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1.
Elife ; 62017 12 28.
Artigo em Inglês | MEDLINE | ID: mdl-29283340

RESUMO

Although individuals of many species inexorably age, a number of observations established that the rate of aging is modulated in response to a variety of mild stresses. Here, we investigated how heat stress promotes longevity in yeast. We show that upon growth at higher temperature, yeast cells relax the retention of DNA circles, which act as aging factors in the mother cell. The enhanced frequency at which circles redistribute to daughter cells was not due to changes of anaphase duration or nuclear shape but solely to the downregulation of the diffusion barrier in the nuclear envelope. This effect depended on the PKA and Tor1 pathways, downstream of stress-response kinase Pkc1. Inhibition of these responses restored barrier function and circle retention and abrogated the effect of heat stress on longevity. Our data indicate that redistribution of aging factors from aged cells to their progeny can be a mechanism for modulating longevity.


Assuntos
Temperatura Alta , Saccharomycetales/fisiologia , Saccharomycetales/efeitos da radiação , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , DNA Circular/metabolismo , DNA Fúngico/metabolismo , Membrana Nuclear/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteína Quinase C/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
2.
Small ; 13(34)2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28696538

RESUMO

Transparent microtubes can function as unique cell culture scaffolds, because the tubular 3D microenvironment they provide is very similar to the narrow space of capillaries in vivo. However, how to realize the fabrication of microtube-arrays with variable cross-section dynamically remains challenging. Here, a dynamic holographic processing method for producing high aspect ratio (≈20) microtubes with tunable outside diameter (6-16 µm) and inside diameter (1-10 µm) as yeast culture scaffolds is reported. A ring-structure Bessel beam is modulated from a typical Gaussian-distributed femtosecond laser beam by a spatial light modulator. By combining the axial scanning of the focused beam and the dynamic display of holograms, dimension-controllable microtube arrays (straight, conical, and drum-shape) are rapidly produced by two-photon polymerization. The outside and inside diameters, tube heights, and spatial arrangements are readily tuned by loading different computer-generated holograms and changing the processing parameters. The transparent microtube array as a nontrivial tool for capturing and culturing the budding yeasts reveals the significant effect of tube diameter on budding characteristics. In particular, the conical tube with the inside diameter varying from 5 to 10 µm has remarkable asymmetrical regulation on the growth trend of captured yeasts.


Assuntos
Nanoestruturas/química , Fótons , Técnicas de Cultura de Células , Lasers , Polimerização , Saccharomycetales/efeitos da radiação
3.
Cold Spring Harb Protoc ; 2017(1)2017 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-28049774

RESUMO

The cell cycle of budding yeast can be arrested at specific positions by different genetic and chemical methods. These arrests enable study of cell cycle phase-specific phenotypes that would be missed during examination of asynchronous cultures. Some methods for arrest are reversible, with kinetics that enable release of cells back into a synchronous cycling state. Benefits of chemical and genetic methods include scalability across a large range of culture sizes from a few milliliters to many liters, ease of execution, the absence of specific equipment requirements, and synchronization and release of the entire culture. Of note, cell growth and division are decoupled during arrest and block-release experiments. Cells will continue transcription, translation, and accumulation of protein while arrested. If allowed to reenter the cell cycle, cells will do so as a population of mixed, larger-than-normal cells. Despite this important caveat, many aspects of budding yeast physiology are accessible using these simple chemical and genetic tools. Described here are methods for the block and release of cells in G1 phase and at the M/G1 transition using α-factor mating pheromone and the temperature-sensitive cdc15-2 allele, respectively, in addition to methods for arresting the cell cycle in early S phase and at G2/M by using hydroxyurea and nocodazole, respectively.


