RESUMO
Low-grade gliomas are primary brain tumors that arise from glial cells and are usually treated with temozolomide (TMZ) as a chemotherapeutic option. They are often incurable, but patients have a prolonged survival. One of the shortcomings of the treatment is that patients eventually develop drug resistance. Recent findings show that persisters, cells that enter a dormancy state to resist treatment, play an important role in the development of resistance to TMZ. In this study we constructed a mathematical model of low-grade glioma response to TMZ incorporating a persister population. The model was able to describe the volumetric longitudinal dynamics, observed in routine FLAIR 3D sequences, of low-grade glioma patients acquiring TMZ resistance. We used the model to explore different TMZ administration protocols, first on virtual clones of real patients and afterwards on virtual patients preserving the relationships between parameters of real patients. In silico clinical trials showed that resistance development was deferred by protocols in which individual doses are administered after rest periods, rather than the 28-days cycle standard protocol. This led to median survival gains in virtual patients of more than 15 months when using resting periods between two and three weeks and agreed with recent experimental observations in animal models. Additionally, we tested adaptive variations of these new protocols, what showed a potential reduction in toxicity, but no survival gain. Our computational results highlight the need of further clinical trials that could obtain better results from treatment with TMZ in low grade gliomas.
Assuntos
Neoplasias Encefálicas , Glioma , Humanos , Antineoplásicos Alquilantes/farmacologia , Antineoplásicos Alquilantes/uso terapêutico , Dacarbazina/efeitos adversos , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/patologia , Glioma/tratamento farmacológico , Glioma/patologia , Temozolomida/farmacologia , Temozolomida/uso terapêuticoRESUMO
Cardiometabolic status is a key factor in mortality by cardiovascular disease (CVD) in systemic lupus erythematosus (SLE). This study evaluated the association of cardiometabolic risk status with clinical activity and damage in SLE patients. A cross-sectional study was conducted in 158 SLE patients and 123 healthy subjects (HS). Anthropometry, glucose, hs-CRP, lipid profile, oxLDL, sCD36, anti-oxLDL antibodies, and cardiometabolic indexes were evaluated. SLE patients had dyslipidemia, higher sCD36, anti-oxLDL antibodies, hs-CRP, and risk (ORâ¯>â¯2) to present Castelli scoreâ¯≥â¯4.5, HDL-Câ¯<â¯40â¯mg/dL and LDL-Câ¯≥â¯100â¯mg/dL. Disease evolution time was correlated with glucose and BMI, damage with TG, and clinical activity with TG, TG/HDL-C ratio, and Kannel index. Active SLE patients had risk (ORâ¯>â¯2) to present a Castelli scoreâ¯≥â¯4.5, Kannel scoreâ¯≥â¯3, TG/HDL-C ratioâ¯≥â¯3 and HDL-Câ¯<â¯40â¯mg/dL. In conclusion, SLE patients have high cardiometabolic risk to CVD related to disease evolution time, and clinical activity.
