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1.
Aquat Toxicol ; 228: 105613, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32949975

RESUMO

Cyanobacteria are known for their ability to produce and release mixtures of up to thousands of compounds into the environment. Recently, the production of novel metabolites, retinoids, was reported for some cyanobacterial species along with teratogenic effects of samples containing these compounds. Retinoids are natural endogenous substances derived from vitamin A that play a crucial role in early vertebrate development. Disruption of retinoid signalling- especially during the early development of the nervous system- might lead to major malfunctions and malformations. In this study, the toxicity of cyanobacterial biomass samples from the field containing retinoids was characterized by in vivo and in vitro bioassays with a focus on the potential hazards towards nervous system development and function. Additionally, in order to identify the compounds responsible for the observed in vitro and in vivo effects the complex cyanobacterial extracts were fractionated (C18 column, water-methanol gradient) and the twelve obtained fractions were tested in bioassays. In all bioassays, all-trans retinoic acid (ATRA) was tested along with the environmental samples as a positive control. Retinoid-like activity (mediated via the retinoic acid receptor, RAR) was measured in the transgenic cell line p19/A15. The in vitro assay showed retinoid-like activity by specific interaction with RAR for the biomass samples. Neurotoxic effects of selected samples were studied on zebrafish (Danio rerio) embryos using the light/dark transition test (Viewpoint, ZebraLab system) with 120 hpf larvae. In the behavioural assay, the cyanobacterial extracts caused significant hyperactivity in zebrafish at 120 hpf after acute exposure (3 h prior to the measurement) at concentrations below the teratogenicity LOEC (0.2 g dw L-1). Similar effect was observed after exposure to fractions of the extracts with detected retinoid-like activity and additive effect was observed after combining the fractions. However, the effect on behaviour was not observed after exposure to ATRA only. To provide additional insight into the behavioural effects and describe the underlying mechanism gene expression of selected biomarkers was measured. We evaluated an array of 28 genes related to general toxicity, neurodevelopment, retinoid and thyroid signalling. We detected several affected genes, most notably, the Cyp26 enzymes that control endogenous ATRA concentration, which documents an effect on retinoid signalling.


Assuntos
Comportamento Animal/efeitos dos fármacos , Cianobactérias/metabolismo , Embrião não Mamífero/efeitos dos fármacos , Tretinoína/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/crescimento & desenvolvimento , Animais , Bioensaio , Biomassa , Linhagem Celular Tumoral , Cianobactérias/crescimento & desenvolvimento , Embrião não Mamífero/metabolismo , Expressão Gênica/efeitos dos fármacos , Camundongos , Receptores do Ácido Retinoico/genética , Receptores do Ácido Retinoico/metabolismo , Tretinoína/metabolismo , Poluentes Químicos da Água/metabolismo , Peixe-Zebra/metabolismo
2.
PLoS One ; 15(9): e0238832, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32970701

RESUMO

Monitoring of cyanobacteria in freshwater ecosystems is a complex task, which is time consuming and expensive due to the chaotic population dynamics and highly heterogeneous distribution of cyanobacteria populations in water bodies. The financial cost constitutes a strong limitation for the implementation of long-term monitoring programs in developing countries, particularly in Africa. The work presented here was performed in the framework of an international project addressing the sustainable monitoring and management of surface water resources used for the production of drinking water in three African countries. We tested the potential of a citizen approach for monitoring cyanobacterial blooms, which are a growing threat to the drinking water supply. This pilot study was designed, implemented and evaluated in close interaction with the Pasteur Institute of the Ivory Coast and with the populations of three villages located on the shoreline of a freshwater lagoon located near Abidjan city. Based on the use of a smartphone application, the citizens of the three villages were invited to report water color changes, as these changes could reflect cyanobacteria proliferations. A two-year experimentation period has shown that it is possible to mobilize the local populations to monitor cyanobacterial blooms. The data collected by citizens were consistent with the data obtained by a classical monitoring of cyanobacteria performed over seven months, but it appeared that new approaches were needed to validate the citizen data. This participatory approach also provided great improvements to the understanding and awareness of local populations regarding water quality and cyanobacterial bloom issues. Finally, we discuss some of the difficulties and limitations of our participatory monitoring approach that should be considered by further implementations. Despite these difficulties, our work suggests that citizen monitoring is a promising approach that may complement the classical approach to sustainable monitoring of cyanobacteria in developing countries.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Lagos/microbiologia , Costa do Marfim , Países em Desenvolvimento , Projetos Piloto , Qualidade da Água/normas , Abastecimento de Água/normas
3.
Ecotoxicol Environ Saf ; 202: 110937, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800220