Assuntos
Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos da radiação , Divisão Celular/efeitos dos fármacos , Divisão Celular/efeitos da radiação , Genética Microbiana/métodos , Técnicas Microbiológicas/métodos , Saccharomycetales/fisiologia , Proteínas de Ciclo Celular/genética , Temperatura Alta , Fator de Acasalamento/metabolismo , Proteínas Mutantes/metabolismo , Saccharomycetales/efeitos dos fármacos , Saccharomycetales/crescimento & desenvolvimento , Saccharomycetales/efeitos da radiação
4.
Nucleic Acids Res ; 45(4): 1879-1888, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-27923995

RESUMO

RAD52 is a homologous recombination (HR) protein that is conserved from bacteriophage to humans. Simultaneously attenuating expression of both the RAD52 gene, and the HR and tumor suppressor gene, BRCA2, in human cells synergistically reduces HR - indicating that RAD52 and BRCA2 control independent mechanisms of HR. We have expressed the human RAD52 gene (HsRAD52) in budding yeast strains lacking the endogenous RAD52 gene and found that HsRAD52 supports repair of DNA double-strand breaks (DSB) by a mechanism of HR that conserves genome structure. Importantly, this mechanism of HR is independent of RAD51, which encodes the central strand exchange protein in yeast required for conservative HR. In contrast, BRCA2 exerts its effect on HR in human cells together with HsRAD51, potentially explaining the synergistic effect of attenuating the expression of both HsRAD52 and BRCA2. This suggests that multiple mechanisms of conservative DSB repair may contribute to tumor suppression in human cells.


Assuntos
Quebras de DNA de Cadeia Dupla , Reparo do DNA , Recombinação Homóloga , Rad51 Recombinase/metabolismo , Proteína Rad52 de Recombinação e Reparo de DNA/genética , Proteína Rad52 de Recombinação e Reparo de DNA/metabolismo , Saccharomycetales/genética , Imunoprecipitação da Cromatina , Expressão Ectópica do Gene , Humanos , Imunoprecipitação , Mutação , Ligação Proteica , Mapeamento de Interação de Proteínas , Tolerância a Radiação/genética , Radiação Ionizante , Saccharomycetales/metabolismo , Saccharomycetales/efeitos da radiação , Técnicas do Sistema de Duplo-Híbrido
5.
Nanotechnology ; 27(8): 085103, 2016 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-26808118

RESUMO

Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated (•)OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling.


Assuntos
Fungicidas Industriais/farmacologia , Fusarium/efeitos dos fármacos , Nanopartículas/química , Doenças das Plantas/prevenção & controle , Saccharomycetales/efeitos dos fármacos , Prata/farmacologia , Titânio/farmacologia , Parede Celular/efeitos dos fármacos , Dissulfetos/química , Fungicidas Industriais/síntese química , Fusarium/patogenicidade , Fusarium/fisiologia , Fusarium/efeitos da radiação , Química Verde , Radical Hidroxila/antagonistas & inibidores , Radical Hidroxila/metabolismo , Luz , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/microbiologia , Malus/efeitos dos fármacos , Malus/microbiologia , Testes de Sensibilidade Microbiana , Micotoxinas/antagonistas & inibidores , Micotoxinas/biossíntese , Nanopartículas/ultraestrutura , Naftoquinonas/antagonistas & inibidores , Naftoquinonas/metabolismo , Processos Fotoquímicos , Doenças das Plantas/microbiologia , Saccharomycetales/patogenicidade , Saccharomycetales/fisiologia , Saccharomycetales/efeitos da radiação , Prata/química , Solanum tuberosum/efeitos dos fármacos , Solanum tuberosum/microbiologia , Titânio/química
6.
Methods Mol Biol ; 1033: 207-17, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23996180

RESUMO

Recent development of methods for genetic incorporation of unnatural amino acids into proteins in live cells enables us to analyze protein interactions by site-specific photocrosslinking. Here we describe a method to incorporate p-benzoyl-L-phenylalanine (pBpa), a photoreactive unnatural amino acid, into defined positions of a target protein in living yeast cells. Photocrosslinking using the pBpa-incorporated proteins has been proven to be a powerful method for analyzing protein-protein interactions at the spatial resolution of amino-acid residues. Since photocrosslinking can be performed for pBpa-incorporated proteins that are properly assembled into a protein complex in living cells, this method will allow us to reveal protein-protein interactions of the target proteins at work.


