The Origin of RNA and the Formose-Ribose-RNA Pathway.

Prebiotic pre-Darwinian reactions continued throughout biochemical or Darwinian evolution. Early chemical processes could have occurred on Earth between 4.5 and 3.6 billion years ago when cellular life was about to come into being. Pre-Darwinian evolution assumes the development of hereditary elements but does not regard them as self-organizing processes. The presence of biochemical self-organization after the pre-Darwinian evolution did not justify distinguishing between different types of evolution. From the many possible solutions, evolution selected from among those stable reactions that led to catalytic networks, and under gradually changing external conditions produced a reproducible, yet constantly evolving and adaptable, living system. Major abiotic factors included sunlight, precipitation, air, minerals, soil and the Earth's atmosphere, hydrosphere and lithosphere. Abiotic sources of chemicals contributed to the formation of prebiotic RNA, the development of genetic RNA, the RNA World and the initial life forms on Earth and the transition of genRNA to the DNA Empire, and eventually to the multitude of life forms today. The transition from the RNA World to the DNA Empire generated new processes such as oxygenic photosynthesis and the hierarchical arrangement of processes involved in the transfer of genetic information. The objective of this work is to unite earlier work dealing with the formose, the origin and synthesis of ribose and RNA reactions that were published as a series of independent reactions. These reactions are now regarded as the first metabolic pathway.

Apoptotic Janus-faced mycotoxins against thoracal and breast metastases.

Abdominal organs (liver, kidney, spleen) are frequent targets of cancer cell invasion but their primary tumours are less known for their metastatic potential to other organs e.g. to the breast. Despite the known connection of the pathogenesis from breast cancer to liver metastasis, the study of the spread in the opposite direction has been neglected. The notion that breast cancer could be a metastasis besides being a primary tumour is based on rodents' tumour models upon implantation of tumour cells under the capsule of the kidney or under the Glisson's capsule of the liver of rats and mice. Tumour cells develop into a primary tumour at the site of subcutaneous implantation. The metastatic process starts with peripheral disruptions of blood vessels near the surface of primary tumours. Tumour cells released into the abdomen cross the apertures of the diaphragm, enter the thoracal lymph nodes and accumulate in parathymic lymph nodes. Abdominal colloidal carbon particles injected into the abdomen faithfully mimicked the migration of tumour cells and deposited in parathymic lymph nodes (PTNs). An explanation is provided why the connection between abdominal tumours and mammary tumours escaped attention, notably, parathymic lymph nodes in humans were referred to as internal mammary or parasternal lymph nodes. The apoptotic effect of Janus-faced cytotoxins is suggested to provide a new approach against the spread of abdominal primary tumours, and metastatic development.

Macromolecular Structure of Linearly Arranged Eukaryotic Chromosomes.

Eukaryotic chromosomes have not been visualized during the interphase. The fact that chromosomes cannot be seen during the interphase of the cell cycle does not mean that there are no means to make them visible. This work provides visual evidence that reversible permeabilization of the cell membrane followed by the regeneration of cell membranes allows getting a glimpse behind the nuclear curtain. Reversibly permeable eukaryotic cells have been used to synthesize nascent DNA, analyze the 5'-end of RNA primers, view individual replicons and visualize interphase chromosomes. Dextran T-150 in a slightly hypotonic buffer prevented cells from disruption. Upon reversal of permeabilization, the nucleus could be opened at any time during the interphase. A broad spectrum of a flexible chromatin folding pattern was revealed through a series of transient geometric forms of chromosomes. Linear attachment of chromosomes was visualized in several mammalian and lower eukaryotic cells. The linear connection of chromosomes is maintained throughout the cell cycle showing that rather than individual chromosomes, a linear array of chromosomes is the functional giant macromolecule. This study proves that not only the prokaryotic genome but also linearly attached eukaryotic chromosomes form a giant macromolecular unit.

Janus-Faced Molecules against Plant Pathogenic Fungi.

