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1.
Ecotoxicol Environ Saf ; 205: 111131, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32827964

RESUMO

Arsenic (As) is one of the most toxic contaminants to food crops, and as such, decreasing crops uptake and accumulation of As cannot be overemphasized. Here, we characterized a functional wheat NIP2;1 homolog of the As transporter, TaNIP2;1. TaNIP2;1 expression was suppressed by arsenite (As(III)) in wheat. Ectopic expression of TaNIP2;1 in the Δfps1 yeast mutant enhanced yeast sensitivity towards As(III). Conversely, the elevated expression of TaNIP2;1 in Δacr3 mutants decreased yeast sensitivity to arsenate (As(V)), demonstrating that TaNIP2;1 showed both influx and efflux transport activities for As(III) in yeasts. This is further supported by increased As concentration in the yeast cells that overproduce TaNIP2;1 in Δfps1, while As concentration decreased in Δacr3. Furthermore, ectopic expression of TaNIP2;1 in Arabidopsis confirmed that TaNIP2;1 can transport As into plants, as supported by increased sensitivity to and uptake of As(III). No change in plant sensitivity was found to Cu(II), Cd(II), Zn(II) or Ni(II), indicating that transport activity of TaNIP2;1 is specific for As(III). Taken together, our data show that TaNIP2;1 may be involved in As(III) transportation in plants. This finding reveals a functional gene that can be manipulated to reduce As content in wheat.


Assuntos
Aquagliceroporinas/genética , Arabidopsis/efeitos dos fármacos , Arsenitos/toxicidade , Expressão Ectópica do Gene/efeitos dos fármacos , Poluentes do Solo/toxicidade , Triticum/efeitos dos fármacos , Adaptação Fisiológica/efeitos dos fármacos , Aquagliceroporinas/metabolismo , Aquaporinas/genética , Aquaporinas/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arsenitos/metabolismo , Bioacumulação , Transporte Biológico , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/metabolismo , Poluentes do Solo/metabolismo , Triticum/genética , Triticum/metabolismo
2.
Ecotoxicol Environ Saf ; 205: 111175, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32836161

RESUMO

Mangroves are susceptible to contamination due to their proximity to shores and human activities. Exposure to excessive trace metals can disturb their physiological functions and may eventually lead to death. Rhizophora mucronata is a common species growing in the mangrove forests of Thailand. Previous studies have shown that seedlings of R. mucronata are tolerant of trace metal and that they accumulate a large metal content in their root tissue. However, knowledge of their tolerance mechanisms is still lacking. To elicit the role of metal detoxification and sequestration by phytochelatins (PC) in the roots of R. mucronata seedlings, the impacts of Cu and Zn exposure were assessed on 1) physiological characteristics 2) the concentration of glutathione (GSH), a precursor of PC and 3) the level of the transcripts encoding phytochelatin synthase (PCS), the key enzyme for PC biosynthesis. Seedlings of R. mucronata were exposed to Cu and Zn in a hydroponic experiment (200 mg Cu or Zn/L in 1/4× Hoagland solution containing 8‰ NaCl, single addition). We found that both trace metals were largely accumulated in the roots. Only Cu-treated seedlings showed a decrease in the photosynthetic efficiency, in line with observed toxicity symptoms (i.e. bent stems and slight wilting of leaves). Metal accumulation, however, did not induce oxidative stress in the roots as indicated by similar level of total reactive species and lipid peroxidation across treatments. The GSH content in the roots exposed to Cu was significantly reduced while no change was observed in Zn-exposed roots. Coordinated semi-quantitative PCR and RT-qPCR revealed pcs down-regulation in Cu-treated roots, whereas Zn-treated roots showed a down-regulation on day 1 and a subsequent recovery on day 5. Failure of detoxification and sequestration of excess Cu due to GSH limitation and down-regulation of pcs may lead to the phytotoxic effects observed in Cu-treated plants. Our results suggest that both GSH and PC play an important role in trace metal tolerance in R. mucronata seedlings.


Assuntos
Aminoaciltransferases/genética , Cobre/toxicidade , Glutationa/metabolismo , Rhizophoraceae/efeitos dos fármacos , Oligoelementos/metabolismo , Zinco/toxicidade , Adaptação Fisiológica/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Rhizophoraceae/genética , Rhizophoraceae/metabolismo , Plântula/efeitos dos fármacos , Plântula/genética , Plântula/metabolismo
3.
Ecotoxicol Environ Saf ; 205: 111152, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32846297

RESUMO

Root exudates are the most direct manifestation of the response of plants changes in the external environment. Therefore, based on non-targeted gas chromatography-time-of-flight mass spectrometry and metabolomics, the response of Sedum plumbizincicola root exudates to Cd stress was used to reveal the possible mechanism of resistance to or accumulation of Cd. The results showed that Cd significantly changed the composition and contents of S. plumbizincicola root exudates. A total of 155 metabolites were identified in S. plumbizincicola root exudates, among which 33 showed significant differences under Cd stress, including organic acids, amino acids, lipids, and polyols. Cd stress suppressed organic acid metabolism and lipid metabolism in S. plumbizincicola and significantly affected amino acid metabolism. There were 16 metabolic pathways related to Cd stress, among which arginine and proline metabolism, valine, leucine, and isoleucine biosynthesis, glycine, serine, and threonine metabolism, glutathione metabolism, and purine metabolism were the key pathways with the highest correlation, and were closely related to the stress resistance of S. plumbizincicola.


