RESUMO
Glyphosate, a commonly used organophosphorus herbicide in rice-crayfish cropping regions, may alter regional phosphorus cycle processes while affecting the structure of microbial communities. However, the effects of glyphosate residues on rice-crayfish systems remain unclear. In this study, we assessed the spatial and temporal distribution characteristics of glyphosate and its primary degradation products, as well as the impact mechanisms of glyphosate on microbial communities and the phosphorus cycle in rice-crayfish systems such as paddy fields, breeding ditches and recharge rivers. The detection rates of glyphosate and aminomethylphosphonic acid (AMPA) were 100% in rice-crayfish systems. Concentrations of glyphosate in the water phase and soil/sediment were as high as 0.012 µg/L and 7.480 µg/kg, respectively, and concentrations of AMPA were as high as 17.435 µg/L and 13.200 µg/kg, respectively. Glyphosate concentrations were not affected by rainfall or sampling site, but concentrations of AMPA in the water phase of recharge rivers were affected by rainfall. The glyphosate concentration was significantly and positively correlated with RBG-16-58-14 abundance, and the AMPA concentration was significantly and positively correlated with Actinobacteria and Lysobacter abundance, and negatively correlated with Cyanobacteria abundance (P < 0.05). The highest abundances of phoD, phnK, and ppx genes were found in all soils/sediments. Glyphosate concentration in soil/sediment was significantly and positively correlated with the abundance of phoD gene encoding an organophosphorus-degrading enzyme and ppx gene encoding poly inorganic phosphate (Pi) hydrolase (P < 0.05). In addition, the glyphosate concentration was significantly and positively correlated with the Ca-bonded Pi content (P < 0.05). This implies that glyphosate may promote the production of stable Pi in rice-crayfish systems by increasing the abundance of phoD and ppx genes. The results of this study reveal the impact mechanism of glyphosate on the phosphorus cycle in rice-crayfish systems and provide a basis for the risk assessment of glyphosate.
RESUMO
Accelerated eutrophication in lakes reduces the number of submerged macrophytes and alters the residues of glyphosate and its degradation products. However, the effects of submerged macrophytes on the fate of glyphosate remain unclear. We investigated eight lakes with varying trophic levels along the middle and lower reaches of the Yangtze River in China, of which five lakes contained either glyphosate or aminomethylphosphate (AMPA). Glyphosate and AMPA residues were significantly positively correlated with the trophic levels of lakes (P < 0.01). In lakes, glyphosate is degraded through the AMPA and sarcosine pathways. Eight shared glyphosate-degrading enzymes and genes were observed in different lake sediments, corresponding to 44 degrading microorganisms. Glyphosate concentrations in sediments were significantly higher in lakes with lower abundances of soxA (sarcosine oxidase) and soxB (sarcosine oxidase) (P < 0.05). In the presence of submerged macrophytes, oxalic and malonic acids secreted by the roots of submerged macrophytes increased the abundance of glyphosate-degrading microorganisms containing soxA or soxB (P < 0.05). These results revealed that a decrease in the number of submerged macrophytes in eutrophic lakes may inhibit glyphosate degradation via the sarcosine pathway, leading to a decrease in glyphosate degradation and an increase in glyphosate residues.
Assuntos
Lagos , Sarcosina , Lagos/química , Sarcosina Oxidase , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico , Exsudatos e Transudatos , China , Eutrofização , GlifosatoRESUMO
Eutrophication is a severe worldwide concern caused by excessive phosphorus release. Thus, significant efforts have been made to develop phosphorus removal techniques, particularly by nanomaterial adsorption. However, because of the limitations associated with nanoparticles including easy agglomeration, and separation challenges, a novel nanocomposite adsorbent with great adsorption performance is urgently required. A sponge adsorbent (MS-CMC@La) was developed in this study to remove phosphorus using melamine sponge (MS), LaCl3, and sodium carboxymethyl cellulose (CMC). The results of SEM/EDS, FTIR, and XPS demonstrated that La was well-dispersed on MS-CMC@La. Adsorption isotherm and kinetics met with the Langmuir model (R2 = 0.981) and the pseudo-second-order kinetics (R2 = 0.989), respectively. The maximum adsorption capacity of MS-CMC@La was found to be 15.28 mg/g; the material exhibited excellent selectivity toward phosphorus in the presence of coexisting anion except of F-; the adsorption behavior was greatly impacted by pH. Furthermore, the electrostatic attraction, ligand exchange and inner-sphere coordination regulate the phosphate adsorption mechanism, with inner-sphere coordination dominating. In summary, the nano-enriched materials developed in this study are capable of facilitating the application of functionalized sponges in the field of wastewater.
