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1.
Candida parapsilosis mitochondria contain three respiratory chains: the classical respiratory chain (CRC), a secondary parallel chain (PAR) and an “alternative” oxidative pathway (AOX). We report here the existence of similar pathways in C. albicans. To observe the capacity of each pathway to sustain yeast growth, C. albicans cells were cultured in the presence of inhibitors of these pathways. Antimycin A and KCN totally abrogated yeast growth, while rotenone did not prevent proliferation. Furthermore, rotenone promoted only partial respiratory inhibition. Lower concentrations of KCN that promote partial inhibition of respiration did not inhibit yeast growth, while partial inhibition of respiration with antimycin A did. Similarly, AOX inhibitor BHAM decreased O2 consumption slightly but completely stunted cell growth. Reactive oxygen species production and oxidized glutathione levels were enhanced in cells treated with antimycin A or BHAM, but not rotenone or KCN. These findings suggest that oxidative stress prevents C. albicans growth. 相似文献
2.
Marianne Goyer Alicia Loiselet Fabienne Bon Coralie L’Ollivier Michael Laue Gudrun Holland Alain Bonnin Frederic Dalle 《PloS one》2016,11(3)
C. albicans is a commensal yeast of the mucous membranes in healthy humans that can also cause disseminated candidiasis, mainly originating from the digestive tract, in vulnerable patients. It is necessary to understand the cellular and molecular mechanisms of the interaction of C. albicans with enterocytes to better understand the basis of commensalism and pathogenicity of the yeast and to improve the management of disseminated candidiasis. In this study, we investigated the kinetics of tight junction (TJ) formation in parallel with the invasion of C. albicans into the Caco-2 intestinal cell line. Using invasiveness assays on Caco-2 cells displaying pharmacologically altered TJ (i.e. differentiated epithelial cells treated with EGTA or patulin), we were able to demonstrate that TJ protect enterocytes against invasion of C. albicans. Moreover, treatment with a pharmacological inhibitor of endocytosis decreased invasion of the fungus into Caco-2 cells displaying altered TJ, suggesting that facilitating access of the yeast to the basolateral side of intestinal cells promotes endocytosis of C. albicans in its hyphal form. These data were supported by SEM observations of differentiated Caco-2 cells displaying altered TJ, which highlighted membrane protrusions engulfing C. albicans hyphae. We furthermore demonstrated that Als3, a hypha-specific C. albicans invasin, facilitates internalization of the fungus by active penetration and induced endocytosis by differentiated Caco-2 cells displaying altered TJ. However, our observations failed to demonstrate binding of Als3 to E-cadherin as the trigger mechanism of endocytosis of C. albicans into differentiated Caco-2 cells displaying altered TJ. 相似文献
3.
Anil Kumar Dudani Lalit K. Srivastava Rajendra Prasad 《Biochemical and biophysical research communications》1984,119(3):962-967
The status of glyoxalase-I was explored in exponentially growing and G1 arrested temperature sensitive (ts) cell division cycle (cdc) mutants of Saccharomyces cerevisiae. It was observed that the specific activity of this enzyme was correlated with overall growth status. The activity was high in actively growing cells and was low in G1 arrested cells. Specific activities of glyoxalase-I were also low in G1 arrested prolonged stationary phase (PSP) cells of S. cerevisiae and Candida albicans. The activity of glyoxalase-I recovered when G1 arrested S. cerevisiae (ts) cells were allowed to regrow under permissive conditions. Results demonstrate that although glyoxalase-I activity is a good indicator of cell growth status, it is not involved in cell cycle regulation of this eukaryotic organism. 相似文献
4.
Inhibition of yeast-to-hypha transition in Candida albicans by phorbasin H isolated from Phorbas sp.
So-Hyoung Lee Ju-eun Jeon Chan-Hong Ahn Soon-Chun Chung Jongheon Shin Ki-Bong Oh 《Applied microbiology and biotechnology》2013,97(7):3141-3148
Phorbasin H is a diterpene acid of a bisabolane-related skeletal class isolated from the marine sponge Phorbas sp. In this study, we examined whether phorbasin H acted as a yeast-to-hypha transition inhibitor of Candida albicans. Growth experiments suggest that this compound does not inhibit yeast cell growth but inhibits filamentous growth in C. albicans. Northern blot analysis of signaling pathway components indicated that phorbasin H inhibited the expression of mRNAs related to cAMP–Efg1 pathway. The exogenous addition of db-cAMP to C. albicans cells had no influence on the frequency of hyphal formation. The expression of hypha-specific HWP1 and ALS3 mRNAs, both of which are positively regulated by the important regulator of cell wall dynamics Efg1, was significantly inhibited by the addition of phorbasin H. This compound also reduced the ability of C. albicans cells to adhere in a dose-dependent manner. Our findings suggest that phorbasin H impacts the activity of the cAMP–Efg1 pathway, thus leading to an alteration of C. albicans morphology. 相似文献
5.
