epidemiological features of the studied isolates. This work provides new knowledge on P. brasiliensis genetics/genomics, important for future research in basic cellular/molecular mechanisms and for the development/design of molecular techniques in this fungus.

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Section: Discussionmentioning

confidence: 92%

Genome size and ploidy of Paracoccidioides brasiliensis reveals a haploid DNA content: Flow cytometry and GP43 sequence analysis

Almeida¹,

Matute²,

Carmona³

et al. 2007

Fungal Genetics and Biology

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“…As to its timing, there are three logical possibilities, i.e., at "Start" concomitantly with DNA synthesis as in the case of S. cerevisiae (Lew 1997), concomitantly with initiation of budding under the control of the B-factor, or concomitantly with the actual onset of mitosis as in Schizosaccharomyces pombe (Ding et al 1997). It is relevant that C. neoformans cells exhibit a high probability of spontaneous diploidization (Hata et al 2000), which is explained naturally if spindle pole body duplication is committed together with DNA synthesis at "Start" as follows. Execution of the B-factor is easily prolonged under several conditions until the G 2 phase, i.e., budding does not occur even after completion of DNA synthesis (legend to Fig.…”

Section: Discussionmentioning

confidence: 99%

Effects of growth temperature upshift on cell cycle progression in Cryptococcus neoformans

2003

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Cell cycle progression of Cryptococcus neoformans was studied for cells grown exponentially at 15°, 24°, and 30°C. Except for speed, cell cycle progression was similar. In particular, budding occurred relatively soon after initiation of DNA synthesis at 15°, 24°, and 30°C. After growth temperature was shifted from 15° to 30°C, cells were transiently arrested before initiation of DNA synthesis. Thus, similar to Saccharomyces cerevisiae, "Start" was the main susceptible cell cycle controlling point in C. neoformans. However, after spontaneous release from arrest as above, cells were further arrested in the unbudded state. Thus, the timing of budding was delayed just before the G 2 phase, or even until after entering the G 2 phase, but it was also transient, and 5 h after the shift buds emerged relatively soon after initiation of DNA synthesis. Thus, C. neoformans cells can respond adaptively to mild stress by delaying budding. The existence of the second susceptible cell cycle control point, i.e., budding, appears to endow C. neoformans with a unique characteristic of stronger inhibition of multiplication than growth. A model of the C. neoformans cell cycle is also presented.

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“…These cells should be in the earliest morphologically discernible cell cycle point. DNA content of these cells was standardized as = 1. c Single colony isolated before use, as described in [10]. Where single-cell isolation was not done, only cells having similar sizes were measured to avoid possible errors due to involvement of di¡erent ploidy (see [10] for detail).…”

Section: Resultsmentioning

confidence: 99%

“…This independence between DNA synthesis and budding enables cells to continue to grow even after the cell population stops dividing, producing large unbudded G 2 cells in the stationary phase [4], in contrast to the smaller cells in S. cerevisiae [9]. Recently we reported that ploidy shift occurs frequently in C. neoformans [10]. This may be attributed to a relaxed coordination of DNA synthesis and budding; ploidy shift may result if a cell that has completed DNA synthesis remains unbudded for some period, and then starts a new cell cycle (DNA synthesis) without completing the previous cell division cycle.…”

Section: Discussionmentioning

confidence: 99%

Bud emergence is gradually delayed from S to G2 with progression of growth phase in Cryptococcus neoformans

Ohkusu

2001

FEMS Microbiology Letters

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The G 2 index of the yeast Cryptococcus neoformans determined by laser scanning cytometer was 2^3 times higher than the budding index during transition to the stationary phase of the culture, indicating that buds emerged in the G 2 phase of the cell cycle. To clarify whether buds also emerge in G 2 during exponential growth of the culture, DNA content for each cell was measured with a fluorescence microscope equipped with a photomultiplier. The DNA content of cells having tiny buds varied rather widely, depending on growth phases and strains used. Typically, buds of C. neoformans emerged soon after initiation of DNA synthesis in the early exponential phase. However, bud emergence was delayed to G 2 during transition to the stationary phase, and in the early stationary phase budding scarcely occurred, although roughly half of the cells completed DNA synthesis. Thus, the timing of budding in C. neoformans was actually shifted to later cell cycle points with progression of the growth phase of the culture. ß

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Cells of Different Ploidy Are Often Present Together in Cryptococcus neoformans Strains.

Abstract: We examined the ploidy of C. neoformans strains using both laser scanning cytometry and a transfers. Thus, a cellular ploidy shift was shown to occur widely in C. neoformans strains.

Cited by 9 publications

References 9 publications

Genome size and ploidy of Paracoccidioides brasiliensis reveals a haploid DNA content: Flow cytometry and GP43 sequence analysis

Genome size and ploidy of Paracoccidioides brasiliensis reveals a haploid DNA content: Flow cytometry and GP43 sequence analysis

Effects of growth temperature upshift on cell cycle progression in Cryptococcus neoformans

Bud emergence is gradually delayed from S to G2 with progression of growth phase in Cryptococcus neoformans

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