Assuntos
Lantânio , Poluentes Químicos da Água , Fósforo , Fosfatos , Águas Residuárias , Adsorção , Cinética , Concentração de Íons de HidrogênioRESUMO
Microplastics (MPs) are persistent organic pollutants globally, with a continuous increase in MP wastes near and away from the regions of human activities. Studies to date aimed to explore the impact of MPs on ecosystems, but the area of research could not go beyond environmental pollution caused by MPs. To address the menace of MPs, scientists need to pay enough attention to the biogeochemical cycles, microbial communities, and functional microorganisms. Hence, this study aimed to evaluate the impact of adding 0.3% (mass ratio) [low-concentration (LC) group] and 1% [high-concentration (HC) group] of polyamide (PA) MP to the soil microenvironment with regard to the aforementioned parameters. PA MP decreased the soil microbial diversity (Shannon and Simpson indices, P < 0.05). At the phylum level, PA MP increased the abundance of Acidobacteria, Firmicutes, and Crenarchaeota (P < 0.05); at the genus level, it enhanced that of Geobacter, Thiobacillus, Pseudomonas, and Bradyrhizobium (P < 0.01) while decreased that of Bacillus, Flavisolibacter, Geothrix, and Pseudarthrobacter (P < 0.05). PA MP affected the carbon (C) cycle. PA MP accelerated the soil C fixation by enhancing the abundance of the genes accA and pccA. The LC PA MP accelerated organic C degradation and methane metabolism by changing the abundance of mnp, chiA, mcrA, pmoA, and mmoX genes, while the HC PA MP inhibited them with increasing the experimental time. Regarding the effects of PA on the nitrogen (N) cycle, the PA MP promoted N assimilation and ammonification by increasing the abundance of the genes gdh and ureC, the impact of PA MP on N fixation and denitrification depended on its concentration and treating time. This study showed that PA MP impacted the microbial consortium, it also affected the C and N cycles and its effect depended on its concentration and the treating time.
Assuntos
Microbiota , Microplásticos , Humanos , Solo/química , Plásticos/farmacologia , Nylons , Carbono/farmacologia , Consórcios Microbianos , Ciclo do NitrogênioRESUMO
A novel adsorbent (FeOOH@PU) for hexavalent chromium [Cr(VI)] removal was synthesized using a polyurethane foam (PU) and FeOOH via a facile one-step method. Scanning electron microscopy (SEM), FTIR, X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopy (EDS) characterized the adsorbent. The influence of environmental factors was investigated to evaluate the adsorption behavior for Cr(VI). Furthermore, adsorption dynamic and adsorption isotherm models described the adsorption performance. This adsorbent also treated electroplating wastewater and remediated simulated Cr(VI) contaminated soil. The adsorbent effectively removed Cr(VI) with a high adsorption rate; its equilibrium rate constant was 13 times that of FeOOH. Cr(VI) removal was a monolayer adsorption process and the maximum adsorption capacity of FeOOH@PU reached 34.9 mg Cr/g. Electrostatic attraction was the mechanism of Cr(VI) removal. Electroplating wastewater became clear and the Cr(VI) concentration decreased from 9.76 to 0.042 mg/L after treatment with FeOOH@PU. Cr enrichment in rice seedlings grown in remediated soil decreased from 7.687 to 6.295 mg Cr/kg. These results suggested that FeOOH@PU was a promising adsorbent for Cr(VI) removal and Cr(VI) stabilization.