Compositional and immunobiological analyses of extracellular vesicles released by Candida albicans
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Gabriele Vargas Juliana D. B. Rocha Debora Leite Oliveira Priscila Costa Albuquerque Susana Frases Suelen S. Santos Joshua Daniel Nosanchuk Andre Marco Oliveira Gomes Lia C. A. S. Medeiros Kildare Miranda Tiago J. P. Sobreira Ernesto S. Nakayasu Emma A. Arigi Arturo Casadevall Allan J. Guimaraes Marcio L. Rodrigues Celio Geraldo Freire‐de‐Lima Igor C. Almeida Leonardo Nimrichter 《Cellular microbiology》2015,17(3):389-407
The release of extracellular vesicles (EV) by fungal organisms is considered an alternative transport mechanism to trans‐cell wall passage of macromolecules. Previous studies have revealed the presence of EV in culture supernatants from fungal pathogens, such as Cryptococcus neoformans, Histoplasma capsulatum, Paracoccidioides brasiliensis, Sporothrix schenckii, Malassezia sympodialis and Candida albicans. Here we investigated the size, composition, kinetics of internalization by bone marrow‐derived murine macrophages (MO) and dendritic cells (DC), and the immunomodulatory activity of C. albicans EV. We also evaluated the impact of EV on fungal virulence using the Galleria mellonella larvae model. By transmission electron microscopy and dynamic light scattering, we identified two populations ranging from 50 to 100 nm and 350 to 850 nm. Two predominant seroreactive proteins (27 kDa and 37 kDa) and a group of polydispersed mannoproteins were observed in EV by immunoblotting analysis. Proteomic analysis of C. albicans EV revealed proteins related to pathogenesis, cell organization, carbohydrate and lipid metabolism, response to stress, and several other functions. The major lipids detected by thin‐layer chromatography were ergosterol, lanosterol and glucosylceramide. Short exposure of MO to EV resulted in internalization of these vesicles and production of nitric oxide, interleukin (IL)‐12, transforming growth factor‐beta (TGF‐β) and IL‐10. Similarly, EV‐treated DC produced IL‐12p40, IL‐10 and tumour necrosis factor‐alpha. In addition, EV treatment induced the up‐regulation of CD86 and major histocompatibility complex class‐II (MHC‐II). Inoculation of G. mellonella larvae with EV followed by challenge with C. albicans reduced the number of recovered viable yeasts in comparison with infected larvae control. Taken together, our results demonstrate that C. albicans EV were immunologically active and could potentially interfere with the host responses in the setting of invasive candidiasis. 相似文献
6.
Summary Analysis of the cell cycle by three methods has revealed unusual kinetics of proliferation in tumour derived suspensions ofCrepis capillaris. The different methods of analysis yield different estimates of cycle phase durations, and such discrepancies have been explained in terms of low growth fractions with rapid total cycle traverse. Specifically, confidence in the estimation of G2 duration by the fraction of labelled mitosis analysis, and comparison with shorter G2 estimates obtained by the two other methods, suggests that cells drop out in G1. However, cells which do not drop out of the proliferative compartment traverse G1 extremely rapidly. Extremely short cell cycle durations in which the G1 phase is virtually non-existent are uncharacteristic of plant cell suspension cultures, in which the G1 phase has previously been shown to be extended as compared with meristematic root tip cells. A model has been proposed in which a central core of rapidly dividing cells continuously loses cells into a subpopulation of resting or G0 cells with the G1 DNA content. Similarities between plant and animal tumours with respect to cell growth and division are discussed. 相似文献
7.
8.
