Efecto radioprotector del ácido tánico y vinos de la var vitis vinífera L. cv tannat en Saccharomyces cerevisiae / Radioprotective effect of tannic acid and wines of the vitis vinifera L. cv tannat on Saccharomyces cerevisiae / Proteção contra radiação por vinho tinto var tannat e ácido tanico em Saccharomyces cerevisiae

El vino tinto variedad Vitis vinifera L. cv Tannat en los últimos años ha tomado relevancia por su alta concentración de polifenoles, esto le podría significar un rol protector sobre el genoma disminuyendo la formación de lesiones oxidativas. Los efectos a nivel celular de las radiaciones ionizantes en blancos como el ADN, componentes de cascadas de transducción de señales, resultan en lesiones letales, mutagénicas y recombinogénicas y en retardos en el ciclo celular. Se utilizó como modelo eucariota poblaciones de Saccharomyces cerevisiae en fase exponencial expuestas a radiación gamma (200 Gy) en presencia, o ausencia, de vino Tannat (10 % v/v) o de ácido tánico (60 µg/mL). Se estimaron las probabilidades de sobrevida y frecuencia mutagénica en distintas condiciones. Las muestras celulares expuestas a radiación ionizante presentaron una fracción de sobrevida de 0.21 ± 0.02 mientras que en las muestras irradiadas en presencia de vino Tannat o de ácido tánico la fracción de sobrevida fue de 0.33 ± 0.03 y 0.30 ± 0.03 respectivamente. Se observó en las poblaciones irradiadas un aumento significativo de la probabilidad de mutagénesis. En el caso de los tratamientos combinados se observó que la frecuencia mutagénica fue significativamente menor (gamma Tannat: 33%, gamma ácido tánico: 45% ). Estos resultados preliminares podrían indicar radioprotección moderada por parte de los compuestos estudiados, efecto que podría explicarse por las interacciones redox del ácido tánico y polifenoles contenidos en el vino con los radicales libres formados por las radiaciones ionizantes, además de la activación de vías de reparación genómica.

The red wine variety Vitis vinifera L. cv Tannat in recent years has gained relevance due to its high concentration of polyphenols, this could mean a protective role on the genome, reducing the formation of oxidative lesions. The effects at the cellular level of ionizing radiation on targets such as DNA, components of signal transduction cascades, result in lethal, mutagenic and recombinogenic lesions and delays in the cell cycle. Exponential phase populations of Saccharomyces cerevisiae exposed to gamma radiation (200 Gy) in the presence or absence of Tannat wine (10% v / v) or tannic acid (60 µg / ml) were used as a eukaryotic model. The probabilities of survival and mutagenic frequency in different conditions were estimated. Cellular samples exposed to ionizing radiation presented a survival fraction of 0.21 ± 0.02, while in samples irradiated in the presence of Tannat wine or tannic acid, the survival fraction was 0.33 ± 0.03 and 0.30 ± 0.03 respectively. A significant increase in the probability of mutagenesis was observed in irradiated populations. In the case of the combined treatments, it was observed that the mutagenic frequency was significantly lower (Tannat gamma: 33%, Tannic acid gamma: 45%). These preliminary results could indicate moderate radioprotection by the compounds studied, an effect that could be explained by the redox interactions of tannic acid and polyphenols contained in wine with the free radicals formed by ionizing radiation, in addition to the activation of genomic repair pathways.

A variedade de vinho tinto Vitis vinifera L. cv Tannat nos últimos anos tem ganhado relevância devido à sua alta concentração de polifenóis, o que pode significar um papel protetor do genoma, reduzindo a formação de lesões oxidativas. Os efeitos no nível celular da radiação ionizante em alvos como o DNA, componentes de cascatas de transdução de sinal, resultam em lesões letais, mutagênicas e recombinogênicas e atrasos no ciclo celular. Populações de fase exponencial de Saccharomyces cerevisiae expostas à radiação gama (200 Gy) na presença ou ausência de vinho Tannat (10% v / v) ou ácido tânico (60 µg / ml) foram utilizadas como modelo eucariótico. Foram estimadas as probabilidades de sobrevivência e frequência mutagênica em diferentes condições. As amostras celulares expostas à radiação ionizante apresentaram uma fração de sobrevivência de 0,21 ± 0,02, enquanto nas amostras irradiadas na presença de vinho Tannat ou ácido tânico, a fração de sobrevivência foi de 0,33 ± 0,03 e 0,30 ± 0,03, respectivamente. Um aumento significativo na probabilidade de mutagênese foi observado nas populações irradiadas. No caso dos tratamentos combinados, observou-se que a frequência mutagênica foi significativamente menor (Tannat gama: 33%, ácido tânico gama: 45%). Esses resultados preliminares podem indicar radioproteção moderada pelos compostos estudados, efeito que pode ser explicado pelas interações redox do ácido tânico e polifenóis contidos no vinho com os radicais livres formados pela radiação ionizante, além da ativação de vias de reparo genômico.

