Chronic undernutrition impairs renal mitochondrial respiration accompanied by intense ultrastructural damage in juvenile rats.

This study investigated whether chronic undernutrition alters the mitochondrial structure and function in renal proximal tubule cells, thus impairing fluid transport and homeostasis. We previously showed that chronic undernutrition downregulates the renal proximal tubules (Na++K+)ATPase, the main molecular machine responsible for fluid transport and ATP consumption. Male rats received a multifactorial deficient diet, the so-called Regional Basic Diet (RBD), mimicking those used in impoverished regions worldwide, from weaning to a juvenile age (3 months). The diet has a low content (8 %) of poor-quality proteins, low lipids, and no vitamins compared to control (CTR). We investigated citrate synthase activity, mitochondrial respiration (oxygraphy) in phosphorylating and non-phosphorylating conditions with different substrates/inhibitors, potential across the internal membrane (Δψ), and anion superoxide/H2O2 formation. The data were correlated with ultrastructural alterations evaluated using transmission electron microscopy (TEM) and focused ion beam scanning electron microscopy (FIB-SEM). Citrate synthase activity decreased (∼50 %) in RBD rats, accompanied by a similar reduction in respiration in non-phosphorylating conditions, maximum respiratory capacity, and ATP synthesis. The Δψ generation and its dissipation after carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone remained unmodified in the survival mitochondria. H2O2 production increased (∼100 %) after Complex II energization. TEM demonstrated intense matrix vacuolization and disruption of cristae junctions in a subpopulation of RBD mitochondria, which was also demonstrated in the 3D analysis of FIB-SEM tomography. In conclusion, chronic undernutrition impairs mitochondrial functions in renal proximal tubules, with profound alterations in the matrix and internal membrane ultrastructure that culminate with the compromise of ATP supply for transport processes.

CCL2 and Lactate from Chemotherapeutics-Treated Fibroblasts Drive Malignant Traits by Metabolic Rewiring in Low-Migrating Breast Cancer Cell Lines.

While cytostatic chemotherapy targeting DNA is known to induce genotoxicity, leading to cell cycle arrest and cytokine secretion, the impact of these drugs on fibroblast-epithelial cancer cell communication and metabolism remains understudied. Our research focused on human breast fibroblast RMF-621 exposed to nonlethal concentrations of cisplatin and doxorubicin, revealing reduced proliferation, diminished basal and maximal mitochondrial respirations, heightened mitochondrial ROS and lactate production, and elevated MCT4 protein levels. Interestingly, RMF-621 cells enhanced glucose uptake, promoting lactate export. Breast cancer cells MCF-7 exposed to conditioned media (CM) from drug-treated stromal RMF-621 cells increased MCT1 protein levels, lactate-driven mitochondrial respiration, and a significantly high mitochondrial spare capacity for lactate. These changes occurred alongside altered mitochondrial respiration, mitochondrial membrane potential, and superoxide levels. Furthermore, CM with doxorubicin and cisplatin increased migratory capacity in MCF-7 cells, which was inhibited by MCT1 (BAY-8002), glutamate dehydrogenase (EGCG), mitochondrial pyruvate carrier (UK5099), and complex I (rotenone) inhibitors. A similar behavior was observed in T47-D and ZR-75-1 breast cancer cells. This suggests that CM induces metabolic rewiring involving elevated lactate uptake to sustain mitochondrial bioenergetics during migration. Treatment with the mitochondrial-targeting antioxidant mitoTEMPO in RMF-621 and the addition of an anti-CCL2 antibody in the CM prevented the promigratory MCF-7 phenotype. Similar effects were observed in THP1 monocyte cells, where CM increased monocyte recruitment. We propose that nonlethal concentrations of DNA-damaging drugs induce changes in the cellular environment favoring a promalignant state dependent on mitochondrial bioenergetics.

A practical and robust method to evaluate metabolic fluxes in primary pancreatic islets.

