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1.
Molecules ; 26(13)2021 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-34206860

RESUMO

In this paper, a combination of modification of the source and regulation of the process was used to control the degradation of PBDEs by plants and microorganisms. First, the key proteins that can degrade PBDEs in plants and microorganisms were searched in the PDB (Protein Data Bank), and a molecular docking method was used to characterize the binding ability of PBDEs to two key proteins. Next, the synergistic binding ability of PBDEs to the two key proteins was evaluated based on the queuing integral method. Based on this, three groups of three-dimensional quantitative structure-activity relationship (3D-QSAR) models of plant-microbial synergistic degradation were constructed. A total of 30 PBDE derivatives were designed using BDE-3 as the template molecule. Among them, the effect on the synergistic degradation of six PBDE derivatives, including BDE-3-4, was significantly improved (increased by more than 20%) and the environment-friendly and functional evaluation parameters were improved. Subsequently, studies on the synergistic degradation of PBDEs and their derivatives by plants and microorganisms, based on the molecular docking method, found that the addition of lipophilic groups by modification is beneficial to enhance the efficiency of synergistic degradation of PBDEs by plants and microorganisms. Further, while docking PBDEs, the number of amino acids was increased and the binding bond length was decreased compared to the template molecules, i.e., PBDE derivatives could be naturally degraded more efficiently. Finally, molecular dynamics simulation by the Taguchi orthogonal experiment and a full factorial experimental design were used to simulate the effects of various regulatory schemes on the synergistic degradation of PBDEs by plants and microorganisms. It was found that optimal regulation occurred when the appropriate amount of carbon dioxide was supplied to the plant and microbial systems. This paper aims to provide theoretical support for enhancing the synergistic degradation of PBDEs by plants and microorganisms in e-waste dismantling sites and their surrounding polluted areas, as well as, realize the research and development of green alternatives to PBDE flame retardants.


Assuntos
Retardadores de Chama/análise , Éteres Difenil Halogenados/química , Plantas/metabolismo , Poluentes do Solo/química , Solo/química , Dióxido de Carbono/química , Dióxido de Carbono/metabolismo , Bases de Dados de Proteínas , Éteres Difenil Halogenados/análise , Modelos Moleculares , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Relação Quantitativa Estrutura-Atividade , Microbiologia do Solo
2.
Int J Mol Sci ; 22(9)2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-34063012

RESUMO

Single-walled carbon nanotubes (SWCNTs) emerge as promising novel carbon-based nanoparticles for use in biomedicine, pharmacology and precision agriculture. They were shown to penetrate cell walls and membranes and to physically interact and exchange electrons with photosynthetic complexes in vitro. Here, for the first time, we studied the concentration-dependent effect of foliar application of copolymer-grafted SWCNTs on the structural and functional characteristics of intact pea plants. The lowest used concentration of 10 mg L-1 did not cause any harmful effects on the studied leaf characteristics, while abundant epicuticular wax generation on both leaf surfaces was observed after 300 mg L-1 treatment. Swelling of both the granal and the stromal regions of thylakoid membranes was detected after application of 100 mg L-1 and was most pronounced after 300 mg L-1. Higher SWCNT doses lead to impaired photosynthesis in terms of lower proton motive force generation, slower generation of non-photochemical quenching and reduced zeaxanthin content; however, the photosystem II function was largely preserved. Our results clearly indicate that SWCNTs affect the photosynthetic apparatus in a concentration-dependent manner. Low doses (10 mg L-1) of SWCNTs appear to be a safe suitable object for future development of nanocarriers for substances that are beneficial for plant growth.