Assuntos
Cádmio/toxicidade , Metaboloma/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Exsudatos de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Sedum/efeitos dos fármacos , Poluentes do Solo/toxicidade , Adaptação Fisiológica/efeitos dos fármacos , Bioacumulação/efeitos dos fármacos , Biodegradação Ambiental , Cádmio/metabolismo , Metabolômica , Raízes de Plantas/metabolismo , Sedum/metabolismo , Poluentes do Solo/análise
4.
Aquat Toxicol ; 226: 105584, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32795838

RESUMO

There is increasing evidence about negative effects of fungicides on non-target organisms, including parasitic species, which are key elements in food webs. Previous experiments showed that environmentally relevant concentrations of fungicide tebuconazole are toxic to the microparasite Metschnikowia bicuspidata, a yeast species that infects the planktonic crustacean Daphnia spp. However, due to their short-term nature, this and other experimental studies were not able to test if parasites could potentially adapt to these contaminants. Here, we tested if M. bicuspidata parasite can adapt to tebuconazole selective pressure. Infected D. magna lineages were reared under control conditions (no tebuconazole) and environmentally realistic tebuconazole concentrations, for four generations, and their performance was compared in a follow-up reciprocal assay. Additionally, we assessed whether the observed effects were transient (phenotypic) or permanent (genetic), by reassessing parasite fitness after the removal of selective pressure. Parasite fitness was negatively affected throughout the multigenerational exposure to the fungicide: prevalence of infection and spore load decreased, whereas host longevity increased, in comparison to control (naive) parasite lineages. In a follow-up reciprocal assay, tebuconazole-conditioned (TEB) lineages performed worse than naive parasite lineages, both in treatments without and with tebuconazole, confirming the cumulative negative effect of tebuconazole. The underperformance of TEB lineages was rapidly reversed after removing the influence of the selective pressure (tebuconazole), demonstrating that the costs of prolonged exposure to tebuconazole were phenotypic and transient. The microparasitic yeast M. bicuspidata did not reveal potential for rapid evolution to an anthropogenic selective pressure; instead, the long-term exposure to tebuconazole was hazardous to this non-target species. These findings highlight the potential environmental risks of azole fungicides on non-target parasitic fungi. The underperformance of these microbes and their inability to adapt to such stressors can interfere with the key processes where they intervene. Further research is needed to rank fungicides based on the hazard to non-target fungi (parasites, but also symbionts and decomposers), towards more effective management and protective legislation.


Assuntos
Daphnia/efeitos dos fármacos , Fungicidas Industriais/toxicidade , Metschnikowia/efeitos dos fármacos , Modelos Biológicos , Triazóis/toxicidade , Poluentes Químicos da Água/toxicidade , Adaptação Fisiológica/efeitos dos fármacos , Animais , Daphnia/microbiologia , Interações entre Hospedeiro e Microrganismos/efeitos dos fármacos , Metschnikowia/crescimento & desenvolvimento
5.
Ecotoxicol Environ Saf ; 204: 111005, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32738624

RESUMO

Freezing temperatures is an important stressor in the arctic regions and has a significant influence on the population dynamics and geographic distribution of terrestrial invertebrates. Toxic metals in the environment can interfere with protective cold-acclimation responses of organisms. It is therefore important to evaluate the combined effects of cold stress and environmental contaminants. Here, we aimed to investigate the effects of Hg (HgCl2) on various physiological aspects of freeze-tolerance in the earthworm (Enchytraeus albidus). We measured the levels of the cryoprotectant glucose, the glycogen content (source of glucose molecules for cryoprotection and fuel for metabolism), and changes in the composition of membrane phospholipid fatty acids (PLFA) as an indicator of lipid peroxidation. Freezing at -6 °C had no effect on survival in uncontaminated soil, however, survival of freezing in Hg contaminated soil was clearly reduced, especially at extended exposure times. Thus, the LC50 value in frozen soil decreased from 8.3 mg Hg kg-1 (when exposed for 17 days) to only 4.2 mg Hg kg-1 after 36 days' exposure indicating that combined effects of Hg and freezing became larger at prolonged exposure times. Hg caused a depletion of glycogen reserves (almost 50% at 12 mg kg-1 dry soil), but despite this effect worms were able to maintain a constant cryoprotectant level (about 0.12 mg glucose mg-1 dry weight) at all Hg concentrations. Hg had clear negative effects on the proportion of unsaturated PLFAs, which could be an indication of lipid peroxidation. Since a high proportion of unsaturated fatty acids in the membrane is important for invertebrate freeze-tolerance, our results suggest that the negative effect of Hg on freeze-tolerance in E. albidus is related to degraded membrane functionality at low temperature.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Congelamento , Cloreto de Mercúrio/efeitos adversos , Oligoquetos/efeitos dos fármacos , Animais , Crioprotetores/farmacologia , Relação Dose-Resposta a Droga , Ácidos Graxos/metabolismo , Glucose/farmacologia , Glicogênio/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Mercúrio/efeitos adversos
6.
PLoS One ; 15(7): e0234999, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32702039