Interactions between microtubules and filamentous actin (F-actin) are essential to many cellular processes, but their mechanisms
are poorly understood. We investigated possible roles of the myosin family of proteins in the interactions between filamentous
actin (F-actin) and microtubules of budding yeast Saccharomyces cerevisiae with the general myosin ATPase inhibitor 2,3-butanedione-2-monoxime (BDM). The growth of S. cerevisiae was completely inhibited by BDM at 20 mmol/L and the effect of BDM on cell growth was reversible. In more than 80% of BDM-treated
budding yeast cells, the polarized distribution of F-actin was lost and fewer F-actin dots were observed. When cells were
synchronized in G1 with α-factor and released in the presence of BDM, cell number did not increase and cells were mainly arrested in G1 DNA content without any bud, suggesting that myosin activity is required for new bud formation and the start of a new cell
cycle. More than 10% of the BDM-treated cells also revealed defects in nuclear migration to the bud neck as well as in nuclear
shape. Consistent with these defects, the orientation of mitotic spindles was random in the 57% of cells treated with 20 mmol/L
BDM and immunostained with anti-tubulin antibody. Furthermore, microtubule structures were completely disorganized in most
of the cells incubated in 50 mmol/L BDM, while similar amounts of tubulin proteins were present in both BDM-treated and untreated
cells. These results show that the general myosin inhibitor BDM disorganizes microtubule structures as well as F-actin, and
suggest that BDM-sensitive myosin activities are necessary for the interaction of F-actin and microtubules to coordinate polarized
bud growth and the shape and migration of the nucleus in S. cerevisiae.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Júnia Oliveira Barbosa Rodnei Dennis Rossoni Simone Furgeri Godinho Vilela Janaína Araújo de Alvarenga Marisol dos Santos Velloso Márcia Cristina de Azevedo Prata Antonio Olavo Cardoso Jorge Juliana Campos Junqueira 《PloS one》2016,11(3)
Streptococcus mutans and Candida albicans are found together in the oral biofilms on dental surfaces, but little is known about the ecological interactions between these species. Here, we studied the effects of S. mutans UA159 on the growth and pathogencity of C. albicans. Initially, the effects of S. mutans on the biofilm formation and morphogenesis of C. albicans were tested in vitro. Next, we investigate the influence of S. mutans on pathogenicity of C. albicans using in vivo host models, in which the experimental candidiasis was induced in G. mellonella larvae and analyzed by survival curves, C. albicans count in hemolymph, and quantification of hyphae in the host tissues. In all the tests, we evaluated the direct effects of S. mutans cells, as well as the indirect effects of the subproducts secreted by this microorganism using a bacterial culture filtrate. The in vitro analysis showed that S. mutans cells favored biofilm formation by C. albicans. However, a reduction in biofilm viable cells and inhibition of hyphal growth was observed when C. albicans was in contact with the S. mutans culture filtrate. In the in vivo study, injection of S. mutans cells or S. mutans culture filtrate into G. mellonella larvae infected with C. albicans increased the survival of these animals. Furthermore, a reduction in hyphal formation was observed in larval tissues when C. albicans was associated with S. mutans culture filtrate. These findings suggest that S. mutans can secrete subproducts capable to inhibit the biofilm formation, morphogenesis and pathogenicity of C. albicans, attenuating the experimental candidiasis in G. mellonella model. 相似文献
10.
E. N. Lorenzón P. R. S. Sanches L. G. Nogueira T. M. Bauab E. M. Cilli 《Amino acids》2013,44(6):1521-1528
Antimicrobial peptides (AMPs) are a promising solution to face the antibiotic-resistant problem because they display little or no resistance effects. Dimeric analogues of select AMPs have shown pharmacotechnical advantages, making these molecules promising candidates for the development of novel antibiotic agents. Here, we evaluate the effects of dimerization on the structure and biological activity of the AMP aurein 1.2 (AU). AU and the C- and N-terminal dimers, (AU)2K and E(AU)2, respectively, were synthesized by solid-phase peptide synthesis. Circular dichroism spectra indicated that E(AU)2 has a “coiled coil” structure in water while (AU)2K has an α-helix structure. In contrast, AU displayed typical spectra for disordered structures. In LPC micelles, all peptides acquired a high amount of α-helix structure. Hemolytic and vesicle permeabilization assays showed that AU has a concentration dependence activity, while this effect was less pronounced for dimeric versions, suggesting that dimerization may change the mechanism of action of AU. Notably, the antimicrobial activity against bacteria and yeast decreased with dimerization. However, dimeric peptides promoted the aggregation of C. albicans. The ability to aggregate yeast cells makes dimeric versions of AU attractive candidates to inhibit the adhesion of C. albicans to biological targets and medical devices, preventing disease caused by this fungus. 相似文献
11.