The high cytotoxicity of the secondary metabolites of mycotoxins is capable of killing microbes and tumour cells alike, similarly to the genotoxic effect characteristic of Janus-faced molecules. The "double-edged sword" effect of several cytotoxins is known, and these agents have, therefore, been utilized only reluctantly against fungal infections. In this review, consideration was given to (a) toxins that could be used against plant and human pathogens, (b) animal models that measure the effect of antifungal agents, (c) known antifungal agents that have been described and efficiently prevent the growth of fungal cells, and (d) the chemical interactions that are characteristic of antifungal agents. The utilization of apoptotic effects against tumour growth by agents that, at the same time, induce mutations may raise ethical issues. Nevertheless, it deserves consideration despite the mutagenic impact of Janus-faced molecules for those patients who suffer from plant pathogenic fungal infections and are older than their fertility age, in the same way that the short-term cytotoxicity of cancer treatment is favoured over the long-term mutagenic effect.

Prebiotic Pathway from Ribose to RNA Formation.

At the focus of abiotic chemical reactions is the synthesis of ribose. No satisfactory explanation was provided as to the missing link between the prebiotic synthesis of ribose and prebiotic RNA (preRNA). Hydrogen cyanide (HCN) is assumed to have been the principal precursor in the prebiotic formation of aldopentoses in the formose reaction and in the synthesis of ribose. Ribose as the best fitting aldopentose became the exclusive sugar component of RNA. The elevated yield of ribose synthesis at higher temperatures and its protection from decomposition could have driven the polymerization of the ribose-phosphate backbone and the coupling of nucleobases to the backbone. RNA could have come into being without the involvement of nucleotide precursors. The first nucleoside monophosphate is likely to have appeared upon the hydrolysis of preRNA contributed by the presence of reactive 2'-OH moieties in the preRNA chain. As a result of phosphorylation, nucleoside monophosphates became nucleoside triphosphates, substrates for the selective synthesis of genRNA.

Antifungal Activity of Gentamicin B1 Against Systemic Plant Mycoses.

BACKGROUND: Gentamicin is a broad-spectrum aminoglycoside antibiotic produced by Micromonospora purpurea bacteria, effective against Gram-negative bacterial infections. Major fractions of the gentamicin complex (C1, C1a, C2, C2a) possess weak antifungal activity and one of the minor components (A, A1-A4, B, B1, X), gentamicin B1 was found to be a strong antifungal agent. METHODS: This work uses in vitro and in vivo dilution methods to compare the antifusarial, antiaspergillic and anticryptococcal effects of gentamicin derivatives and structurally-related congeners. RESULTS: The in vitro antifusarial activity of gentamicin B1 (minimum inhibitory concentration (MIC) 0.4 µg/mL) and structurally-related compounds (MIC 0.8-12.5 µg/mL) suggests that the purpuroseamine ring substituents are responsible for the specific antimycotic effect. The functional groups of the garoseamine and 2-deoxystreptamine rings of gentamicin derivatives are identical in gentamicin compounds and are unlikely to exert a significant antifungal effect. Among soil dermatophytes, Microsporum gypseum was more susceptible to gentamicin B1 (MIC 3.1 µg/mL) than Trichophyton gypseum (MIC 25 µg/mL). The in vitro antifungal effect of gentamicin B1 against plant pathogenic fungi was comparable to primary antifungal agents. CONCLUSION: Gentamicin is already in medical use. In vitro and preclinical in vivo synergisms of gentamicin B1 with amphotericin B suggest immediate clinical trials starting with subtoxic doses.

Retrospective evaluation of in vitro effect of gentamicin B1 against Fusarium species.

The in vitro susceptibility of gentamicin fractions against Fusarium growth was the subject of this retrospective study. Fusariosis was earlier an exceptionally rare human disease and an unrealistic idea to treat soil saprophytes and plant pathogens with expensive antibiotics such as gentamicins or their minor components. Disseminated fusariosis is now the second most frequent lethal fungal infection after aspergillosis especially in neutropenic patients with hematologic malignancy. Results of this study obtained between May and November 1973 were interesting but not practicable and remained unpublished. Seven Fusarium and 28 other fungal strains were tested for their susceptibility to gentamicin B1. The anti-Fusarium activity of gentamicin B1 was between 0.2 and 3.1 µg/ml minimum inhibitory concentration (MIC) values. The MIC values of clotrimazol and amphotericin B against Fusarium species were significantly higher, 3.1-12.5 µg/ml and 3.1-50 µg/ml, respectively. Gentamicin B1 and its structurally related congeners including hygromycin B, paromomycin, tobramycin (nebramycin factor 5'), nebramycin (nebramycin factor 4), and sisomicin exerted strong in vitro inhibition against Fusarium species between 0.2 and 12.5 µg/ml concentrations. The antibacterial MIC concentration of gentamicin B1 tested on 20 bacterial strains ranged between 0.1 and 50 µg/ml. Gentamicin B1, a minor fraction of the gentamicin complex, inhibited effectively the growth of Gram-positive (Staphylococcus, Streptococcus, Bacillus subtilis) bacteria and Gram-negative (Escherichia coli, Salmonella, Proteus, Pseudomonas) pathogens. Gentamicins and related aminoglycoside antibiotics are used in medical practice. It is proposed that due to the increasing incidence of fusariosis and drug resistance, gentamicin components, particularly minor fraction B1 and related aminoglycoside antibiotics, could be tested for their in vivo activity against fusariosis and aspergillosis either alone or in combination with other antifungal agents.