Assuntos
Proteínas Fúngicas/metabolismo , Mapeamento de Interação de Proteínas/métodos , Saccharomycetales/metabolismo , Sequência de Aminoácidos , Proteínas Fúngicas/química , Proteínas de Transporte da Membrana Mitocondrial/química , Dados de Sequência Molecular , Processos Fotoquímicos , Ligação Proteica , Saccharomycetales/genética , Saccharomycetales/efeitos da radiação , Raios Ultravioleta
7.
Can J Microbiol ; 58(10): 1174-82, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23009616

RESUMO

The present work aimed to investigate whether exposure to static magnetic field (SMF) and extremely low frequency magnetic field (ELF-MF) can induce biomolecular changes on Tuber borchii hyphal growth. Tuber borchii mycelium was exposed for 1 h for 3 consecutive days to a SMF of 300 mT or an ELF-MF of 0.1 mT 50 Hz. Gene expression and biochemical analyses were performed. In mycelia exposed to ELF-MF, some genes involved in hyphal growth, investigated using quantitative real-time polymerase chain reaction, were upregulated, and the activity of many glycolytic enzymes was increased. On the contrary, no differences were observed in gene expression after exposure to SMF treatment, and only the activities of glucose 6-phosphate dehydrogenase and hexokinase increased. The data herein presented suggest that the electromagnetic field can act as an environmental factor in promoting hyphal growth and can be used for applicative purposes, such as the set up of new in vitro cultivation techniques.


Assuntos
Campos Eletromagnéticos , Campos Magnéticos , Micélio/efeitos da radiação , Saccharomycetales/efeitos da radiação , Metabolismo Energético/efeitos da radiação , Regulação Fúngica da Expressão Gênica/efeitos da radiação , Genes Fúngicos/genética , Glucose/metabolismo , Hifas/crescimento & desenvolvimento , Hifas/efeitos da radiação , Micélio/genética , Saccharomycetales/genética
8.
J Lab Autom ; 17(6): 417-24, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22786982

RESUMO

We evaluated fermentation capabilities of five strains of Scheffersomyces stipitis (WT-2-1, WT-1-11, 14-2-6, 22-1-1, and 22-1-12) that had been produced by UV-C mutagenesis and selection for improved xylose fermentation to ethanol using an integrated automated robotic work cell. They were incubated under both facultative and anaerobic conditions to evaluate ethanol production on glucose, xylose, cellobiose, and a combination of all three sugars. The medium contained 50 g/L total sugar and 5 g/L yeast extract. The strains performed significantly better under facultative compared with anaerobic conditions. As expected, glucose was the most readily fermented sugar with ~100% fermentation efficiency (FE) under facultative conditions but only 5% to 16% FE anaerobically. Xylose utilization was 20% to 40% FE under facultative conditions but 9% to 25% FE anaerobically. Cellobiose was the least fermented sugar, at 18% to 27% FE facultatively and 8% to 11% anaerobically. Similar trends occurred in the sugar mixture. Under facultative conditions, strain 22-1-12 produced 19.6 g/L ethanol on glucose, but strain 14-2-6 performed best on xylose (4.5 g/L ethanol) and the sugar combination (8.0 g/L ethanol). Ethanol titers from glucose under anaerobic conditions were again highest with strain 22-1-12, but none of the strains produced ethanol from xylose. Future trials will evaluate nutrient addition to boost microaerophilic xylose fermentation.