RESUMO

Cyanobacteria have been considered a major global threat because of their widespread ability to proliferate and contaminate inland and marine waters with toxic metabolites. For this reason, to avoid risks to humans and environmental health, regulatory legislation and guidelines have been established based on extensive toxicological data. However, most of what is known in this field come from works on microcystin (MC) variants, which effects were almost exclusively tested in metazoan models. In this work, we used acute end-point toxicological assays and high-resolution hybrid quadrupole time-of-flight mass spectrometer coupled with electrospray ionization source (ESI-Q-TOF-MS) analyses to evaluate the deleterious impact of aqueous extracts prepared from cultures of cyanobacteria and environmental bloom biomasses over a non-metazoan model organism, the cosmopolitan fresh/brackish water unicellular microeukaryote, Paramecium caudatum (Ciliophora). Our data suggest that all extracts produced time-dependent effects on P. caudatum survival, irrespective of their metabolite profile; and that this ciliate is more sensitive to extracts containing microginins than to extracts with only MCs, stressing that more toxicological investigations should be performed on the environmental impact of neglected cyanotoxins. Further, our data provide evidence that P. caudatum may be more sensitive to cyanotoxins than vertebrates, indicating that guidelines values, set on metazoans are likely to be inaccurate to protect organisms from basal food web positions. Thus, we highly recommend the widespread use of microeukaryotes, such as ciliates in environmental risk assessment frameworks for the establishment of more reliable cyanotoxin monitoring guideline values.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Paramecium caudatum/fisiologia , Animais , Biomassa , Cilióforos , Cadeia Alimentar , Água Doce/microbiologia , Humanos , Microcistinas
4.
Aquat Toxicol ; 225: 105515, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32516672

RESUMO

Heavy metals can cause a significant damage to submerged macrophytes and affect its periphyton biofilms in aquatic environments. This study investigated the effects of heavy metals such as copper (Cu), lead (Pb), cadmium (Cd) and their mixture on physiological and biochemical responses and ultrastructure characteristics of Vallisneria natans (V. natans). Furthermore, differences in structures of microbial communities were observed in biofilms. The results showed that Cu2+, Pb2+, Cd2+ and their mixture could destroy cell structure and photosynthetic system, and directly caused oxidative damage to submerged macrophyte and induced antioxidant enzyme system. In general, biomass and total chlorophyll content of V. natans noticeably decreased, while the activities of superoxide dismutase, peroxidase and catalase were enhanced by heavy metal stress inducement in restricted range, and the malondialdehyde content increased with the aggravation of the damage. The single heavy metal stress played a negative impact, however, the combined stress was not always synergistic effects on plants. High-throughput sequencing analysis suggested that heavy metals changed the abundance and structure of the microbial biofilm community. Proteobacteria and Bacteroidete were the dominant bacteria under heavy metal stress and other species and abundance of bacteria such as Firmicute, Cyanobacteria, Chloroflexi, Actinobacteria, Verrucomicrobia, Acidobacteria, Deinococcus-Thermus, Chlamydiae were also present. These findings provided useful information for further understanding about submerged macrophytes and periphyton biofilms responsed to heavy metal stress in aquatic environments in the future.


Assuntos
Biofilmes/efeitos dos fármacos , Hydrocharitaceae/efeitos dos fármacos , Metais Pesados/toxicidade , Microbiota/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Antioxidantes/metabolismo , Biofilmes/crescimento & desenvolvimento , Biomassa , Clorofila/metabolismo , Cianobactérias/efeitos dos fármacos , Cianobactérias/crescimento & desenvolvimento , Sinergismo Farmacológico , Firmicutes/efeitos dos fármacos , Firmicutes/crescimento & desenvolvimento , Hydrocharitaceae/microbiologia , Hydrocharitaceae/ultraestrutura , Malondialdeído/metabolismo , Perifíton/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos
5.
PLoS One ; 15(6): e0234110, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32530916