Expression of antimicrobial peptide Cecropin P1 in Saccharomyces cerevisiae and its antibacterial and antiviral activity in vitro

BACKGROUND: Cecropin P1, acting as an antimicrobial, has a broad-spectrum antibacterial activity with some antiviral and antifungal properties. It is a promising natural alternative to antibiotics which is originally isolated from the pig intestinal parasitic nematode Ascaris suum. Many studies have shown that Cecropin P1 is helpful for the prevention or treatment of clinical diseases. Therefore, it is very necessary to establish a safe, nontoxic, and efficient expression method of Cecropin P1. RESULTS: The results indicated that the recombinant protein was about 5.5 kDa showed by Tricine­SDS­ PAGE and Western blot. And Cecropin P1 was efficiently secreted and expressed after 12 h of induction, with an increasing yield over the course of the induction. Its maximum concentration was 7.83 mg/L after concentration and purification. In addition, in vitro experiments demonstrated that Cecropin P1 not only exerted a strong inhibitory effect on Escherichia coli, Salmonella sp., Shigella sp., and Pasteurella sp., but also displayed an antiviral activity against PRRSV NADC30-Like strain. CONCLUSIONS: Collectively, the strategy of expressing Cecropin P1 in Saccharomyces cerevisiae is harmless, efficient, and safe for cells. In addition, the expressed Cecropin P1 has antiviral and antibacterial properties concurrently.

Analysis of radioprotection and antimutagenic effects of Ilex paraguariensis infusion and its component rutin

DNA repair pathways, cell cycle checkpoints, and redox protection systems are essential factors for securing genomic stability. The aim of the present study was to analyze the effect of Ilex paraguariensis (Ip) infusion and one of its polyphenolic components rutin on cellular and molecular damage induced by ionizing radiation. Ip is a beverage drank by most inhabitants of Argentina, Paraguay, Southern Brazil, and Uruguay. The yeast Saccharomyces cerevisiae (SC7Klys 2-3) was used as the eukaryotic model. Exponentially growing cells were exposed to gamma rays (γ) in the presence or absence of Ip or rutin. The concentrations used simulated those found in the habitual infusion. Surviving fractions, mutation frequency, and DNA double-strand breaks (DSB) were determined after treatments. A significant increase in surviving fractions after gamma irradiation was observed following combined exposure to γ+R, or γ+Ip. Upon these concomitant treatments, mutation and DSB frequency decreased significantly. In the mutant strain deficient in MEC1, a significant increase in γ sensitivity and a low effect of rutin on γ-induced chromosomal fragmentation was observed. Results were interpreted in the framework of a model of interaction between radiation-induced free radicals, DNA repair pathways, and checkpoint controls, where the DNA damage that induced activation of MEC1 nodal point of the network could be modulated by Ip components including rutin. Furthermore, ionizing radiation-induced redox cascades can be interrupted by rutin potential and other protectors contained in Ip.

Inhibitor tolerance of a recombinant flocculating industrial Saccharomyces cerevisiae strain during glucose and xylose co-fermentation

ABSTRACT Lignocellulose-derived inhibitors have negative effects on the ethanol fermentation capacity of Saccharomyces cerevisiae. In this study, the effects of eight typical inhibitors, including weak acids, furans, and phenols, on glucose and xylose co-fermentation of the recombinant xylose-fermenting flocculating industrial S. cerevisiae strain NAPX37 were evaluated by batch fermentation. Inhibition on glucose fermentation, not that on xylose fermentation, correlated with delayed cell growth. The weak acids and the phenols showed additive effects. The effect of inhibitors on glucose fermentation was as follows (from strongest to weakest): vanillin > phenol > syringaldehyde > 5-HMF > furfural > levulinic acid > acetic acid > formic acid. The effect of inhibitors on xylose fermentation was as follows (from strongest to weakest): phenol > vanillin > syringaldehyde > furfural > 5-HMF > formic acid > levulinic acid > acetic acid. The NAPX37 strain showed substantial tolerance to typical inhibitors and showed good fermentation characteristics, when a medium with inhibitor cocktail or rape straw hydrolysate was used. This research provides important clues for inhibitors tolerance of recombinant industrial xylose-fermenting S. cerevisiae.