Assuntos
Cloroplastos/ultraestrutura , Nanotubos de Carbono/química , Ervilhas/fisiologia , Ervilhas/ultraestrutura , Fotossíntese , Folhas de Planta/anatomia & histologia , Dióxido de Carbono/metabolismo , Carotenoides/metabolismo , Permeabilidade da Membrana Celular , Clorofila/metabolismo , Fluorescência , Nanotubos de Carbono/ultraestrutura , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/ultraestrutura , Prótons , Tilacoides/metabolismo , Fatores de Tempo , Xantofilas/metabolismo
3.
Methods Mol Biol ; 2276: 305-324, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34060051

RESUMO

Specific bioenergetic signature reports on the current metabolic state of the cell, which may be affected by metabolic rearrangement, dysfunction or dysregulation of relevant signaling pathways, altered physiological condition or energy stress. A combined analysis of respiration , glycolytic flux, Krebs cycle activity, ATP levels, and total biomass allows informative initial assessment. Such simple, high-throughput, multiparametric methodology, called cell energy budget (CEB ) platform, is presented here and demonstrated with particular cell and tissue models. The CEB uses a commercial fluorescent lanthanide probe pH-Xtra™ to measure extracellular acidification (ECA) associated with lactate (L-ECA) and combined lactate/CO2 (T-ECA), a phosphorescent probe MitoXpress®-Xtra to measure oxygen consumption rate (OCR), a bioluminescent ATP kit, and an absorbance-based total protein assay. All the assays are performed on a standard multi-label reader. Using the same readouts, the CEB approach can be extended to more detailed mechanistic studies, by targeting specific pathways in cell bioenergetics and measuring other cellular parameters, such as NAD(P)H, Ca2+, mitochondrial pH, membrane potential, redox state, with conventional fluorescent or luminescent probes.


Assuntos
Trifosfato de Adenosina/metabolismo , Dióxido de Carbono/metabolismo , Células/metabolismo , Ensaios de Triagem em Larga Escala/métodos , Ácido Láctico/metabolismo , Animais , Metabolismo Energético , Espaço Extracelular/química , Espaço Extracelular/metabolismo , Corantes Fluorescentes/química , Concentração de Íons de Hidrogênio , Consumo de Oxigênio/fisiologia , Células PC12 , Ratos
4.
Int J Mol Sci ; 22(9)2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-34063101

RESUMO

Photosynthetic organisms commonly develop the strategy to keep the reaction center chlorophyll of photosystem I, P700, oxidized for preventing the generation of reactive oxygen species in excess light conditions. In photosynthesis of C4 plants, CO2 concentration is kept at higher levels around ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) by the cooperation of the mesophyll and bundle sheath cells, which enables them to assimilate CO2 at higher rates to survive under drought stress. However, the regulatory mechanism of photosynthetic electron transport for P700 oxidation is still poorly understood in C4 plants. Here, we assessed gas exchange, chlorophyll fluorescence, electrochromic shift, and near infrared absorbance in intact leaves of maize (a NADP-malic enzyme C4 subtype species) in comparison with mustard, a C3 plant. Instead of the alternative electron sink due to photorespiration in the C3 plant, photosynthetic linear electron flow was strongly suppressed between photosystems I and II, dependent on the difference of proton concentration across the thylakoid membrane (ΔpH) in response to the suppression of CO2 assimilation in maize. Linear relationships among CO2 assimilation rate, linear electron flow, P700 oxidation, ΔpH, and the oxidation rate of ferredoxin suggested that the increase of ΔpH for P700 oxidation was caused by the regulation of proton conductance of chloroplast ATP synthase but not by promoting cyclic electron flow. At the scale of intact leaves, the ratio of PSI to PSII was estimated almost 1:1 in both C3 and C4 plants. Overall, the photosynthetic electron transport was regulated for P700 oxidation in maize through the same strategies as in C3 plants only except for the capacity of photorespiration despite the structural and metabolic differences in photosynthesis between C3 and C4 plants.


Assuntos
Dióxido de Carbono/metabolismo , Fotossíntese , Folhas de Planta/metabolismo , Zea mays/metabolismo , Escuridão , Transporte de Elétrons , Ferredoxinas/metabolismo , Cinética , Modelos Biológicos , Oxirredução , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Prótons , Teoria Quântica
5.
Int J Mol Sci ; 22(9)2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-34068564

RESUMO

Ischemic stroke is a leading cause of death and disability worldwide. The only pharmacological treatment available to date for cerebral ischemia is tissue plasminogen activator (t-PA) and the search for successful therapeutic strategies still remains a major challenge. The loss of cerebral blood flow leads to reduced oxygen and glucose supply and a subsequent switch to the glycolytic pathway, which leads to tissue acidification. Carbonic anhydrase (CA, EC 4.2.1.1) is the enzyme responsible for converting carbon dioxide into a protons and bicarbonate, thus contributing to pH regulation and metabolism, with many CA isoforms present in the brain. Recently, numerous studies have shed light on several classes of carbonic anhydrase inhibitor (CAI) as possible new pharmacological agents for the management of brain ischemia. In the present review we summarized pharmacological, preclinical and clinical findings regarding the role of CAIs in strokes and we discuss their potential protective mechanisms.


