Hypothesis: is yeast a clock model to study the onset of humans aging phenotypes?

In this paper we report the growth and aging of yeast colonies derived from single cells isolated by micromanipulation and seeded one by one on separated plates to avoid growth interference by surrounding colonies. We named this procedure clonal life span, and it could represent a third way of studying aging together with the replicative life span and chronological life span. In this study we observed over time the formation of cell mass similar to the human "senile warts" (seborrheic keratoses), the skin lesions that often appear after 30 years of life and increase in number and size over the years. We observed that similar signs of aging appear in yeast colonies after about 27 days of growth and increase during aging. In this respect we hypothesize to use yeast as a clock to study the onset of human aging phenotypes

Increased levels of RNA oxidation enhance the reversion frequency in aging pro-apoptotic yeast mutants

Despite recent advances in understanding the complexity of RNA processes, regulation of the metabolism of oxidized cellular RNAs and the mechanisms through which oxidized ribonucleotides affect mRNA translation, and consequently cell viability, are not well characterized. We show here that the level of oxidized RNAs is markedly increased in a yeast decapping Kllsm4Δ1 mutant, which accumulates mRNAs, ages much faster that the wild type strain and undergoes regulated-cell-death. We also found that in Kllsm4Δ1 cells the mutation rate increases during chronological life span indicating that the capacity to han- dle oxidized RNAs in yeast declines with aging. Lowering intracellular ROS levels by antioxidants recovers the wild- type phenotype of mutant cells, including reduced amount of oxidized RNAs and lower mutation rate. Since mRNA oxidation was reported to occur in different neurodegen- erative diseases, decapping-deficient cells may represent a useful tool for deciphering molecular mechanisms of cell response to such conditions, providing new insights into RNA modification-based pathogenesis

Performance of the auxotrophic Saccharomyces cerevisiae BY4741 as host for the production of IL-1β in aerated fed-batch reactor: role of ACA supplementation, strain viability, and maintenance energy

<p>Abstract</p> <p>Background</p> <p><it>Saccharomyces cerevisiae </it>BY4741 is an auxotrophic commonly used strain. In this work it has been used as host for the expression and secretion of human interleukin-1<it>β </it>(IL1<it>β</it>), using the cell wall protein Pir4 as fusion partner. To achieve high cell density and, consequently, high product yield, BY4741 [PIR4-IL1<it>β</it>] was cultured in an aerated fed-batch reactor, using a defined mineral medium supplemented with casamino acids as ACA (auxotrophy-complementing amino acid) source. Also the <it>S. cerevisiae </it>mutant BY4741 Δ<it>yca1 </it>[PIR4-IL1<it>β</it>], carrying the deletion of the <it>YCA1 </it>gene coding for a caspase-like protein involved in the apoptotic response, was cultured in aerated fed-batch reactor and compared to the parental strain, to test the effect of this mutation on strain robustness. Viability of the producer strains was examined during the runs and a mathematical model, which took into consideration the viable biomass present in the reactor and the glucose consumption for both growth and maintenance, was developed to describe and explain the time-course evolution of the process for both, the BY4741 parental and the BY4741 Δ<it>yca1 </it>mutant strain.</p> <p>Results</p> <p>Our results show that the concentrations of ACA in the feeding solution, corresponding to those routinely used in the literature, are limiting for the growth of <it>S. cerevisiae </it>BY4741 [PIR4-IL1<it>β</it>] in fed-batch reactor. Even in the presence of a proper ACA supplementation, <it>S. cerevisiae </it>BY4741 [PIR4-IL1<it>β</it>] did not achieve a high cell density. The Δ<it>yca1 </it>deletion did not have a beneficial effect on the overall performance of the strain, but it had a clear effect on its viability, which was not impaired during fed-batch operations, as shown by the <it>k</it>_{<it>d </it>}value (0.0045 h^-1), negligible if compared to that of the parental strain (0.028 h^-1). However, independently of their robustness, both the parental and the Δ<it>yca1 </it>mutant ceased to grow early during fed-batch runs, both strains using most of the available carbon source for maintenance, rather than for further proliferation. The mathematical model used evidenced that the energy demand for maintenance was even higher in the case of the Δ<it>yca1 </it>mutant, accounting for the growth arrest observed despite the fact that cell viability remained comparatively high.</p> <p>Conclusions</p> <p>The paper points out the relevance of a proper ACA formulation for the outcome of a fed-batch reactor growth carried out with <it>S. cerevisiae </it>BY4741 [PIR4-IL1<it>β</it>] strain and shows the sensitivity of this commonly used auxotrophic strain to aerated fed-batch operations. A Δ<it>yca1 </it>disruption was able to reduce the loss of viability, but not to improve the overall performance of the process. A mathematical model has been developed that is able to describe the behaviour of both the parental and mutant producer strain during fed-batch runs, and evidence the role played by the energy demand for maintenance in the outcome of the process.</p