RESUMO

Acid adaptation enhances survival of foodborne pathogens under lethal acid conditions that prevail in several food-related ecosystems. In the present study, the role of undissociated acetic acid in inducing acid resistance of Salmonella Enteritidis Phage Type 4 both in laboratory media and in an acid food matrix was investigated. Several combinations of acetic acid (0, 15, 25, 35 and 45 mM) and pH values (4.0, 4.5, 5.0, 5.5, 6.0) were screened for their ability to activate acid resistance mechanisms of pathogen exposed to pH 2.5 (screening assay). Increased survival was observed when increasing undissociated acetic acid within a range of sublethal concentrations (1.9-5.4 mM), but only at pH 5.5 and 6.0. No effect was observed at lower pH values, regardless of the undissociated acetic acid levels. Three combinations (15mM/pH5.0, 35mM/pH5.5, 45mM/pH6.0) were selected and further used for adaptation prior to inoculation in commercial tarama (fish roe) salad, i.e., an acid spread (pH 4.35 ± 0.02), stored at 5°C. Surprisingly and contrary to the results of the screening assay, none of the acid adaptation treatments enhanced survival of Salmonella Enteritidis in the food matrix, as compared to non-adapted cells (control). Further examination of the food pH value, acidulant and storage (challenge) temperature on the responses of the pathogen adapted to 15mM/pH5.0, 35mM/pH5.5 and 45mM/pH6.0 was performed in culture media. Cells adapted to 35mM/pH5.5 were unable to induce acid resistance when exposed to pH 4.35 (tarama salad pH value) at 37°C and 5°C, whereas incubation under refrigeration (5°C) at pH 4.35 sensitized 45mM/pH6.0 adapted cells against the subsequent acid and cold stress. In conclusion, pre-exposure to undissociated acetic acid affected the adaptive responses of Salmonella Enteritidis Phage Type 4 in a concentration- and pH-dependent manner, with regard to conditions prevailing during acid challenge.


Assuntos
Ácido Acético/farmacologia , Adaptação Fisiológica/efeitos dos fármacos , Bacteriófagos , Microbiologia de Alimentos , Salmonella enteritidis/virologia , Ácidos/farmacologia , Animais , Relação Dose-Resposta a Droga , Produtos Pesqueiros/microbiologia , Concentração de Íons de Hidrogênio , Refrigeração
7.
Chemosphere ; 260: 127594, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32673874

RESUMO

Salinization of freshwater ecosystems caused by human activities and climate change is a global problem that threatens freshwater resources and aquatic organisms. The aggravation of salinization and the presence of cyanobacterial blooms may pose a serious threat to crustacean zooplankton Daphnia. To test the consequences of these effects, we exposed Daphnia magna to the combined treatments of different chloride concentrations and three food compositions (100% Chlorella pyrenoidosa, 90% C. pyrenoidosa + 10% toxic Microcystis aeruginosa, 80% C. pyrenoidosa + 20% toxic M. aeruginosa) for 21 days, recorded relevant life history indicators, and fitted them using Sigmoidal and Gaussian model if appropriate. Results showed that both increased chloride and the presence of toxic M. aeruginosa in the food had significantly negative effects on key life history traits and clearance rate, and the two factors also had a significant interaction on the survival, development, and reproduction of D. magna. The maximum values of the key life-history traits and clearance rate, the median effect chloride concentrations, and the optimal chloride concentrations derived from the models showed that the survival, reproduction, and clearance rate of D. magna were threatened by high chloride concentrations, which were exacerbated by the presence of toxic M. aeruginosa, but lower concentration of chloride was beneficial to D. magna to resist toxic M. aeruginosa. In conclusion, the combined effects of increasing chloride concentration and cyanobacterial blooms have severely adverse impacts on cladocerans, which may cause cladocera population to decline more rapidly and potentially disrupt the food webs of aquatic ecosystems.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Daphnia/efeitos dos fármacos , Água Doce/química , Microcystis/crescimento & desenvolvimento , Cloreto de Sódio/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Chlorella/crescimento & desenvolvimento , Daphnia/crescimento & desenvolvimento , Daphnia/fisiologia , Ecossistema , Cadeia Alimentar , Humanos , Traços de História de Vida , Reprodução/efeitos dos fármacos
8.
PLoS Pathog ; 16(7): e1008700, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32687537

RESUMO

With antibiotic resistance rates on the rise, it is critical to understand how microbial species interactions influence the evolution of resistance. In obligate mutualisms, the survival of any one species (regardless of its intrinsic resistance) is contingent on the resistance of its cross-feeding partners. This sets the community antibiotic sensitivity at that of the 'weakest link' species. In this study, we tested the hypothesis that weakest link dynamics in an obligate cross-feeding relationship would limit the extent and mechanisms of antibiotic resistance evolution. We experimentally evolved an obligate co-culture and monoculture controls along gradients of two different antibiotics. We measured the rate at which each treatment increased antibiotic resistance, and sequenced terminal populations to question whether mutations differed between mono- and co-cultures. In both rifampicin and ampicillin treatments, we observed that resistance evolved more slowly in obligate co-cultures of E. coli and S. enterica than in monocultures. While we observed similar mechanisms of resistance arising under rifampicin selection, under ampicillin selection different resistance mechanisms arose in co-cultures and monocultures. In particular, mutations in an essential cell division protein, ftsI, arose in S. enterica only in co-culture. A simple mathematical model demonstrated that reliance on a partner is sufficient to slow the rate of adaptation, and can change the distribution of adaptive mutations that are acquired. Our results demonstrate that cooperative metabolic interactions can be an important modulator of resistance evolution in microbial communities.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Resistência Microbiana a Medicamentos/fisiologia , Escherichia coli/fisiologia , Interações Microbianas/fisiologia , Salmonella enterica/fisiologia , Adaptação Fisiológica/genética , Ampicilina/farmacologia , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Técnicas de Cocultura , Escherichia coli/efeitos dos fármacos , Interações Microbianas/efeitos dos fármacos , Modelos Teóricos , Mutação , Rifampina/farmacologia , Salmonella enterica/efeitos dos fármacos
9.
Ecotoxicol Environ Saf ; 201: 110784, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32485494

RESUMO

Biscutella auriculata L. is one of the rare species that is able to grow in a very contaminated mining area in Villamayor de Calatrava (Ciudad Real, Spain). In an effort to understand the mechanisms involved in the tolerance of this plant to high metal concentrations, we grew B. auriculata in the presence of 125 µM Cd(NO3)2 for 15 days and analysed different parameters associated with plant growth, nitric oxide and reactive oxygen species metabolism, metal uptake and translocation, photosynthesis rate and biothiol (glutathione and phytochelatins) content. Treatment with Cd led to growth inhibition in both the leaves and the roots, as well as a reduction of photosynthetic parameters, transpiration and stomatal conductance. The metal was mainly accumulated in the roots and in the vascular tissue, although most Cd was detected in areas surrounding their epidermal cells, while in the leaves the metal accumulated mainly in spongy mesophyll, stomata and trichrome. Based on the Cd bioaccumulation (5.93) and translocation (0.15) factors, this species denoted enrichment of the metal in the roots and its low translocation to the upper tissues. Biothiol analysis showed a Cd-dependent increase of reduced glutathione (GSH) as well as the phytochelatins (PC2 and PC3) in both roots and leaves. Cd-promoted oxidative damage occurred mainly in the leaves due to disturbances in enzymatic and nonenzymatic antioxidants, while the roots did not show significant damage as a result of induction of antioxidant defences. It can be concluded that B. auriculata is a new Cd-tolerant plant with an ability to activate efficient metal-sequestering mechanisms in the root surface and leaves and to induce PCs, as well as antioxidative defences in roots.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Brassicaceae/efeitos dos fármacos , Cádmio/toxicidade , Mineração , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Brassicaceae/metabolismo , Cádmio/metabolismo , Glutationa/metabolismo , Modelos Teóricos , Oxirredução , Fotossíntese/efeitos dos fármacos , Fitoquelatinas/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo , Espanha
10.
Ecotoxicol Environ Saf ; 201: 110855, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32540620