Improved and adopted murine models to combat pulmonary aspergillosis.

The insufficient basic and clinical knowledge about invasive mold infections necessitated to review aspergillosis rodent models. The scope of this review has two major aspects. (1) It briefly summarizes Aspergillus toxicoses, the adverse effects of Aspergillus mycotoxins, the virulence factors of Aspergillus fumigatus, and how mild Aspergillus infections can turn to immunosuppressive diseases, ultimately to lethal invasive pulmonary aspergillosis. (2) The second major aspect of the review deals with earlier and recent murine models of pulmonary aspergillosis. Particular attention will be paid to the development of unified and generally applicable methods to detect, follow, and combat aspergillosis by medical treatments. Additionally, the review raises the question of responsibility regarding the application of immunosuppressive agents that initiate, contribute, and aggravate aspergillosis. Future studies of immunosuppression by chemical agents impacting aspergillosis deserve more studies.

Murine model to follow hyphal development in invasive pulmonary aspergillosis.

Aspergillus fumigatus is an opportunistic pathogen, the leading cause of invasive and disseminated aspergillosis in systemic immunocompromised patients, and an important cause of mortality. The aim of the present study was to adapt a pulmonary aspergillosis murine model, to determine pathodynamical parameters quantitatively, and to follow the progression of fungal infection in vivo. The nasal inoculation of Aspergillus conidia in mice previously subjected to immunosuppression with cyclophosphamide (CP) turned out to be a more suitable model than that of immunosuppressed with hydrocortisone (HC). The following parameters were found to correlate quantitatively with the progress of the infection: (i) survival rate, (ii) weight loss of mice, (iii) infected focal plaque size, (iv) hyphal density, (v) hyphal length distribution of A. fumigatus, and the (vi) the histopathological status and scores. These parameters will be essential elements for the development of antifungal drugs and therapies, and important for the investigation of the pathogenicity in different strains of A. fumigatus.

Methods to detect apoptotic cell death.

In concert with the increased understanding that there are many ways for cells to die, several methods have been developed to detect cell death. The classification of cell death posed some difficulties that were overcome by implementing strict selection criteria that should also apply to the detection methods. The selection of assays is based on morphological criteria and distinguishable marks of apoptotic patways. The detection of apoptosis includes methods related to membrane alterations, DNA fragmentation, cytotoxicity and cell proliferation, mitochondrial damage, immunological detection and mechanism based assays. Other less frequently used detections of apoptosis are: (a) light-scattering flow cytometry to avoid underestimating the extent and timing of apoptosis, (b) time-lapse microscopy perfusion platform to support the temporal aspects of detection, to measure cell surface area and cellular adhesion, and (c) genotoxicity specific chromatin changes. Attention is called to the advantages and limitations of various methods.

Mille modis morimur: We die in a thousand ways.

Dying cells subjected to apoptotic programs are engulfed by neighboring cells or by professional phagocytes, without inflammation or immunological reactions in the tissue where apoptosis takes place. Apoptotic cells release danger-associated project signals to their neighbours, through different molecular patterns, stimulate antigen production and immune responses. Microenvironmental effects with several functional consequences indicate that cell death is a complex process and may take place in several ways. This idea is expressed by the title of the Special Issue and by the title of the guest editorial "Mille modis morimur" meaning that not only multicellular organisms, but also single cells may die in a thousand ways. This idea is demonstrated by the papers serving as examples for cell death. Apoptosis was induced by clary sage oil in Candida cells. Heavy metal (Gd) induced cell motility and apoptosis was found in mammalian cells. RNA oxidation enhanced the reversion frequency of apoptosis in yeast mutants. The frequency of apoptotic micronucleus formation increased in a concentration-dependent manner by methotrexate. The antioxidant coenzyme Q10 protected renal proximal tubule cells against nicotine-induced apoptosis. The synergy of 2-deoxy-D-glucose combined with berberine induced lysosome/autophagy. The mitochondrial apoptotic pathway could be regulated by glucocorticoid receptor in collaboration with Bcl-2 family proteins in developing T cells. Cylindrospermopsin induced biochemical changes led to apoptosis in plants. Mechanisms of stress seriously impacted the risk of apoptosis. Transcriptional control of apoptotic cell clearance was achieved by macrophage nuclear receptors. Finally, the clinical aspects of apoptosis-induced lymphopenia were reviewed in sepsis and other severe injuries. These examples not only support the view of many ways of cell death, but predict further potential ways to induce or reduce the risk of cell death.