On‐site secretory vesicle delivery drives filamentous growth in the fungal pathogen Candida albicans
Allon Weiner Franois Orange Sandra Lacas‐Gervais Katya Rechav Vikram Ghugtyal Martine Bassilana Robert A. Arkowitz 《Cellular microbiology》2019,21(1)
Candida albicans is an opportunistic fungal pathogen that colonises the skin as well as genital and intestinal mucosa of most healthy individuals. The ability of C. albicans to switch between different morphological states, for example, from an ellipsoid yeast form to a highly polarised, hyphal form, contributes to its success as a pathogen. In highly polarised tip‐growing cells such as neurons, pollen tubes, and filamentous fungi, delivery of membrane and cargo to the filament apex is achieved by long‐range delivery of secretory vesicles tethered to motors moving along cytoskeletal cables that extend towards the growing tip. To investigate whether such a mechanism is also critical for C. albicans filamentous growth, we studied the dynamics and organisation of the C. albicans secretory pathway using live cell imaging and three‐dimensional electron microscopy. We demonstrate that the secretory pathway is organised in distinct domains, including endoplasmic reticulum membrane sheets that extend along the length of the hyphal filament, a sub‐apical zone exhibiting distinct membrane structures and dynamics and a Spitzenkörper comprised of uniformly sized secretory vesicles. Our results indicate that the organisation of the secretory pathway in C. albicans likely facilitates short‐range “on‐site” secretory vesicle delivery, in contrast to filamentous fungi and many highly polarised cells. 相似文献
12.
Roberto Osvaldo Suárez-Alvarez Armando Pérez-Torres Maria Lucia Taylor 《Mycopathologia》2010,170(2):79-87
The adherence of Histoplasma capsulatum yeasts to lung, spleen, liver, gut, and trachea cryosections of Artibeus hirsutus bats and inbred BALB/c mice (control) was studied after in vitro yeast-tissue incubations. Candida albicans yeasts were used as a well-known adherent fungal model in the mice host, and latex beads were used as a negative adherence
control. Adhered yeast cells were identified by using crystal violet staining and the immunoperoxidase method with specific
antibodies. H. capsulatum yeasts adhered to all tissues tested, mainly in the lung. Moreover, H. capsulatum yeasts adhered preferentially to white and red spleen pulp, in contrast to the dispersed distribution of C. albicans yeasts. H. capsulatum yeasts were mostly found on the sinusoidal face of hepatocytes. In general, the gut showed a higher number of adhered H. capsulatum yeasts than the trachea in both bats and mice. H. capsulatum and C. albicans yeasts developed high selectivity for the lamina propria of the gut. In addition, H. capsulatum yeasts interacted better with the lamina propria and adventitia of the trachea. The number of H. capsulatum yeast cells that adhered to each tissue section type was always greater than the corresponding number of C. albicans yeast cells, and latex beads never adhered to the tissue sections. Controls with anti-H. capsulatum and normal rabbit sera showed a significant blockage of H. capsulatum yeast adherence to lung tissue. This is the first study describing the patterns of H. capsulatum yeast adherence to different bat and mouse tissues. 相似文献
13.
The proliferation of normal non-tumourigenic mouse fibroblasts is stringently controlled by regulatory mechanisms located in the postmitotic stage of G1 (which we have designated G1 pm). Upon exposure to growth factor depletion or a lowered de novo protein synthesis, the normal cells leave the cell cycle from G1 pm and enter G0. The G1 pm phase is characterized by a remarkably constant length (the duration of which is 3 h in Swiss 3T3 cells), whereas the intercellular variability of intermitotic time is mainly ascribable to late G1 or pre S phase (G1 ps) (Zetterberg & Larsson (1985) Proc. Natl. Acad. Sci. USA 82 , 5365). As shown in the present study two tumour-transformed derivatives of mouse fibroblasts, i.e. BPA31 and SVA31, did not respond at all, or only responded partially, respectively, to serum depletion and inhibition of protein synthesis. If the tumour cells instead were subjected to 25-hydroxycholesterol (an inhibitor of 3-hydroxy-3 methyglutaryl coenzyme A reductase activity), their growth was blocked as measured by growth curves and [3H]-thymidine uptake. Time-lapse analysis revealed that the cells were blocked specifically in early G1 (3-4h after mitosis), and DNA cytometry confirmed that the arrested cells contained a G1 amount of DNA. Closer kinetic analysis revealed that the duration of the postmitotic phase containing cells responsive to 25-hydroxycholesterol was constant. These data suggest that transformed 3T3 cells also contain a ‘G1 pm program’, which has to be completed before commitment to mitosis. By repeating the experiments on a large number of tumour-transformed cells, including human carcinoma cells and glioma cells, it was demonstrated that all of them possessed a G1 pm-like stage. Our conclusion is that G1 pm is a general phenomenon in mammalian cells, independent of whether the cells are normal or neoplastic. 相似文献
14.