Assuntos
Doenças Cardiovasculares/epidemiologia , Dislipidemias/epidemiologia , Lúpus Eritematoso Sistêmico/patologia , Adulto , Glicemia/análise , Índice de Massa Corporal , Proteína C-Reativa/análise , Antígenos CD36/sangue , Colesterol/sangue , Estudos Transversais , Dislipidemias/patologia , Feminino , Glucose/metabolismo , Humanos , Lipoproteínas LDL/sangue , Pessoa de Meia-Idade , Obesidade/epidemiologia , Fatores de RiscoRESUMO
Here we put forward a mathematical model describing the response of low-grade (WHO grade II) oligodendrogliomas (LGO) to temozolomide (TMZ). The model describes the longitudinal volumetric dynamics of tumor response to TMZ of a cohort of 11 LGO patients treated with TMZ. After finding patient-specific parameters, different therapeutic strategies were tried computationally on the 'in-silico twins' of those patients. Chemotherapy schedules with larger-than-standard rest periods between consecutive cycles had either the same or better long-term efficacy than the standard 28-day cycles. The results were confirmed in a large trial of 2000 virtual patients. These long-cycle schemes would also have reduced toxicity and defer the appearance of resistances. On the basis of those results, a combination scheme consisting of five induction TMZ cycles given monthly plus 12 maintenance cycles given every three months was found to provide substantial survival benefits for the in-silico twins of the 11 LGO patients (median 5.69 years, range: 0.67 to 68.45 years) and in a large virtual trial including 2000 patients. We used 220 sets of experiments in-silico to show that a clinical trial incorporating 100 patients per arm (standard intensive treatment versus 5 + 12 scheme) could demonstrate the superiority of the novel scheme after a follow-up period of 10 years. Thus, the proposed treatment plan could be the basis for a standardized TMZ treatment for LGO patients with survival benefits.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Encefálicas/tratamento farmacológico , Oligodendroglioma/tratamento farmacológico , Adulto , Idoso , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The presence of arsenic in soil and water is a constant threat to plant growth in many regions of the world. Phytohormones act in the integration of growth control and stress response, but their role in plant responses to arsenic remains to be elucidated. Here, we show that arsenate [As(V)], the most prevalent arsenic chemical species in nature, causes severe depletion of endogenous cytokinins (CKs) in the model plant Arabidopsis (Arabidopsis thaliana). We found that CK signaling mutants and transgenic plants with reduced endogenous CK levels showed an As(V)-tolerant phenotype. Our data indicate that in CK-depleted plants exposed to As(V), transcript levels of As(V)/phosphate-transporters were similar or even higher than in wild-type plants. In contrast, CK depletion provoked the coordinated activation of As(V) tolerance mechanisms, leading to the accumulation of thiol compounds such as phytochelatins and glutathione, which are essential for arsenic sequestration. Transgenic CK-deficient Arabidopsis and tobacco lines show a marked increase in arsenic accumulation. Our findings indicate that CK is an important regulatory factor in plant adaptation to arsenic stress.
Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Arsênio/metabolismo , Arsênio/toxicidade , Citocininas/farmacologia , Compostos de Sulfidrila/metabolismo , Butionina Sulfoximina/farmacologia , Regulação para Baixo/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Glutationa/metabolismo , Inativação Metabólica/efeitos dos fármacos , Fenótipo , Fitoquelatinas/metabolismo , Regulação para Cima/efeitos dos fármacosRESUMO
Reactive oxygen species (ROS) are metabolic by-products in aerobic organisms including plants. Endogenously produced ROS act as cellular messengers and redox regulators involved in several plant biological processes, but excessive accumulation of ROS cause oxidative stress and cell damage. Understanding ROS signalling and stress responses requires precise imaging and quantification of local, subcellular and global ROS dynamics with high selectivity, sensitivity, and spatiotemporal resolution. Several fluorescent vital dyes have been tested so far, which helped to provide relevant spatially resolved information of oxidative stress dynamics in plants subjected to harmful environmental conditions. However, certain plant characteristics, such as high background fluorescence of plant tissues in vivo and antioxidant mechanisms, can interfere with ROS detection. The development of improved small-molecule fluorescent dyes and protein-based ROS sensors targeted to subcellular compartments will enable in vivo monitoring of ROS and redox changes in photosynthetic organisms.
Assuntos
Antioxidantes/metabolismo , Estresse Oxidativo , Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Antioxidantes/química , Corantes Fluorescentes/química , Oxirredução , Plantas/química , Espécies Reativas de Oxigênio/químicaRESUMO
BACKGROUND: Preterm neonates exhibit several deficiencies that endanger their lives. Understanding those disturbances will provide tools for the management of preterm neonates. The present work focuses on arginine and citrulline which has been flagged among the biochemical landmarks of prematurity. METHODS: We examined blood samples of preterm newborns as compared with mature neonates to determine the levels of arginine and citrulline by capillary zone electrophoresis with laser induced fluorescence detection (CZE-LIFD). RESULTS: Significantly lower levels of arginine and citrulline were found in preterm neonates than in mature neonates (P<.01). Interestingly there was a highly significant correlation between the two amino acids in mature neonates (P<.0001). Such correlation was present in preterm neonates too (P<.01). Pearson coefficient showed that 60% of the citrulline concentration depends on arginine concentration in mature neonates. Only 20% of the citrulline concentration depends on arginine concentration in preterm neonates. Although the ratio arginine/citrulline was lower in preterm neonates than in mature neonates the difference was not statistically significant. CONCLUSIONS: These results suggest that less arginine is converted to citrulline to form nitric oxide in preterm than in full-term neonates. The result is discussed in terms of the immature enzymatic systems in the preterm neonate.