Gadolinium induced effects on mammalian cell motility, adherence and chromatin structure.

The toxicity of gadolinium is reduced by chelating agents that render this heavy metal into contrast complexes used for medical magnetic resonance imaging. However, the dissociation of gadolinium chelates is known to generate Gd3+ ions, the cellular toxicity of which has not been tested in details. The cytotoxic effects of Gd(III) ions were evaluated by monitoring the proliferation, measuring the cellular motility and following chromatin changes in various cell lines upon Gd3+ treatment. Measurements applied long-term scanning microscopy and a perfusion platform that replaced the medium with test solutions, bypassed physical contact with the cell culture during experiments, and provided uninterrupted high time-resolution time-lapse photomicrography for an extended period of time. Genotoxicity specific chromatin changes characteristic to Gd(III) were distinguished in human skin keratinocytes (HaCaT), human limbal stem cells (HuLi), colorectal adenocarcinoma (CaCO2), murine squamous carcinoma (SCC) and Indian muntjac (IM) cell lines. Characteristic features of Gd(III) toxicity were: loss of cellular motility, irreversible attachment of cells to the growth surface and cell death. Injury-specific chromatin changes manifested at micromolar Gd3+ concentrations as premature chromatin condensation and highly condensed sticky chromatin patches. Gd(III) concentration- and cell type-dependent reduction of normal adherence, as well as premature chromatin condensation confirmed apoptosis. The risk related to the release of toxic Gd3+ ions from gadolinium complexes and their effects on mono- and multi-layer cellular barriers have to be reconsidered when these chelated complexes are used as contrasting agents especially in relation to possible blood-brain barrier damages.

Micronucleus formation during chromatin condensation and under apoptotic conditions.

In early S phase the newly replicated DNA is folded back to increasingly compact structures. The process of chromatin condensation inside the nucleus starts with the formation of a micronucleus observed in five established cell lines (K562, CHO, Indian muntjac, murine preB and SCC). Supercoiling of chromatin generates a polarized end-plate region extruded from the nucleus. The extruded chromatin is turned around itself forming the head portion (micronucleus) visible by fluorescence microscopy until the middle of S phase when chromatin structures are succeeded by distinguishable early forms of chromosomes. The generation of micronuclei upon apoptotic treatment was achieved by the methotrexate (MTX) treatment of cells. A close correlation was found between the frequency of micronucleus and MTX concentration, with low frequency at low (0.1 µM) and increasingly higher frequency between 1 and 100 µM concentrations. Characteristic deformation and shrinkage of nuclei indicated apoptosis. High MTX concentration (100 µM) caused the enlargement and necrotic disruption of nuclei. Inhibition of DNA synthesis during replicative DNA synthesis by biotinylated nucleotide prevented the formation of metaphase chromosomes and elevated the frequency of early intermediates of chromosome condensation including micronucleus formation. Based on these observations the micronucleus is regarded as: (a) a regularly occuring element of early chromatin condensation and (b) a typical sign of nuclear membrane damage under toxic conditions. Explanation is given why the micronucleus is hidden in nuclei under normal chromatin condensation and why chromatin motifs including micronuclei become visible upon cellular damage.

In Situ Electron Microscopy of Lactomicroselenium Particles in Probiotic Bacteria.