Assuntos
Isquemia Encefálica/tratamento farmacológico , Inibidores da Anidrase Carbônica/uso terapêutico , Anidrases Carbônicas/genética , AVC Isquêmico/tratamento farmacológico , Bicarbonatos/metabolismo , Encéfalo/metabolismo , Encéfalo/patologia , Isquemia Encefálica/genética , Isquemia Encefálica/patologia , Dióxido de Carbono/metabolismo , Humanos , Infarto da Artéria Cerebral Média/tratamento farmacológico , Infarto da Artéria Cerebral Média/genética , Infarto da Artéria Cerebral Média/patologia , AVC Isquêmico/genética , Sulfonamidas/uso terapêutico
6.
Methods Mol Biol ; 2290: 229-252, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34009594

RESUMO

Photosynthetic cyanobacteria are not only model organisms for studying photosynthesis and biological cycling of carbon in biosphere but also potential "green microbial factories" to produce renewable fuels and chemicals, due to their capability to utilizing solar energy and CO2. Therefore, strategies for gene regulation and carbon flux redirection are important for both fundamental research and metabolic engineering of cyanobacteria. To address the challenges, regulatory tools based on artificial small RNAs have been developed with satisfactory effects for single or multiple gene(s) regulation in various cyanobacterial species. When combined with the promoters of varying gradient strength and the inducible switches developed in recent years, it is now feasible to realize precise gene regulation in photosynthetic cyanobacteria for producing fuels and chemicals. Here in this chapter, we provide a detailed introduction of the design principles and constructing methods of the artificial sRNA tools to achieve accurate inducible regulation of cyanobacterial gene(s).


Assuntos
Cianobactérias/genética , Regulação Bacteriana da Expressão Gênica/genética , Pequeno RNA não Traduzido/síntese química , Biocombustíveis , Carbono/metabolismo , Ciclo do Carbono , Dióxido de Carbono/metabolismo , Expressão Gênica/genética , Engenharia Metabólica/métodos , Fotossíntese/fisiologia , RNA/metabolismo , Pequeno RNA não Traduzido/metabolismo , Biologia Sintética/métodos
7.
Semin Dial ; 34(3): 257-262, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33969909

RESUMO

The COVID-19 pandemic significates an enormous number of patients with pneumonia that get complicated with severe acute respiratory distress syndrome (ARDS), some of them with refractory hypercapnia and hypoxemia that need mechanical ventilation (MV). Those patients who are not candidate to extracorporeal membrane oxygenation (ECMO), the extracorporeal removal of CO2 (ECCO2 R) can allow ultra protective MV to limit the transpulmonary pressures and avoid ventilatory induced lung injury (VILI). We report a first case of prolonged ECCO2 R support in 38 year male with severe COVID-19 pneumonia refractory to conventional support. He was admitted tachypneic and oxygen saturation 71% without supplementary oxygen. The patient's clinical condition worsens with severe respiratory failure, increasing the oxygen requirement and initiating MV in the prone position. After 21 days of protective MV, PaCO2 rise to 96.8 mmHg, making it necessary to connect to an ECCO2 R system coupled continuous veno-venous hemodialysis (CVVHD). However, due to the lack of availability of equipment in the context of the pandemic, a pediatric gas exchange membrane adapted to CVVHD allowed to maintain the removal of CO2 until completing 27 days, being finally disconnected from the system without complications and with a satisfactory evolution.