Antioxidant potential of yerba mate (Ilex paraguariensis St. Hil.) extracts in Saccharomyces cerevisae deficient in oxidant defense genes / Potencial antioxidante de extratos de erva-mate (Ilex paraguariensis St. Hil.) em Saccharomyces cerevisiae deficientes para genes de defesa oxidante

Abstract Yerba-mate (Ilex paraguariensis St. Hil) is mainly consumed as “chimarrão”, a hot drink highly appreciated in Brazil, Argentina, Paraguay and Uruguay. This study evaluated the antioxidant potential of aqueous extracts of I. paraguariensis precipitated with ethanol. The leaves were processed as for tea product (TM) and oxidized (OX). The antioxidant potential was evaluated in cells of Saccharomyces cerevisiae deficient in antioxidant defense genes. Three strains evaluated were: a wild (EG) and two mutants (ctt1Δ e ctt1Δsod1Δ). These strains were pre-treated with the yerba-mate extracts (TM e OX) and submitted to oxidative stress induced by hydrogen peroxide. None of the extracts produced loss of cell viability. The extracts exerted antioxidant activity, protecting the strains (except sod1∆ctt1∆). The TM extract was more effective than OX. I. paraguariensis extracts showed a potential to be explored in the development of new products.

Resumo A erva-mate (Ilex paraguariensis St. Hil) é consumida principalmente como “chimarrão”, uma bebida quente muito apreciada no Brasil, Argentina, Paraguai e Uruguai. Este estudo avaliou o potencial antioxidante de extratos aquosos de I. paraguariensis precipitado com etanol. Folhas de erva-mate foram processados de maneira semelhante ao processamento do chá-preto (OX) e na forma de mate (TM). O potencial antioxidante foi avaliado sobre células de Saccharomyces cerevisiae deficientes para genes de defesa antioxidante. Três linhagens celulares foram estudadas: uma selvagem (EG) e duas mutantes (ctt1Δ e ctt1Δsod1Δ). As linhagens foram pré-tratadas com os extratos de erva-mate (TM e OX) e submetidos ao estresse oxidativo induzido por peróxido de hidrogênio. Nenhum dos extratos produziu perda de viabilidade celular. Os extratos exerceram atividade antioxidante, protegendo as linhagens (exceto a sod1Δctt1Δ). O extrato TM foi mais eficaz em relação ao OX. Extratos de I. paraguariensis apresentaram potencial para ser explorado no desenvolvimento de novas formulações.

Antioxidant, antimicrobial, toxicity and analgesic properties of ethanol extract of Solena amplexicaulis root

BACKGROUND: This study was subjected to investigate different pharmacological properties of ethanol extract ofSolena amplexicaulis root. RESULTS: The extract contains flavonoid, alkaloid, saponin and steroid compounds. The extract exhibited excellent antioxidant activity in DPPH radical scavenging activity. The extract also showed potent activity in brine shrimp lethality bioassay. The LC50 value was found to 44.677 µg/ml. The extract showed better anti-bacterial activity against gram-negative bacteria. In antifungal assay, the maximum 79.31% of anti-mycotic activity was observed against Aspergillus ochraceus while minimum 44.2% against Rhizopus oryzae. MIC value ranged between 1500 - 3000 µg/ml. The extract was found moderately toxic with a 24-hr LD50 value of 81.47 mg/kg in Swiss albino mice. The degree of inhibition by the ethanolic extract of the root was found less than that of standard analgesic drug diclofenac sodium. The extract also showed moderate anti-inflammatory and antinociceptive activity and anti-diabetic property. Reducing power of the extract was comparable with standard ascorbic acid. Moderate in vitro thrombolytic activity, lipid peroxidation inhibition property, metal chelating ability and stress-protective activity was also observed. CONCLUSION: Ethanol extract of Solena amplexicaulis root can be valuable for treatment of different diseases.