OBJECTIVE: Evaluation of mitochondrial oxygen consumption and ATP production is important to investigate pancreatic islet pathophysiology. Most studies use cell lines due to difficulties in measuring primary islet respiration, which requires specific equipment and consumables, is expensive and poorly reproducible. Our aim was to establish a practical method to assess primary islet metabolic fluxes using standard commercial consumables. METHODS: Pancreatic islets were isolated from mice/rats, dispersed with trypsin, and adhered to pre-coated standard Seahorse or Resipher microplates. Oxygen consumption was evaluated using a Seahorse Extracellular Flux Analyzer or a Resipher Real-time Cell Analyzer. RESULTS: We provide a detailed protocol with all steps to optimize islet isolation with high yield and functionality. Our method requires a few islets per replicate; both rat and mouse islets present robust basal respiration and proper response to mitochondrial modulators and glucose. The technique was validated by other functional assays, which show these cells present conserved calcium influx and insulin secretion in response to glucose. We also show that our dispersed islets maintain robust basal respiration levels, in addition to maintaining up to 89% viability after five days in dispersed cultures. Furthermore, OCRs can be measured in Seahorse analyzers and in other plate respirometry systems, using standard materials. CONCLUSIONS: Overall, we established a practical and robust method to assess islet metabolic fluxes and oxidative phosphorylation, a valuable tool to uncover basic ß-cell metabolic mechanisms as well as for translational investigations, such as pharmacological candidate discovery and islet transplantation protocols.

Parkin is a critical player in the effects of caffeine over mitochondrial quality control pathways during skeletal muscle regeneration in mice.

AIM: This study aimed to investigate the effects of caffeine on pathways associated with mitochondrial quality control and mitochondrial capacity during skeletal muscle regeneration, focusing on the role of Parkin, a key protein involved in mitophagy. METHODS: We used in vitro C2C12 myoblast during differentiation with and without caffeine in the medium, and we evaluated several markers of mitochondrial quality control pathways and myotube growth. In vivo experiments, we used C57BL/6J (WT) and Parkintm 1Shn lineage (Parkin-/- ) mice and injured tibial anterior muscle. The mice regenerated TA muscle for 3, 10, and 21 days with or without caffeine ingestion. TA muscle was used to analyze the protein content of several markers of mitochondrial quality pathways, muscle satellite cell differentiation, and protein synthesis. Furthermore, it analyzed mtDNA, mitochondrial respiration, and myofiber growth. RESULTS: C2C12 differentiation experiments showed that caffeine decreased Parkin content, potentially leading to increased DRP1 and PGC-1α content and altered mitochondrial population, thereby enhancing growth capacity. Using Parkin-/- mice, we found that caffeine intake during the regenerative process induces an increase in AMPKα phosphorylation and PGC-1α and TFAM content, changes that were partly Parkin-dependent. In addition, the absence of Parkin potentiates the ergogenic effect of caffeine by increasing mitochondrial capacity and myotube growth. Those effects are related to increased ATF4 content and activation of protein synthesis pathways, such as increased 4E-BP1 phosphorylation. CONCLUSION: These findings demonstrate that caffeine ingestion changes mitochondrial quality control during skeletal muscle regeneration, and Parkin is a central player in those mechanisms.

Embryo development is impaired by sperm mitochondrial-derived ROS.

BACKGROUND: Basal energetic metabolism in sperm, particularly oxidative phosphorylation, is known to condition not only their oocyte fertilising ability, but also the subsequent embryo development. While the molecular pathways underlying these events still need to be elucidated, reactive oxygen species (ROS) could have a relevant role. We, therefore, aimed to describe the mechanisms through which mitochondrial activity can influence the first stages of embryo development. RESULTS: We first show that embryo development is tightly influenced by both intracellular ROS and mitochondrial activity. In addition, we depict that the inhibition of mitochondrial activity dramatically decreases intracellular ROS levels. Finally, we also demonstrate that the inhibition of mitochondrial respiration positively influences sperm DNA integrity, most likely because of the depletion of intracellular ROS formation. CONCLUSION: Collectively, the data presented in this work reveals that impairment of early embryo development may result from the accumulation of sperm DNA damage caused by mitochondrial-derived ROS.