Assuntos
COVID-19/terapia , Dióxido de Carbono/metabolismo , Pneumonia Viral/terapia , Pneumonia Viral/virologia , Terapia de Substituição Renal , Insuficiência Respiratória/terapia , Insuficiência Respiratória/virologia , Adulto , Humanos , Masculino , Pandemias , SARS-CoV-2
8.
Toxins (Basel) ; 13(5)2021 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-33946501

RESUMO

Non-proteinogenic neurotoxic amino acid ß-N-methylamino-L-alanine (BMAA) is synthesized by cyanobacteria, diatoms, and dinoflagellates, and is known to be a causative agent of human neurodegenerative diseases. Different phytoplankton organisms' ability to synthesize BMAA could indicate the importance of this molecule in the interactions between microalgae in nature. We were interested in the following: what kinds of mechanisms underline BMAA's action on cyanobacterial cells in different nitrogen supply conditions. Herein, we present a proteomic analysis of filamentous cyanobacteria Nostoc sp. PCC 7120 cells that underwent BMAA treatment in diazotrophic conditions. In diazotrophic growth conditions, to survive, cyanobacteria can use only biological nitrogen fixation to obtain nitrogen for life. Note that nitrogen fixation is an energy-consuming process. In total, 1567 different proteins of Nostoc sp. PCC 7120 were identified by using LC-MS/MS spectrometry. Among them, 123 proteins belonging to different functional categories were selected-due to their notable expression differences-for further functional analysis and discussion. The presented proteomic data evidences that BMAA treatment leads to very strong (up to 80%) downregulation of α (NifD) and ß (NifK) subunits of molybdenum-iron protein, which is known to be a part of nitrogenase. This enzyme is responsible for catalyzing nitrogen fixation. The genes nifD and nifK are under transcriptional control of a global nitrogen regulator NtcA. In this study, we have found that BMAA impacts in a total of 22 proteins that are under the control of NtcA. Moreover, BMAA downregulates 18 proteins that belong to photosystems I or II and light-harvesting complexes; BMAA treatment under diazotrophic conditions also downregulates five subunits of ATP synthase and enzyme NAD(P)H-quinone oxidoreductase. Therefore, we can conclude that the disbalance in energy and metabolite amounts leads to severe intracellular stress that induces the upregulation of stress-activated proteins, such as starvation-inducible DNA-binding protein, four SOS-response enzymes, and DNA repair enzymes, nine stress-response enzymes, and four proteases. The presented data provide new leads into the ecological impact of BMAA on microalgal communities that can be used in future investigations.


Assuntos
Diamino Aminoácidos/farmacologia , Fixação de Nitrogênio/efeitos dos fármacos , Nostoc/efeitos dos fármacos , Proteínas de Bactérias/metabolismo , Bicarbonatos/metabolismo , Metabolismo dos Carboidratos/efeitos dos fármacos , Dióxido de Carbono/metabolismo , Regulação para Baixo/efeitos dos fármacos , Nitrogênio/metabolismo , Nitrogenase/metabolismo , Nostoc/metabolismo , Nostoc/fisiologia , Fosforilação/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Proteômica , Estresse Fisiológico/efeitos dos fármacos
9.
J Plant Physiol ; 261: 153427, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33940557

RESUMO

Metamitron (MET) is a fruitlet thinning compound for apple trees, needing better understanding of its action on leaf energy metabolism, depending on nighttime temperature. A trial under environmental controlled conditions was set with 'Golden Reinders' potted trees, under 25/7.5 and 25/15 °C (diurnal/nighttime temperature), with (MET, 247.5 ppm) or without (CTR) application, and considering the monitoring of photosynthetic and respiration components from day 1 (D1) to 14 (D14). Net photosynthesis (Pn) decline promoted by MET after D1 was not stomatal related. Instead, non-stomatal constraints, reflected on the photosynthetic capacity (Amax), included a clear photosystem (PS) II inhibition (but barely of PSI), as shown by severe reductions in thylakoid electron transport at PSII level, maximal (Fv/Fm) and actual (Fv'/Fm') PSII photochemical efficiencies, estimate of quantum yield of linear electron transport (Y(II)), and the rise in PSII photoinhibition status (Fs/Fm' and PIChr) and uncontrolled energy dissipation (Y(NO)). To Pn inhibition also contributed the impact in RuBisCO along the entire experiment, regardless of night temperature, here reported for the first time. Globally, MET impact on the photosynthetic parameters was usually greater under 7.5 °C, with maximal impacts between D4 and D7, probably associated to a less active metabolism at lower temperature. Cellular energy metabolism was further impaired under 7.5 °C, through moderate inhibition of NADH-dependent malate dehydrogenase (MDH) and pyruvate kinase (PK) enzymes involved in respiration, in contrast with the increase of dark respiration in MET 7.5 until D7. The lower impact on PK and MDH under 15 °C and a likely global higher active metabolism at that temperature would agree with the lowest sucrose levels in MET 15 at D4 and D7. Our findings showed that MET alters the cell energy machinery in a temperature dependent manner, affecting the sucrose balance mainly at 15 °C, justifying the observed greater thinning potential.