Assuntos
Etanol/metabolismo , Engenharia Metabólica/métodos , Mutagênese , Saccharomycetales/metabolismo , Saccharomycetales/efeitos da radiação , Raios Ultravioleta , Aerobiose , Anaerobiose , Automação Laboratorial/métodos , Celobiose/metabolismo , Meios de Cultura/química , Fermentação , Glucose/metabolismo , Programas de Rastreamento/métodos , Saccharomycetales/genética , Xilose/metabolismo
9.
Curr Microbiol ; 65(2): 122-7, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22562600

RESUMO

In this article, we investigated the effect of exogenous calcium on improving viability of Debaryomyces hansenii and Pichia membranaefaciens under heat stress, and evaluated the role of calcium in reducing oxidant damage of proteins in the yeast cells. The results indicated that high concentration of exogenous calcium in culture medium was beneficial for enhancing the tolerance of the biocontrol yeasts to heat stress. The possible mechanism of calcium improving the viability of yeasts was attributed to enhancement of antioxidant enzyme activities, decrease in ROS accumulation and reduction of oxidative damage of intracellular protein in yeast cells under heat stress. D. hansenii is more sensitive to calcium as compared to P. membranaefaciens. Our results suggest that application of exogenous calcium combined with biocontrol yeasts is a practical approach for the control of postharvest disease in fruit.


Assuntos
Cálcio/metabolismo , Viabilidade Microbiana/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Saccharomycetales/metabolismo , Saccharomycetales/efeitos da radiação , Estresse Fisiológico , Meios de Cultura/química , Proteínas Fúngicas/metabolismo , Temperatura Alta , Oxirredução
10.
J Ind Microbiol Biotechnol ; 39(1): 163-73, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21748309

RESUMO

Scheffersomyces (formerly Pichia) stipitis NRRL Y-7124 was mutagenized using UV-C irradiation to produce yeast strains for anaerobic conversion of lignocellulosic sugars to ethanol. UV-C irradiation potentially produces large numbers of random mutations broadly and uniformly over the whole genome to generate unique strains. Wild-type cultures of S. stipitis NRRL Y-7124 were subjected to UV-C (234 nm) irradiation targeted at approximately 40% cell survival. When surviving cells were selected in sufficient numbers via automated plating strategies and cultured anaerobically on xylose medium for 5 months at 28°C, five novel mutagenized S. stipitis strains were obtained. Variable number tandem repeat analysis revealed that mutations had occurred in the genome, which may have produced genes that allowed the anaerobic utilization of xylose. The mutagenized strains were capable of growing anaerobically on xylose/glucose substrate with higher ethanol production during 250- to 500-h growth than a Saccharomyces cerevisiae yeast strain that is the standard for industrial fuel ethanol production. The S. stipitis strains resulting from this intense multigene mutagenesis strategy have potential application in industrial fuel ethanol production from lignocellulosic hydrolysates.


Assuntos
Etanol/metabolismo , Mutagênese , Saccharomycetales/genética , Saccharomycetales/metabolismo , Raios Ultravioleta , Xilose/metabolismo , Anaerobiose , Animais , Fermentação , Glucose/metabolismo , Lignina/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomycetales/crescimento & desenvolvimento , Saccharomycetales/efeitos da radiação
11.
Appl Microbiol Biotechnol ; 93(6): 2591-601, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22116630

RESUMO

The xylose-fermenting yeast Spathaspora passalidarum showed excellent fermentation performance utilizing glucose and xylose under anaerobic conditions. But this yeast is highly sensitive to the inhibitors such as furfural present in the pretreated lignocellulosic biomass. In order to improve the inhibitor tolerance of this yeast, a combination of UV mutagenesis and protoplast fusion was used to construct strains with improved performance. Firstly, UV-induced mutants were screened and selected for improved tolerance towards furfural. The most promised mutant, S. passalidarum M7, produced 50% more final ethanol than the wild-type strain in a synthetic xylose medium containing 2 g/l furfural. However, this mutant was unable to grow in a medium containing 75% liquid fraction of pretreated wheat straw (WSLQ), in which furfural and many other inhibitors were present. Hybrid yeast strains, obtained from fusion of the protoplasts of S. passalidarum M7 and a robust yeast, Saccharomyces cerevisiae ATCC 96581, were able to grow in 75% WSLQ and produce around 0.4 g ethanol/g consumed xylose. Among the selected hybrid strains, the hybrid FS22 showed the best fermentation capacity in 75% WSLQ. Phenotypic and partial molecular analysis indicated that S. passalidarum M7 was the dominant parental contributor to the hybrid. In summary, the hybrids are characterized by desired phenotypes derived from both parents, namely the ability to ferment xylose from S. passalidarum and an increased tolerance to inhibitors from S. cerevisiae ATCC 96581.