Embryo development is impaired by sperm mitochondrial-derived ROS

BACKGROUND: Basal energetic metabolism in sperm, particularly oxidative phosphorylation, is known to condition not only their oocyte fertilising ability, but also the subsequent embryo development. While the molecular pathways underlying these events still need to be elucidated, reactive oxygen species (ROS) could have a relevant role. We, therefore, aimed to describe the mechanisms through which mitochondrial activity can influence the first stages of embryo development. RESULTS: We first show that embryo development is tightly influenced by both intracellular ROS and mitochondrial activity. In addition, we depict that the inhibition of mitochondrial activity dramatically decreases intracellular ROS levels. Finally, we also demonstrate that the inhibition of mitochondrial respiration positively influences sperm DNA integrity, most likely because of the depletion of intracellular ROS formation. CONCLUSION: Collectively, the data presented in this work reveals that impairment of early embryo development may result from the accumulation of sperm DNA damage caused by mitochondrial-derived ROS.

Disruption of Bioenergetics in the Intestine of Wistar Rats Caused by Hydrogen Sulfide and Thiosulfate: A Potential Mechanism of Chronic Hemorrhagic Diarrhea in Ethylmalonic Encephalopathy.

Ethylmalonic encephalopathy (EE) is a severe inherited metabolic disorder that causes tissue accumulation of hydrogen sulfide (sulfide) and thiosulfate in patients. Although symptoms are predominantly neurological, chronic hemorrhagic diarrhea associated with intestinal mucosa abnormalities is also commonly observed. Considering that the pathophysiology of intestinal alterations in EE is virtually unknown and that sulfide and thiosulfate are highly reactive molecules, the effects of these metabolites were investigated on bioenergetic production and transfer in the intestine of rats. We observed that sulfide reduced NADH- and FADH2-linked mitochondrial respiration in the intestine, which was avoided by reduced glutathione (GSH) but not by melatonin. Thiosulfate did not change respiration. Moreover, both metabolites markedly reduced the activity of total, cytosolic and mitochondrial isoforms of creatine kinase (CK) in rat intestine. Noteworthy, the addition of GSH but not melatonin, apocynin, and Trolox (hydrosoluble vitamin E) prevented the change in the activities of total CK and its isoforms caused by sulfide and thiosulfate, suggesting a direct protein modification on CK structure by these metabolites. Sulfide further increased thiol content in the intestine, suggesting a modulation in the redox state of these groups. Finally, sulfide and thiosulfate decreased the viability of Caco-2 intestinal cells. Our data suggest that bioenergetic impairment caused by sulfide and thiosulfate is a mechanism involved in the gastrointestinal abnormalities found in EE.

Cytotoxicity of quercetin is related to mitochondrial respiration impairment in Saccharomyces cerevisiae.

Quercetin is a flavonol ubiquitously present in fruits and vegetables that shows a potential therapeutic use in non-transmissible chronic diseases, such as cancer and diabetes. Although this phytochemical has shown promising health benefits, the molecular mechanism behind this compound is still unclear. Interestingly, quercetin displays toxic properties against phylogenetically distant organisms such as bacteria and eukaryotic cells, suggesting that its molecular target resides on a highly conserved pathway. The cytotoxicity of quercetin could be explained by energy depletion occasioned by mitochondrial respiration impairment and its concomitant pleiotropic effect. Thereby, the molecular basis of quercetin cytotoxicity could shed light on potential molecular mechanisms associated with its health benefits. Nonetheless, the evidence supporting this hypothesis is still lacking. Thus, this study aimed to evaluate whether quercetin supplementation affects mitochondrial respiration and whether this is related to quercetin cytotoxicity. Saccharomyces cerevisiae was used as a study model to assess the effect of quercetin on energetic metabolism. Herein, we provide evidence that quercetin supplementation: (1) decreased the exponential growth of S. cerevisiae in a glucose-dependent manner; (2) affected diauxic growth in a similar way to antimycin A (complex III inhibitor of electron transport chain); (3) suppressed the growth of S. cerevisiae cultures supplemented with non-fermentable carbon sources (glycerol and lactate); (4) promoted a glucose-dependent inhibition of the basal, maximal, and ATP-linked respiration; (5) diminished complex II and IV activities. Altogether, these data indicate that quercetin disturbs mitochondrial respiration between the ubiquinone pool and cytochrome c, and this phenotype is associated with its cytotoxic properties.