Assuntos
Malus/metabolismo , Fotossíntese , Folhas de Planta/metabolismo , Temperatura , Triazinas/metabolismo , Dióxido de Carbono/metabolismo , Transporte de Elétrons/efeitos dos fármacos , Malus/efeitos dos fármacos , Fotoperíodo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/efeitos dos fármacos , Tilacoides/efeitos dos fármacos , Tilacoides/metabolismo , Triazinas/administração & dosagem
10.
Auton Neurosci ; 233: 102810, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33894532

RESUMO

We have considered some of the available evidence to account for the impact of SARS-CoV on the regulatory control of the autonomic nervous and respiratory systems. Apart from stimulating general interest in the subject, our hope was to provide putative explanations for some of the patients' symptoms based on described physiological and pathophysiological mechanisms seen in other diseases. Herein, we have focused on the carotid bodies. In this hypothetical viewpoint, we have discussed the plasticity of the carotid body chemoreflex and made a comparison between acute and chronic exposures to high altitude with COVID-19. From these discussions, we have postulated that the sensitivity of the hypoxic ventilatory response may well determine the outcome of disease severity and those that live at high altitude may be more resistant. We have provided insight into silent hypoxia and attempted to explain an absence of ventilatory drive and anxiety yet maintenance of consciousness. In an attempt to discover more about the mysteries of COVID-19, we conclude with questions and some hypothetical studies that may answer them.


Assuntos
Sistema Nervoso Autônomo/fisiopatologia , COVID-19/fisiopatologia , Corpo Carotídeo/fisiopatologia , Altitude , Dióxido de Carbono/metabolismo , Circulação Cerebrovascular , Humanos , Hipóxia/fisiopatologia
11.
Plant Sci ; 307: 110891, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33902852

RESUMO

Potassium (K) regulates plant metabolism and enhances plant's ability to adapt to adversity. However, under different K deficiency stress, the net photosynthetic rate (An) was reduced, influenced by CO2 conductance or biochemical capacities. The interplay between metabolome and photosynthetic characteristics under K deficiency stress was analyzed to explore the mechanisms by which K regulates photosynthetic capacity. With increasing K deficiency stress, dominations limiting An varied from CO2 conductance to biochemical limitations. Multivariate analyses indicated that organic acids, amino acids and sedoheptulose-7-bisphosphate were significantly related to An, CO2 conductance and carboxylation rate. Under moderate K deficiency, organic acids were up-regulated. Acidification of subcellular compartments reduced sedoheptulose-1,7-bisphosphatase activity, inducing downregulation of sedoheptulose-7-bisphosphate and hindrance of ribulose bisphosphate regeneration. Moreover, increased CO2 shortage with increasing K deficiency induced a shift of increased citric acid to amino acid synthesis, causing excessive accumulation of amino acids. In addition, the reduced serine level indicated impaired photorespiration. These two changes triggered more serious reduction in photosynthetic capacity. The intimate, changes in photosynthetic capacities were tightly coupled with shifts in central C metabolism, which provides insights into the methods used to enhance An and plant's adaptability to abiotic stresses, through the regulation of C metabolites using molecular technology.