Heterologous protein production by yeast in aerated fed-batch cultures:relevance of the host strain viability.

The auxotrofic S. cerevisiae BY4741, carrying the fusion PIR4-IL1β, and able to secrete the human interleukin-1β into the culture medium, has been employed in an aerated bioreactor working as a fed-batch. Notwithstanding proper formulation of the culture medium, the performance of the host strain BY4741 [Pir4-IL1β] in fed-batch was not satisfactory: biomass density was far from that expected, glucose and ethanol accumulated during the runs. To test if the oxidative stress was responsible for the observed behaviour, the mutant BY4741 Δyca1, deleted for the YCA1 gene, coding for a caspase-like protein involved in yeast apoptosis, was transformed with the expression cassette containing the fusion PIR4-IL1β, and assayed in the same aerated fed-batch system. The different performances exhibited by both BY4741[Pir4-IL1β] and BY4741 Δyca1 [Pir4-IL1β], together with the study of death kinetics during operation runs, evidenced the relevance of strain viability in the operative conditions employed

Annurca apple (M. pumila Miller cv Annurca) extracts act against stress and ageing in S. cerevisiae yeast cells

During the past years, a number of studies have demonstrated the positive effect of apple on ageing and different diseases such as cancer, degenerative and cardiovascular diseases. The unicellular yeast Saccharomyces cerevisiae represents a simple eukaryotic model to study the effects of different compounds on lifespan. We previously demonstrated that apple extracts have anti-ageing effects in this organism because of their antioxidant properties. In particular, the effect is related to the presence in this fruit of polyphenols, which give a large contribution to the antioxidant activity of apples

Swapping of the N-terminus of VDAC1 with VDAC3 restores full activity of the channel and confers anti-aging features to the cell

AbstractVoltage-dependent anion-selective channels (VDACs) are pore-forming proteins allowing the permeability of the mitochondrial outer membrane. The VDAC3 isoform is the least abundant and least active in a complementation assay performed in a yeast strain devoid of porin-1. We swapped the VDAC3 N-terminal 20 amino acids with homologous sequences from the other isoforms. The substitution of the VDAC3 N-terminus with the VDAC1 N-terminus caused the chimaera to become more active than VDAC1. The VDAC2 N-terminus improved VDAC3 activity, though to a lesser extent. The VDAC3 carrying the VDAC1 N-terminus was able to complement the lack of the yeast porin in mitochondrial respiration and in modulation of reactive oxygen species (ROS). This chimaera increased life span, indicating a more efficient bioenergetic metabolism and/or a better protection from ROS