Electron microscopy was used to test whether or not (a) in statu nascendi synthesized, and in situ measured, nanoparticle size does not differ significantly from the size of nanoparticles after their purification; and (b) the generation of selenium is detrimental to the bacterial strains that produce them. Elemental nano-sized selenium produced by probiotic latic acid bacteria was used as a lactomicroselenium (lactomicroSel) inhibitor of cell growth in the presence of lactomicroSel, and was followed by time-lapse microscopy. The size of lactomicroSel produced by probiotic bacteria was measured in situ and after isolation and purification. For these measurements the TESLA BS 540 transmission electron microscope was converted from analog (aTEM) to digital processing (dTEM), and further to remote-access internet electron microscopy (iTEM). Lactobacillus acidophilus produced fewer, but larger, lactomicroSel nanoparticles (200-350 nm) than Lactobacillus casei (L. casei), which generated many, smaller lactomicroSel particles (85-200 nm) and grains as a cloudy, less electrodense material. Streptococcus thermophilus cells generated selenoparticles (60-280 nm) in a suicidic manner. The size determined in situ in lactic acid bacteria was significantly lower than those measured by scanning electron microscopy after the isolation of lactomicroSel particles obtained from lactobacilli (100-500 nm), but higher relative to those isolated from Streptococcus thermopilus (50-100 nm). These differences indicate that smaller lactomicroSel particles could be more toxic to the producing bacteria themselves and discrepancies in size could have implications with respect to the applications of selenium nanoparticles as prebiotics.

Methotrexate induced apoptotic and necrotic chromatin changes in rat myeloid leukemia cells.

OBJECTIVE: It was tested as to why low-dose methotrexate (MTX) effective against rheumatoid arthritis poses considerable health risk at higher doses. METHODS: The tumorigenic potential of My1/De blast cells was followed by cytology and by the kinetics of (18)FDG uptake. The toxicity of MTX on chromatin condensation was compared to predictive normal intermediates of chromosome condensation in control cells. RESULTS: MTX below 0.1 µg/ml did not cause visible changes in interphase chromatin structure. At its lowest toxic concentration (0.1 µg/ml) chromatin margination was confined to the outer edge of the nucleus. Between 0.1 and 5 µg/ml concentrations apoptotic chromatin shrinkage correlated with the dose of MTX. Apoptosis was exerted in early S phase excluding the mitotic effect. At higher MTX concentrations (>10 µg/ml) necrotic disruption and expansion took place. The lowest necrotic concentration (10 µg/ml) was close to highest apoptotic MTX concentration (5 µg/ml). CONCLUSIONS: The switch from apoptosis to inflammatory necrosis taking place within a narrow concentration range supports the notion of a narrow therapeutic spectrum. Chromatin changes are early markers of genotoxicity at much lower concentrations than citogenetic changes in properly chosen sensitive cells.

Apoptotic agents inducing genotoxicity-specific chromatin changes.

To visualize characteristic chromatin distortions we have distinguished first among regularly occurring intermediates of chromatin structures in mammalian (Indian muntjac, CHO, murine preB, rat liver, rat myeloid leukemia, K562 human erythroid leukemia) and Drosophila nuclei. Fluorescence microscopy of chromatin structures isolated from nuclei of reversibly permeable cells revealed a common pathway of chromatin condensation in mammalian cells. Different intermediates in mammalian and Drosophila cells indicate alternative mechanisms of chromosome condensation. Genotoxic agents such as irradiation (alpha, gamma, UV-B) and heavy metals (Cd, Pb, Ni, Hg, Ag) caused alterations in chromatin structures leading to apoptosis. Injury-specific chromatin changes manifested at significantly lower concentrations than non-specific signs of cellular toxicity, suggesting that preapoptotic events are useful indicators of genotoxicity.

Time-lapse video microscopy and image analysis of adherence and growth patterns of Candida albicans strains.

Digital image analysis of high time resolution video microscopy was used to investigate hyphal growth dynamics in different Candida albicans strains. The effects of the quorum sensing molecules tyrosol and farnesol, the deletion of the fungus specific protein phosphatase Z1 CaPPZ1), and the hypha-specific cyclin (HGC1) genes were analyzed by this method. Our system monitored cell growth in a CO2 incubator under near-physiological conditions and measured three major parameters under the following stringent conditions: (a) the time of yeast cell adherence, (b) the time of hyphal outgrowth, and (c) the rate of hyphal growth. This method showed that hyphal extension of wild-type SC5314 cells was accelerated by tyrosol and inhibited by farnesol. Hyphal growth rate was moderately lower in cappz1 and strongly reduced in hgc1 mutants. In addition, tyrosol treatment caused a firm adherence, while farnesol treatment and hgc1 mutation prevented the adherence of yeast cells to the surface of the culture flask. Transition from yeast-to-hyphal state was faster after tyrosol treatment, while it was reduced in farnesol-treated cells as well as in the cappz1 and hgc1 mutants. Our data confirm the notion that the attachment of yeast cells, the yeast-to-hyphal transition, and hyphal growth rate are closely related processes. Time-lapse video microscopy combined with image analysis offers a convenient and reliable method of testing chemicals, including potential drug candidates, and genetic manipulations on the dynamic morphological changes in C. albicans strains.