Antibiotic therapy does not alter mitochondrial bioenergetics in lymphocytes of patients with septic shock - A prospective cohort study.

Antibiotics may trigger alterations in mitochondrial function, which has been explored in cells culture, and in animal model of sepsis. This study sought to evaluate whether antibiotic therapy affects mitochondrial bioenergetics in a 68-patients clinical study. We studied mitochondrial respiratory rates at two time points: the first day of antibiotic administration and three days after. The Δbasal, ΔCI, ΔCII respiration, and ΔBCE respiratory rates were not different between patients administered with polymyxin, vancomycin, amoxicillin-clavulanate, and azithromycin compared to those who were not administered. Specific beta-lactams are associated with specific modifications in mitochondrial respiratory endpoints - patients who used meropenem had higher delta C2 values compared to those who did not (p = 0.03). Patients who used piperacillin-tazobactam had lower delta C1 (p = 0.03) values than those who did not, but higher delta C2 values (p = 0.02). These mitochondrial metabolic signatures in isolated lymphocytes challenges the proposed effects of antibiotics in mitochondrial bioenergetics of cell cultures, but at current status have an uncertain clinical significance.

Snf1p/Hxk2p/Mig1p pathway regulates hexose transporters transcript levels, affecting the exponential growth and mitochondrial respiration of Saccharomyces cerevisiae.

The Crabtree effect molecular regulation comprehension could help to improve ethanol production with biotechnological purposes and a better understanding of cancer etiology due to its similarity with the Warburg effect. Snf1p/Hxk2p/Mig1p pathway has been linked with the transcriptional regulation of the hexose transporters and phenotypes associated with the Crabtree effect. Nevertheless, direct evidence linking the genetic control of the hexose transporters with modulation of the Crabtree effect phenotypes by the Snf1p/Hxk2p/Mig1p pathway is still lacking. In this sense, we provide evidence that SNF1 and HXK2 genes deletion affects exponential growth, mitochondrial respiration, and transcript levels of hexose transporters in a glucose-dependent manner. The Vmax of the hexose transporters with the high transcript levels was correlated positively with the exponential growth and negatively with the mitochondrial respiration. HXT2 gene transcript levels were the most affected by the deletion of the SNF1/HXK2/MIG1 pathway. Deleting the orthologous genes SNF1 and HXK2 in Kluyveromyces marxianus (Crabtree negative yeast) has an opposite effect compared to Saccharomyces cerevisiae in growth and mitochondrial respiration. Overall, these results indicate that the SNF1/HXK2/MIG1 pathway regulates transcript levels of the hexose transporters, which shows an association with the exponential growth and mitochondrial respiration in a glucose-dependent manner.

Allergens of the urushiol family promote mitochondrial dysfunction by inhibiting the electron transport at the level of cytochromes b and chemically modify cytochrome c1.

BACKGROUND: Urushiols are pro-electrophilic haptens that cause severe contact dermatitis mediated by CD8+ effector T-cells and downregulated by CD4+ T-cells. However, the molecular mechanism by which urushiols stimulate innate immunity in the initial stages of this allergic reaction is poorly understood. Here we explore the sub-cellular mechanisms by which urushiols initiate the allergic response. RESULTS: Electron microscopy observations of mouse ears exposed to litreol (3-n-pentadecyl-10-enyl-catechol]) showed keratinocytes containing swollen mitochondria with round electron-dense inclusion bodies in the matrix. Biochemical analyses of sub-mitochondrial fractions revealed an inhibitory effect of urushiols on electron flow through the mitochondrial respiratory chain, which requires both the aliphatic and catecholic moieties of these allergens. Moreover, urushiols extracted from poison ivy/oak (mixtures of 3-n-pentadecyl-8,11,13 enyl/3-n-heptadecyl-8,11 enyl catechol) exerted a higher inhibitory effect on mitochondrial respiration than did pentadecyl catechol or litreol, indicating that the higher number of unsaturations in the aliphatic chain, stronger the allergenicity of urushiols. Furthermore, the analysis of radioactive proteins isolated from mitochondria incubated with 3H-litreol, indicated that this urushiol was bound to cytochrome c1. According to the proximity of cytochromes c1 and b, functional evidence indicated the site of electron flow inhibition was within complex III, in between cytochromes bL (cyt b566) and bH (cyt b562). CONCLUSION: Our data provide functional and molecular evidence indicating that the interruption of the mitochondrial electron transport chain constitutes an important mechanism by which urushiols initiates the allergic response. Thus, mitochondria may constitute a source of cellular targets for generating neoantigens involved in the T-cell mediated allergy induced by urushiols.