First Case of Continuous Ambulatory Peritoneal Dialysis-Related Peritonitis Caused by Cryptococcus arboriformis

No abstract available.

Characteristics of Saccharomyces cerevisiae yeasts exhibiting rough colonies and pseudohyphal morphology with respect to alcoholic fermentation

Among the native yeasts found in alcoholic fermentation, rough colonies associated with pseudohyphal morphology belonging to the species Saccharomyces cerevisiae are very common and undesirable during the process. The aim of this work was to perform morphological and physiological characterisations of S. cerevisiae strains that exhibited rough and smooth colonies in an attempt to identify alternatives that could contribute to the management of rough colony yeasts in alcoholic fermentation. Characterisation tests for invasiveness in Agar medium, killer activity, flocculation and fermentative capacity were performed on 22 strains (11 rough and 11 smooth colonies). The effects of acid treatment at different pH values on the growth of two strains ("52" -rough and "PE-02" smooth) as well as batch fermentation tests with cell recycling and acid treatment of the cells were also evaluated. Invasiveness in YPD Agar medium occurred at low frequency; ten of eleven rough yeasts exhibited flocculation; none of the strains showed killer activity; and the rough strains presented lower and slower fermentative capacities compared to the smooth strains in a 48-h cycle in a batch system with sugar cane juice. The growth of the rough strain was severely affected by the acid treatment at pH values of 1.0 and 1.5; however, the growth of the smooth strain was not affected. The fermentative efficiency in mixed fermentation (smooth and rough strains in the same cell mass proportion) did not differ from the efficiency obtained with the smooth strain alone, most likely because the acid treatment was conducted at pH 1.5 in a batch cell-recycle test. A fermentative efficiency as low as 60% was observed with the rough colony alone.

Evaluation of stress tolerance and fermentative behavior of indigenous Saccharomyces cerevisiae

Sixty six indigenous Saccharomyces cerevisiae strains were evaluated in stressful conditions (temperature, osmolarity, sulphite and ethanol tolerance) and also ability to flocculate. Eighteen strains showed tolerant characteristics to these stressful conditions, growing at 42 ºC, in 0.04% sulphite, 1 mol L-1 NaCl and 12% ethanol. No flocculent characteristics were observed. These strains were evaluated according to their fermentative performance in sugar cane juice. The conversion factors of substrates into ethanol (Yp/s), glycerol (Yg/s) and acetic acid (Yac/s), were calculated. The highest values of Yp/s in sugar cane juice fermentation were obtained by four strains, one isolated from fruit (0.46) and the others from sugar cane (0.45, 0.44 and 0.43). These values were higher than the value obtained using traditional yeast (0.38) currently employed in the Brazilian bioethanol industry. The parameters Yg/s and Yac/s were low for all strains. The UFLA FW221 presented the higher values for parameter related to bioethanol production. Thus, it was tested in co-culture with Lactobacillus fermentum. Besides this, a 20-L vessel for five consecutive batches of fermentation was performed. This strain was genetically stable and remained viable during all batches, producing high amounts of ethanol. The UFLA FW221 isolated from fruit was suitable to produce bioethanol in sugar cane juice. Therefore, the study of the biodiversity of yeasts from different environmental can reveal strains with desired characteristics to industrial applications.

Brazilian propolis protects Saccharomyces cerevisiae cells against oxidative stress

Propolis is a natural product widely used for humans. Due to its complex composition, a number of applications (antimicrobial, antiinflammatory, anesthetic, cytostatic and antioxidant) have been attributed to this substance. Using Saccharomyces cerevisiae as a eukaryotic model we investigated the mechanisms underlying the antioxidant effect of propolis from Guarapari against oxidative stress. Submitting a wild type (BY4741) and antioxidant deficient strains (ctt1∆, sod1∆, gsh1∆, gtt1∆ and gtt2∆) either to 15 mM menadione or to 2 mM hydrogen peroxide during 60 min, we observed that all strains, except the mutant sod1∆, acquired tolerance when previously treated with 25 µg/mL of alcoholic propolis extract. Such a treatment reduced the levels of ROS generation and of lipid peroxidation, after oxidative stress. The increase in Cu/Zn-Sod activity by propolis suggests that the protection might be acting synergistically with Cu/Zn-Sod.