Neutrophil activation by Candida glabrata but not Candida albicans promotes fungal uptake by monocytes
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Seána Duggan Fabian Essig Kerstin Hünniger Zeinab Mokhtari Laura Bauer Teresa Lehnert Susanne Brandes Antje Häder Ilse D. Jacobsen Ronny Martin Marc Thilo Figge Oliver Kurzai 《Cellular microbiology》2015,17(9):1259-1276
Candida albicans and Candida glabrata account for the majority of candidiasis cases worldwide. Although both species are in the same genus, they differ in key virulence attributes. Within this work, live cell imaging was used to examine the dynamics of neutrophil activation after confrontation with either C. albicans or C. glabrata. Analyses revealed higher phagocytosis rates of C. albicans than C. glabrata that resulted in stronger PMN (polymorphonuclear cells) activation by C. albicans. Furthermore, we observed differences in the secretion of chemokines, indicating chemotactic differences in PMN signalling towards recruitment of further immune cells upon confrontation with Candida spp. Supernatants from co‐incubations of neutrophils with C. glabrata primarily attracted monocytes and increased the phagocytosis of C. glabrata by monocytes. In contrast, PMN activation by C. albicans resulted in recruitment of more neutrophils. Two complex infection models confirmed distinct targeting of immune cell populations by the two Candida spp.: In a human whole blood infection model, C. glabrata was more effectively taken up by monocytes than C. albicans and histopathological analyses of murine model infections confirmed primarily monocytic infiltrates in C. glabrata kidney infection in contrast to PMN‐dominated infiltrates in C. albicans infection. Taken together, our data demonstrate that the human opportunistic fungi C. albicans and C. glabrata are differentially recognized by neutrophils and one outcome of this differential recognition is the preferential uptake of C. glabrata by monocytes. 相似文献
15.
Candida albicans colonization and dissemination from the murine gastrointestinal tract: the influence of morphology and Th17 immunity
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Kong Chen Graeme I. Murray David Kadosh Alistair J. P. Brown Neil A. R. Gow Donna M. MacCallum Jay K. Kolls Gordon D. Brown 《Cellular microbiology》2015,17(4):445-450
The ability of Candida albicans to cause disease is associated with its capacity to undergo morphological transition between yeast and filamentous forms, but the role of morphology in colonization and dissemination from the gastrointestinal (GI) tract remains poorly defined. To explore this, we made use of wild‐type and morphological mutants of C. albicans in an established model of GI tract colonization, induced following antibiotic treatment of mice. Our data reveal that GI tract colonization favours the yeast form of C. albicans, that there is constitutive low level systemic dissemination in colonized mice that occurs irrespective of fungal morphology, and that colonization is not controlled by Th17 immunity in otherwise immunocompetent animals. These data provide new insights into the mechanisms of pathogenesis and commensalism of C. albicans, and have implications for our understanding of human disease. 相似文献
16.
R. M. Klein 《Cell proliferation》1979,12(6):649-657
Neonatal administration of guanethidine-sulfate results in an alteration of the cell proliferative pattern of the small intestinal epithelium of the young adult rat. Sympathectomy with guanethidine has previously been shown to depress mitotic, labelling, and total cellular migration indices while increasing the generation cycle time (TC) of small intestinal crypt cells as measured by a stathmokinetic method. The present study showed that the G1, S and G2 phases of the crypt cell cycle are altered by sympathectomy, G1 accounting for most of the increase in TC. In addition, the percentage of [3H]-thymidine labelled crypt cells is reduced and the duration of crypt cell transit is lengthened by guanethidine-induced sympathectomy. 相似文献
17.