Brazilian sunberry (Solanum oocarpum Sendtn): Alkaloid composition and improvement of mitochondrial functionality and insulin secretion of INS-1E cells.

Chronic high-glucose levels induce the generation of reactive oxygen species leading to mitochondrial dysfunction, which is one of the pathological triggers in the development of diabetes. This study investigated the alkaloid composition of two fruits of the genus Solanum, fruta-do-lobo (Solanum lycocarpum) and juá-açu (Solanum oocarpum), and their capacity to protect against oxidative damage and defective insulin secretion induced by chronic high-glucose levels. LC-MS and molecular network of fruit crude extracts reveals that juá-açu and fruta-do-lobo contain kukoamines and glycoalkaloids, respectively. Two purification processes were used to enrich those alkaloids. Fruta-do-lobo extract rich in glycoalkaloids showed a strong cytotoxicity effect, however the juá-açu enriched extract was able to protect mitochondrial functionality against glucotoxicity and stimulate insulin secretion even under conditions of hyperglycemia. These results are promising and suggest that juá-açu is a potential source of bioactive compounds for adjuvant/co-adjuvant therapy for diabetes.

Hypoxia tolerance in two amazon cichlids: mitochondrial respiration and cellular metabolism adjustments are result of species environmental preferences and distribution.

The amazon fishes' responses to hypoxia seem to be related to the Amazon basin diversity of aquatic environments, which present drastic daily and seasonal variations in the dissolved oxygen concentration. Among these fishes' adaptation to hypoxia, behavioral, metabolic, physiological, and biochemical responses are well known for some species. In this work, we aimed to identify how two different aquatic environments, normoxic forest streams and hypoxic lakes, dictate the responses to hypoxia for two cichlid species, Mesonauta festivus and Aequidens pallidus. In our results, we found that A. pallidus is less tolerant to hypoxia, which seems to be related to this animal's natural normoxic environment. Even though this species modulated the mitochondrial respiration in order to improve the oxygen use, it also showed a lower decrease in metabolic rate when exposed to hypoxia and no activation of the anaerobic metabolism. Instead, M. festivus showed a higher decrease in metabolic rate and an activation of the anaerobic metabolism. Our data reveal that the natural dissolved oxygen influences the hypoxia tolerance and the species' tolerance is related to its ability to perform metabolic depression. The interest results are the absence of mitochondrial respiration influences in these processes. The results observed with A. pallidus bring to light also the importance of preserving the forests, in which streams hold very specialized species acclimated to normoxia and lower temperature. The importance of hypoxia tolerance is, thus, important to keep fish assemblage and is thought to be a strong driver of fish biodiversity.

Allergens of the urushiol family promote mitochondrial dysfunction by inhibiting the electron transport at the level of cytochromes b and chemically modify cytochrome c1