Assuntos
Águas Residuárias , Poluentes Químicos da Água , Cromo/química , Microscopia Eletrônica de Varredura , Adsorção , Poluentes Químicos da Água/análise , Cinética , Concentração de Íons de HidrogênioRESUMO
Glyphosate and its metabolite aminomethylphosphonic acid (AMPA) draw great concern due to their potential threat to aquatic ecosystems. The individual and combined effects of glyphosate and AMPA on aquatic plants in different ecological niches need to be explored. This study aimed to investigate the ecotoxicity of glyphosate and AMPA on the emergent macrophyte Acorus calamus, phytoplankton Chlorella vulgaris, and submerged macrophyte Vallisneria natans after their exposure to glyphosate and AMPA alone and to their mixture. Medium and low concentrations of glyphosate (≤ 0.5 mg L-1) significantly inhibited the growth of V. natans and promoted the growth of C. vulgaris (P < 0.05) but had no significant effect on the growth of A. calamus (P > 0.05). AMPA (≤ 5.0 mg L-1) did not significantly influence the relative growth rate (except C. vulgaris) or malonaldehyde levels but significantly altered the expression levels of chlorophyll-related genes and superoxide dismutase [Cu-Zn] genes in the aquatic plants examined. AMPA mainly affected the oxidative phosphorylation pathway in V. natans and not those in other two plants, indicating that V. natans was more sensitive to AMPA-induced oxidative damage. Moreover, antagonistic effects on plant growth were observed when plants were exposed to low concentrations of glyphosate + AMPA (≤ 0.1 + 0.1 mg L-1). When the concentration of glyphosate + AMPA reached 0.5 + 0.5 and 5.0 + 5.0 mg L-1, the growth of the submerged macrophyte was additively or synergistically inhibited, but the growth of the emergent macrophyte and phytoplankton was antagonistically inhibited. Our results indicated that both the individual and combined effects of glyphosate and AMPA might alter the vertical structure of shallow lakes and accelerate the conversion of shallow lakes from grass-based to algal-based lakes.
Assuntos
Chlorella vulgaris , Herbicidas , Herbicidas/toxicidade , Ecossistema , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico , Plantas , Fitoplâncton , GlifosatoRESUMO
Pseudomonas sp. Y-5, a strain with simultaneous nitrification and denitrification (SND) capacity, was isolated from the Wuhan Municipal Sewage Treatment Plant. This strain could rapidly remove high concentrations of inorganic nitrogen. Specifically, Pseudomonas sp. Y-5 removed 103 mg/L of NH4+-N in 24 h without nitrate or nitrite accumulation when NH4+-N was its sole nitrogen source. The NH4+-N removal efficiency (RE) was 97.26%, and the average removal rate (RR) was 4.30 mg/L/h. Strain Y-5 also removed NO3--N and NO2--N even in aerobic conditions, with average RRs of 4.39 and 4.23 mg/L/h, respectively, and REs of up to 99.34% and 95.81% within 24 h. When cultured in SND medium (SNDM-1), strain Y-5 achieved an NH4+-N RE of up to 97.80% and a total nitrogen (TN) RE of 93.01%, whereas NO3--N was fully depleted in 48 h. Interestingly, high nitrite concentrations did not inhibit the nitrification capacity of Y-5 when grown in SNDM-2, the RE of NH4+-N and TN reached 96.29% and 94.26%, respectively, and nitrite was consumed completely. Strain Y-5 also adapted well to high concentrations of ammonia (~401.68 mg NH4+-N/L) or organic nitrogen (~315.12 mg TN/L). Our results suggested that Pseudomonas sp. Y-5 achieved efficient simultaneous nitrification and denitrification, thus demonstrating its potential applicability in the treatment of nitrogen-polluted wastewater.
Assuntos
Nitrificação , Nitrogênio , Aerobiose , Amônia , Desnitrificação , Processos Heterotróficos , Nitratos , Nitritos , Dióxido de Nitrogênio , Pseudomonas , Esgotos , Águas ResiduáriasRESUMO
Microplastics (MPs) are ubiquitous in farmland soils. However, few studies have evaluated their effects on the microbial community structure and nitrogen cycle of farmland soils. Here, 0.3% and 1% (mass percentage) of polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polylactic acid (PLA) MPs were added to paddy soil to evaluate their impact on the paddy soil microenvironment. The alpha index of the PLA MP treatment was significantly different from that of the control group (p-value < 0.05). In contrast, the indices of the PET and PVC MP treatments were not different from the control (p-value > 0.05). Among the MP treatments, the alpha index of the PLA MP group was significantly different from the PET and PVC MP groups (p-value < 0.05). PCoA analysis also indicated that there were differences between PLA and other MP groups, and different MP concentrations and exposure times had a great impact on microbial composition. The three MPs affected NH4+ metabolism by changing the abundance of a NH2OH-forming gene (amoA) and an organic nitrogen-forming gene (gdh), as well as the abundances of Thiobacillus, Bradyrhizobium, Anaeromyxobacter, Geobacter, and Desulfobacca. Further, the MPs affected NO3- metabolism by regulating the abundance of the nirS and nirK genes and the abundance of Nitrospirae. In contrast, NO2- metabolism was not significantly affected by the MPs due to the low concentration of NO2-, which was attributed to the high abundance of nirS and nirK in the sample. Taken together, our findings indicated that MP addition may have an inhibitory effect on the nitrogen cycle in paddy soils and that the effect of degradable MPs may be greater than that of their non-degradable counterparts. Given the increasing severity of worldwide MP contamination, additional studies are required to assess their impact on global ecosystems and biogeochemical cycles.
Assuntos
Microbiota , Solo , Microplásticos , Ciclo do Nitrogênio , Plásticos , Microbiologia do SoloRESUMO
The accumulation of atrazine in sediments raises wide concern due to its potential negative effects on aquatic environments. Here we collected sediments and different submerged macrophytes to simulate natural shallow lakes and to measure atrazine levels and submerged macrophyte biomass. We determined gene expressions in submerged macrophytes treated with or without atrazine. We also examined atrazine concentrations and its metabolite structures in submerged macrophytes. When the initial concentration of atrazine in sediments ranged from 0.1 to 2.0 mg kg-1 dry weight (DW), atrazine levels in the pore water of the sediments ranged from 0.003 to 0.05 mg L-1 in 90 days. Atrazine did not show obvious long-term effects on the biomass of Potamogeton crispus and Myriophyllum spicatum (P > 0.05). On day 90, gene expressions related to cell wall in P. crispus were changed by atrazine phytotoxicity. Moreover, the decrease in the number genes controlling light-harvesting chlorophyll a/b-binding proteins verified the toxic effects of atrazine on the photosynthesis of M. spicatum. Compared with unexposed plants on day 90, ribosome pathway was significantly enriched with differentially expressed genes after submerged macrophytes were exposed to 2.0 mg kg-1 DW atrazine (P < 0.05). In addition, shoots and roots of P. crispus and M. spicatum could absorb the equal amount of atrazine (P > 0.05). Once absorbed by submerged macrophytes, atrazine was degraded into 1-hydroxyisopropylatrazine, hydroxyatrazine, deethylatrazine, didealkylatrazine, cyanuric acid, and biuret, and some of its metabolites could conjugate with organic acids, cysteinyl ß-alanine, and glucose. This study establishes a foundation for aquatic ecological risk assessments and the phytoremediation of atrazine in sediments.
Assuntos
Atrazina , Potamogetonaceae , Atrazina/toxicidade , Clorofila A , Lagos , TranscriptomaRESUMO
The halophilic archaea (haloarchaea) live in hyersaline environments such as salt lakes, salt ponds and marine salterns. To cope with the salt stress conditions, haloarchaea have developed two fundamentally different strategies: the "salt-in" strategy and the "compatible-solute" strategy. Although investigation of the molecular mechanisms underlying the tolerance to high salt concentrations has made outstanding achievements, experimental study from the aspect of transcription is rare. In the present study, we monitored cellular physiology of Natrinema sp. J7-2 cells incubated in different salinity media (15%, 25% and 30% NaCl) from several aspects, such as cellular morphology, growth, global transcriptome and the content of intracellular free amino acids. The results showed that the cells were polymorphic and fragile at a low salt concentration (15% NaCl) but had a long, slender rod shape at high salt concentrations (25% and 30% NaCl). The cells grew best in 25% NaCl, mediocre in 30% NaCl and struggled in 15% NaCl. An RNA-seq analysis revealed differentially expressed genes (DEGs) in various salinity media. A total of 1,148 genes were differentially expressed, consisting of 719 DEGs (348 up-regulated and 371 down-regulated genes) between cells in 15% vs 25% NaCl, and 733 DEGs (521 up-regulated and 212 down-regulated genes) between cells in 25% vs 30% NaCl. Moreover, 304 genes were commonly differentially expressed in both 15% vs 25% and 25% vs30% NaCl. The DEGs were enriched in different KEGG metabolic pathways, such as amino acids, glycerolipid, ribosome, nitrogen, protoporphyrin, porphyrin and porhiniods. The intracellular predominant free amino acids consisted of the glutamate family (Glu, Arg and Pro), aspartate family (Asp) and aromatic amino acids (Phe and Trp), especially Glu and Asp.