RESUMO

Sediments from stratified marine environments often show an enhanced preservation of organic matter (OM) which is attributed to the limitation, or absence, of oxygen in the bottom waters and surface sediments. Yet there is still a limited knowledge about the changes that the associated biomarker signals undergo in the different parts of a stratified environment, and as to which extent the situation in the productive upper parts of the water column is eventually reflected in the sedimentary record. To better understand these processes we studied particulate matter samples from the stratified, partly anoxic Eastern Gotland Basin (EGB, Central Baltic Sea) during a strong cyanobacterial bloom in August 2016. Endmember samples representing the main biomass producers within the phytoplankton (cyanobacteria) and mesozooplankton (copepods) were obtained from different levels of the water column. Major extractable lipids (fatty acids, n-alcohols, sterols, and selected hydrocarbons) were analysed from the same materials and compared to samples cored from the underlying surface sediments (0-12 cm). Given the annually recurring phenomenon of cyanobacterial blooms we anticipated to find a considerable lipid footprint of the major primary producers in the sedimentary record of the EGB. Unexpectedly, however, lipids in the surface sediments largely derived from the storage lipids (mainly wax esters) of the copepod Pseudocalanus spp. which thrived in deeper, more saline and oxygen-depleted waters. Carbon number and unsaturation patterns suggest that the component n-alcohols of these wax esters are transformed into the corresponding n-fatty acids prior to further degradation in the sediment. In the EGB deposits, most of the plankton-derived lipids studied appear to be degraded on a time scale of decades. In terms of relative abundances, long-chain n-alkyl lipids and C29 sterols from terrestrial plant sources instead become predominant in the deeper sediment layers. Likewise, higher stanol/sterol ratios of C27-sterols vs. C29-sterols indicate a more intense biodegradation of planktonic OM as compared to terrestrial OM. Our observations indicate that primary produced particulate OM is heavily modified by mesozooplankton grazing. This overprint adds on the influence of heterotrophic microorganisms and, in the sediment, preferential preservation of terrestrial biomarkers. Taken together, these factors result in a major decoupling of the biomarker signals between the productive upper mixed layer and the oxygen-depleted bottom waters and sediments of the EGB.


Assuntos
Biomarcadores/análise , Sedimentos Geológicos/análise , Lipídeos/análise , Zooplâncton/metabolismo , Animais , Países Bálticos , Copépodes/crescimento & desenvolvimento , Copépodes/metabolismo , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Ácidos Graxos/análise , Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos/análise , Esteróis/análise , Poluentes Químicos da Água/análise , Zooplâncton/crescimento & desenvolvimento
6.
Chemosphere ; 256: 127101, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32450355

RESUMO

Previous studies of the dynamics of sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) have focused on deep stratified lakes. The objective of this study is to present an in-depth investigation of the structure and dynamics of sulfur bacteria (including SRB and SOB) in the water column of shallow freshwater lakes. A cyanobacterial bloom biomass (CBB)-amended mesocosm experiment was conducted in this study, in which water was taken from a shallow eutrophic lake with sulfate levels near 40 mg L-1. Illumina sequencing was used to investigate SRB and SOB species involved in CBB decomposition and the effects of the increases in sulfate input on the water column microbial community structure. The accumulation of dissolved sulfide (∑H2S) produced by SRB during CBB decomposition stimulated the growth of SOB, and ∑H2S was then oxidized back to sulfate by SOB in the water column. Chlorobaculum sequences (the main SOB species in the study) were significantly influenced by increases in sulfate input, with relative abundance increasing approximately four-fold in treatments amended with 40 mg L-1 sulfate (referred to as 40S) when compared to the treatment without additional sulfate addition (referred to as CU). Additionally, an increase in SOB number was observed from day 26-37, concurrent with the decrease in SRB number, indicating the succession of sulfur bacteria. These findings suggest that biological sulfur oxidation and succession of sulfur bacteria occur in the water column during CBB decomposition in shallow freshwater ecosystems, and the increases in sulfate input stimulate microbial sulfur oxidation.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Lagos/microbiologia , Biomassa , Chlorobi , Ecossistema , Oxirredução , Sulfatos , Sulfetos , Enxofre/química
7.
PLoS One ; 15(4): e0231690, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32353002

RESUMO

The Baltic Sea summer phytoplankton community plays an important role in biogeochemical cycling and in the transfer of energy through the food web via zooplankton. We aimed to improve the understanding of the degree to which large-scale versus local environmental dynamics regulate phytoplankton dynamics by analyzing time series at the Baltic Sea scale. We used dynamic factor analysis to study if there are common patterns of interannual variation that are shared ("common trends") among summer phytoplankton total and class-level biomass time series observed across Baltic Sea latitudinal gradients in salinity and temperature. We evaluated alternative hypotheses regarding common trends among summer phytoplankton biomass: Baltic Sea-wide common trends; common trends by geography (latitude and basin); common trends differing among functional groups (phytoplankton classes); or common trends driven by both geography and functional group. Our results indicated little support for a common trend in total summer phytoplankton biomass. At a finer resolution, classes had common trends that were most closely associated with the cryptophyte and cyanobacteria time series with patterns that differed between northern and southern sampling stations. These common trends were also very sensitive to two anomalous years (1990, 2008) of cryptophyte biomass. The Baltic Sea Index, a regional climate index, was correlated with two common class trends that shifted in mean state around the mid-1990s. The limited coherence in phytoplankton biomass variation over time despite known, large-scale, ecosystem shifts suggests that stochastic dynamics at local scales limits the ability to observe common trends at the scale of monitoring data collection.