BACKGROUND: Urushiols are pro-electrophilic haptens that cause severe contact dermatitis mediated by CD8+ effector T-cells and downregulated by CD4+ T-cells. However, the molecular mechanism by which urushiols stimulate innate immunity in the initial stages of this allergic reaction is poorly understood. Here we explore the sub-cellular mechanisms by which urushiols initiate the allergic response. RESULTS: Electron microscopy observations of mouse ears exposed to litreol (3-n-pentadecyl-10-enyl-catechol]) showed keratinocytes containing swollen mitochondria with round electron-dense inclusion bodies in the matrix. Biochemical analyses of sub-mitochondrial fractions revealed an inhibitory effect of urushiols on electron flow through the mitochondrial respiratory chain, which requires both the aliphatic and catecholic moieties of these allergens. Moreover, urushiols extracted from poison ivy/oak (mixtures of 3-n-pentadecyl-8,11,13 enyl/3-n-heptadecyl-8,11 enyl catechol) exerted a higher inhibitory effect on mitochondrial respiration than did pentadecyl catechol or litreol, indicating that the higher number of unsaturations in the aliphatic chain, stronger the allergenicity of urushiols. Furthermore, the analysis of radioactive proteins isolated from mitochondria incubated with 3H-litreol, indicated that this urushiol was bound to cytochrome c1. According to the proximity of cytochromes c1 and b, functional evidence indicated the site of electron flow inhibition was within complex III, in between cytochromes bL (cyt b566) and bH (cyt b562). CONCLUSION: Our data provide functional and molecular evidence indicating that the interruption of the mitochondrial electron transport chain constitutes an important mechanism by which urushiols initiates the allergic response. Thus, mitochondria may constitute a source of cellular targets for generating neoantigens involved in the T-cell mediated allergy induced by urushiols.

Combined treatment of menadione and calcitriol increases the antiproliferative effect by promoting oxidative/nitrosative stress, mitochondrial dysfunction, and autophagy in breast cancer MCF-7 cells.

The aim of this study was to determine new insights into the molecular mechanisms involved in the antiproliferative action of menadione + calcitriol (MEN+D) on MCF-7 cells. After 24 h, MEN+D inhibited the cell growth but was not observed with each single treatment. The combined drugs reduced the mitochondrial respiration at that time, as judged by an increase in the proton leak and a decrease in the ATP generation and coupling efficiency. At longer times, 48 or 96 h, either D or MEN reduced the proliferation, but the effect was higher when both drugs were used together. The combined treatment increased the superoxide anion ([Formula: see text]) and nitric oxide (NO•) contents as well as acidic vesicular organelles (AVOs) formation. The percentage of cells showing the lower mitochondrial membrane potential (ΔΨm) was highly increased by the combined therapy. LC3-II protein expression was enhanced by any treatment. In conclusion, the antiproliferative action of MEN+D involves oxidative/nitrosative stress, mitochondrial alteration, and autophagy. This combined therapy could be useful to treat breast cancer cells because it inhibits multiple oncogenic pathways more effectively than each single agent.

Biochemical Properties and Effects on Mitochondrial Respiration of Aqueous Extracts of Basidiomycete Mushrooms.

There are different varieties of mushrooms not yet studied spread all over the planet. The objective of this study was to evaluate biochemical properties and effects on mitochondrial respiration of eight Basidiomycete mushrooms: Flaviporus venustus EF30, Hydnopolyporus fimbriatus EF41 and EF44, Inonotus splitgerberi EF46, Oudemansiella canarii EF72, Perenniporia sp. EF79, Phellinus linteus EF81, and Pleurotus albidus EF84. Total phenols, ABTS, TEAC, FRAP, and ORAC were measured in order to determine the antioxidant capacity. Antimicrobial potential was studied by disc-diffusion and microdilution method. Cytotoxicity was determined in murine peritoneal macrophages. The bioenergetic aspects were evaluated by the uncoupling of the oxidative phosphorylation in mitochondrias. The H. fimbriatus mushroom was the one that presented the most significant results for the antioxidant assays. Three mushrooms presented antimicrobial activity, indicating a potential for formulation of drugs. The results suggest that I. spligerberi has an uncoupling activity, even at the lowest concentration tested, dissipating the mitochondrial electrochemical gradient. On the other hand, P. albidus has effect only on succinate-oxidase activity without influencing mitochondrial respiratory efficiency. Therefore, both interfere negatively in mitochondrial respiration. In relation with the cytotoxicity in peritoneal macrophages, O. canarii and F. venustus were cytotoxic in this type of cells.

Differential Effects of Exogenous Resveratrol on the Growth and Energy Metabolism of Zea mays and the Weed Ipomoea grandifolia.