Assuntos
Arginina/sangue , Citrulina/sangue , Doenças do Prematuro/sangue , Doenças do Prematuro/epidemiologia , Recém-Nascido Prematuro/sangue , Estudos de Coortes , Eletroforese Capilar , Feminino , Humanos , Recém-Nascido , Doenças do Recém-Nascido/sangue , Doenças do Recém-Nascido/epidemiologia , Masculino , Óxido Nítrico , Espectrometria de FluorescênciaRESUMO
Stress constantly challenges plant adaptation to the environment. Of all stress types, arsenic was a major threat during the early evolution of plants. The most prevalent chemical form of arsenic is arsenate, whose similarity to phosphate renders it easily incorporated into cells via the phosphate transporters. Here, we found that arsenate stress provokes a notable transposon burst in plants, in coordination with arsenate/phosphate transporter repression, which immediately restricts arsenate uptake. This repression was accompanied by delocalization of the phosphate transporter from the plasma membrane. When arsenate was removed, the system rapidly restored transcriptional expression and membrane localization of the transporter. We identify WRKY6 as an arsenate-responsive transcription factor that mediates arsenate/phosphate transporter gene expression and restricts arsenate-induced transposon activation. Plants therefore have a dual WRKY-dependent signaling mechanism that modulates arsenate uptake and transposon expression, providing a coordinated strategy for arsenate tolerance and transposon gene silencing.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arseniatos/metabolismo , Elementos de DNA Transponíveis/genética , Fatores de Transcrição/metabolismo , Arabidopsis/efeitos dos fármacos , Arseniatos/toxicidade , Sequência de Bases , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Regulação para Baixo/efeitos dos fármacos , Histonas/metabolismo , Lisina/metabolismo , Dados de Sequência Molecular , Fenótipo , Proteínas de Transporte de Fosfato/metabolismo , Fosfatos/metabolismo , Regiões Promotoras Genéticas/genética , Ligação Proteica/efeitos dos fármacos , Proteínas Repressoras/metabolismoRESUMO
The accumulation of toxic metals and metalloids, such as cadmium (Cd), mercury (Hg), or arsenic (As), as a consequence of various anthropogenic activities, poses a serious threat to the environment and human health. The ability of plants to take up mineral nutrients from the soil can be exploited to develop phytoremediation technologies able to alleviate the negative impact of toxic elements in terrestrial ecosystems. However, we must select plant species or populations capable of tolerating exposure to hazardous elements. The tolerance of plant cells to toxic elements is highly dependent on glutathione (GSH) metabolism. GSH is a biothiol tripeptide that plays a fundamental dual role: first, as an antioxidant to mitigate the redox imbalance caused by toxic metal(loid) accumulation, and second as a precursor of phytochelatins (PCs), ligand peptides that limit the free ion cellular concentration of those pollutants. The sulphur assimilation pathway, synthesis of GSH, and production of PCs are tightly regulated in order to alleviate the phytotoxicity of different hazardous elements, which might induce specific stress signatures. This review provides an update on mechanisms of tolerance that depend on biothiols in plant cells exposed to toxic elements, with a particular emphasis on the Hg-triggered responses, and considering the contribution of hormones to their regulation.