Antioxidant and antitopoisomerase activities in plant extracts of some Colombian flora from La Marcada Natural Regional Park

Many plants have been used to treat some diseases and infections since time immemorial, and this potential has been exploited by the pharmaceutical industry in the search of new analgesic, anticarcinogenic and antimicrobial agents, among other active agents. in order to contribute with bioprospection studies on the Colombian flora, 35 extracts from 13 plant species belonging to seven families (Apocynaceae, Cactaceae, Costaceae, Eremolepidaceae, Passifloraceae, Solanaceae and Urticaceae) were collected from La Marcada Natural Regional Park (LMNRP), Colombia. Dichloromethane, n-hexane and aqueous-methanol crude extracts were prepared and evaluated for their activity against Saccharomyces cerevisiae RS322N, R52Y and RS321 strains in the yeast mutant assay and their antioxidant capacity through the DPPH test. The dichloromethane extract from Myriocarpa stipitata (Urticaceae) showed moderate inhibitory activity against the three S. cerevisiae strains tested. The capacity of the dichloromethane extract from M. stipitata to inhibit the enzyme topoisomerase I and to cause DNA damage was inferred from these results. In the DPPH assay, the n-hexane crude extract from Costus sp. (Costaceae) showed good antioxidant activity (48%); in addition, the crude dichloromethane and aqueous-methanol extracts from Rhipsalis micrantha (Cactaceae) showed moderate antioxidant activity with percentage of 29 and 21%, respectively. Rev. Biol. Trop. 59 (3): 1089-1097. Epub 2011 September 01.

Desde tiempos inmemoriales, muchas plantas han sido usadas para el tratamiento de varias enfermedades e infecciones, este potencial ha sido explotado por la industria farmacéutica en la búsqueda de nuevos agentes analgésicos, anticancerígenos y antimicrobianos, entre otros. Consientes con esto, se evaluó la actividad de 35 extractos de 13 especies de plantas recolectadas en el Parque Regional Natural La Marcada (PRNLM, Colombia) contra las cepas mutadas de Saccharomyces cerevisiae RS322N, R52Y y RS321 en el ensayo de la levadura mutada y la capacidad antioxidante de los extractos a través del método del DPPH. El extracto crudo de diclorometano de Myriocarpa stipitata (Urticaceae) presentó actividad moderada contra las tres cepas de S. cerevisiae evaluadas. Lo cual permitió inferir la capacidad del extracto de diclorometano de esta especie para inhibir la enzima topoisomerasa I y causar daño al ADN. Además, en el ensayo del DPPH, el extracto de n-hexano crudo de Costus sp (Costaceae) mostró actividad antioxidante buena (48%), mientras que los extractos de diclorometano y acuoso metanólico crudos de Rhipsalis micrantha (Cactaceae) tuvieron actividad antioxidante moderada, con valores del 29 y 21%, respectivamente.

Cadmium-induced oxidative stress in Saccharomyces cerevisiae.

The present study was undertaken to determine the effect of cadmium (Cd) on the antioxidant status of the yeast Saccharomyces cerevisiae. S. cerevisiae serves as a good eukaryotic model system for the study of the molecular mechanisms of oxidative stress. We investigated the adaptative response of S. cerevisiae exposed to Cd. Yeast cells could tolerate up to 100 μM Cd and an inhibition in the growth and viability was observed. Exposure of yeast cells to Cd showed an increase in malondialdehyde and glutathione. The activities of catalase, superoxide dismutase and glutathione peroxidase were also high in Cd-exposed cells. The incorporation of Cd led to significant increase in iron, zinc and inversely the calcium, copper levels were reduced. The results suggest that antioxidants were increased and are involved in the protection against macromolecular damage during oxidative stress; presumably, these enzymes are essential for counteracting the pro-oxidant effects of Cd.