Assuntos
Brassica napus/metabolismo , Dióxido de Carbono/metabolismo , Carbono/metabolismo , Produtos Agrícolas/metabolismo , Fotossíntese/fisiologia , Folhas de Planta/metabolismo , Potássio/metabolismo
12.
Int J Mol Sci ; 22(9)2021 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33919261

RESUMO

Carbon dioxide (CO2), a vital molecule of the carbon cycle, is a critical component in living organisms' metabolism, performing functions that lead to the building of compounds fundamental for the life cycle. In all living organisms, the CO2/bicarbonate (HCO3-) balancing is governed by a superfamily of enzymes, known as carbonic anhydrases (CAs, EC 4.2.1.1). CAs catalyze the pivotal physiological reaction, consisting of the reversible hydration of the CO2 to HCO3- and protons. Opportunistic and pathogenic fungi can sense the environmental CO2 levels, which influence their virulence or environmental subsistence traits. The fungal CO2-sensing is directly stimulated by HCO3- produced in a CA-dependent manner, which directly activates adenylyl cyclase (AC) involved in the fungal spore formation. The interference with CA activity may impair fungal growth and virulence, making this approach interesting for designing antifungal drugs with a novel mechanism of action: the inhibition of CAs linked to the CO2/HCO3-/pH chemosensing and signaling. This review reports that sulfonamides and their bioisosteres as well as inorganic anions can inhibit in vitro the ß- and α-CAs from the fungi, suggesting how CAs may be considered as a novel "pathogen protein" target of many opportunistic, pathogenic fungi.


Assuntos
Inibidores da Anidrase Carbônica/farmacologia , Anidrases Carbônicas/efeitos dos fármacos , Fungos/enzimologia , Sulfonamidas/farmacologia , Antifúngicos/farmacologia , Dióxido de Carbono/metabolismo , Fungos/efeitos dos fármacos
13.
Sci Data ; 8(1): 97, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33795698

RESUMO

The photosynthetic pathway of plants is a fundamental trait that influences terrestrial environments from the local to global level. The distribution of different photosynthetic pathways in Australia is expected to undergo a substantial shift due to climate change and rising atmospheric CO2; however, tracking change is hindered by a lack of data on the pathways of species, as well as their distribution and relative cover within plant communities. Here we present the photosynthetic pathways for 2428 species recorded across 541 plots surveyed by Australia's Terrestrial Ecosystem Research Network (TERN) between 2011 and 2017. This dataset was created to facilitate research exploring trends in vegetation change across Australia. Species were assigned a photosynthetic pathway using published literature and stable carbon isotope analysis of bulk tissue. The photosynthetic pathway of species can be extracted from the dataset individually, or used in conjunction with vegetation surveys to study the occurrence and abundance of pathways across the continent. This dataset will be updated as TERN's plot network expands and new information becomes available.


Assuntos
Fotossíntese , Plantas/metabolismo , Atmosfera/química , Austrália , Dióxido de Carbono/análise , Dióxido de Carbono/metabolismo , Mudança Climática , Ecossistema
14.
Science ; 372(6538)2021 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-33833098

RESUMO

Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.


Assuntos
Carboxiliases/química , Carboxiliases/metabolismo , Chlorella/enzimologia , Ácidos Graxos/metabolismo , Proteínas de Algas/química , Proteínas de Algas/metabolismo , Alcanos/metabolismo , Substituição de Aminoácidos , Aminoácidos/metabolismo , Bicarbonatos/metabolismo , Biocatálise , Dióxido de Carbono/metabolismo , Domínio Catalítico , Cristalografia por Raios X , Descarboxilação , Transporte de Elétrons , Flavina-Adenina Dinucleotídeo/química , Ligação de Hidrogênio , Luz , Modelos Moleculares , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Oxirredução , Fótons , Conformação Proteica , Temperatura
15.
Ecotoxicol Environ Saf ; 217: 112235, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33873079

