5 research outputs found
Integrative Omics reveals changes in the cellular landscape of peroxisome-deficient pex3 yeast cells
Full text linkPeroxisomes are organelles that are crucial for cellular metabolism, but they also play important roles in non-metabolic processes such as signalling, stress response or antiviral defense. To uncover the consequences of peroxisome deficiency, we compared Saccharomyces cerevisiae wild-type with pex3 cells, which lack peroxisomes, employing quantitative proteomics and transcriptomics technologies. Cells were grown on acetate, a carbon source that requires peroxisomal enzymes of the glyoxylate cycle to generate energy and essential carbohydrates, and that does not repress the expression of peroxisomal genes. Our integrative omics analysis reveals that the absence of peroxisomes induces distinct responses at the level of the transcriptome and proteome. Transcripts of genes and corresponding proteins that are associated with peroxisomal β-oxidation were mostly increased in pex3 cells. In contrast, levels of peroxins were regulated at protein but not at transcript level. Membrane-bound peroxins were reduced, whereas the soluble receptors Pex5 and Pex7 were increased in abundance in pex3 cells. Interestingly, we found several non-peroxisomal transcript and proteins regulated in pex3 cells including mitochondrial proteins involved in respiration or import processes, which led to the identification of the mitochondrial pyruvate carrier Mpc1/3 as so far unnoticed transporter present in the peroxisomal membrane. Our results reveal the impact of the absence of peroxisomes in pex3 yeast cells and represent a rich resource of genes/proteins for follow-up studies to obtain a deeper understanding of peroxisome biology in a cellular context. </p
The Hansenula polymorpha mitochondrial carrier family protein Mir1 is dually localized at peroxisomes and mitochondria
Full text linkPeroxisomes are ubiquitous cell organelles involved in various metabolic pathways. In order to properly function, several cofactors, substrates and products of peroxisomal enzymes need to pass the organellar membrane. So far only a few transporter proteins have been identified. We analysed peroxisomal membrane fractions purified from the yeast Hansenula polymorpha by untargeted label-free quantitation mass spectrometry. As expected, several known peroxisome-associated proteins were enriched in the peroxisomal membrane fraction. In addition, several other proteins were enriched, including mitochondrial transport proteins. Localization studies revealed that one of them, the mitochondrial phosphate carrier Mir1, has a dual localization on mitochondria and peroxisomes. To better understand the molecular mechanisms of dual sorting, we localized Mir1 in cells lacking Pex3 or Pex19, two peroxins that play a role in targeting of peroxisomal membrane proteins. In these cells Mir1 only localized to mitochondria, indicating that Pex3 and Pex19 are required to sort Mir1 to peroxisomes. Analysis of the localization of truncated versions of Mir1 in wild-type H. polymorpha cells revealed that most of them localized to mitochondria, but only one, consisting of the transmembrane domains 3-6, was peroxisomal. Peroxisomal localization of this construct was lost in a MIR1 deletion strain, indicating that full-length Mir1 was required for the localization of the truncated protein to peroxisomes. Our data suggest that only full-length Mir1 sorts to peroxisomes, while Mir1 contains multiple regions with mitochondrial sorting information. Data are available via ProteomeXchange with identifier PXD050324.</p
Can current moisture responses predict soil CO2 efflux under altered precipitation regimes?: a synthesis of manipulation experiments
Full text linkAs a key component of the carbon cycle, soil CO2 efflux (SCE) is being increasingly studied to improve our mechanistic understanding of this important carbon flux. Predicting ecosystem responses to climate change often depends on extrapolation of current relationships between ecosystem processes and their climatic drivers to conditions not yet experienced by the ecosystem. This raises the question of to what extent these relationships remain unaltered beyond the current climatic window for which observations are available to constrain the relationships. Here, we evaluate whether current responses of SCE to fluctuations in soil temperature and soil water content can be used to predict SCE under altered rainfall patterns. Of the 58 experiments for which we gathered SCE data, 20 were discarded because either too few data were available or inconsistencies precluded their incorporation in the analyses. The 38 remaining experiments were used to test the hypothesis that a model parameterized with data from the control plots (using soil temperature and water content as predictor variables) could adequately predict SCE measured in the manipulated treatment. Only for 7 of these 38 experiments was this hypothesis rejected. Importantly, these were the experiments with the most reliable data sets, i.e., those providing high-frequency measurements of SCE. Regression tree analysis demonstrated that our hypothesis could be rejected only for experiments with measurement intervals of less than 11 days, and was not rejected for any of the 24 experiments with larger measurement intervals. This highlights the importance of high-frequency measurements when studying effects of altered precipitation on SCE, probably because infrequent measurement schemes have insufficient capacity to detect shifts in the climate dependencies of SCE. Hence, the most justified answer to the question of whether current moisture responses of SCE can be extrapolated to predict SCE under altered precipitation regimes is "no" – as based on the most reliable data sets available. We strongly recommend that future experiments focus more strongly on establishing response functions across a broader range of precipitation regimes and soil moisture conditions. Such experiments should make accurate measurements of water availability, should conduct high-frequency SCE measurements, and should consider both instantaneous responses and the potential legacy effects of climate extremes. This is important, because with the novel approach presented here, we demonstrated that, at least for some ecosystems, current moisture responses could not be extrapolated to predict SCE under altered rainfall conditions
Exercício e efeitos da Doxorubicina na função testicular
Full text linkMestrado em Biomedicina MolecularA Doxorubicina (DOX) é um agente antineoplásico de grande eficácia utilizado no tratamento de vários tipos de tumores. No entanto, a sua utilização clínica é limitada devido à sua toxicidade em vários órgãos, com destaque para o coração. Outros órgãos afectados por este fármaco incluem fígado, cérebro, rins e testículos. Algumas estratégias farmacológicas e não farmacológicas têm sido desenvolvidas de forma a contrariar os seus efeitos secundários tóxicos, incluindo suplementação com antioxidantes e, mais recentemente, exercício físico. Assim, o objectivo do presente estudo é avaliar o efeito da actividade física na funcionalidade testicular, bem como no stress oxidativo e apoptose, sugeridos para a acção tóxica da DOX.
