Recently the concept of eukaryotic cell cycle regulation has changed enormously because of the development of new concepts and techniques applied in studying the yeast cell cycle. Experimental facts and speculations are presented here, with emphasis on the role of the cytoskeleton in the control of division in yeast cells.

• MeSH
• buněčný cyklus fyziologie   MeSH
• cytoskelet chemie   fyziologie   MeSH
• kvasinky cytologie   ultrastruktura   MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

The incorporation of histone H3 with an acetylated lysine 56 (H3K56ac) into the nucleosome is important for chromatin remodeling and serves as a marker of new nucleosomes during DNA replication and repair in yeast. However, in human cells, the level of H3K56ac is greatly reduced, and its role during the cell cycle is controversial. Our aim was to determine the potential of H3K56ac to regulate cell cycle progression in different human cell lines. A significant increase in the number of H3K56ac foci, but not in H3K56ac protein levels, was observed during the S and G2 phases in cancer cell lines, but was not observed in embryonic stem cell lines. Despite this increase, the H3K56ac signal was not present in late replication chromatin, and H3K56ac protein levels did not decrease after the inhibition of DNA replication. H3K56ac was not tightly associated with the chromatin and was primarily localized to active chromatin regions. Our results support the role of H3K56ac in transcriptionally active chromatin areas but do not confirm H3K56ac as a marker of newly synthetized nucleosomes in DNA replication.

• Klíčová slova
• Cell cycle, Chromatin, DNA replication, H3K56ac, Mammalian cells, Nucleosome,
• MeSH
• buněčný cyklus genetika   fyziologie   MeSH
• chromatin metabolismus   MeSH
• G2 fáze genetika   MeSH
• histony metabolismus   MeSH
• HL-60 buňky MeSH
• hmotnostní spektrometrie MeSH
• lidé MeSH
• nukleozomy metabolismus   MeSH
• replikace DNA genetika   fyziologie   MeSH
• S fáze genetika   MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   MeSH
• Saccharomyces cerevisiae genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chromatin MeSH
• histony MeSH
• nukleozomy MeSH
• Saccharomyces cerevisiae - proteiny MeSH

Yeast cells must grow to a critical size before committing to division. It is unknown how size is measured. We find that as cells grow, mRNAs for some cell-cycle activators scale faster than size, increasing in concentration, while mRNAs for some inhibitors scale slower than size, decreasing in concentration. Size-scaled gene expression could cause an increasing ratio of activators to inhibitors with size, triggering cell-cycle entry. Consistent with this, expression of the CLN2 activator from the promoter of the WHI5 inhibitor, or vice versa, interfered with cell size homeostasis, yielding a broader distribution of cell sizes. We suggest that size homeostasis comes from differential scaling of gene expression with size. Differential regulation of gene expression as a function of cell size could affect many cellular processes.

• Klíčová slova
• Cln3, cell cycle, cell cycle control, cell cycle regulation, cell size control, growth Whi5, growth control of division, size homeostasis, start, yeast cell cycle,
• MeSH
• buněčné dělení genetika   MeSH
• buněčný cyklus genetika   MeSH
• cykliny genetika   MeSH
• G1 fáze genetika   MeSH
• regulace genové exprese u hub genetika   MeSH
• Saccharomyces cerevisiae - proteiny genetika   MeSH
• Saccharomyces cerevisiae genetika   růst a vývoj   MeSH
• velikost buňky * MeSH
• vývojová regulace genové exprese genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• CLN2 protein, S cerevisiae MeSH Prohlížeč
• cykliny MeSH
• Saccharomyces cerevisiae - proteiny MeSH

Cardiolipin synthesis was studied during the aerobic synchronous growth of aerobically grown yeast Saccharomyces cerevisiae. The time course of the synthesis was stepwise and the rise in cardiolipin level in cells coincided in time with the increase in cytochrome oxidase activity. This finding supports the notion of discontinuous completion of the inner mitochondrial membrane and hints at a close relation between cardiolipin and cytochrome oxidase activity.

• MeSH
• aerobióza MeSH
• buněčné dělení MeSH
• fosfolipidy metabolismus   MeSH
• kardiolipiny biosyntéza   MeSH
• mitochondrie enzymologie   MeSH
• respirační komplex IV metabolismus   MeSH
• Saccharomyces cerevisiae enzymologie   růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fosfolipidy MeSH
• kardiolipiny MeSH
• respirační komplex IV MeSH

When investigating changes of respiratory activity during the cell cycle of mother and daughter Candida cells significant oscillations of specific rate of oxygen consumption were detected; specific growth rate also varied. The oscillations were less pronounced when the inoculum was obtained from the chemostat at the high dilution rates of 0.25 and 0.35/h.

• MeSH
• biologické modely MeSH
• buněčný cyklus * MeSH
• Candida růst a vývoj   metabolismus   fyziologie   MeSH
• energetický metabolismus MeSH
• glukosa metabolismus   MeSH
• interfáze MeSH
• spotřeba kyslíku * MeSH
• viabilita buněk MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glukosa MeSH

The study of the cell cycle of a yeast strain made it possible to define two parameters: T, the time elapsing between the appearance of two consecutive buds on a mother cell, and theta, the time elapsing between the appearance of a bud and the beginning of the first mitotic cycle. The influence of these two parameters on the growth rate of the strain is studied.

• MeSH
• biologické modely * MeSH
• buněčný cyklus MeSH
• kultivační média MeSH
• mitóza MeSH
• Saccharomyces cerevisiae růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kultivační média MeSH

CSL proteins [named after the homologs CBF1 (RBP-Jκ in mice), Suppressor of Hairless and LAG-1] are conserved transcription factors found in animals and fungi. In the fission yeast Schizosaccharomyces pombe, they regulate various cellular processes, including cell cycle progression, lipid metabolism and cell adhesion. CSL proteins bind to DNA through their N-terminal Rel-like domain and central β-trefoil domain. Here, we investigated the importance of DNA binding for CSL protein functions in fission yeast. We created CSL protein mutants with disrupted DNA binding and found that the vast majority of CSL protein functions depend on intact DNA binding. Specifically, DNA binding is crucial for the regulation of cell adhesion, lipid metabolism, cell cycle progression, long non-coding RNA expression and genome integrity maintenance. Interestingly, perturbed lipid metabolism leads to chromatin structure changes, potentially linking lipid metabolism to the diverse phenotypes associated with CSL protein functions. Our study highlights the critical role of DNA binding for CSL protein functions in fission yeast.

• Klíčová slova
• CSL proteins, Cell adhesion, Chromatin structure, DNA binding, Fission yeast, Genome integrity, Lipid metabolism,
• MeSH
• buněčný cyklus genetika   MeSH
• DNA fungální metabolismus   genetika   MeSH
• DNA vazebné proteiny metabolismus   genetika   MeSH
• metabolismus lipidů genetika   MeSH
• proteiny buněčného cyklu * MeSH
• regulace genové exprese u hub MeSH
• Schizosaccharomyces pombe - proteiny * metabolismus   genetika   MeSH
• Schizosaccharomyces * metabolismus   genetika   MeSH
• transkripční faktory * MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA fungální MeSH
• DNA vazebné proteiny MeSH
• DSC1 protein, S pombe MeSH Prohlížeč
• proteiny buněčného cyklu * MeSH
• Schizosaccharomyces pombe - proteiny * MeSH
• transkripční faktory * MeSH

A mathematical model of the cell cycle regulation in S. cerevisiae is proposed. The model is based on the assumption of the G1----S phase transition control mediated by two signals. One of them is correlated with the cellular energy level--its messenger could be cAMP; the second one depends on the change of the cellular growth rate (reaching the critical size) and remains hypothetical.

• MeSH
• AMP cyklický fyziologie   MeSH
• biologické modely * MeSH
• buněčný cyklus * MeSH
• matematika MeSH
• počítačová simulace MeSH
• Saccharomyces cerevisiae růst a vývoj   MeSH
• systémy druhého messengeru MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• AMP cyklický MeSH

During the last decade, the cell cycle and its control by cyclin-dependent kinases (CDKs) has been extensively studied in eukaryotes. The regulation of CDK activity includes, among others, its activation by Cdc25 phosphatase at G2/M. However, within the plant kingdom studies of this regulation have lagged behind and a plant cdc25 homologue has not been identified yet. Here, we report on the effects of transformation of tobacco (Nicotiana tabacum L., cv. Samsun) with fission yeast (Schizosaccharomyces pombe) cdc25 (Spcdc25) on de novo plant organ formation, a process dependent on rate and orientation of cell division. On shoot-inducing medium (low 1-naphthylacetic acid (NAA), high 6-benzylaminopurine (BAP)) the number of shoots formed on internode segments cultured from transgenic plants was substantially higher than in the non-transformed controls. Anatomical observations indicated that the shoot formation process was accelerated but with no changes in the quality and sequence of shoot development. Surprisingly, and in contrast to the controls, when on root-inducing medium (high NAA, low BAP) cultured segments from transgenic plants failed to initiate hardly any roots. Instead, they continued to form shoots at low frequencies. Moreover, in marked contrast to the controls, stem segments from transgenic plants were able to form shoots even without the addition of exogenous growth regulators to the medium. The results indicate that Spcdc25 expression in culture tobacco stem segments mimicked the developmental effects caused by an exogenous hormone balance shifted towards cytokinins. The observed cytokinin-like effects of Spcdc25 transformation are consistent with the concept of an interaction between cell cycle regulators and phytohormones during plant development.

• MeSH
• cytokininy farmakologie   MeSH
• fungální proteiny biosyntéza   fyziologie   MeSH
• genetická transkripce MeSH
• kořeny rostlin účinky léků   růst a vývoj   MeSH
• kultivační média MeSH
• kyseliny indoloctové farmakologie   MeSH
• proteiny buněčného cyklu biosyntéza   fyziologie   MeSH
• ras-GRF1 biosyntéza   fyziologie   MeSH
• RNA biosyntéza   MeSH
• Schizosaccharomyces genetika   metabolismus   MeSH
• tabák účinky léků   genetika   růst a vývoj   MeSH
• výhonky rostlin účinky léků   růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• cytokininy MeSH
• fungální proteiny MeSH
• kultivační média MeSH
• kyseliny indoloctové MeSH
• proteiny buněčného cyklu MeSH
• ras-GRF1 MeSH
• RNA MeSH

When investigating the effect of aeration capacity KLa of a cultivation device on the cell cycle of daughter cells of Candida utilis it was found that the length of a phase (S + G2) of the cell cycle is influenced by the rate of oxygen transfer. An increase of KLa of a cultivation device achieved by increasing the specific output of mechanical energy for air dispersion and mixing may lead to cell damage and to changes in the cell cycle. The effect of high intensity of aeration and mixing is thus invalidated.

• MeSH
• buněčný cyklus MeSH
• Candida cytologie   MeSH
• fermentace MeSH
• kultivační média MeSH
• kyslík farmakologie   MeSH
• spotřeba kyslíku MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kultivační média MeSH
• kyslík MeSH