Candida africana differs from the common strains of C. albicans and C. dubliniensis morphologically, physiologically, genetically, and, in particular, clinically. This fungal pathogen is primarily recovered
from genital specimens, especially in vaginal specimens. In this investigation, we reexamined 195 vaginal C. albicans isolates for the presence of C. africana and C. dubliniensis by using hyphal wall protein 1 (HWP1) gene polymorphisms. All study isolates were confirmed to be C. albicans, and none were verified as either C. africana or C. dubliniensis. In conclusion, the HWP1 gene polymorphisms offer a useful tool in the discrimination of C. africana, C. albicans, and C. dubliniensis. Further studies may highlight the pathogenesis and importance of this yeast in vulvovaginal candidiasis. 相似文献
18.
We demonstrate here the regulatory role of cAMP in cell cycle of Candida albicans. cAMP was found to be a positive signal for growth and morphogenesis. Phosphodiesterase inhibitor aminophylline exhibited
significant effects, i.e., increased growth, as well as induced morphogenesis. Atropine and trifluoperazine negatively regulated
(inhibited) growth and did not induce morphogenesis. These changes were attributed to increase in cAMP levels and protein
kinase A (PKA) activity in presence of aminophylline, while reduction was observed in atropine and trifluoperazine (TFP) grown
cells. Alteration in cAMP signaling pathway affected the cell cycle progression in Candida albicans. Increased cAMP levels in aminophylline grown cells reduced the duration of cell cycle by inciting the cell cycle-specific
expression of G1 cyclins (CLN1 and CLN2). However atropine and trifluoperazine delayed the expression of G1 cyclins and hence prolonged the cell cycle. Implication
of cAMP signaling pathway in both the cell cycle and morphogenesis further opened the channels to explore the potential of
this pathway to serve as a target for development of new antifungal drugs. 相似文献
19.
Candida albicans biofilms on most medical devices are exposed to a flow of body fluids that provide water and nutrients to the fungal cells.
While C. albicans biofilms grown in vitro under static conditions have been exhaustively studied, the same is not true for biofilms developed
under continuous flow of replenishing nutrients. Here, we describe a simple flow biofilm (FB) model that can be built easily
with materials commonly available in most microbiological laboratories. We demonstrate that C. albicans biofilms formed using this flow system show increased architectural complexity compared to biofilms grown under static conditions.
C. albicans biofilms under continuous medium flow grow rapidly, and by 8 h show characteristics similar to 24 h statically grown biofilms.
Biomass measurements and microscopic observations further revealed that after 24 h of incubation, FB was more than twofold
thicker than biofilms grown under static conditions. Microscopic analyses revealed that the surface of these biofilms was
extremely compact and wrinkled, unlike the open hyphal layer typically seen in 24 h static biofilms. Results of antifungal
drug susceptibility tests showed that C. albicans cells in FB exhibited increased resistance to most clinically used antifungal agents. 相似文献
20.
Caffeine potentiates the lethal effects of ultraviolet and ionising radiation on wild-type Schizosaccharomyces pombe cells. In previous studies this was attributed to the inhibition by caffeine of a novel DNA repair pathway in S. pombe that was absent in the budding yeast Saccharomyces cerevisiae. Studies with radiation-sensitive S. pombe mutants suggested that this caffeine-sensitive pathway could repair ultraviolet radiation damage in the absence of nucleotide
excision repair. The alternative pathway was thought to be recombinational and to operate in the G2 phase of the cell cycle. However, in this study we show that cells held in G1 of the cell cycle can remove ultraviolet-induced lesions in the absence of nucleotide excision repair. We also show that
recombination-defective mutants, and those now known to define the alternative repair pathway, still exhibit the caffeine
effect. Our observations suggest that the basis of the caffeine effect is not due to direct inhibition of recombinational
repair. The mutants originally thought to be involved in a caffeine-sensitive recombinational repair process are now known
to be defective in arresting the cell cycle in S and/or G2 following DNA damage or incomplete replication. The gene products may also have an additional role in a DNA repair or damage
tolerance pathway. The effect of caffeine could, therefore, be due to interference with DNA damage checkpoints, or inhibition
of the DNA damage repair/tolerance pathway. Using a combination of flow cytometric analysis, mitotic index analysis and fluorescence
microscopy we show that caffeine interferes with intra-S phase and G2 DNA damage checkpoints, overcoming cell cycle delays associated with damaged DNA. In contrast, caffeine has no effect on
the DNA replication S phase checkpoint in reponse to inhibition of DNA synthesis by hydroxyurea.
Received: 16 June 1998 / Accepted: 13 July 1998 相似文献