Trinta e seis ratos macho Sprag-Dawley foram divididos em 6 grupos: salino sedentário (SAL+SED), sedentáros tratados com doses sub-crónicas de DOX – injecções de 2mg.Kg-1 durante sete semanas (DOX+SED), salinos treinados na passadeira durante 12 semanas (SAL+TM), treinados tratados com DOX (DOX+TM), salinos realizando exercício voluntário em roda livre (SAL+FW) e tratados realizando exercício voluntário em roda livre (DOX+FW). Vinte e quatro horas depois da última sessão de exercício, os animais foram sacrificados, os espermatozóides foram obtidos e tratados para estudos de contagem e de motilidade. Os testículos foram recolhidos para posterior análise de marcadores de stress oxidativo (actividade da aconitase, concentrações de substâncias reactivas de ácido tiobarbiturico, malondialdeido (MDA) e de grupos sulfidril (-SH) e sinalização apoptotica (actividades das caspases 3,8 e 9). O tratamento com DOX induziu uma diminuição significativa na contagem e motilidade dos espermatozóides, independentemente da actividade física. Apesar de existir uma tendência para um aumento de MDA e diminuição de –SH com o tratamento com DOX, não foi detectado qualquer efeito significativo nos marcadores de stress oxidativo e apoptose. Não foi observado qualquer efeito do exercício nestes parâmetros. Concluindo, o exercício físico não influenciou o impacto que a DOX teve na funcionalidade testicular. Surpreendentemente, nem a DOX nem o exercício modularam o ambiente redox e a sinalização apoptótica nos testículos, considerando os marcadores analisados.The anthracycline Doxorubicin (DOX) is a widely used antineoplastic agent against several tumors with high efficacy. However, the clinical use of this drug is limited by its dose-related toxicity in several organs with particular emphasis on the heart. Other organs affected by DOX include liver, brain, kidney and testes. Several pharmacological and non-pharmacological strategies have been designed to antagonize the toxic side effects of DOX, including antioxidant supplementation and, recently, physical exercise. Therefore, the aim of the present study is to analyze the effect of physical exercise in testes function as well as oxidative damage and apoptosis, suggested mechanisms by which DOX exerts its toxic effects.
Thirty-six Sprag Dawley male rats were randomly divided into 6 groups as follows: Saline Sedentary (SAL+SED), Sedentary sub-chronically treated with DOX – 2mg.Kg-1 injections for 7 weeks (DOX+SED), Saline endurance treadmill trained for 12 weeks (SAL+TM), trained receiving DOX (DOX+TM), saline voluntary exercised in a free-wheel (SAL+FW) and voluntary exercised receiving DOX (DOX+FW). Twenty-four hours after the last exercise bout, animals were sacrificed; sperm was obtained and treated for counting and motility studies. Testes were harvested for tissues analysis of markers of oxidative stress and damage (aconitase activity, thiobarbituric acid reactive substances, as MDA, and sulfhydryl –SH groups content) and apoptotic signaling (caspases 3,8 and 9 activities). DOX treatment induced significant decrease in sperm count and motility, irrespective of exercise training status. Despite a tendency for MDA increase and –SH decrease with DOX treatment, no significant effect was detected in either markers of oxidative damage or apoptosis. No exercise effect was observed as well.
In summary, chronic physical exercise did not influence DOX-induced testes dysfunction. Surprisingly, neither DOX nor exercise modulated testes redox environment and apoptotic signaling, at least seen by the measured markers