Oxidative stress response to menadione and cumene hydroperoxide in the opportunistic fungal pathogen Candida glabrata

Candida glabrata is an opportunistic fungal pathogen that can cause severe invasive infections and can evade phagocytic cell clearance. We are interested in understanding the virulence of this fungal pathogen, in particular its oxidative stress response. Here we investigated C. glabrata, Saccharomyces cerevisiae and Candida albicans responses to two different oxidants: menadione and cumene hydroperoxide (CHP). In log-phase, in the presence of menadione, C. glabrata requires Cta1p (catalase), while in a stationary phase (SP), Cta1p is dispensable. In addition, C. glabrata is less resistant to menadione than C. albicans in SP. The S. cerevisiae laboratory reference strain is less resistant to menadione than C. glabrata and C. albicans; however S. cerevisiaeclinical isolates (CIs) are more resistant than the lab reference strain. Furthermore, S. cerevisiae CIs showed an increased catalase activity. Interestingly, in SP C. glabrata and S. cerevisiae are more resistant to CHP than C. albicans and Cta1p plays no apparent role in detoxifying this oxidant.

[CNS, cytotoxicity and antimicrobial activities of [+]-dihydroperfamine and its derivatives]

In this work [+]-dihydroperfamine was isolated from Haplophyllum tuberculatum and several derivatives, namely, anhydroperforine, dihydroperfaminole, haplophyllidine, [-]-perforine and [+]-perforine were prepared. Dihydroperfamine and its derivatives were investigated for prolongation of sleeping time of pentobarbitone. Their cytotoxic activity was performed using a mechanism-based bioassay utilizing genetically engineered mutants of the yeast Saccharomyces cerevisiae. In addition, their antimicrobial activity was also tested using agar dilution method. The results showed that dihydroperfamine and its derivatives except haplophyllidine prolonged the hypnotic duration of pentobarbital. Dihydroperfamine was the only compound that possessed cytotoxic activity against strain I. On the other hand, all compounds were antimicrobially inactive

Identificación rápida y sensibilidad a toxinas killer de levaduras aisladas de micosis no sistémicas / Rapid identification and susceptibility to killer toxins of yeasts isolated from non-systemic mycoses

La identificación rápida y segura de los agentes etiológicos y el desarrollo de nuevos antifúngicos con blancos de acción más específicos resultarán en tratamientos de las micosis más efectivos y menos lesivos. Mediante un método molecular rápido (ITS1-5.8S ADNr-ITS2 PCR-RFLP) se identificaron 53 aislamientos de levaduras provenientes de infecciones no sistémicas registradas en hospitales públicos de la ciudad de Neuquén y en un centro oftalmológico de Buenos Aires durante el año 2005. Adicionalmente y utilizando el método de inhibición del crecimiento en placa, se evaluó la sensibilidad de estas levaduras a toxinas killer producidas por levaduras indígenas de la Patagonia y por cepas de referencia. Ocho especies de levaduras fueron identificadas entre los aislamientos clínicos: Candida albicans (52%) , Candida parapsilosis (17%) , Candida tropicalis (10%) , Candida krusei (5%) , Candida glabrata (4%) , Candida guilliermondii (4%) , Kluyveromyces lactis (4%) y Saccharomyces cerevisiae (4%) . El 69% de los aislamientos de la especie mayoritaria, C. albicans, se relacionó con infecciones vaginales. Por otra parte, el 61% de las levaduras provenientes de infecciones oculares correspondió a la especie C. parapsilosis. En las condiciones de ensayo, las toxinas producidas por las levaduras killer indígenas DVMais5 y HCMeiss5 pertenecientes a las especies Pichia anomala y P. kluyveri, respectivamente, exhibieron el mayor espectro de acción sobre las levaduras aisladas de materiales clínicos.

The use of quick and reliable yeast identification methods, as well as the development of new antifungal agents with more specific targets, will enable a more efficient treatment of mycoses. In the present work, a total of 53 clinical isolates obtained from non-systemic infections in Neuquén Hospitals and an ophthalmologic clinic in Buenos Aires during 2005, were identified by means of a rapid molecular method (ITS1-5.8S ADNr-ITS2 PCR-RFLP). Additionally, the killer susceptibility of the isolates was tested against reference and indigenous killer yeasts on plate tests. Eight yeast species were identified among the clinical isolates: Candida albicans (52%), Candida parapsilosis (17%), Candida tropicalis (10%), Candida krusei (5%), Candida glabrata (4%) , Candida guilliermondii (4%) , Kluyveromyces lactis (4%) and Saccharomyces cerevisiae (4%) . Sixty-nine percent of the isolates corresponding to the predominant species ( C. albicans) were related to vaginal infections. On the other hand, 61% of the yeasts associated with ocular infections were identified as C. parapsilosis. Two indigenous killer isolates DVMais5 and HCMeiss5, belonging to Pichia anomala and P. kluyveri respectively, exhibited the broadest killer spectrum against clinical isolates.

Pharmacology and toxicology of diphenyl diselenide in several biological models

The pharmacology of synthetic organoselenium compounds indicates that they can be used as antioxidants, enzyme inhibitors, neuroprotectors, anti-tumor and anti-infectious agents, and immunomodulators. In this review, we focus on the effects of diphenyl diselenide (DPDS) in various biological model organisms. DPDS possesses antioxidant activity, confirmed in several in vitro and in vivo systems, and thus has a protective effect against hepatic, renal and gastric injuries, in addition to its neuroprotective activity. The activity of the compound on the central nervous system has been studied since DPDS has lipophilic characteristics, increasing adenylyl cyclase activity and inhibiting glutamate and MK-801 binding to rat synaptic membranes. Systemic administration facilitates the formation of long-term object recognition memory in mice and has a protective effect against brain ischemia and on reserpine-induced orofacial dyskinesia in rats. On the other hand, DPDS may be toxic, mainly because of its interaction with thiol groups. In the yeast Saccharomyces cerevisiae, the molecule acts as a pro-oxidant by depleting free glutathione. Administration to mice during cadmium intoxication has the opposite effect, reducing oxidative stress in various tissues. DPDS is a potent inhibitor of d-aminolevulinate dehydratase and chronic exposure to high doses of this compound has central effects on mouse brain, as well as liver and renal toxicity. Genotoxicity of this compound has been assessed in bacteria, haploid and diploid yeast and in a tumor cell line.

Functional complementation of a yeast knockout strain by Schistosoma mansoni Rho1 GTPase in the presence of caffeine, an agent that affects mutants defective in the protein kinase C signal transduction pathway

In a previous study, the Schistosoma mansoni Rho1 protein was able to complement Rho1 null mutant Saccharomyces cerevisiae cells at restrictive temperatures and under osmotic stress (low calcium concentration) better than the human homologue (RhoA). It is known that under osmotic stress, the S. cerevisiae Rho1 triggers two distinct pathways: activation of the membrane 1,3-beta-glucan synthase enzymatic complex and activation of the protein kinase C1 signal transduction pathway, promoting the transcription of response genes. In the present work the SmRho1 protein and its mutants smrho1E97P, smrho1L101T, and smrho1E97P, L101T were used to try to clarify the basis for the differential complementation of Rho1 knockout yeast strain by the human and S. mansoni genes. Experiments of functional complementation in the presence of caffeine and in the presence of the osmotic regulator sorbitol were conducted. SmRho1 and its mutants showed a differential complementation of the yeast cells in the presence of caffeine, since smrho1E97P and smrho1E97P, L101T mutants showed a delay in the growth when compared to the yeast complemented with the wild type SmRho1. However, in the presence of sorbitol and caffeine the wild type SmRho1 and mutants showed a similar complementation phenotype, as they allowed yeast growth in all caffeine concentrations tested.

Comportamiento de una cepa salvaje de Saccharomyces cerevisiae killer y su isogénica sensible respecto de diferentes fuentes de nitrógeno en cultivos mixtos / Behaviour of a wild Saccharomyces cerevisiae killer yeast and its isogenic sensitive one with respect to different nitrogen sources in mixed cultures

La composición química del vino constituye el fundamento de la posterior respuesta sensorial del producto y está determinada por varios factores, como las relaciones levadura-levadura. Se denomina fenómeno killer a la secreción por parte de ciertas cepas de levadura de una proteína tóxica que mata a células denominadas sensibles. El conocimiento del comportamiento en condición aeróbica de cultivos mixtos killer-sensible es útil para relacionarlo con la primera fase de la fermentación enológica, ya que en ella puede definirse la prevalencia o no de la cepa killer. Además, el empleo de mutantes con el plásmido curado permite comparaciones más precisas. El objetivo fue analizar el mecanismo de competencia por sustrato en levaduras killer de Saccharomyces cerevisiae y su mutante sensible con el plásmido curado, empleando distintas fuentes de nitrógeno. Si las muestras se incuban a temperatura de inactivación de la toxina, se evita la infraestimación de células sensibles. Los resultados del co-cultivo de las cepas en proporciones iguales muestran el rol desempeñado por la fuente de nitrógeno en la actividad killer. Cuando el inóculo es 10%K-90%S, el modelo de exclusión competitiva planteado para levaduras killer deja paso a otras variables de competencia.