Assuntos
Glutationa/metabolismo , Metaloides/toxicidade , Metais/toxicidade , Reguladores de Crescimento de Plantas/metabolismo , Fenômenos Fisiológicos Vegetais/efeitos dos fármacos , Compostos de Sulfidrila/metabolismo , Homeostase , Mercúrio/toxicidade , OxirreduçãoRESUMO
Understanding the cellular mechanisms of plant tolerance to mercury (Hg) is important for developing phytoremediation strategies of Hg-contaminated soils. The early responses of alfalfa (Medicago sativa) seedlings to Hg were studied using transcriptomics analysis. A Medicago truncatula microarray was hybridized with high-quality root RNA from M. sativa treated with 3 µM Hg for 3, 6 and 24 h. The transcriptional pattern data were complementary to the measurements of root growth inhibition, lipid peroxidation, hydrogen peroxide (H2 O2 ) accumulation and NADPH-oxidase activity as stress indexes. Of 559 differentially expressed genes (DEGs), 91% were up-regulated. The majority of DEGs were shared between the 3 and 6 h (60%) time points, including the 'stress', 'secondary metabolism' and 'hormone metabolism' functional categories. Genes from ethylene metabolism and signalling were highly represented, suggesting that this phytohormone may be relevant for metal perception and homeostasis. Ethylene-insensitive alfalfa seedlings preincubated with the ethylene signalling inhibitor 1-methylcyclopronene and Arabidopsis thaliana ein2-5 mutants confirmed that ethylene participates in the early perception of Hg stress. It modulates root growth inhibition, NADPH-oxidase activity and Hg-induced apoplastic H2 O2 accumulation. Therefore, ethylene signalling attenuation could be useful in future phytotechnological applications to ameliorate stress symptoms in Hg-polluted plants.
Assuntos
Adaptação Fisiológica/genética , Etilenos/metabolismo , Expressão Gênica , Genes de Plantas , Medicago/genética , Mercúrio/farmacologia , Estresse Fisiológico/genética , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Medicago/metabolismo , Medicago sativa/genética , Medicago sativa/metabolismo , Medicago truncatula/genética , Medicago truncatula/metabolismo , Mercúrio/metabolismo , NADPH Oxidases/metabolismo , Estresse Oxidativo , Reguladores de Crescimento de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , RNA de Plantas , Plântula , Transdução de Sinais , Transcriptoma , Regulação para CimaRESUMO
In this work, we propose a mathematical model that describes liver evolution and concentrations of alanine aminotransferase and aspartate aminotransferase in a group of rats damaged with carbon tetrachloride. Carbon tetrachloride was employed to induce cirrhosis. A second groups damaged with carbon tetrachloride was exposed simultaneously a plant extract as hepatoprotective agent. The model reproduces the data obtained in the experiment reported in [Rev. Cub. Plant. Med. 22(1), 2017], and predicts that using the plants extract helps to get a better natural recovery after the treatment. Computer simulations show that the extract reduces the damage velocity but does not avoid it entirely. The present paper is the first report in the literature in which a mathematical model reliably predicts the protective effect of a plant extract mixture in rats with cirrhosis disease. The results reported in this manuscript could be used in the future to help in fighting cirrhotic conditions in humans, though more experimental and mathematical work is required in that case.
Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Extratos Vegetais , Humanos , Ratos , Animais , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Tetracloreto de Carbono/toxicidade , Doença Hepática Induzida por Substâncias e Drogas/tratamento farmacológico , Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Doença Hepática Induzida por Substâncias e Drogas/patologia , Fígado/patologia , Cirrose Hepática/tratamento farmacológico , Cirrose Hepática/patologia , Modelos TeóricosRESUMO
Better understanding of mercury (Hg) accumulation, distribution, and speciation in plants is required to evaluate potential risks for the environment and to optimize phytostabilization strategies for Hg-contaminated soils. The behavior of Hg in alfalfa (Medicago sativa) plants grown under controlled conditions in a hydroponic system (30 µM HgCl2) was compared with that of naturally occurring Horehound (Marrubium vulgare) plants collected from a mining soil polluted with Hg (Almadenejos, Spain) to characterize common mechanisms of tolerance. Synchrotron X-ray Fluorescence microprobe (µ-SXRF) showed that Hg accumulated at the root apex of alfalfa and was distributed through the vascular system to the leaves. Transmission electron microscopy (TEM) implied association of Hg with cell walls, accompanied by their structural changes, in alfalfa roots. Extended X-ray absorption fine structure (EXAFS) determined that Hg was principally bound to biothiols and/or proteins in M. sativa roots, stems, and leaves. However, the major fraction of Hg detected in M. vulgare plants consisted of mineral species, possibly associated with soil components. Interestingly, the fraction of Hg bound to biothiols/proteins (i.e., metabolically processed Hg) in leaves of both plants (alfalfa and M. vulgare) was similar, in spite of the big difference in Hg accumulation in roots, suggesting that some tolerance mechanisms might be shared.