Assuntos
Halobacteriaceae/metabolismo , Cloreto de Sódio/farmacologia , Transcriptoma/efeitos dos fármacos , Aminoácidos/metabolismo , Regulação para Baixo/efeitos dos fármacos , Halobacteriaceae/efeitos dos fármacos , Halobacteriaceae/crescimento & desenvolvimento , Microscopia Eletrônica , Porfirinas/metabolismo , RNA/química , RNA/isolamento & purificação , RNA/metabolismo , Análise de Sequência de RNA , Regulação para Cima/efeitos dos fármacosRESUMO
Although viruses of haloarchaea are the predominant predator in hypersaline ecosystem, the culture studies about halovirus-host systems are infancy. The main reason is the tradition methodology (plaque assay) for virus-host interaction depends on culturable and susceptible host. Actually, more than 90% of haloarchaea are unculturable. Therefore, it is necessary to establish an approach for detecting the dynamics of virus in hypersaline environment without culture. In this study, we report a convenient method to determine the dynamics of halovirus SNJ1 based on quantitative real-time PCR (qPCR). All findings showed that the qPCR method was specific (single peak in melt curves), accurate (a good linear relationship between the log of the PFU and the Ct values, R2 = 0.99), reproducible (low coefficient of variations, below 1%). Additionally, the physicochemical characteristics of the samples tested did not influence the stability of qPCR. Therefore, the qPCR method has the potential value in quantifying and surveying haloviruses in halophilic ecological system.
Assuntos
Vírus de DNA/classificação , Vírus de DNA/genética , Reação em Cadeia da Polimerase em Tempo Real , China , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reprodutibilidade dos Testes , Ensaio de Placa Viral , Microbiologia da ÁguaRESUMO
Halovirus is a major force that affects the evolution of extreme halophiles and the biogeochemistry of hypersaline environments. However, until now, the systematic studies on the halovirus ecology and the effects of salt concentration on virus-host systems are lacking. To provide more valuable information for understanding ecological strategies of a virus-host system in the hypersaline ecosystem, we studied the interaction between halovirus SNJ1 and its host Natrinema sp.J7-2 under various NaCl concentrations. We found that the adsorption rate and lytic rate increased with salt concentration, demonstrating that a higher salt concentration promoted viral adsorption and proliferation. Contrary to the lytic rate, the lysogenic rate decreased as the salt concentration increased. Our results also demonstrated that cells incubated at a high salt concentration prior to infection increased the ability of the virus to adsorb and lyse its host cells; therefore, the physiological status of host cells also affected the virus-host interaction. In conclusion, SNJ1 acted as a predator, lysing host cells and releasing progeny viruses in hypersaline environments; in low salt environments, viruses lysogenized host cells to escape the damage from low salinity.
Assuntos
DNA Viral/genética , Euryarchaeota/efeitos dos fármacos , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Vírus não Classificados/efeitos dos fármacos , Replicação do DNA/efeitos dos fármacos , DNA Viral/metabolismo , Ecossistema , Euryarchaeota/ultraestrutura , Euryarchaeota/virologia , Lisogenia/efeitos dos fármacos , Salinidade , Vírus não Classificados/crescimento & desenvolvimento , Vírus não Classificados/patogenicidadeRESUMO
A temperate haloarchaeal virus, SNJ1, was induced from the lysogenic host, Natrinema sp. J7-1, with mitomycin C, and the virus produced plaques on lawns of Natrinema sp. J7-2. Optimization of the induction conditions allowed us to increase the titer from ~10(4) PFU/ml to ~10(11) PFU/ml. Single-step growth curves exhibited a burst size of ~100 PFU/cell. The genome of SNJ1 was observed to be a circular, double-stranded DNA (dsDNA) molecule (16,341 bp). Surprisingly, the sequence of SNJ1 was identical to that of a previously described plasmid, pHH205, indicating that this plasmid is the provirus of SNJ1. Several structural protein-encoding genes were identified in the viral genome. In addition, the comparison of putative packaging ATPase sequences from bacterial, archaeal and eukaryotic viruses, as well as the presence of lipid constituents from the host phospholipid pool, strongly suggest that SNJ1 belongs to the PRD1-type lineage of dsDNA viruses, which have an internal membrane.