Assuntos
Furaldeído/metabolismo , Protoplastos/citologia , Saccharomyces cerevisiae/citologia , Saccharomycetales/genética , Saccharomycetales/metabolismo , Xilose/metabolismo , Etanol/metabolismo , Fermentação , Mutagênese/efeitos da radiação , Protoplastos/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharomycetales/citologia , Saccharomycetales/efeitos da radiação , Raios Ultravioleta
12.
Mikrobiol Z ; 72(6): 36-42, 2010.
Artigo em Ucraniano | MEDLINE | ID: mdl-21381315

RESUMO

The features of radial growth of three microscopic fungi species were investigated at illumination by yellow, blue, green and red light. The studied species of fungi differed by isolation site (some of them were isolated from the places of high radioactive pollution, others--from the places with background level of radioactivity) and pigmentation degree (melanin-containing and light-colored). The parameters of radial growth, which are the integral indexes of the fungal organism physiology state were investigated: radial growth rate, branching degree and summarizing index--the intensity of substrate consumption. It was shown that the melanin-containing fungi Cladosporium cladosporioides growth was twice more rapid in response to blue and yellow light. Whereas such light depressed growth of non-pigmented strain of the same species as compared to control. A light response of other pigment-containing species Hormoconis resinae was far less expressed, and the light-colored species Paecilomyces lilacinus had no response to any offered conditions of illumination.


Assuntos
Luz , Fungos Mitospóricos/crescimento & desenvolvimento , Fungos Mitospóricos/efeitos da radiação , Radiação Ionizante , Acidente Nuclear de Chernobyl , Fungos Mitospóricos/isolamento & purificação , Paecilomyces/crescimento & desenvolvimento , Paecilomyces/isolamento & purificação , Paecilomyces/efeitos da radiação , Saccharomycetales/crescimento & desenvolvimento , Saccharomycetales/isolamento & purificação , Saccharomycetales/efeitos da radiação , Ucrânia
13.
J Food Sci ; 75(7): M503-7, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21535563

RESUMO

UNLABELLED: The effects of UV-C radiation on microbial growth in vitro (Monilinia fruticola) and in inoculated Yali pears (Pyrus bretschneideri Rehd.) were investigated. Moreover, postharvest quality and the activities of defense and antioxidant enzymes were analyzed after the pears were exposed to UV-C irradiation at an energy level of 5 kJ m⁻².The results showed that spore germination of M. fructicola was significantly inhibited by each of the 3 doses (1, 5, and 10 kJ m⁻²) in vitro. In the in vivo assays, lesion diameter on the fruit being inoculated before or after the UV-C treatment was both significantly lower than that on the fruit of control. Meanwhile, the activities of phenylalanine ammonia lyase, ß-1,3-glucanase, superoxide dismutase, catalase, and glutathione reductase were induced to high levels by UV-C treatment. We conclude that UV-C treatment could reduce postharvest disease by the germicidal and induced effects and maintain the quality by enhancing the antioxidant enzyme activities. PRACTICAL APPLICATION: UV-C radiation has recently been proposed as a new technology to avoid chemical fungicides. However, there are few studies regarding the effect of UV-C treatment on Yali pear. In this study, we found that 5 kJ m⁻² UV-C irradiation can control postharvest disease and maintain the quality of Yali pear. This method may be applied to reduce the decay of Yali pears during exporting and storage.