RESUMO

Ocean acidification (OA) has posed formidable threats to marine calcifiers. In response to elevated CO2 levels, marine calcifiers have developed multiple strategies to survive, such as taking advantage of apoptosis, but its regulation mechanism remains largely unknown. Here, we used the Pacific oyster Crassostrea gigas as model to understand the apoptotic responses and regulation mechanism at short- (7 d) to long-term (56 d) CO2 exposure (pH = 7.50). The apoptosis of hemocytes was significantly induced after short-term treatment (7-21 d) but was suppressed under long-term CO2 exposure (42-56 d). Similarly, caspase-3 and caspase-9 were also increased post short-term exposure and fell back to normal levels after long-term exposure. These data together indicated diverse regulation mechanisms of apoptosis through different exposure periods. Through analysis of the B-cell lymphoma 2 (Bcl-2) family mitochondrial apoptosis regulators, we showed that only CgBcl-XL's expression kept at high levels after 42- and 56-day CO2 exposure. CgBcl-XL shared sequence, and structural similarity with its mammalian counterpart, and knockdown of CgBcl-XL in hemocytes via RNA interference promoted apoptosis. The protein level of CgBcl-XL was significantly increased after long-term CO2 exposure (28-56 d), and its distribution in hemocytes became more concentrated and dense. Therefore, CgBcl-XL serves as an essential anti-apoptotic protein for tipping the balance of cell apoptosis, which may play a key role in survival under long-term CO2 exposure. These results reveal a potential adaptation strategy of oysters towards OA and the variable environment changes through the modulation of apoptosis.


Assuntos
Crassostrea/fisiologia , Aclimatação , Animais , Apoptose , Dióxido de Carbono/metabolismo , Dióxido de Carbono/fisiologia , Crassostrea/metabolismo , Hemócitos/metabolismo , Homeostase , Concentração de Íons de Hidrogênio , Mitocôndrias , Água do Mar/química
16.
Int J Mol Sci ; 22(9)2021 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33919137

RESUMO

Introduction of C4 photosynthetic traits into C3 crops is an important strategy for improving photosynthetic capacity and productivity. Here, we report the research results of a variant line of sorghum-rice (SR) plant with big panicle and high spikelet density by introducing sorghum genome DNA into rice by spike-stalk injection. The whole-genome resequencing showed that a few sorghum genes could be integrated into the rice genome. Gene expression was confirmed for two C4 photosynthetic enzymes containing pyruvate, orthophosphate dikinase and phosphoenolpyruvate carboxykinase. Exogenous sorghum DNA integration induced a series of key traits associated with the C4 pathway called "proto-Kranz" anatomy, including leaf thickness, bundle sheath number and size, and chloroplast size in bundle sheath cells. Significantly, transgenic plants exhibited enhanced photosynthetic capacity resulting from both photosynthetic CO2-concentrating effect and improved energy balance, which led to an increase in carbohydrate levels and productivity. Furthermore, such rice plant exhibited delayed leaf senescence. In summary, this study provides a proof for the feasibility of inducing the transition from C3 leaf anatomy to proto-Kranz by spike-stalk injection to achieve efficient photosynthesis and increase productivity.


Assuntos
Oryza/fisiologia , Fotossíntese , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Sorghum/fisiologia , Dióxido de Carbono/metabolismo , Genoma de Planta , Oryza/anatomia & histologia , Oryza/genética , Folhas de Planta/anatomia & histologia , Folhas de Planta/genética , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/anatomia & histologia , Plantas Geneticamente Modificadas/genética , Sorghum/anatomia & histologia , Sorghum/genética
17.
Int J Mol Sci ; 22(6)2021 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-33799806

RESUMO

Carbonic anhydrases (CAs) have been identified as ideal catalysts for CO2 sequestration. Here, we report the sequence and structural analyses as well as the molecular dynamics (MD) simulations of four γ-CAs from thermophilic bacteria. Three of these, Persephonella marina, Persephonella hydrogeniphila, and Thermosulfidibacter takaii originate from hydrothermal vents and one, Thermus thermophilus HB8, from hot springs. Protein sequences were retrieved and aligned with previously characterized γ-CAs, revealing differences in the catalytic pocket residues. Further analysis of the structures following homology modeling revealed a hydrophobic patch in the catalytic pocket, presumed important for CO2 binding. Monitoring of proton shuttling residue His69 (P. marina γ-CA numbering) during MD simulations of P. hydrogeniphila and P. marina's γ-CAs (γ-PhCA and γ-PmCA), showed a different behavior to that observed in the γ-CA of Escherichia coli, which periodically coordinates Zn2+. This work also involved the search for hotspot residues that contribute to interface stability. Some of these residues were further identified as key in protein communication via betweenness centrality metric of dynamic residue network analysis. T. takaii's γ-CA showed marginally lower thermostability compared to the other three γ-CA proteins with an increase in conformations visited at high temperatures being observed. Hydrogen bond analysis revealed important interactions, some unique and others common in all γ-CAs, which contribute to interface formation and thermostability. The seemingly thermostable γ-CA from T. thermophilus strangely showed increased unsynchronized residue motions at 423 K. γ-PhCA and γ-PmCA were, however, preliminarily considered suitable as prospective thermostable CO2 sequestration agents.