Assuntos
Biomassa , Fitoplâncton/crescimento & desenvolvimento , Estações do Ano , Criptófitas/crescimento & desenvolvimento , Cianobactérias/crescimento & desenvolvimento , Modelos Estatísticos
8.
J Photochem Photobiol B ; 205: 111822, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32135470

RESUMO

The enormous attraction on CO2 biofixation using photosynthetic microorganisms such as cyanobacteria has been risen due to its promising efficiency and valuable by-products production. In this study, an isolated cyanobacterium from hot spring in Taiwan, Thermosynechococcus sp. CL-1 (TCL-1) was evaluated for its growth factors arrangement effect on the biomass productivity and CO2 biofixation. The initial biomass concentration, and nutrient supply level variation influenced TCL-1 biomass productivity and CO2 biofixation rate while the adjusted and controlled pH value gave an insignificant difference on its performance. The initial biomass concentration of 3 g L-1 gave the best result on biomass productivity and CO2 fixation which reached 143.4 mg L-1 h-1 and 224 mg L-1 h-1 respectively. Regarding to the result of this study, controlled pH value by the CO2 supply inside the reactor, produced an insignificant difference in TCL-1 performance compared to those with the uncontrolled pH value. The variation of nutrient supply level was achieved by the variation of macronutrient and micronutrient supply inside the medium. The G-solution contains metals and other micronutrient elements which are necessary for the growth of TCL-1. The combination between 5-folds MF medium as the macronutrient, and 3-folds G-solution as the micronutrient supply, present the best TCL-1 performance on biomass productivity and CO2 fixation rate.


Assuntos
Dióxido de Carbono/metabolismo , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Biomassa , Concentração de Íons de Hidrogênio , Nutrientes/metabolismo
9.
An Acad Bras Cienc ; 92(1): e20181102, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187255

RESUMO

Significant reductions in the water levels of lakes are influenced by droughts and freshwater demands, especially in semi-arid regions, where hydric stress is greater. The aim of this study was to investigate the dynamics of phytoplankton during two different water volume periods resulting from an extended drought in a semi-arid lake. Another objective was to compare two functional approaches to test which one of these best captures phytoplankton variability as a function of environmental variability. Multivariate analyses performed using the Reynolds Functional Groups (RFG) and Morphology-Based Functional Groups (MBFG) classification schemes indicated two periods, high and a low water volume. The results demonstrated the importance of light availability on phytoplankton assemblages as these two periods showed significant differences in water transparency and phytoplankton composition. During extended droughts the reduction in water volume enhances the development of bloom-forming cyanobacteria through the limitation of light in a eutrophic man-made lake. Moreover, both functional traits approaches demonstrated the effect of light availability on phytoplankton assemblage composition and can be applied in similar systems. However, the RFG classification provides more information and allows a more detailed description of the algal assemblages.


Assuntos
Monitoramento Ambiental , Lagos/química , Fitoplâncton/crescimento & desenvolvimento , Biomassa , Brasil , Cianobactérias/crescimento & desenvolvimento , Lagos/análise , Dinâmica Populacional , Estações do Ano
10.
Nat Microbiol ; 5(5): 757-767, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32203409

RESUMO

Photosynthetic organisms regulate their responses to many diverse stimuli in an effort to balance light harvesting with utilizable light energy for carbon fixation and growth (source-sink regulation). This balance is critical to prevent the formation of reactive oxygen species that can lead to cell death. However, investigating the molecular mechanisms that underlie the regulation of photosynthesis in cyanobacteria using ensemble-based measurements remains a challenge due to population heterogeneity. Here, to address this problem, we used long-term quantitative time-lapse fluorescence microscopy, transmission electron microscopy, mathematical modelling and genetic manipulation to visualize and analyse the growth and subcellular dynamics of individual wild-type and mutant cyanobacterial cells over multiple generations. We reveal that mechanical confinement of actively growing Synechococcus sp. PCC 7002 cells leads to the physical disassociation of phycobilisomes and energetic decoupling from the photosynthetic reaction centres. We suggest that the mechanical regulation of photosynthesis is a critical failsafe that prevents cell expansion when light and nutrients are plentiful, but when space is limiting. These results imply that cyanobacteria must convert a fraction of the available light energy into mechanical energy to overcome frictional forces in the environment, providing insight into the regulation of photosynthesis and how microorganisms navigate their physical environment.