Assuntos
Irradiação de Alimentos , Frutas/microbiologia , Frutas/efeitos da radiação , Viabilidade Microbiana/efeitos da radiação , Pyrus/microbiologia , Pyrus/efeitos da radiação , Ácido Ascórbico/metabolismo , Irradiação de Alimentos/métodos , Frutas/metabolismo , Glucana 1,3-beta-Glucosidase/metabolismo , Oxirredutases/metabolismo , Fenilalanina Amônia-Liase/metabolismo , Proteínas de Plantas/metabolismo , Pyrus/metabolismo , Controle de Qualidade , Saccharomycetales/isolamento & purificação , Saccharomycetales/fisiologia , Saccharomycetales/efeitos da radiação , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação , Raios Ultravioleta
14.
Mol Cell Biol ; 28(15): 4782-93, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18541674

RESUMO

Following genotoxic insults, eukaryotic cells trigger a signal transduction cascade known as the DNA damage checkpoint response, which involves the loading onto DNA of an apical kinase and several downstream factors. Chromatin modifications play an important role in recruiting checkpoint proteins. In budding yeast, methylated H3-K79 is bound by the checkpoint factor Rad9. Loss of Dot1 prevents H3-K79 methylation, leading to a checkpoint defect in the G(1) phase of the cell cycle and to a reduction of checkpoint activation in mitosis, suggesting that another pathway contributes to Rad9 recruitment in M phase. We found that the replication factor Dpb11 is the keystone of this second pathway. dot1Delta dpb11-1 mutant cells are sensitive to UV or Zeocin treatment and cannot activate Rad53 if irradiated in M phase. Our data suggest that Dpb11 is held in proximity to damaged DNA through an interaction with the phosphorylated 9-1-1 complex, leading to Mec1-dependent phosphorylation of Rad9. Dpb11 is also phosphorylated after DNA damage, and this modification is lost in a nonphosphorylatable ddc1-T602A mutant. Finally, we show that, in vivo, Dpb11 cooperates with Dot1 in promoting Rad9 phosphorylation but also contributes to the full activation of Mec1 kinase.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Dano ao DNA , Complexos Multiproteicos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomycetales/metabolismo , Saccharomycetales/efeitos da radiação , Raios Ultravioleta , Sequência Consenso , Quebras de DNA de Cadeia Dupla/efeitos da radiação , Ativação Enzimática/efeitos da radiação , Fosforilação , Fosfotirosina/metabolismo , Saccharomycetales/citologia , Saccharomycetales/enzimologia
15.
Colloids Surf B Biointerfaces ; 36(2): 101-4, 2004 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-15261013

RESUMO

Pyruvic acid lay on the center position of Eremothecium ashbyii metabolic fluxes, during fermentation, a high performance liquid chromatography (HPLC) method is presented for the simultaneous determination of pyruvic acid in the Eremothecium ashbyii cell culture of both with ultrasound stimulation and the control. Dry weight and riboflavin are also mentored. The results of this study show that the ultrasound stimulation can give rise to pyruvic acid change, at the same time; change of pyruvic acid concentration is correlative to that of dry weight of mycelium and content of riboflavin.


Assuntos
Ácido Pirúvico/metabolismo , Ultrassom , Cromatografia Líquida de Alta Pressão , Meios de Cultura/análise , Meios de Cultura/química , Meios de Cultura/efeitos da radiação , Fermentação/efeitos da radiação , Concentração de Íons de Hidrogênio , Micélio/química , Micélio/efeitos da radiação , Ácido Pirúvico/análise , Ácido Pirúvico/efeitos da radiação , Riboflavina/análise , Riboflavina/metabolismo , Riboflavina/efeitos da radiação , Saccharomycetales/crescimento & desenvolvimento , Saccharomycetales/metabolismo , Saccharomycetales/efeitos da radiação , Fatores de Tempo
16.
Int J Hyperthermia ; 18(1): 40-9, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11820467