Assuntos
Monitoramento Ambiental , Hidroponia , Marrubium/crescimento & desenvolvimento , Marrubium/metabolismo , Medicago sativa/crescimento & desenvolvimento , Medicago sativa/metabolismo , Mercúrio/metabolismo , Meio Ambiente , Marrubium/efeitos dos fármacos , Medicago sativa/efeitos dos fármacos , Medicago sativa/ultraestrutura , Mercúrio/toxicidade , Especificidade de Órgãos/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/ultraestrutura , Espectrometria por Raios XRESUMO
Heavy metals in soil are known to affect rhizobia-legume interaction reducing not only rhizobia viability, but also nitrogen fixation. In this work, we have compared the response of the symbiotic interaction established between the peanut (Arachis hypogaea L.) and a sensitive (Bradyrhizobium sp. SEMIA6144) or a tolerant (Bradyrhizobium sp. NLH25) strain to Cd under exposure to this metal. The addition of 10 µM Cd reduced nodulation and nitrogen content in both symbiotic associations, being the interaction established with the sensitive strain more affected than that with the tolerant one. Plants inoculated with the sensitive strain accumulated more Cd than those inoculated with the tolerant strain. Nodules showed an increase in reactive oxygen species (ROS) production when exposed to Cd. The histological structure of the nodules exposed to Cd revealed a deposit of unknown material on the cortex and a significant reduction in the infection zone diameter in both strains, and a greater number of uninfected cells in those nodules occupied by the sensitive strain. In conclusion, Cd negatively impacts on peanut-bradyrhizobia interaction, irrespective of the tolerance of the strains to this metal. However, the inoculation of peanut with Bradyrhizobium sp. NLH25 results in a better symbiotic interaction suggesting that the tolerance observed in this strain could limit Cd accumulation by the plant.
Assuntos
Arachis/microbiologia , Bradyrhizobium/efeitos dos fármacos , Cádmio/toxicidade , Arachis/efeitos dos fármacos , Arachis/metabolismo , Bradyrhizobium/metabolismo , Bradyrhizobium/fisiologia , Poluentes Ambientais/toxicidade , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Estresse Oxidativo , Raízes de Plantas/anatomia & histologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Microbiologia do Solo , Simbiose/efeitos dos fármacosRESUMO
Cadmium (Cd) and mercury (Hg) are ubiquitous soil pollutants that promote the accumulation of reactive oxygen species, causing oxidative stress. Tolerance depends on signalling processes that activate different defence barriers, such as accumulation of small heat sock proteins (sHSPs), activation of antioxidant enzymes, and the synthesis of phytochelatins (PCs) from the fundamental antioxidant peptide glutathione (GSH), which is probably modulated by ethylene. We studied the early responses of alfalfa seedlings after short exposure (3, 6, and 24 h) to moderate to severe concentration of Cd and Hg (ranging from 3 to 30 µM), to characterize in detail several oxidative stress parameters and biothiol (i.e., GSH and PCs) accumulation, in combination with the ethylene signalling blocker 1-methylcyclopropene (1-MCP). Most changes occurred in roots of alfalfa, with strong induction of cellular oxidative stress, H2O2 generation, and a quick accumulation of sHSPs 17.6 and 17.7. Mercury caused the specific inhibition of glutathione reductase activity, while both metals led to the accumulation of PCs. These responses were attenuated in seedlings incubated with 1-MCP. Interestingly, 1-MCP also decreased the amount of PCs and homophytochelatins generated under metal stress, implying that the overall early response to metals was controlled at least partially by ethylene.