Assuntos
Cianobactérias/fisiologia , Fotossíntese/fisiologia , Cianobactérias/citologia , Cianobactérias/crescimento & desenvolvimento , Fluorescência , Luz , Modelos Teóricos , Ficobilissomas/fisiologia , Synechococcus/crescimento & desenvolvimento , Synechococcus/fisiologia
11.
PLoS One ; 15(3): e0229148, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32160215

RESUMO

Lake Lesser Prespa in Greece is a vital breeding habitat for the Dalmatian and Great White Pelican and a shelter for numerous rare and endemic species. However, eutrophication processes are distressing the lake system and the outbreaks of cyanobacterial blooms during the warm months may pose a threat to aquatic organisms due to the presence of microcystins (MCs). In this study we hypothesize that nutrients (eutrophication), nutrient-rich pelican droppings (guanotrophication) and warming (climate change) can affect the algal growth and MCs production in the water layer of Lake Lesser Prespa. Seston collected from three lake sites was incubated at ambient (20°C) and high (30°C) temperature with or without the addition of nutrients (nitrogen (N), phosphorus (P)), or pelican droppings. Results showed increased chlorophyll-a at higher temperature (30°C). N addition yielded higher chlorophyll-a levels than the non-treated water or when only P was added. The addition of both N and P as well as the addition of pelican dropping resulted in the highest chlorophyll-a at both temperatures. Notably, in the dropping-treatments, cyanobacteria and MCs were promoted while changes were evoked in the relative contribution of toxic MC-variants. Guanotrophication may thus influence the cyanobacterial dynamics and most likely their toxicity profile at Lesser Prespa.


Assuntos
Clorófitas , Mudança Climática , Cianobactérias , Eutrofização , Lagos , Microcistinas/metabolismo , Animais , Aves/metabolismo , Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Fezes , Grécia , Microcistinas/toxicidade , Temperatura
12.
PLoS One ; 15(3): e0230071, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32210450

RESUMO

Microbialites are highly diverse microbial communities that represent modern examples of the oldest life forms, stromatolites (dated >3.7 Ga). Bacalar Lagoon, in Mexico, harbors the largest freshwater microbialite occurrences of the world; yet diverse anthropogenic activities are changing the oligotrophic conditions of the lagoon. The objective of this work was to perform a spatial exploration of the microbialites of Bacalar Lagoon, analyze their prokaryote diversity, following a high throughput sequencing approach of the V4 region of the 16S rDNA, and correlate to the environmental parameters that influence the structure of these communities. The results indicate the presence of microbialites throughout the periphery of the lagoon. The microbiome of the microbialites is composed primarily of Proteobacteria (40-80%), Cyanobacteria (1-11%), Bacteroidetes (7-8%), Chloroflexi (8-14%), Firmicutes (1-23%), Planctomycetes (1-8%), and Verrucomicrobia (1-4%). Phylogenetic distance analyses suggests two distinct groups of microbialites associated with regions in the lagoon that have differences in their environmental parameters, including soluble reactive silicate (in the north), bicarbonates and available forms of nitrogen (ammonium, nitrates and nitrites) (in the south). These microbialite groups had differences in their microbiome composition associated to strong anthropogenic pressure on water quality (agriculture, landfill leachate, lack of water treatment infrastructure and intensive tourism), which were related to a loss of microbial diversity.


Assuntos
Bacteroidetes/classificação , Biodiversidade , Cianobactérias/classificação , Água Doce/microbiologia , Sedimentos Geológicos/microbiologia , Microbiota , Proteobactérias/classificação , Bacteroidetes/genética , Bacteroidetes/crescimento & desenvolvimento , Cianobactérias/genética , Cianobactérias/crescimento & desenvolvimento , Sedimentos Geológicos/análise , Sequenciamento de Nucleotídeos em Larga Escala , México , Nutrientes , Filogenia , Proteobactérias/genética , Proteobactérias/crescimento & desenvolvimento , RNA Ribossômico 16S/genética
13.
Aquat Toxicol ; 222: 105463, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32172181

