Cell division in yeasts

Johnson, Byron F.; Calleja, G. B.; Boisclair, Isabelle; Yoo, Bong Y.

doi:10.1016/0014-4827(79)90466-x

Cited by 39 publications

(10 citation statements)

References 16 publications

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“…Of the 507 tabulated, 307 were closed. This correspondence of fluorophotomicrographs and electron micrographs has been briefly noted before (Johnson et al 1974). There are several consequences of the variable forms: The conoid septum and Z-form septum both lead to quantitatively enhanced septum growth (larger area) and, for a given amount of septal growth, considerably enhanced circumference at the closing, leading edge.…”

Section: Morphometric Analysis and Pull/pushmentioning

confidence: 94%

“…We too do not see them divide. This failure of fission apparently follows from their complex primary septa (Figure 4) which ordinarily would be lysed in the fission step of normal fission yeast cells as deduced (Johnson et al 1973(Johnson et al , 1974; and later) but demonstrated by Martin-Cuadrado et al 2003. One supposes that the relevant fission enzymes are not induced at the aberrant septa, or if induced, cannot find their substrates deep in the closed but malformed septa, or become sequestered by the abundant but extraneous CFW + material.…”

Section: Morphometric Analysis and Pull/pushmentioning

confidence: 95%

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Second thoughts on septation by the fission yeast, Schizosaccharomyces pombe: pull vs. push mechanisms with an appendix – dimensional modelling of the flat and variable septa

Johnson

Yoo

Calleja

et al. 2005

Antonie Van Leeuwenhoek

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The correlation of contraction by an actomyosin band with the closing of the septum of dividing cells of the fission yeast, Schizosaccharomyces pombe, cannot suggest cause-and-effect because contraction would be apparent whether the membrane enveloping the centripetally closing septum were pulled or were pushed. Thus the common observation of contraction is not critical. Diagrams of published electron micrographs of dividing wild-type fission yeasts illustrate variable (tilted) septal images that are counterintuitive to a pull model. Circumference calculations based on those images suggest that some variable forms might be only 6% closed even though their two-dimensional profiles would be 50% closed, if they were not tilted. Development of multiseptate forms of cdc4-8 and cdc4-377 temperature sensitive mutants incubated at their restrictive temperature was followed. These multiseptate forms are shown to have functional (functional in terms of generating divided uninucleate cytoplasts) but grotesque septa which are formed in the absence of actomyosin bands. By contrast, the myosin of the plant phragmoplast is not properly oriented for contractility, and Dictyostelium (attached cells) and Saccharomyces (mutants) have been shown to divide in the absence of myosin II, just as S. pombe does (above). Hence contractility, the essence of a pull model for septum closure, would seem to be non-essential. Other, non-contractile mechanisms of myosin are emphasized, and a push model becomes a rational default hypothesis. The essence of push models is that their synthesis/assembly mechanisms are driving force sufficient for septum closure.

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Section: Morphometric Analysis and Pull/pushmentioning

confidence: 94%

Section: Morphometric Analysis and Pull/pushmentioning

confidence: 95%

Second thoughts on septation by the fission yeast, Schizosaccharomyces pombe: pull vs. push mechanisms with an appendix – dimensional modelling of the flat and variable septa

Johnson

Yoo

Calleja

et al. 2005

Antonie Van Leeuwenhoek

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“…For transmission electron microscopy studies, C. albicans cells from standard cultures were transferred into ice‐cold PBS, and the cell density was adjusted to 10 6 cell mL −1 . Yeast cells were stained with freshly prepared 2% KMnO 4 solution for 1 h at room temperature, and washed with distilled water according to Johnson et al (1973). Photomicrographs were taken with a JEOL Jam‐1010 transmission electron microscope (JEOL, Tokyo, Japan), and cell wall structures, nuclei and mitochondria of C. albicans AF06 and ATCC 14053 strains were compared visually.…”