Assuntos
Vírus de Archaea/genética , DNA Viral/genética , DNA/genética , Genoma Viral , Halobacteriaceae/virologia , Provírus/genética , Sequência de Aminoácidos , DNA Circular/genética , Ordem dos Genes , Dados de Sequência Molecular , Fases de Leitura Aberta , Plasmídeos , Análise de Sequência de DNA , Carga Viral , Ensaio de Placa Viral , Proteínas Virais/genética , Ativação ViralRESUMO
Halophage SNJ1 was induced with mitomycin C from Natrinema sp. strain F5. The phage produces plaques on Natrinema sp. strain J7 only. The phage has a head of about 67 nm in diameter and a tail of 570 nm in length and belongs morphologically to the family Siphoviridae. The phage is strongly salt dependent; NaCl concentration affects the integrity of SNJ1, phage adsorption, and plaque formation. The optimal NaCl concentration for phage adsorption and plaque formation is 30% and 25%, respectively.
Assuntos
Vírus de Archaea , Halobacteriaceae/virologia , Lisogenia/fisiologia , Siphoviridae , Ativação Viral/fisiologia , Vírus de Archaea/classificação , Vírus de Archaea/fisiologia , Vírus de Archaea/ultraestrutura , Mitomicina/farmacologia , Siphoviridae/classificação , Siphoviridae/fisiologia , Siphoviridae/ultraestrutura , Cloreto de Sódio/farmacologia , Ensaio de Placa ViralRESUMO
Homologous recombination (HR) was found to be so frequent in haloarchaea that its significance in evolution and diversity of this clade of life might have been underestimated. However, so far there has been no report on recombination function carried on plasmid. Here we report that a 4.8-kb SnaBI-PvuII digested segment from pHH205 might carry such a function. Four constructed plasmids: pUN, pUN-205, pUM and pUM-205, with pUN and pUN205 containing Nov(R) gene, pUM and pUM-205 carrying Mev(R) gene, were used to transform Haloferax volcanii DS52 (radA(-)). The results showed that only pUN-205 and pUM-205 containing the 4.8-kb SnaBI-PvuII digested segment from pHH205 were able to shift Nov(R) and Mev(R) gene into the chromosome of Haloferax volcanii DS52 through HR, whereas those in pUN and pUM could not, which indicated that the segment from pHH205 does contain a recombination function.
Assuntos
Genes Arqueais , Haloferax volcanii/genética , Plasmídeos/genética , Recombinação Genética , Cromossomos de Archaea , Halobacterium salinarum/genética , Plasmídeos/isolamento & purificação , Transformação GenéticaRESUMO
Autofluorescence has an advantage over the extrinsic fluorescence of an unperturbed environment during investigation, especially in complex system such as biological cells and tissues. NADH is an important fluorescent substance in living cells. The time courses of intracellular NADH autofluorescence in the process of yeast cells exposed to H(2)O(2) and ONOO(-) have been recorded in detail in this work. In the presence of different amounts of H(2)O(2) and ONOO(-), necrosis, apoptosis and reversible injury are initiated in yeast cells, which are confirmed by acridine orange/ethidum bromide and Annexin V/propidium iodide staining. It is found that intracellular NADH content increases momently in the beginning of the apoptotic process and then decreases continually till the cell dies. The most remarkable difference between the apoptotic and the necrotic process is that the NADH content in the latter case changes much more sharply. Further in the case of reversible injury, the time course of intracellular NADH content is completely different from the above two pathways of cell death. It just decreases to some degree firstly and then resumes to the original level. Based on the role of NADH in mitochondrial respiratory chain, the time course of intracellular NADH content is believed to have reflected the response of mitochondrial redox state to oxidative stress. Thus, it is found that the mitochondrial redox state changes differently in different pathways of oxidative injury in yeast cells.
Assuntos
NAD/química , Estresse Oxidativo , Saccharomyces cerevisiae/metabolismo , Apoptose , Fluorescência , Peróxido de Hidrogênio/toxicidade , Mitocôndrias/metabolismo , Modelos Biológicos , Oxirredução , Espécies Reativas de Oxigênio/toxicidade , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/efeitos dos fármacos , Superóxidos/toxicidadeRESUMO
A novel transformation system, in which neither a nonphysiological concentration of Ca2+ and temperature shifts nor electronic shocks were required, was developed to determine whether Escherichia coli is naturally transformable. In the new protocol, E. coli was cultured normally to the stationary phase and then cultured statically at 37 degrees C in Luria-Bertani broth. After static culture, transformation occurred in bacteria spread on Luria-Bertani plates. The protein synthesis inhibitor chloramphenicol inhibited this transformation process. The need for protein synthesis in plated bacteria suggests that the transformation of E. coli in this new system is regulated physiologically.