RESUMO

Massive use of glyphosate-based herbicides in agricultural activities has led to the appearance of this herbicide in freshwater systems, which represents a potential threat to these systems and their communities. These herbicides can affect autotrophic and heterotrophic picoplankton abundance. However, little is known about glyphosate impact on the whole structure of these assemblages. Herein, we used an 8-day long microcosm approach under indoor controlled conditions to analyze changes in the structure of picoplankton exposed to a single pulse of glyphosate. The analyzed picoplankton correspond to two outdoor ponds with contrasting states: "clear" (chlorophyll-a = 3.48 µg L-1± 1.15; nephelometric turbidity, NTU = 1) and "turbid" (chlorophyll-a = 105.96 µg L-1 ± 15.3; NTU = 48). We evaluated herbicide impact on different picoplankton cytometric populations and further explored changes in bacterial dominant operational taxonomic units (OTUs) fingerprinting. We observed that glyphosate induced a drastic decrease in the abundance of phycocyanin-rich picocyanobacteria. Particularly, in the turbid system this effect resulted in an 85 % decrease in the abundance of the whole autotrophic picoplankton. Glyphosate also changed the structure of the heterotrophic fraction by means of changing bacterial dominant OTUs fingerprinting patterns in both systems and by shifting the relative abundances of cytometric groups in the clear scenario. These results demonstrate that upon glyphosate exposure picoplanktonic fractions face not only the already reported changes in abundance, but also alterations in the composition of cytometric groups and of bacterial dominant operational taxonomic units. This research provides suitable and still little explored tools to analyze agrochemical effects on picoplanktonic communities.


Assuntos
Processos Autotróficos/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/toxicidade , Processos Heterotróficos/efeitos dos fármacos , Plâncton/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Agricultura , Clorofila A/metabolismo , Cianobactérias/efeitos dos fármacos , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Água Doce/química , Glicina/toxicidade , Plâncton/crescimento & desenvolvimento , Plâncton/metabolismo
14.
Ecotoxicol Environ Saf ; 195: 110408, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32179236

RESUMO

Microcystin-LR (MC-LR) is a widely known hepatotoxin which could induce the occurrence and metastasis of hepatocellular carcinoma. In recent years, with the frequent outbreak of cyanobacteria, the harm of MC-LR has gradually attracted more attention. Hence, this study focused on the effect of MC-LR on DNA damage in HepG2 cells, identifying the types and sources of free radicals that make an important function on this issue. Our data suggested that MC-LR induced concentration- and time-dependent increasement of DNA double-strand breaks (DSBs). After exposure to 1 µM MC-LR for 3 days, the protein expression and immunofluorescence staining of γ-H2AX was significantly increased. Using a scavenger of mitochondrial O2.- (4-hydroxy-tempo), a inhibitor of mitochondrial NOS (7-nitroindazole), and a scavenger of ONOO- (uric acid), it was revealed that ONOO- originated from mitochondria made a significant contribution to the genotoxicity of MC-LR. Moreover, a significant decreasement of mitochondrial membrane potential (MMP) was observed. These findings suggested that peroxynitrite targeting mitochondria plays a vital role in the MC-LR-induced genotoxic response in mammalian cells.


Assuntos
Quebras de DNA de Cadeia Dupla , Microcistinas/toxicidade , Mitocôndrias Hepáticas/efeitos dos fármacos , Ácido Peroxinitroso/metabolismo , Animais , Carcinoma Hepatocelular/genética , Cianobactérias/crescimento & desenvolvimento , Células Hep G2 , Histonas/metabolismo , Humanos , Neoplasias Hepáticas/genética , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo
15.
Sci Rep ; 10(1): 2781, 2020 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-32066776

RESUMO

Harmful algal blooms formed by colony-forming cyanobacteria deteriorate water resources by producing cyanotoxins, which frequently occur at high intracellular concentrations. We aimed to localize toxic microcystins (MCs) and bioactive anabaenopeptins (APs) at the subcellular level under noninvasive conditions. Since both metabolites are synthesized nonribosomally, the relaxed specificity of key enzymes catalyzing substrate activation allowed chemical labeling through a standard copper-catalyzed click chemistry reaction. The genera Planktothrix and Microcystis specifically incorporated unnatural amino acids such as N-propargyloxy-carbonyl-L-lysine or O-propargyl-L-tyrosine, resulting in modified AP or MC peptides carrying the incorporated alkyne moiety. The labeled cells were quantitatively differentiated from the unlabeled control cells. MCs and APs occurred intracellularly as distinct entities showing a cell-wide distribution but a lowered spatial overlap with natural autofluorescence. Using the immunofluorescence technique, colocalization with markers of individual organelles was utilized to relate the distribution of labeled MCs to cellular compartments, e.g., using RbcL and FtsZ (cytosol) and PsbA (thylakoids). The colocalization correlation coefficients calculated pairwise between organelles and autofluorescence were highly positive as opposed to the relatively low positive indices derived from labeled MCs. The lower correlation coefficients imply that only a portion of the labeled MC molecules were related spatially to the organelles in the cell.