An increase in crop competitiveness relative to weed interference has the potential to reduce crop yield losses. In this study, the effects of phytoalexin resveratrol were examined in Zea mays L. (corn) and in the weed species Ipomoea grandifolia (Dammer) O'Donell (morning glory). At a concentration range from 220 to 2200 µM resveratrol exerted a stimulus on Z. mays seedling growth that was more pronounced at low concentrations; in the weed species I. grandifolia, resveratrol exerted inhibitory action on seedling growth in all of the assayed concentration range. In I. grandifolia, resveratrol also inhibited the respiratory activity of the primary roots. In mitochondria isolated from Z. mays roots, resveratrol at concentrations above 440 µM inhibited the respiration coupled to ADP phosphorylation and the activities of NADH-oxidase, succinate-oxidase, and ATPsynthase. These effects were not reproduced in Z. mays grown in the presence of resveratrol as the respiratory activities of the roots were not affected. The finding that the resveratrol exerts beneficial effects on growth of Z. mays seedlings and inhibits the growth of I. grandifolia heightens the potential of resveratrol application for crop protection.

Resveratrol cytotoxicity is energy-dependent.

Resveratrol is a phytochemical that may promote health. However, it has also been reported to be a toxic compound. The molecular mechanism by which resveratrol acts remains unclear. The inhibition of the oxidative phosphorylation (OXPHOS) pathway appears to be the molecular mechanism of resveratrol. Taking this into account, we propose that the cytotoxic properties of resveratrol depend on the energy (e.g., carbohydrates, lipids, and proteins) availability in the cells. In this regard, in a condition with low energy accessibility, resveratrol could enhance ATP starvation to lethal levels. In contrast, when cells are supplemented with high quantities of energy and resveratrol, the inhibition of OXPHOS might produce a low-energy environment, mimicking the beneficial effects of caloric restriction. This review suggests that investigating a possible complex relationship between caloric intake and the differential effects of resveratrol on OXPHOS may be justified. PRACTICAL APPLICATIONS: A low-calorie diet accompanied by significant levels of resveratrol might modify cellular bioenergetics, which could impact cellular viability and enhance the anti-cancer properties of resveratrol.

A simple method for mitochondrial respiration and calcium uptake assessment in pollen tubes.

Key mitochondrial processes are known to be widely conserved throughout the eukaryotic domain. However, the scarce availability of working materials may restrict the assessment of such mitochondrial activities in several working models. Pollen tube mitochondrial studies represent one example of this, where tests have been often restricted due the physical impossibility of performing experiments with isolated mitochondria in enough quantities. Here we detail a method to measure in situ mitochondrial respiratory chain activity and calcium transport in tobacco pollen tubes. •Digitonin-mediated plasmalemma permeabilization allows efficient assessment of mitochondrial respiration and calcium uptake.•This method allows quick, reliable and portable measurements from low to high cellular densities, versus methods requiring intracellular calcium reporters.

SNF1 controls the glycolytic flux and mitochondrial respiration.

The switch between mitochondrial respiration and fermentation as the main ATP production pathway through an increase glycolytic flux is known as the Crabtree effect. The elucidation of the molecular mechanism of the Crabtree effect may have important applications in ethanol production and lay the groundwork for the Warburg effect, which is essential in the molecular etiology of cancer. A key piece in this mechanism could be Snf1p, which is a protein that participates in the nutritional response including glucose metabolism. Thus, this work aimed to recognize the role of the SNF1 gene on the glycolytic flux and mitochondrial respiration through the glucose concentration variation to gain insights about its relationship with the Crabtree effect. Herein, we found that SNF1 deletion in Saccharomyces cerevisiae cells grown at 1% glucose, decreased glycolytic flux, increased NAD(P)H concentration, enhanced HXK2 gene transcription, and decreased mitochondrial respiration. Meanwhile, the same deletion increased the mitochondrial respiration of cells grown at 10% glucose. Altogether, these findings indicate that SNF1 is important to respond to glucose concentration variation and is involved in the switch between mitochondrial respiration and fermentation.