Wine chemical composition is the outcome of complex chemosensory interactions that are difficult to predict because of the influences of many variables, like as yeast-yeast interactions. Killer phenomenon implicates the secretion of a toxic protein by some yeasts, that kill other yeasts called sensitive. The knowledge of the behaviour of killer-sensitive mixed cultures in aerobic conditions is useful to be related with the first stages of oenological fermentation. In these stages it can be defined the killer prevalence in the medium. Also, the use of cured plasmid mutants allows better comparisons. The objective was to analyse the mechanism of substrate competition in Saccharomyces cerevisiae killer strains and its sensitive cured plasmid mutant, using different nitrogen sources. When samples were incubated at the toxin inactivation temperature, the infraestimation of sensitive cells is avoided. Results obtained in co-cultures (50%K-50%S) show the role of the nitrogen source in killer activity. Results obtained with 10%K-90%S inoculum, show that there are another competence variables than the competitive exclusion model for killer yeasts.

Genotoxic, neurotoxic and neuroprotective activities of apomorphine and its oxidized derivative 8-oxo-apomorphine

Apomorphine is a dopamine receptor agonist proposed to be a neuroprotective agent in the treatment of patients with Parkinson's disease. Both in vivo and in vitro studies have shown that apomorphine displays both antioxidant and pro-oxidant actions, and might have either neuroprotective or neurotoxic effects on the central nervous system. Some of the neurotoxic effects of apomorphine are mediated by its oxidation derivatives. In the present review, we discuss recent studies from our laboratory in which the molecular, cellular and neurobehavioral effects of apomorphine and its oxidized derivative, 8-oxo-apomorphine-semiquinone (8-OASQ), were evaluated in different experimental models, i.e., in vitro genotoxicity in Salmonella/microsome assay and WP2 Mutoxitest, sensitivity assay in Saccharomyces cerevisiae, neurobehavioral procedures (inhibition avoidance task, open field behavior, and habituation) in rats, stereotyped behavior in mice, and Comet assay and oxidative stress analyses in mouse brain. Our results show that apomorphine and 8-OASQ induce differential mutagenic, neurochemical and neurobehavioral effects. 8-OASQ displays cytotoxic effects and oxidative and frameshift mutagenic activities, while apomorphine shows antimutagenic and antioxidant effects in vitro. 8-OASQ induces a significant increase of DNA damage in mouse brain tissue. Both apomorphine and 8-OASQ impair memory for aversive training in rats, although the two drugs showed a different dose-response pattern. 8-OASQ fails to induce stereotyped behaviors in mice. The implications of these findings are discussed in the light of evidence from studies by other groups. We propose that the neuroprotective and neurotoxic effects of dopamine agonists might be mediated, in part, by their oxidized metabolites.

Effect of sugars on the association between cowpea vicilin (7S storage proteins) and fungal cells

Vicilins (7S storage proteins) found in various legume seeds have been previously shown to interfere with the germination of spores or conidia of phytopathogenic fungi and inhibit yeast growth and glucose stimulated acidification of the medium by yeast cells. In the present work vicilins from cowpea (Vigna unguiculata) seeds were added to the growth medium of Saccharomyces cerevisiae cells and Fusarium oxysporum conidia. Helix pomatia lectin, wheat germ agglutinin and Ulex europaeus lectin were used to identify differences in the binding of the vicilins to the surface of cells of S. cerevisiae and F. oxysporum treated with this protein. After the growth period, the material in suspension (yeast cells) was centrifuged and the final pellet was also treated with different sugar (glucose, sucrose, glucosamine, N-acetyl-glucosamine) concentrations and 0.1 M HCl for extraction of vicilins associated to chitinous structures present in yeast cells. Our results showed that vicilin sub-units were present in the different sugar extracts of yeast cells pretreated with the vicilins and these proteins were eluted by 0.5 M solutions of sugars in the following order of efficiency of elution: N-acetyl-glucosamine, sucrose/glucose and glucosamine.