Assuntos
Toxinas Bacterianas/isolamento & purificação , Cianobactérias/química , Microcistinas/isolamento & purificação , Peptídeos Cíclicos/isolamento & purificação , Aminoácidos/química , Aminoácidos/metabolismo , Toxinas Bacterianas/química , Química Click , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Água Doce/química , Proliferação Nociva de Algas , Microcistinas/química , Peptídeos Cíclicos/química
16.
Chemosphere ; 247: 125960, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32069727

RESUMO

The increasing freshwater ecosystem nutrient budget is a critical anthropogenic factor promoting freshwater eutrophication and episodic bloom of harmful algae which threaten water quality and public health. To understand how the eutrophic freshwater ecosystem responds in term of phytoplankton community structure dynamics to a sudden rise in nutrient concentrations, a microcosm study by nutrient addition bioassay was implemented in Xiangxi Bay (XXB) of Three Gorges Reservoir, China. Our results showed that dissolved trace elements supply adequately altered the phytoplankton community structure creating a regime shift from cyanobacteria-dominated to essentially Chlorophytes-dominated system, relative abundance (>70%). Combined N, P, and Si led to maximum growth stimulation accompanied by the highest chlorophyll yield (82.7 ± 14.01 µgL-1) and growth rate (1.098 ± 0.12 µgL-1d-1). N separate additions resulted in growth responses which did not differ while P -addition differed significantly (p∠0.05) with the control justifying a P limited system. Si enrichment stimulated diatom growth, relative abundance (20.62%) and maximum utility rate (USi = 83.37 ± 0.33%). This study also reveals that increasing nutrient loading from anthropogenic sources adequately decrease the ecological diversity (H < 1) and community overlap (CC ≤ 0.5) intensifying competition and succession which then select the fast-growing taxa to dominate and expand. Result points to the need for multiple nutrient control of N, P and Si loading into XXB through a prudent nutrient management protocol for lasting bloom mitigation in the tributary bay.


Assuntos
Ecossistema , Nutrientes/farmacologia , Fitoplâncton/crescimento & desenvolvimento , Baías , Bioensaio , China , Clorofila/análise , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Eutrofização , Água Doce/química
17.
Aquat Toxicol ; 220: 105399, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896464

RESUMO

There is little information in scientific literature as to how conditions created by a microcystin (MC) producing cyanobacterial bloom affect the oxidant/antioxidant, biotransformation and neurotoxicity parameters in adult frogs in situ. We investigated biochemical parameters in the skin and muscle of Pelophylax kl. esculentus from Lake Ludas (Serbia) by comparing frogs that live on the northern bloom side (BS) of the lake with those that inhabit the southern no-bloom side (NBS). A higher protein carbonylation level and lower antioxidant defense system capability in the skin of frogs living in conditions of the cyanobacterial bloom were observed. Inhibition of glutathione-dependent machinery was the major mechanism responsible for the induction of cyanobacterial bloom-mediated oxidative stress in frog skin. On the other hand, the detected higher ability of muscle to overcome bloom prooxidant toxicity was linked to a higher efficiency of the biotransformation system through glutathione-S-transferase activity and/or was the consequence of indirect exposure of the tissue to the bloom. Our results have also revealed that the cyanobacterial bloom conditions induced the cholinergic neurotransmitter system in both tissues. This study provides a better understanding of the ecotoxicological impact of the MC producing cyanobacterial bloom on frogs in situ. However, further investigations of the complex mechanism involved in cyanobacterial bloom toxicity in real environmental conditions are required.


Assuntos
Toxinas Bacterianas/toxicidade , Cianobactérias/metabolismo , Eutrofização , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Músculos/efeitos dos fármacos , Rana esculenta/metabolismo , Pele/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Toxinas Bacterianas/metabolismo , Biotransformação , Cianobactérias/crescimento & desenvolvimento , Monitoramento Ambiental , Lagos/química , Toxinas Marinhas/metabolismo , Microcistinas/metabolismo , Músculos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Rana esculenta/crescimento & desenvolvimento , Sérvia , Pele/metabolismo , Poluentes Químicos da Água/metabolismo
18.
Artigo em Inglês | MEDLINE | ID: mdl-31642727