RESUMO
Background: Temozolomide (TMZ) is an oral alkylating agent active against gliomas with a favorable toxicity profile. It is part of the standard of care in the management of glioblastoma (GBM), and is commonly used in low-grade gliomas (LGG). In-silico mathematical models can potentially be used to personalize treatments and to accelerate the discovery of optimal drug delivery schemes. Methods: Agent-based mathematical models fed with either mouse or patient data were developed for the in-silico studies. The experimental test beds used to confirm the results were: mouse glioma models obtained by retroviral expression of EGFR-wt/EGFR-vIII in primary progenitors from p16/p19 ko mice and grown in-vitro and in-vivo in orthotopic allografts, and human GBM U251 cells immobilized in alginate microfibers. The patient data used to parametrize the model were obtained from the TCGA/TCIA databases and the TOG clinical study. Results: Slow-growth "virtual" murine GBMs benefited from increasing TMZ dose separation in-silico. In line with the simulation results, improved survival, reduced toxicity, lower expression of resistance factors, and reduction of the tumor mesenchymal component were observed in experimental models subject to long-cycle treatment, particularly in slowly growing tumors. Tissue analysis after long-cycle TMZ treatments revealed epigenetically driven changes in tumor phenotype, which could explain the reduction in GBM growth speed. In-silico trials provided support for implementation methods in human patients. Conclusions: In-silico simulations, in-vitro and in-vivo studies show that TMZ administration schedules with increased time between doses may reduce toxicity, delay the appearance of resistances and lead to survival benefits mediated by changes in the tumor phenotype in slowly-growing GBMs.
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Histology involves the observation of structural features in tissues using a microscope. While diffraction-limited optical microscopes are commonly used in histological investigations, their resolving capabilities are insufficient to visualize details at subcellular level. Although a novel set of super-resolution optical microscopy techniques can fulfill the resolution demands in such cases, the system complexity, high operating cost, lack of multi-modality, and low-throughput imaging of these methods limit their wide adoption for histological analysis. In this study, we introduce the photonic chip as a feasible high-throughput microscopy platform for super-resolution imaging of histological samples. Using cryopreserved ultrathin tissue sections of human placenta, mouse kidney, pig heart, and zebrafish eye retina prepared by the Tokuyasu method, we demonstrate diverse imaging capabilities of the photonic chip including total internal reflection fluorescence microscopy, intensity fluctuation-based optical nanoscopy, single-molecule localization microscopy, and correlative light-electron microscopy. Our results validate the photonic chip as a feasible imaging platform for tissue sections and pave the way for the adoption of super-resolution high-throughput multimodal analysis of cryopreserved tissue samples both in research and clinical settings.
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Three-week-old alfalfa (Medicago sativa), barley (Hordeum vulgare) and maize (Zea mays) were exposed for 7 d to 30 µm of mercury (HgCl(2) ) to characterize the Hg speciation in root, with no symptoms of being poisoned. The largest pool (99%) was associated with the particulate fraction, whereas the soluble fraction (SF) accounted for a minor proportion (<1%). Liquid chromatography coupled with electro-spray/time of flight mass spectrometry showed that Hg was bound to an array of phytochelatins (PCs) in root SF, which was particularly varied in alfalfa (eight ligands and five stoichiometries), a species that also accumulated homophytochelatins. Spatial localization of Hg in alfalfa roots by microprobe synchrotron X-ray fluorescence spectroscopy showed that most of the Hg co-localized with sulphur in the vascular cylinder. Extended X-ray Absorption Fine Structure (EXAFS) fingerprint fitting revealed that Hg was bound in vivo to organic-S compounds, i.e. biomolecules containing cysteine. Albeit a minor proportion of total Hg, Hg-PCs complexes in the SF might be important for tolerance to Hg, as was found with Arabidopsis thaliana mutants cad2-1 (with low glutathione content) and cad1-3 (unable to synthesize PCs) in comparison with wild type plants. Interestingly, high-performance liquid chromatography-electrospray ionization-time of flight analysis showed that none of these mutants accumulated Hg-biothiol complexes.