Role of parathymic lymph nodes in metastatic tumor development.

Parathymic lymph nodes as potential sites of tumor progression have been neglected in humans. We have established a rat renal capsule-parathymic lymph node model to study in vivo metastasis. Epithelial liver carcinoma (HeDe) and mesenchymal mesoblastic nephroma (NeDe) cell lines have been established after inducing chemical carcinogenesis in newborn Fisher 344 inbred rats by N-nitrosodimethylamine. Implanting the exact number of tumor cells (HeDe, NeDe) under the renal capsule allowed the standardization and timing of metastatic development. Tumor cells released from the primary tumor in the peritoneal cavity were drained to the parathymic lymph nodes (PTNs) as sentinel lymph nodes. Similarly, tumor cells injected i.p. were engulfed by macrophages, drained through the transdiaphragmatic channels, and transported to the thoracal lymphatics, primarily to PTNs. Tumor cells after transdiaphragmic drainage can enter both anterior mammary and parathymic sentinel lymph nodes. The potential common origin can shed new light on the metastatic cell progression of PTNs and mammary tumors.

Metastatic view of breast cancer.

The ancient view regarding breast cancer as a metastasis has not been supported so far by experimental evidence. We have implanted nephroblastoma tumor cells resulting in a rat metastatic kidney capsule-parathymic lymph node (PTN) model. India ink implantation confirmed the lymphatic connection between the primary tumor of the kidney and PTNs. (18)F-FDG glucose analog distribution provided further evidence that the first metastatic sites of distant tumor progression are PTNs. Tumor invasion caused disruptions in the tissue of the primary renal tumor, releasing cancer cells into the peritoneal cavity. Colloidal particles, among them bacteria and India ink, crossed transdiaphragmatic channels drained from the peritonel cavity to the thoracic lymphatics and entered not only in the parathymic lymph nodes but also in the anterior mammary lymph nodes. The kidney capsule-PTN complex is reflecting a so far unknown mechanism of tumor development and suggests a similar tumor progression directed towards mammary lymph nodes. The mammalian tumor model provides a reasonable explanation for breast cancer development viewed as a metastasis, rather than a primary tumor.

Effect of the fungal mycotoxin patulin on the chromatin structure of fission yeast Schizosaccharomyces pombe.

The fungal mycotoxin patulin is produced by several molds, especially by Aspergillus and Penicillium. The aim of this study was to clarify whether patulin causes alterations in plasma membrane permeability of Schizosaccharomyces pombe lead to cellular shrinkage charateristic to apoptosis or increases cell size indicating necrosis in cells. Transmission and scanning electronmicroscopy revealed that lower concentrations of patulin induced cellular shrinkage and blebbing, higher concentration caused expansion without cellular disruption. Large-scale morphological changes of individual cells were followed by time lapse video microscopy. Patulin caused the elongation and stickiness of cells or rounded up their shapes. To visualize chromatin structures of S. pombe nuclei upon patulin treatment, protoplasts were isolated from S. pombe and subjected to fluorescent microscopy. Chromatin changes in the presence of 50 µM patulin concentration were characterized by elongated nuclei containing sticky fibrillary chromatin and enlarged round shaped nuclei trapped at the fibrillary stage of chromatin condensation. Short (60 min) incubation of S. pombe cells in the presence of high (500 µM) patulin concentration generated patches of condensed chromatin bodies inside the nucleus and caused nuclear expansion, with the rest of chromatin remaining in fibrillary form. Longer (90 min, 500 µM) incubation resulted in fewer highly condensed chromatin patches and in nuclear fragmentation. Although, high patulin concentration increased the size of S. pombe size, it did not lead to necrotic explosion of cells, neither did the fragmented nuclei resemble apoptotic bodies that would have indicated programmed cell death. All these morphological changes and the high rate of cell survival point to rapid adaptation and mixed type of fungistatic effects.