Section: Methodsmentioning

confidence: 99%

Development of oxidative stress tolerance resulted in reduced ability to undergo morphologic transitions and decreased pathogenicity in at-butylhydroperoxide-tolerant mutant ofCandida albicans

Fekete

Emri

Gyetvai

et al. 2007

FEMS Yeast Research

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We tested the hypothesis that adaptation of Candida albicans to chronic oxidative stress inhibits the formation of hyphae and reduces pathogenicity. Candida albicans cells were exposed to increasing concentrations of t-butylhydroperoxide (tBOOH), a lipid peroxidation-accelerating agent, and mutants with heritable tBOOH tolerance were isolated. Hypha formation by the mutants was negligible on Spider agar, indicating that the development of oxidative stress tolerance prevented Candida cells from undergoing dimorphic switches. One of the mutants, C. albicans AF06, was five times less pathogenic in mice than its parental strain, due to its reduced germ tube-, pseudohypha- and hypha-forming capability, and decreased phospholipase secretion. An increased oxidative stress tolerance may therefore be disadvantageous when this pathogen leaves blood vessels and invades deep organs. The AF06 mutant was characterized by high intracellular concentrations of endogenous oxidants, reduced monounsaturated and polyunsaturated fatty acid contents, the continuous induction of the antioxidative defense system, decreased cytochrome c-dependent respiration, and increased alternative respiration. The mutation did not influence growth rate, cell size, cell surface, cellular ultrastructures, including mitochondria, or recognition by human polymorphonuclear leukocytes. The selection of oxidative stress-tolerant respiratory Candida mutants may also occur in vivo, when reduced respiration helps the fungus to cope with antimycotic agents.

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“…For the sister cells to emerge from cell separation as viable entities, an organized and distinct trilaminar structure has to be properly built before the cell separation machinery can act. The mature septum has a three‐layered structure composed of the inner primary septum and the flanking secondary septa (Johnson et al , 1973) (Fig. 1).…”

Section: Septum Structurementioning

confidence: 99%

“…To separate physically, the daughter cells have to cleave the septum that keeps them together. This is accomplished by the breakdown of the primary septum and of a narrow band of the cell wall that surrounds it (Johnson et al , 1973).…”

Section: Introductionmentioning

confidence: 99%

Splitting of the fission yeast septum

Sipiczki

2007

FEMS Yeast Research

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In cell-walled organisms, a cross wall (septum) is produced during cytokinesis, which then splits in certain organisms to allow the daughter cells to separate. The formation and the subsequent cleavage of the septum require wall synthesis and wall degradation, which need to be strictly coordinated in order to prevent cell lysis. The dividing fission yeast (Schizosaccharomyces) cell produces a three-layered septum in which the middle layer and a narrow band of the adjacent cell wall can be degraded without threatening the integrity of the separating daughter cells. This spatially very precise process requires the activity of the Agn1p 1,3-alpha-glucanase and the Eng1p 1,3-beta-glucanase, which are localized to the septum by a complex mechanism involving the formation of a septin ring and the directed activity of the exocyst system. The Sep1p-Ace2p transcription-factor cascade regulates the expression of many genes producing proteins for this complex process. Recent advances in research into the molecular mechanisms of separation and its regulation are discussed in this review.

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Cell division in yeasts

Cited by 39 publications

References 16 publications

Second thoughts on septation by the fission yeast, Schizosaccharomyces pombe: pull vs. push mechanisms with an appendix – dimensional modelling of the flat and variable septa

Second thoughts on septation by the fission yeast, Schizosaccharomyces pombe: pull vs. push mechanisms with an appendix – dimensional modelling of the flat and variable septa

Development of oxidative stress tolerance resulted in reduced ability to undergo morphologic transitions and decreased pathogenicity in at-butylhydroperoxide-tolerant mutant ofCandida albicans

Splitting of the fission yeast septum

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