Assuntos
Proteínas de Bactérias/metabolismo , Biomineralização , Dióxido de Carbono/metabolismo , Anidrases Carbônicas/metabolismo , Sequência de Aminoácidos , Bactérias/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Dióxido de Carbono/química , Anidrases Carbônicas/química , Anidrases Carbônicas/genética , Catálise , Domínio Catalítico , Simulação por Computador , Fontes Termais/microbiologia , Fontes Hidrotermais/microbiologia , Simulação de Dinâmica Molecular , Conformação Proteica , Homologia de Sequência de Aminoácidos , Temperatura , Thermus thermophilus/enzimologia
18.
Scand J Med Sci Sports ; 31(7): 1574-1578, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33793972

RESUMO

This study assessed cardiorespiratory fitness (CRF) and 24-h sleep, sedentary behavior (SB), and physical activity (PA) in Australian truck drivers. Participants (n = 37 men) attended clinic sessions for an exercise test to exhaustion to establish CRF and wore an accelerometer (Actigraph GT3X+) to estimate sleep, SB, and PA. Relative to normative values, CRF was "below percentile 25" in 51% of drivers (mean [SD] VO2peak=30 .1 [7.6] mL.kg-1.min-1). Accelerometer data indicated that total vigorous-intensity (3.5-4.5 min/day) and sustained moderate- to vigorous-intensity PA (>5 min; 0.5-1.6 bouts/day) were limited. The findings show there is a need to design and test PA interventions that can improve poor levels of CRF in truck drivers.


Assuntos
Condução de Veículo , Aptidão Cardiorrespiratória , Exercício Físico , Consumo de Oxigênio/fisiologia , Comportamento Sedentário , Sono , Acelerometria , Austrália , Dióxido de Carbono/metabolismo , Teste de Esforço , Humanos , Masculino , Pessoa de Meia-Idade , Veículos Automotores , Fatores de Tempo
20.
Appl Physiol Nutr Metab ; 46(7): 693-703, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33901405

RESUMO

Face masks are promoted for preventing spread of viruses; however, wearing a mask during exercise might increase CO2 rebreathing, decrease arterial oxygenation, and decrease exercise performance. A systematic review and meta-analysis was conducted on the impact of wearing a mask during exercise. Data sources included SPORTDiscus, PubMed, and Medline. Eligibility criteria included all study designs comparing surgical, N95, or cloth masks to a no mask condition during any type of exercise where exercise performance and/or physiological parameters were evaluated. Healthy and clinical participants were included. Mean differences (MD) or standardized mean differences (SMD) with 95% confidence intervals were calculated and pooled effects assessed. Twenty-two studies involving 1573 participants (620 females, 953 males) were included. Surgical, or N95 masks did not impact exercise performance (SMD -0.05 [-0.16, 0.07] and -0.16 [-0.54, 0.22], respectively) but increased ratings of perceived exertion (SMD 0.33 [0.09, 0.58] and 0.61 [0.23, 0.99]) and dyspnea (SMD 0.6 [0.3, 0.9] for all masks). End-tidal CO2 (MD 3.3 [1.0, 5.6] and 3.7 [3.0, 4.4] mm Hg), and heart rate (MD 2 [0,4] beats/min with N95 masks) slightly increased. Face masks can be worn during exercise with no influences on performance and minimal impacts on physiological variables. PROSPERO registration: CRD42020224988. Novelty: Face masks can be worn during exercise with no impacts on performance and minimal impacts on physiological variables.


Assuntos
COVID-19/prevenção & controle , Exercício Físico/fisiologia , Máscaras/estatística & dados numéricos , Respiradores N95/estatística & dados numéricos , Desempenho Físico Funcional , Dióxido de Carbono/metabolismo , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , SARS-CoV-2
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