RESUMO

Various cellular systems have been analysed for synergistic interactions of the simultaneous action of hyperthermia with physical agents including ionizing radiation, ultraviolet light, and ultrasound, and with chemical agents including thio-TEPA and cis-DDP. Some general rules of synergistic interaction were revealed. First, for every constant rate or intensity of exposure to physical factors or concentration of chemical agents, synergy can be observed only within a certain temperature range that is different for various cellular systems. Secondly, within this range, there is a specific temperature that maximizes the synergistic effect. Any deviation of temperature from the optimal one results in a reduction in synergy. Thirdly, the rate of exposure to physical agents or the concentration of chemical agents strongly influences the synergy; i.e. as the dose rate or concentration is reduced, the temperature for maximum synergism decreases. Possible interpretations of the mechanisms responsible for these relationships of synergy are discussed.


Assuntos
Hipertermia Induzida , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/efeitos da radiação , Saccharomycetales/efeitos dos fármacos , Saccharomycetales/efeitos da radiação , Antineoplásicos/farmacologia , Antineoplásicos Alquilantes/farmacologia , Cisplatino/farmacologia , Sinergismo Farmacológico , Temperatura Alta , Radiação Ionizante , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomycetales/crescimento & desenvolvimento , Tiotepa/farmacologia , Ultrassonografia de Intervenção , Raios Ultravioleta
17.
Environ Microbiol ; 3(9): 545-50, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11683864

RESUMO

Riboflavin (vitamin B2), essential in tiny amounts as a precursor for oxidoreductase coenzymes, is a yellow pigment. Although it causes cytotoxicity via photoinduced damage of macromolecules, several microorganisms are striking overproducers. A question, unanswered for decades, is whether riboflavin overproducers can benefit from this property. Here, we report an ultraviolet (UV) protective effect of riboflavin. The spores of Ashbya gossypii, a riboflavin-overproducing fungus, are more sensitive to UV than those of Aspergillus nidulans. The addition of riboflavin to suspensions improves the UV resistance of both spore types. Interestingly, we show that regulation of sporulation and riboflavin overproduction in A. gossypii are linked. In batch culture, both were elevated when growth ceased. At constant growth rates, obtained in a chemostat culture, neither was elevated. Supplementation of cultures by cAMP, a known stress signal, negatively affected sporulation as well as riboflavin overproduction, establishing a second, independent argument for the linkage.


Assuntos
Riboflavina/fisiologia , Saccharomycetales/fisiologia , Hialina , Cinética , Tolerância a Radiação , Riboflavina/biossíntese , Riboflavina/genética , Saccharomycetales/enzimologia , Saccharomycetales/efeitos da radiação , Esporos Fúngicos/efeitos da radiação , Raios Ultravioleta
18.
Prikl Biokhim Mikrobiol ; 36(1): 37-40, 2000.
Artigo em Russo | MEDLINE | ID: mdl-10752082

RESUMO

Pigmented (Rhodotorula glutinis) and nonpigmented (Lipomyces starkeyi) yeasts were studied. Exogenous stressors (UV irradiation and methylene blue) were shown to change the composition of yeast lipids (especially the ratio of unsaturated fatty acids) and to increase the content of lipid peroxidation products formed (particularly in nonpigmented yeasts). In carotene-synthesizing yeasts, these stressors decreased the amount of carotenoids produced and did not affect the ratio between carotenoid pigments (beta-carotene, torulene, and torularhodin).