RESUMO

The herbicides glyphosate, imazamox and fluridone are herbicides, with low toxicity towards fish and invertebrates, which are applied to waterways to control invasive aquatic weeds. However, the effects of these herbicides on natural isolates of phytoplankton and cyanobacteria are unknown. Three species of microalgae found in the San Francisco Estuary (SFE)/Sacramento-San Joaquin River Delta (Delta) (Microcystis aeruginosa, Chlamydomonas debaryana, and Thalassiosira pseudonana) were exposed to the three herbicides at a range of concentrations in 96-well plates for 5-8 days. All three algal species were the most sensitive to fluridone, with IC50 of 46.9, 21, and 109 µg L-1 for M. aeruginosa, T. pseudonana and C. debaryana, respectively. Imazamox inhibited M. aeruginosa and T. pseudonana growth at 3.6 × 104 µg L-1 or higher, and inhibited C. debaryana growth at 1.0 × 105 µg L-1 or higher. Glyphosate inhibited growth in all species at ca. 7.0 × 104 µg L-1 or higher. Fluridone was the only herbicide that inhibited the microalgae at environmentally relevant concentrations in this study and susceptibility to the herbicide depended on the species. Thus, the application of fluridone may affect cyanobacteria and phytoplankton community composition in water bodies where it is applied.


Assuntos
Cianobactérias/efeitos dos fármacos , Estuários , Herbicidas/toxicidade , Fitoplâncton/efeitos dos fármacos , Rios/química , Poluentes Químicos da Água/toxicidade , Animais , California , Cianobactérias/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Fitoplâncton/crescimento & desenvolvimento , Especificidade da Espécie
19.
Biosci Biotechnol Biochem ; 84(3): 481-490, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31690227

RESUMO

ChlR is a MarR-type transcriptional regulator that activates the transcription of the chlAII-ho2-hemN operon in response to low oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803. Upon exposure to low oxygen conditions, ChlR activates transcription of the operon that encodes enzymes critical to tetrapyrrole biosynthesis under low oxygen conditions. We previously identified a super-activator variant, D35H, of ChlR that constitutively activates transcription of the operon. To gain insight into the low-oxygen induced activation of ChlR, we obtained eight additional super-activator variants of ChlR including D35H from pseudorevertants of a chlAI-disrupted mutant. Most substitutions were located in the N-terminal region of ChlR. Mapping of the substituted amino acid residues provided valuable structural insights that uncovered the activation mechanism of ChlR.


Assuntos
Proteínas de Bactérias/metabolismo , Cianobactérias/metabolismo , Oxigênio/metabolismo , Tetrapirróis/biossíntese , Fatores de Transcrição/metabolismo , Aerobiose , Proteínas de Bactérias/química , Cianobactérias/crescimento & desenvolvimento , Fatores de Transcrição/química
20.
Sci Total Environ ; 698: 134305, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514039

RESUMO

Eutrophy in Albufera of Valencia (Eastern Iberian Peninsula) is a quite old problem since after the intense eutrophication processes throughout the 1960s. The system shifted to a turbid stable state consolidated by the virtual disappearance of macrophytes by the early 1970s. The lagoon has been studied extensively since the 1980s, but efforts to revert the system to a clear state have not yielded the expected results because cultural eutrophication due to the growth of population in its area of influence and the effects of climate change, decreasing rainfall and increasing evaporation. This has driven to an increase in water retention times in the lagoon in recent years, resulting in a phytoplanktonic shift towards potentially toxic cyanobacteria species, often forming blooms. Cyanobacterial blooms severely affect water quality for human use, ranging from recreation and fishing to drinking water resources, as indicated in the surveillance protocol of World Health Organization (WHO). The current state of the lake requires constant monitoring and remote sensing is an optimal tool for the continuous monitoring of the whole water mass. This work is included in the ESAQS project (Ecological Status of AQuatic systems with Sentinel satellites), to establish a protocol for regular and frequent monitoring of the ecological status of reservoirs, lakes and lagoons. Algorithms are developed using the images provided by the Sentinel-2 (A and B), provided with a spatial resolution of 10 m and a temporal frequency of 5 days. In this work we demonstrate that using this new earth observation satellite is possible to develop a consistent and suitable algorithm to estimate the phycocyanin concentration [PC] and establish a protocol for regular and frequent monitoring. Calibrating (R2 = 0.841; n = 21; p < 0.001) and validating (R2 = 0.775; n = 55; p < 0.001; RMSE% = 40) the algorithm with field data are also demonstrated.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Eutrofização , Tecnologia de Sensoriamento Remoto , Fitoplâncton , Espanha , Qualidade da Água
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