Assuntos
Hordeum/química , Medicago sativa/química , Mercúrio/química , Fitoquelatinas/química , Raízes de Plantas/química , Zea mays/química , Arabidopsis/química , Arabidopsis/genética , Cromatografia Líquida , Espectrometria de Massas , Raízes de Plantas/crescimento & desenvolvimento , Espectrometria por Raios XRESUMO
Autophagy constitutes an essential process triggered by oxidative stress that enables cells to recycle damaged biomolecules and organelles, which is eventually traced by immunodetection with anti-ATG8. In parallel with autophagy induction, carbon metabolism in Chlamydomonas reinhardtii under abiotic stress is diverged toward lipid biosynthesis and lipid droplet accumulation, which can be analyzed by a simple thin-layer chromatography and in vivo staining with the fluorescent probe BODIPY 493/503. We show the responses in Chlamydomonas cells exposed to mercury or cadmium (0-50 µM doses), as examples of oxidative stress-mediated changes in autophagy and lipid metabolism, monitored with the procedures described in this report.
Assuntos
Chlamydomonas reinhardtii/metabolismo , Lipidômica/métodos , Estresse Fisiológico/fisiologia , Autofagia/fisiologia , Compostos de Boro , Carbono/metabolismo , Metabolismo dos Lipídeos , Oxirredução , Estresse Oxidativo/fisiologiaRESUMO
Toxic metals such as cadmium (Cd) and mercury (Hg) represent a threat to photosynthetic organisms of polluted aquatic ecosystems, and knowledge about mechanisms of toxicity is essential for appropriate assessment of environmental risks. We used Synchrotron Radiation-Fourier Transformed Infrared microspectroscopy (µSR-FTIR) to characterise major changes of biomolecules caused by Cd and Hg in the model green microalga Chlamydomonas reinhardtii. µSR-FTIR showed several metabolic alterations in different biochemical groups such as carbohydrates, proteins, and lipids in a time-dose dependent manner, with the strongest changes occurring at concentrations above 10 µM Cd and 15 µM Hg after short-term (24 h) treatments. This occurred in a context where metals triggered intracellular oxidative stress and chloroplast damage, along with autophagy induction by overexpressing AUTOPHAGY-RELATED PROTEIN 8 (ATG8). Thin layer chromatography analysis confirmed that toxic metals promoted remarkable changes in lipid profile, with higher degree of esterified fatty acid unsaturation as detected by gas chromatography coupled with mass spectrometry. Under Cd stress, there was specifically higher unsaturation of free fatty acids, while Hg led to stronger unsaturation in monogalactosyldiacylglycerol. µSR-FTIR spectroscopy proved as a valuable tool to identify biochemical alterations in microalgae, information that could be exploited to optimise approaches for metal decontamination.
Assuntos
Mercúrio , Microalgas , Cádmio/toxicidade , Ecossistema , Cromatografia Gasosa-Espectrometria de Massas , Mercúrio/toxicidade , Espectroscopia de Infravermelho com Transformada de Fourier , SíncrotronsRESUMO
Contrast in fluorescence microscopy images allows for the differentiation between different structures by their difference in intensities. However, factors such as point-spread function and noise may reduce it, affecting its interpretability. We identified that fluctuation of emitters in a stack of images can be exploited to achieve increased contrast when compared to the average and Richardson-Lucy deconvolution. We tested our methods on four increasingly challenging samples including tissue, in which case results were comparable to the ones obtained by structured illumination microscopy in terms of contrast.
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Low-grade gliomas (LGGs) are brain tumors characterized by their slow growth and infiltrative nature. Treatment options for these tumors are surgery, radiation therapy and chemotherapy. The optimal use of radiation therapy and chemotherapy is still under study. In this paper, we construct a mathematical model of LGG response to combinations of chemotherapy, specifically to the alkylating agent temozolomide and radiation therapy. Patient-specific parameters were obtained from longitudinal imaging data of the response of real LGG patients. Computer simulations showed that concurrent cycles of radiation therapy and temozolomide could provide the best therapeutic efficacy in-silico for the patients included in the study. The patient cohort was extended computationally to a set of 3000 virtual patients. This virtual cohort was subject to an in-silico trial in which matching the doses of radiotherapy to those of temozolomide in the first five days of each cycle improved overall survival over concomitant radio-chemotherapy according to RTOG 0424. Thus, the proposed treatment schedule could be investigated in a clinical setting to improve combination treatments in LGGs with substantial survival benefits.