scholarly journals Efeito de frações parcialmente purificadas de Saccharomyces cerevisiae na germinação de conídios e formação de apressórios por Colletotrichum sublineolum e Colletotrichum lagenarium

2007 ◽  
Vol 33 (3) ◽  
pp. 233-238 ◽  
Author(s):  
Solange Maria Bonaldo ◽  
Sérgio Florentino Pascholati
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Colletotrichum Lagenarium ◽  
Colletotrichum Sublineolum

O trabalho teve por objetivo verificar o efeito de preparações ou de frações parcialmente purificadas obtidas de S. cerevisiae, autoclavada por 4 horas seqüencialmente, submetidas à cromatografia de troca iônica (CTI) utilizando tampão Tris-HCl ou bicarbonato de amônio, na germinação de esporos (GE) e formação de apressórios (FA) in vitro por C. lagenarium ou C. sublineolum. Para isto, 40 µL de cada preparação ou fração foram colocados em pocinhos de placa de ELISA, juntamente com 40 µL de uma suspensão de esporos (1 x 10(5) conídios/mL) de C. lagenarium ou de C. sublineolum. Após incubação, determinou-se GE e FA. Água destilada esterilizada foi utilizada como controle. Todas as preparações da levedura autoclavada promoveram estímulo da GE, sem a formação de apressórios por ambos os fitopatógenos. Frações provenientes da CTI, com tampão Tris-HCl, induziram a GE por C. sublineolum e C. lagenarium. Na FA de C. lagenarium houve estímulo pelas frações IV, V e VI, sem diferença, no entanto, na FA de C. sublineolum. Para as frações obtidas por CTI, utilizando tampão bicarbonato de amônio, houve estímulo da GE por C. lagenarium nas frações I e IV e efeito inibitório da germinação pelas frações V, VI e VII. Não houve FA na fração I e as demais frações apresentaram efeito inibitório da FA por C. lagenarium. As frações I e II estimularam a GE e a FA por C. sublineolum e demais frações apresentaram efeito inibitório. Assim, evidencia-se a importância da escolha de tampões no processo de purificação de frações de S. cerevisiae, o que pode resultar em frações que estimulem a germinação de esporos de fitopatógenos fúngicos ou em frações com atividade inibitória da germinação, podendo contribuir futuramente no controle de doenças causadas por esses fungos.

Ca-, Mg- és K-sók hatása egyes nehézfémek Saccharomyces cerevisiae törzsekre gyakorolt toxicitására

2008 ◽  
Vol 57 (1) ◽  
pp. 161-175
Author(s):  
Nikoletta Tóth ◽  
Hamuda Hosam E. A. F. Bayoumi ◽  
Attila Palágyi ◽  
Mihály Kecskés
Keyword(s):  
Saccharomyces Cerevisiae

Az utóbbi években egyre több tanulmány született a mikroorganizmusok nehézfém akkumulációjáról. A mikroszervezetek nehézfémekkel szembeni tűrőképességére és nehézfém felvételére a bioremediációs hasznosíthatóságuk miatt egyre nagyobb figyelmet fordítanak. A mikroorganizmusok tulajdonságai nagyon jól hasznosíthatóak a talajszennyezés monitorozásánál. A toxikus nehézfémek komoly ökológiai problémát jelentenek környezetünkben, ezért kiemelkedő fontosságú a nehézfémekkel szennyezett talajok tisztítása. In vitro , két S. cerevisiae törzs (NSS5099 és NSS7002) nehézfémekkel szembeni toleranciáját vizsgáltuk. A két törzs szaporodási kinetikáját olyan táptalajon tanulmányoztuk, amelyhez 50 µM koncentrációban adtunk Cu 2+ -, Pb 2+ -, Cd 2+ - vagy Ni 2+ -ionokat. A vizsgált nehézfémek élesztőtörzsekre gyakorolt toxicitása csökkenő sorrendben: Cu 2+ > Pb 2+ > Cd 2+ > Ni 2+ . A 350 µM koncentrációjú Cu 2+ , Pb 2+ vagy Cd 2+ és 450 µM koncentrációjú Ni 2+ 48 órás inkubációt követően 50%-kal csökkentette az élősejtek számát. Amikor a nehézfémek táptalajba történő adagolása előtt 50 mM Ca(HCO 3 ) 2 , 75 mM MgSO 4 , vagy 150 mM K 2 SO 4 -ot adtunk a közeghez csökkent a nehézfémek sejtekre gyakorolt toxicitása, és több sejt maradt életben. A 350 és 450 µM koncentrációban lévő nehézfémek toxicitását a fémsók 40%-kal csökkentették. A kapott eredmények alapján az NSS7002 törzs sokkal alkalmasabbnak bizonyult a nehézfémekkel szennyezett talajok tisztítására, mint az NSS5099._

scholarly journals Suppressor Analysis of the Saccharomyces cerevisiae Gene REC104 Reveals a Genetic Interaction With REC102

Genetics ◽  
1999 ◽  
Vol 151 (4) ◽  
pp. 1261-1272 ◽  
Author(s):  
Laura Salem ◽  
Natalie Walter ◽  
Robert Malone
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Null Allele ◽  
Genetic Interaction ◽  
In Vitro Mutagenesis ◽  
Conditional Mutations ◽  
Suppressor Analysis

Abstract REC104 is a gene required for the initiation of meiotic recombination in Saccharomyces cerevisiae. To better understand the role of REC104 in meiosis, we used an in vitro mutagenesis technique to create a set of temperature-conditional mutations in REC104 and used one ts allele (rec104-8) in a screen for highcopy suppressors. An increased dosage of the early exchange gene REC102 was found to suppress the conditional recombinational reduction in rec104-8 as well as in several other conditional rec104 alleles. However, no suppression was observed for a null allele of REC104, indicating that the suppression by REC102 is not “bypass” suppression. Overexpression of the early meiotic genes REC114, RAD50, HOP1, and RED1 fails to suppress any of the rec104 conditional alleles, indicating that the suppression might be specific to REC102.

scholarly journals Cells Expressing Murine RAD52 Splice Variants Favor Sister Chromatid Repair

2006 ◽  
Vol 26 (10) ◽  
pp. 3752-3763 ◽  
Author(s):  
Peter H. Thorpe ◽  
Vanessa A. Marrero ◽  
Margaret H. Savitzky ◽  
Ivana Sunjevaric ◽  
Tom C. Freeman ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Sister Chromatid ◽  
Mammalian Cells ◽  
Splice Variants ◽  
Protein A ◽  
Single Stranded Dna ◽  
Culture Cells ◽  
Dominant Phenotype ◽  
Mouse Tissues

ABSTRACT The RAD52 gene is essential for homologous recombination in the yeast Saccharomyces cerevisiae. RAD52 is the archetype in an epistasis group of genes essential for DNA damage repair. By catalyzing the replacement of replication protein A with Rad51 on single-stranded DNA, Rad52 likely promotes strand invasion of a double-stranded DNA molecule by single-stranded DNA. Although the sequence and in vitro functions of mammalian RAD52 are conserved with those of yeast, one difference is the presence of introns and consequent splicing of the mammalian RAD52 pre-mRNA. We identified two novel splice variants from the RAD52 gene that are expressed in adult mouse tissues. Expression of these splice variants in tissue culture cells elevates the frequency of recombination that uses a sister chromatid template. To characterize this dominant phenotype further, the RAD52 gene from the yeast Saccharomyces cerevisiae was truncated to model the mammalian splice variants. The same dominant sister chromatid recombination phenotype seen in mammalian cells was also observed in yeast. Furthermore, repair from a homologous chromatid is reduced in yeast, implying that the choice of alternative repair pathways may be controlled by these variants. In addition, a dominant DNA repair defect induced by one of the variants in yeast is suppressed by overexpression of RAD51, suggesting that the Rad51-Rad52 interaction is impaired.

scholarly journals Discovery of a Novel Class of Orally Active Antifungal β-1,3-d-Glucan Synthase Inhibitors

2011 ◽  
Vol 55 (11) ◽  
pp. 5099-5106 ◽  
Author(s):  
Scott S. Walker ◽  
Yiming Xu ◽  
Ilias Triantafyllou ◽  
Michelle F. Waldman ◽  
Cara Mendrick ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Glabrata ◽  
Pharmacokinetic Data ◽  
Morphological Response ◽  
Glucan Synthase ◽  
Content Type ◽  
Safety Issues ◽  
Spontaneous Mutants ◽  
Orally Active

ABSTRACTThe echinocandins are a class of semisynthetic natural products that target β-1,3-glucan synthase (GS). Their proven clinical efficacy combined with minimal safety issues has made the echinocandins an important asset in the management of fungal infection in a variety of patient populations. However, the echinocandins are delivered only parenterally. A screen for antifungal bioactivities combined with mechanism-of-action studies identified a class of piperazinyl-pyridazinones that target GS. The compounds exhibitedin vitroactivity comparable, and in some cases superior, to that of the echinocandins. The compounds inhibit GSin vitro, and there was a strong correlation between enzyme inhibition andin vitroantifungal activity. In addition, like the echinocandins, the compounds caused a leakage of cytoplasmic contents from yeast and produced a morphological response in molds characteristic of GS inhibitors. Spontaneous mutants ofSaccharomyces cerevisiaewith reduced susceptibility to the piperazinyl-pyridazinones had substitutions inFKS1. The sites of these substitutions were distinct from those conferring resistance to echinocandins; likewise, echinocandin-resistant isolates remained susceptible to the test compounds. Finally, we present efficacy and pharmacokinetic data on an example of the piperazinyl-pyridazinone compounds that demonstrated efficacy in a murine model ofCandida glabratainfection.

scholarly journals Expression and Characterization of the Flocculin Flo11/Muc1, a Saccharomyces cerevisiae Mannoprotein with Homotypic Properties of Adhesion

2007 ◽  
Vol 6 (12) ◽  
pp. 2214-2221 ◽  
Author(s):  
Lois M. Douglas ◽  
Li Li ◽  
Yang Yang ◽  
A. M. Dranginis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Biofilm Formation ◽  
In Vitro System ◽  
Glycosylphosphatidylinositol Anchor ◽  
Fungal Adhesion ◽  
Very High ◽  
Molecular Weight Form

ABSTRACT The Flo11/Muc1 flocculin has diverse phenotypic effects. Saccharomyces cerevisiae cells of strain background Σ1278b require Flo11p to form pseudohyphae, invade agar, adhere to plastic, and develop biofilms, but they do not flocculate. We show that S. cerevisiae var. diastaticus strains, on the other hand, exhibit Flo11-dependent flocculation and biofilm formation but do not invade agar or form pseudohyphae. In order to study the nature of the Flo11p proteins produced by these two types of strains, we examined secreted Flo11p, encoded by a plasmid-borne gene, in which the glycosylphosphatidylinositol anchor sequences had been replaced by a histidine tag. A protein of approximately 196 kDa was secreted from both strains, which upon purification and concentration, aggregated into a form with a very high molecular mass. When secreted Flo11p was covalently attached to microscopic beads, it conferred the ability to specifically bind to S. cerevisiae var. diastaticus cells, which flocculate, but not to Σ1278b cells, which do not flocculate. This was true for the 196-kDa form as well as the high-molecular-weight form of Flo11p, regardless of the strain source. The coated beads bound to S. cerevisiae var. diastaticus cells expressing FLO11 and failed to bind to cells with a deletion of FLO11, demonstrating a homotypic adhesive mechanism. Flo11p was shown to be a mannoprotein. Bead-to-cell adhesion was inhibited by mannose, which also inhibits Flo11-dependent flocculation in vivo, further suggesting that this in vitro system is a useful model for the study of fungal adhesion.

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