RESUMO

Total dissolved gas (TDG) supersaturation generated by discharged flood water may cause the death of fish downstream of dams and severely threaten their survival during the flood season. No study has performed to investigate the effects of TDG on fish dwelling in shallows in China. Furthermore, varied TDG levels are caused by the varied flow of flood water during the spill season. Fish may alternatingly experience intermittent TDG exposure from equilibrated water and TDG-supersaturated water. However, little research on the effects of intermittent TDG exposure on fish has been conducted. To evaluate the tolerance of fish to continuous acute TDG exposure, juvenile yellow catfish living in the shallows were exposed to TDG-supersaturated water at 125%, 130%, 135% and 140% TDG for 96 h. The results showed that the juvenile yellow catfish exhibited obvious gas bubble disease (GBD) and abnormal behaviours (e.g., exophthalmos and bubbles on fins). The survival probability declined with the arising TDG levels. The median survival time (ST50) of yellow catfish was 8.57, 18.1, 33.86 and 58.84 h at above TDG levels, respectively. To further investigate the effects of intermittent TDG exposure on juvenile yellow catfish, the fish were subjected to varied TDG levels (125%, 130%, 135% and 140%) for a specific duration (3 h and 6 h) and then underwent a period of recovery (3, 6 and 9 h) in equilibrated water. The results showed that an increase in recovery time (or decreasing exposure time) can prolong the survival time of yellow catfish and improve their survival probability at the same exposure time (or same recovery time). Compared with that under continuous acute exposure, the ST50 of juvenile yellow catfish increased significantly with intermittent exposure. Intermittent exposure can enhance the tolerance of juvenile yellow catfish to TDG. The application of the results may contribute to the protection of aquatic organisms and the formulation of the scheme of reservoir operation in the Yangtze River.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Peixes-Gato/fisiologia , Gases/toxicidade , Rios/química , Poluentes da Água/toxicidade , Animais , Comportamento Animal/efeitos dos fármacos , China , Gases/análise , Probabilidade , Análise de Sobrevida , Movimentos da Água , Poluentes da Água/análise , Qualidade da Água
11.
Arch Environ Contam Toxicol ; 79(1): 49-59, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32393992

RESUMO

We present a case study on the tissue absorption of copper of a widely distributed moss species, Ptychostomum capillare in the polluted soil of an abandoned copper mine in central Spain. We studied the soil properties in a copper soil pollution gradient and sampled the moss tufts growing on them in four plots with contrasted soil copper levels. We determined the copper content in the soil and in the moss tissues. On these moss samples, we also performed histochemical tests and X-ray dispersive spectrometry coupled with scanning electron microscopy (SEM-EDX), both in untreated shoots and in samples where surface waxes were removed. We checked the behavior of this species using a metallophillous moss, Scopelophila cataractae, for comparative purposes. Copper contents in P. capillare seem to depend more on available, rather than total soil copper contents. Our results indicate that this moss is able to concentrate 12-fold the available soil copper in soil with low available copper content, whereas in the most polluted soil the concentration of Cu in the moss was only half those levels. Both histochemical and SEM-EDX tests show no surface copper in the mosses from the least polluted plot, whereas in samples from the soil with highest copper content, the removal of surface waxes also reduces or removes copper from the moss shoots. Our observations point at a mixed strategy in P. capillare in this copper mine, with metal accumulation behavior in the lowest Cu plot, and an exclusion mechanism involving wax-like substances acting as a barrier in the most polluted plots. These distortions impede the estimation of environmental levels and thus compromise the value of this moss in biomonitoring. We highlight the need of extending these studies to other moss species, especially those used in biomonitoring programs.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Bryopsida/química , Cobre/análise , Monitoramento Ambiental/métodos , Mineração , Poluentes do Solo/análise , Solo/química , Espanha
12.
Ecotoxicol Environ Saf ; 200: 110760, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32454265

RESUMO

An optimal uptake of mineral elements is crucial to ensure both crop yield and quality. The use of biostimulants is taking relevance to improve the nutrition of crops. Sulphur (S) is one of the elements with great potential within biostimulants. Furthermore, soil contamination by heavy metals such as cadmium (Cd) has become a serious environmental problem. Different studies have suggested the use of thiosulphate (TS) as a biostimulant and to increase the phytoremediation capacity of plants. Therefore, in the present study, we use a crop plant with high S requirements such as Brassica oleracea, to test whether TS serves as a biostimulant and whether affects Cd accumulation and tolerance. B. oleracea plants were grown with two different TS doses (2 mM and 4 mM), under Cd toxicity, and with the combination of Cd toxicity and both TS doses. Parameters of biomass, mineral elements accumulation, and stress tolerance were analyzed. The results showed that TS reduced biomass of B. oleracea plants. The application of 2 mM TS increased Cd accumulation whereas the 4 mM dose reduced it. On the other hand, TS incremented micronutrient accumulation on plants subjected to Cd toxicity and increased Zn contents. Besides, the application of 2 mM to Cd-stressed plants enhanced photosynthesis performance and reduced oxidative stress. Finally, TS increased the antioxidant capacity of B. oleracea plants. Briefly, although TS can not be used as a biostimulant it could be used for Cd phytoremediation purposes and to enhance Zn accumulation in B. oleracea plants.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Bioacumulação , Brassica/efeitos dos fármacos , Cádmio/toxicidade , Poluentes do Solo/toxicidade , Tiossulfatos/farmacologia , Antioxidantes/metabolismo , Biodegradação Ambiental , Biomassa , Brassica/metabolismo , Cádmio/metabolismo , Produtos Agrícolas , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Poluentes do Solo/metabolismo
13.
PLoS Pathog ; 16(5): e1008431, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32379814

RESUMO

Bacteria are well known for their extremely high adaptability in stressful environments. The clinical relevance of this property is clearly illustrated by the ever-decreasing efficacy of antibiotic therapies. Frequent exposures to antibiotics favor bacterial strains that have acquired mechanisms to overcome drug inhibition and lethality. Many strains, including life-threatening pathogens, exhibit increased antibiotic resistance or tolerance, which considerably complicates clinical practice. Alarmingly, recent studies show that in addition to resistance, tolerance levels of bacterial populations are extremely flexible in an evolutionary context. Here, we summarize laboratory studies providing insight in the evolution of resistance and tolerance and shed light on how the treatment conditions could affect the direction of bacterial evolution under antibiotic stress.


Assuntos
Adaptação Biológica/efeitos dos fármacos , Bactérias/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Adaptação Biológica/genética , Adaptação Fisiológica/efeitos dos fármacos , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Evolução Molecular
14.
Ecotoxicol Environ Saf ; 196: 110528, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32240865

RESUMO

In plants, tolerance to cadmium (Cd) stress is closely related to indole-3-acetic acid (IAA) and hydrogen peroxide (H2O2). However, it is unclear whether Cd-resistant and -sensitive varieties respond differently to Cd stress. In this study, the effects of dimethylthiourea (DMTU, a H2O2 scavenger) and p-chlorophenoxy isobutyric acid (PCIB, an IAA signaling inhibitor) on root growth, endogenous hormones and antioxidant system were investigated to decipher how DMTU and PCIB treatments alleviate the inhibition of root elongation in Cd-resistant (Commander) and -sensitive (Crossfire III) tall fescue varieties under Cd stress. Both varieties subjected to 10 µM Cd treatments for 12 h presented a substantial decrease in root elongation coupled with a reduction in brassinosteroid (BR) and zeatin riboside (ZR) contents, but the changes in IAA and abscisic acid (ABA) contents under Cd stress were opposite in the two varieties. In addition, the H2O2 content and antioxidant enzyme activities significantly increased in both varieties. However, pretreatment with PCIB or DMTU mitigated the inhibition of root elongation caused by Cd, accompanied by the significant changes of aforementioned physiological parameters. PCIB significantly reduced the IAA content in 'Commander', while DMTU significantly increased the IAA content in 'Crossfire III' and effectively relieved the inhibition of root elongation. But both treatments decreased the Cd-induced H2O2 accumulation. These results indicated that DMTU or PCIB can alleviate the Cd-inhibited root elongation in two varieties whose resistance differed under Cd stress, but they presented differences in the response of hormones, especially IAA, which may be due to the different adaptation mechanisms of two varieties in response to Cd stress.


Assuntos
Cádmio/toxicidade , Ácido Clofíbrico/farmacologia , Festuca/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Poluentes do Solo/toxicidade , Tioureia/análogos & derivados , Ácido Abscísico/metabolismo , Adaptação Fisiológica/efeitos dos fármacos , Festuca/crescimento & desenvolvimento , Festuca/metabolismo , Peróxido de Hidrogênio/metabolismo , Ácidos Indolacéticos/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Tioureia/farmacologia
15.
Artigo em Inglês | MEDLINE | ID: mdl-32135478

RESUMO

Atriplex canescens is a C4 shrub with excellent adaptation to saline and arid environments. Our previous study showed that the secretion of excessive Na+ into leaf salt bladders is a primary strategy in salt tolerance of A. canescens and external 100 mM NaCl can substantially stimulate its growth. To investigate whether NaCl could facilitate Atriplex canescens response to drought stress, five-week-old seedlings were subjected to drought stress (30% of field water capacity) in the presence or absence of additional 100 mM NaCl. The results showed that, under drought stress, the addition of NaCl could substantially improve the growth of A. canescens by increasing leaf relative water content, enhancing photosynthetic activity and inducing a significant declined leaf osmotic potential (Ψs). The addition of NaCl significantly increased Na+ concentration in leaf salt bladders and the Na+ contribution to leaf Ψs, while had no adverse effects on K+ accumulation in leaf laminae. Therefore, the large accumulation of Na+ in salt bladders for enhancing osmotic adjustment (OA) ability is a vital strategy in A. canescens responding to drought stress. In addition, the concentration of free proline, bataine and soluble sugars exhibited a significant increase in the presence of NaCl under drought stress, and the betaine contribution to leaf Ψs was significantly increased by additional NaCl compared with that under drought treatment alone, suggesting that compatible solutes are also involved in OA in addition to functioning as protectants to alleviate water deficit injury.


Assuntos
Adaptação Fisiológica , Atriplex , Secas , Cloreto de Sódio , Estresse Fisiológico , Adaptação Fisiológica/efeitos dos fármacos , Atriplex/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos
16.
Ecotoxicol Environ Saf ; 195: 110524, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32220790

RESUMO

Since the ecosystem is contaminated by lead, decontamination is a difficult and expensive process. Therefore, an alternative would be the use of phytoremediation plants, which have been studied more intensely in recent decades. Astronium graveolens Jacq (Anacardiaceae) is a Cerrado native species and plants of this biome are known to present adaptations and modifications that keep them in this ecosystem. Our aim was to find the tolerance index of A. graveolens to lead doses and to evaluate the morphophysiological alterations of the species when exposed to the heavy metal. The experiment was carried out in a greenhouse in Ilha Solteira-SP, with a completely randomized design and using lead acetate (Pb(C2H3O2)2) as the source of the heavy metal. Samples of the vegetative organs (roots and leaves) were fixed, subsequently dehydrated in an ethyl series, included in hydroxyethyl methacrylate (Leica Historesin) and sectioned for histological slide assembly and subsequent anatomical analysis. The levels of phenolic compounds, protein, amino acid, ammonia, allantoic acid and allantoin were quantified. We calculated the tolerance index for the species. Significant differences were found in leaf and root tissues anatomy, while in relation to the physiology of A. graveolens, a significant difference was observed when the concentration of total ureids in the roots was evaluated. Pb did not interfere with the survivability of the species. In fact, A. graveolens showed a higher secondary growth in the treatment with higher level of lead.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Anacardiaceae/efeitos dos fármacos , Chumbo/toxicidade , Poluentes do Solo/toxicidade , Solo/química , Anacardiaceae/metabolismo , Biodegradação Ambiental , Brasil , Ecossistema , Chumbo/metabolismo , Modelos Teóricos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo
17.
Ecotoxicol Environ Saf ; 194: 110378, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32146194

RESUMO

The primary purpose of this study was to systematically explore the complete metabolic pathway and tolerance mechanism of strain DNB-S1 to dibutyl phthalate (DBP), and the effect of DBP on energy metabolism of DNB-S1. Here, DNB-S1, a strain of Pseudomonas sp. that was highly effective in degrading DBP, was identified, and differentially expressed metabolites and metabolic networks of DBP were studied. The results showed that the differentially expressed metabolites were mainly aromatic compounds and lipid compounds, with only a few toxic intermediate metabolites. It speculated that phthalic acid, salicylic acid, 3-hydroxybenzoate acid, 3-Carboxy-cis, cis-muconate, fumarypyravate were intermediate metabolites of DBP. Their up-regulation indicated that there were two metabolic pathways in the degradation of DBP (protocatechuate pathway and gentisate pathway), which had been verified by peak changes at 290 nm, 320 nm, 330 nm, and 375 nm in the enzymatic method. Also, aspartate, GSH, and other metabolites were up-regulation, indicating that DNB-S1 had a high tolerance to DBP and maintained cell homeostasis, which was also one of the essential reasons to ensure the efficient degradation of DBP. Altogether, this study firstly proposed two pathways to degrade DBP and comprehensively explored the effect of DBP on the metabolic function of DNB-S1, which enriched the study of microbial metabolism of organic pollutants, and which provided a basis for the application of metabolomics.


Assuntos
Dibutilftalato/metabolismo , Poluentes Ambientais/metabolismo , Pseudomonas/metabolismo , Adaptação Fisiológica/efeitos dos fármacos , Biodegradação Ambiental , Dibutilftalato/toxicidade , Metabolismo Energético/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Pseudomonas/efeitos dos fármacos , Pseudomonas/crescimento & desenvolvimento
18.
Ecotoxicol Environ Saf ; 195: 110502, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32203771

RESUMO

Enrichment of the hyperaccumulator bank is important for phytoremediation, and studying new hyperaccumulators has become a research hotspot. In this study, cadmium (Cd), the main representative factor of heavy-metal-polluted water, was the research object, and the Cd bioenrichment ability and tolerance of Myriophyllum aquaticum were studied for the first time. The experiment was conducted for 28 days by establishing experimental groups with different Cd concentrations (0, 10, 20, 40, 80, and 160 mg/L). The results show that M. aquaticum is a new Cd hyperaccumulator. There was no notable damage in the 40 mg/L Cd treatment group, and the Cd enrichment ability of M. aquaticum reached 17,970 ± 1020.01 mg/kg, while the bioconcentration factor (BCF) reached 449.25. At the same time, the antioxidant system (superoxide dismutase (SOD) and peroxidase (POD)) and proline (Pro) levels of M. aquaticum maintained normal plant physiology, but there were physiological anomalies in M. aquaticum at high concentrations and under long-term treatment. The results show that M. aquaticum has a high Cd bioenrichment ability and tolerance in water and can be used for phytoremediation of river water polluted by Cd.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Bioacumulação/efeitos dos fármacos , Cádmio/análise , Saxifragales/metabolismo , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Cádmio/metabolismo , Saxifragales/crescimento & desenvolvimento , Poluentes Químicos da Água/metabolismo
19.
Ecotoxicol Environ Saf ; 195: 110492, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32203777

RESUMO

A pot experiment was conducted to evaluate the effects of combined application of cadmium (Cd)-resistant bacteria (J) and calcium carbonate + sepiolite (G) on both Cd bioavailability in contaminated paddy soil and on Cd accumulation in rice plants. Adding the mixture (J + G) to the soils significantly increased soil pH, decreased extractable Cd contents, and increased Fe/Mn-oxide Cd and organic-bound Cd contents. The applying of J + G, J and G decreased Cd contents in various rice tissues (roots, stems and leaves, husks, and brown rice grains) to different degrees. Compared with those of the CK, Cd contents decreased by 17.8%-53.3% in the roots, 12.3%-27.4% in the stems and leaves, 25.4%-44.6% in the husks, and 28.8%-55.7% in the brown rice grains for the application of J + G; Cd contents decreased by 8.2%-28.5% in the roots, 11.5%-32.0% in the husks, and 27.8%-45.9% in the brown rice grains for the application of J; Cd contents decreased by 12.9%-26.5% in the roots, in the stems and leaves decreased by 4.6%-34.1% in the stems and leaves, 60.2%-79.7% in the husks, and 35.7%-47.6% in the brown rice grains for the application of G. The alone application of bacteria (J) could reduce the bioavailability of Cd in soil and the contents of Cd in brown rice grains to some extent. Moreover, when the bacteria were applied in combination with mineral (J + G), it was a more effective method than the alone application of J or G to reduce the soil Cd bioavailability. Under all the tested conditions, applications of J4+G4 (320 mL kg-1 of J + 8 g kg-1 of G) resulted in the greatest reduction in Cd contents in brown rice grains. Overall, the results indicated that the combination of Cd-resistant bacteria and mineral material could effectively reduce Cd bioavailability in paddy soils and inhibit Cd accumulation in brown rice grains.


Assuntos
Bacillus cereus/crescimento & desenvolvimento , Cádmio/análise , Carbonato de Cálcio/química , Silicatos de Magnésio/química , Oryza/química , Poluentes do Solo/análise , Adaptação Fisiológica/efeitos dos fármacos , Disponibilidade Biológica , Grão Comestível/química , Folhas de Planta/química , Raízes de Plantas/química , Solo/química
20.
Artigo em Inglês | MEDLINE | ID: mdl-32058896

RESUMO

Cold-acclimation is essential for the development of adequate frost-hardiness in cereals and therefore sudden freezes can cause considerable damage to the canopy. However, timely adding of an appropriate signal in the absence of cold acclimation may also harden wheat for the upcoming freeze. The feasibility of the promising signal molecule methylglyoxal was tested here for such applications and the signal mechanism was studied in bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. ssp. durum). Spraying with 10 mM methylglyoxal did not decrease the fresh weight and photosynthetic parameters in most wheat varieties at growth temperature (21 °C). Photosynthetic parameters even improved and chlorophyll content increased in some cases. Increased transcript level of glutathione-S-transferases and omega-3 fatty acid desaturases was detected by qPCR 6 h after the last methylglyoxal spray. Aldo-keto reductase and glyoxalase enzyme activities, as well as sorbitol content of wheat plants increased 24 h after the last 10 mM methylglyoxal spray in most of the cultivars. These mechanisms may explain the increased freezing survival of methylglyoxal pretreated wheat plants from less than 10% to over 30%. Our results demonstrate that exogenous methylglyoxal treatment can be safely added to wheat plants as preparatory treatment without detrimental effects but inducing some of the stress-protective mechanisms, which contribute to frost-hardiness.


Assuntos
Aldeídos , Congelamento , Aldeído Pirúvico , Triticum , Adaptação Fisiológica/efeitos dos fármacos , Aldeídos/metabolismo , Fotossíntese , Aldeído Pirúvico/farmacologia , Triticum/efeitos dos fármacos
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