Assuntos
Metabolismo dos Lipídeos , Rhodotorula/metabolismo , Saccharomycetales/metabolismo , Azul de Metileno , Rhodotorula/efeitos dos fármacos , Rhodotorula/efeitos da radiação , Saccharomycetales/efeitos dos fármacos , Saccharomycetales/efeitos da radiação , Raios Ultravioleta
19.
Lett Appl Microbiol ; 22(1): 80-4, 1996 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8588892

RESUMO

The radiation resistance of a selection of yeasts isolated from sausages was assessed in phosphate-buffered saline and in sausage meat. The yeasts Candida zeylanoides, Debaryomyces hansenii and Trichosporon cutaneum exhibited sigmoidal survival curves in both substrates whilst the more sensitive Sporobolomyces roseus exhibited an exponential survival curve in buffer but a sigmoidal curve in meat. Irradiating C. zeylanoides, D. hansenii and T. cutaneum in sausage meat changed the shape of their survival curves to significantly alter the calculated parameters Ds (the dose in kGy that must be achieved before reduction in numbers occurs) and D10sig (the dose in kGy required after the shoulder to achieve a 1 log cycle reduction in numbers). The Ds values were reduced while higher D10sig values were obtained demonstrating that the sausage meat contributed a protective effect to these yeasts at higher irradiation doses. For the yeast S. roseus, similar numbers of survivors were recovered from both substrates at initial low irradiation doses (0-0.5 kGy) with the protective effect being demonstrated again at higher doses (> 2 kGy). These findings should be considered when defining a commercial process to reduce the numbers of yeasts in these products.


Assuntos
Irradiação de Alimentos , Produtos da Carne/microbiologia , Produtos da Carne/efeitos da radiação , Leveduras/efeitos da radiação , Animais , Candida/isolamento & purificação , Candida/efeitos da radiação , Meios de Cultura , Fungos Mitospóricos/isolamento & purificação , Fungos Mitospóricos/efeitos da radiação , Tolerância a Radiação , Saccharomycetales/isolamento & purificação , Saccharomycetales/efeitos da radiação , Trichosporon/isolamento & purificação , Trichosporon/efeitos da radiação , Leveduras/isolamento & purificação
20.
J Bacteriol ; 170(12): 5572-8, 1988 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-3056904

RESUMO

We have developed an efficient transformation system for the industrial yeast Schwanniomyces occidentalis (formerly Schwanniomyces castellii). The transformation system is based on ade2 mutants of S. occidentalis deficient for phosphoribosylaminoimidazole carboxylase that were generated by mutagenesis. As a selectable marker, we isolated and characterized the S. occidentalis ADE2 gene by complementation in an ade2 strain of Saccharomyces cerevisiae. S. occidentalis was transformed with the recombinant plasmid pADE, consisting of a 4.5-kilobase-pair (kbp) DNA fragment from S. occidentalis containing the ADE2 gene inserted into the S. cerevisiae expression vector pYcDE8 by a modification of the spheroplasting procedure of Beggs (J. D. Beggs, Nature [London] 275:104-108, 1978). Intact plasmids were recovered in Escherichia coli from whole-cell lysates of ADE+ transformants, indicating that plasmids were replicating autonomously. High-molecular-mass species of pADE2 were found by Southern hybridization analysis of intact genomic DNA preparations. The shift to higher molecular mass of these plasmids during electrophoresis in the presence ethidium bromide after exposure to shortwave UV suggests that they exist in a supercoiled form in the transformed host. Subclones of the 4.5-kbp insert indicated that ADE2-complementing activity and sequences conferring autonomous replication in S. occidentalis were located within a 2.7-kbp EcoRI-SphI fragment. Plasmids containing this region cloned into the bacterial vector pUC19 complemented ade2 mutants of S. occidentalis with efficiencies identical to those of the original plasmid pADE.


Assuntos
Clonagem Molecular , Genes Fúngicos , Saccharomycetales/genética , Transformação Genética , Southern Blotting , DNA Fúngico/genética , DNA Fúngico/isolamento & purificação , Metanossulfonato de Etila/farmacologia , Mutação , Hibridização de Ácido Nucleico , Plasmídeos , Mapeamento por Restrição , Saccharomyces cerevisiae/genética , Saccharomycetales/efeitos dos fármacos , Saccharomycetales/efeitos da radiação , Raios Ultravioleta
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