Uso de destiladores de mao con solubles en pollos de engorde

            This study aimed to evaluate the inclusion of distiller's dried grains with soluble (DDGS) of corn in the broiler diet on growth performance, carcass and viscera yield, and biometrics of the gastrointestinal tract. In total, 700 male Cobb 500 broilers were distributed in a completely randomized design with five treatments, seven replicates, and 20 chicks per experimental unit. The treatments consisted of a control and four levels of inclusion of DDGS (4, 8, 12, and 16%) in the diet. The inclusion of the DDGS did not influence the performance in the periods of 1 to 7 and 36 to 42 days of age. For broilers 8 to 35 days old, the feed intake was not altered by the treatments, but the average weight gain and feed conversion (p&lt;0.05) had a quadratic polynomial effect. There was a reduction in carcass and breast weight of broilers slaughtered at 42 days of age fed with 12 and 16% DDGS. The DDGS in diets can be considered an alternative ingredient in diets for broilers up to 12% inclusion.El estudio tuvo como objetivo evaluar la inclusión de granos secos de maíz de destilería con solubles (DDGS) en la dieta de pollos de engorde sobre el rendimiento del crecimiento, la canal y las vísceras, y la biometría del tracto gastrointestinal. En total, se distribuyeron 700 pollos de engorde Cobb 500 machos en un diseño completamente al azar con cinco tratamientos, siete repeticiones y 20 pollos por unidad experimental. Los tratamientos consistieron en un control y cuatro niveles de inclusión de DDGS (4, 8, 12 y 16%) en la dieta. La inclusión de los DDGS no influyó en el rendimiento en los periodos de 1 a 7 y 36 a 42 días de edad. Para pollos de engorde de 8 a 35 días de edad, el consumo de alimento no fue alterado por los tratamientos, pero la ganancia de peso promedio y la conversión alimenticia (p&lt;0.05) tuvieron un efecto polinomial cuadrático. Hubo una reducción en el peso de la canal y de la pechuga de los pollos de engorde sacrificados a los 42 días de edad alimentados con 12 y 16% de DDGS. Los DDGS en dietas pueden considerarse un ingrediente alternativo en dietas para pollos de engorde hasta un 12% de inclusión

Synphilin-1 Enhances α-Synuclein Aggregation in Yeast and Contributes to Cellular Stress and Cell Death in a Sir2-Dependent Manner

© 2010 Büttner et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Parkinson’s disease is characterized by the presence of cytoplasmic inclusions, known as Lewy bodies, containing both aggregated α-synuclein and its interaction partner, synphilin-1. While synphilin-1 is known to accelerate inclusion formation by α-synuclein in mammalian cells, its effect on cytotoxicity remains elusive. Methodology/Principal Findings: We expressed wild-type synphilin-1 or its R621C mutant either alone or in combination with α-synuclein in the yeast Saccharomyces cerevisiae and monitored the intracellular localization and inclusion formation of the proteins as well as the repercussions on growth, oxidative stress and cell death. We found that wild-type and mutant synphilin-1 formed inclusions and accelerated inclusion formation by α-synuclein in yeast cells, the latter being correlated to enhanced phosphorylation of serine-129. Synphilin-1 inclusions co-localized with lipid droplets and endomembranes. Consistently, we found that wild-type and mutant synphilin-1 interacts with detergent-resistant membrane domains, known as lipid rafts. The expression of synphilin-1 did not incite a marked growth defect in exponential cultures, which is likely due to the formation of aggresomes and the retrograde transport of inclusions from the daughter cells back to the mother cells. However, when the cultures approached stationary phase and during subsequent ageing of the yeast cells, both wild-type and mutant synphilin-1 reduced survival and triggered apoptotic and necrotic cell death, albeit to a different extent. Most interestingly, synphilin-1 did not trigger cytotoxicity in ageing cells lacking the sirtuin Sir2. This indicates that the expression of synphilin-1 in wild-type cells causes the deregulation of Sir2-dependent processes, such as the maintenance of the autophagic flux in response to nutrient starvation. Conclusions/Significance: Our findings demonstrate that wild-type and mutant synphilin-1 are lipid raft interacting proteins that form inclusions and accelerate inclusion formation of α-synuclein when expressed in yeast. Synphilin-1 thereby induces cytotoxicity, an effect most pronounced for the wild-type protein and mediated via Sir2-dependent processes.This work was supported by grants from IWT-Vlaanderen (SBO NEURO-TARGET), the K.U.Leuven Research Fund (K.U.Leuven BOF-IOF) and K.U.Leuven R&D to JW, a Tournesol grant from Egide (Partenariat Hubert Curien) in France in collaboration with the Flemish Ministry of Education and the Fund of Scientific Research of Flanders (FWO) in Belgium to JW, MCG and LB, a shared PhD fellowship of the EU-Marie Curie PhD Graduate School NEURAD to JW, MCG and LB, grants of the Austrian Science Fund FWF (Austria) to FM and DR (S-9304-B05), to FM and SB (LIPOTOX), and to SB (T-414-B09; Hertha-Firnberg Fellowship) and an EMBO Installation Grant, a Marie Curie IRG, and a grant of the Fundação para a Ciência e Tecnologia (PTDC/SAU-NEU/105215/2008) to TFO. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript