RESUMO
In recent years, emerging environmental pollutants have increasingly endangered the health of freshwater organisms. The gut microbiota exhibits sensitivity to medications, dietary factors and environmental pollutants, rendering it a novel target for toxicological studies. The gut microbiota can be a potential exposure route affecting the host's health. Herein, we review the current knowledge on two different but concurrent pollutants, microplastics and pesticides, regarding their impact on the gut microbiota, which includes alterations in microbial composition, gene expression, function, and health effects in the hosts. Moreover, synergetic interactions between microplastics and pesticides can exacerbate dysbiosis and health risks. We discuss health-related implications of gut microbial changes based on the consequences in metabolism, immunity, and physiology function. Further research is needed to discover the mechanisms underlying these effects and develop strategies for mitigating their harmful impacts on freshwater animals.
Assuntos
Água Doce , Microbioma Gastrointestinal , Microplásticos , Praguicidas , Poluentes Químicos da Água , Microbioma Gastrointestinal/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Microplásticos/toxicidade , Animais , Praguicidas/toxicidadeRESUMO
OBJECTIVES: This lab-scale study aimed to investigate the effect of total ammonia nitrogen (TAN) stress on the methanogenic activity and the taxonomic and functional profiles of the microbial community of anaerobic sludge (AS) from a full-scale bioreactor. METHODS: The AS was subjected to a stepwise increase in TAN every 14 days at concentrations of 1, 2, 2.5, 3, 3.5, and 4 g TAN/L (Acclimated-AS or AAS). This acclimation stage was followed by an ammonia stress stage (4 g/L). A blank-AS (BAS) was maintained without TAN during the acclimation stage. In the second stress stage (ST), the BAS was divided into two new treatments: a control (BAS') and one that received a shock load of TAN of 4 g/L (SBAS'). Methane production was measured, and a metagenomic analysis was conducted to describe the microbial community. RESULTS: A decrease in the relative abundance of Methanothrix soehngenii of 16 % was related to a decrease of 23 % in the methanogenic capacity of AAS when comparing with the final stage of BAS. However, recovery was observed at 3.5 g TAN/L, and a shift to methylotrophic metabolism occurred, indicated by a 4-fold increase in abundance of Methanosarcina mazei. The functional analysis of sludge metagenomes indicated that no statistical differences (p > 0.05, RM ANOVA) were found in the relative abundance of methanogenic genes that initiate acetoclastic and hydrogenotrophic pathways (acetyl-CoA synthetase, ACSS; acetate kinase, ackA; phosphate acetyltransferase, pta; and formylmethanofuran dehydrogenase subunit A, fwdA) into the BAS and AAS during the acclimation phase. The same was observed between groups of genes associated with methanogenesis from methylated compounds. In contrast, statistical differences (p < 0.05, one-way ANOVA) in the relative abundance of these genes were recorded during ST. The functional profiles of the genes involved in acetoclastic, hydrogenotrophic, and methylotrophic methanogenic pathways were brought to light for acclimatation and stress experimental stages. CONCLUSIONS: TAN inhibited methanogenic activity and acetoclastic metabolism. The gradual acclimatization to TAN leads to metabolic and taxonomic changes that allow for the subsequent recovery of methanogenic functionality. The study highlights the importance of adequate management of anaerobic bioprocesses with high nitrogen loads to maintain the methanogenic functionality of the microbial community.
Assuntos
Amônia , Reatores Biológicos , Metano , Esgotos , Metano/metabolismo , Amônia/metabolismo , Anaerobiose , Reatores Biológicos/microbiologia , Esgotos/microbiologia , Nitrogênio/metabolismoRESUMO
The micronucleus (MN) test may be used to evaluate genome instability in birds and the potential of different species to function as biomarkers of genotoxicity. However, little is known regarding genome instability in seabird embryos or the instability present among embryonic development stages. Therefore, the present study aimed to describe the frequencies of micronucleated erythrocytes (MNE) and micronucleated polychromatic erythrocytes (MNPCE) in blood samples collected from the embryos of eight seabird species nesting on the coast of Sinaloa, Mexico. An additional description of blood cell maturation along with embryo development during incubation was conducted based on the proportion of polychromatic erythrocytes (PCE), and the potential relationships between metals (Hg and Cd concentrations in egg content) and the MN frequencies in embryo blood were evaluated. The PCE proportion appears to decline as incubation advances (initial stage > intermediate stage > advanced stage), and the values varied between species (Suliformes/Pelecaniformes < Charadriiformes: Laridae), which may be related to differences among incubation periods and reproductive strategies. Interspecific variation in the MNPCE frequency was found in embryos showing advanced development, which could be related to both variations in life-history traits and ecological factors and not Hg or Cd exposure. The genomic instability values in this study are the first to be reported for embryos of seabird species nesting in a subtropical coastal region.
Assuntos
Cádmio , Micronúcleos com Defeito Cromossômico , Animais , Gravidez , Feminino , Micronúcleos com Defeito Cromossômico/induzido quimicamente , México , Testes para Micronúcleos , Eritrócitos , Aves , Instabilidade Genômica , BiomarcadoresRESUMO
Aquatic ecosystems have been suffering deleterious effects due to the development of different economic activities. Metal(loid)s are one of the most persistent chemicals in environmental reservoirs, and may produce adverse effects on different organisms. Since fishes have been largely used in studies of metal(loid)s exposure, tilapia and largemouth bass were collected in three ecosystems from the Yaqui River Basin to measure the concentrations of metal(loid)s (chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn) arsenic (As), mercury (Hg), and selenium (Se)) and some biomarkers (somatic indices, metallothionein expression and histopathological analysis) in tissues of both species. Metal(loid) concentrations varied seasonally among ecosystems in tissues of both species. The elements varied seasonally and spatially in tissues of both species, with a general distribution of liver > gills > gonads. Also, biomarkers showed variations indicative that the fish species were exposed to different environmental stressor conditions. The highest values of some biomarkers were in largemouth bass, possibly due to differences in their biological characteristics, mainly feeding habits. The multivariate analysis showed positive associations between metal(loid)s and biomarkers, which are usually associated to the use of these elements in metabolic and/or regulatory physiological processes. Both fish species presented histological damage at different levels, from SI types (changes that are reversible for organ structure) to SII types (changes that are more severe but may be repairable). Taken together, the results from this study suggest that the Yaqui River Basin is moderately impacted by metals and metalloids.
Assuntos
Bass , Ciclídeos , Mercúrio , Tilápia , Poluentes Químicos da Água , Animais , Bass/metabolismo , Ecossistema , Rios/química , México , Monitoramento Ambiental/métodos , Metais/metabolismo , Mercúrio/análise , Biomarcadores/metabolismo , Poluentes Químicos da Água/análiseRESUMO
We evaluated the multi-and transgenerational effects of single and combined environmentally relevant concentrations of glyphosate (GLY) and chlorpyrifos (CPF) in the estuarine rotifer Proales similis. The acute and chronic toxicities of GLY and CPF were determined as individual compounds and as a mixture. Rotifers were exposed to environmental concentrations of GLY (1, 10, 100, and 1000⯵g/L) and CPF (0.1, 1, 5, and 10⯵g/L). The main findings were as follows: (i) the LC50 values were 33.91â¯mg/L (GLY) and 280⯵g/L (CPF); (ii) the toxic unit (TU50) of the mixture was 0.30, corresponding to 10.17â¯mg/L GLY and 83⯵g/L CPF; (iii) the multigenerational study indicated that the tested concentrations of GLY and CPF, both single and combined, significantly and consistently decreased the growth rates of P. similis from the F0 to F6 generations; (iv) in most cases, GLY and CPF mixtures induced a strong synergistic effect; and (v) transgenerational effects were detected in the F4 generation, especially GLY and CPF in higher equitoxic proportions. These effects seem to dissipate in F5. Across multigeneration, a slight recovery could indicate population resilience to pollution. Our findings suggest that a mixture of GLY and CPF at environmental concentrations is likely to occur under real field conditions, increasing the risk to marine and estuarine invertebrates such as rotifers.
Assuntos
Clorpirifos , Rotíferos , Animais , Clorpirifos/toxicidade , Glicina/toxicidade , Dose Letal Mediana , GlifosatoRESUMO
To balance the risks and benefits of fish consumption, selenium, fatty acids (DHA + EPA), and mercury in fishery products were determined. Analyzed products were canned tuna, frozen tuna (Thunnus albacares), smoked striped marlin (Tetrapturus audax), fresh Pacific sierra (Scomberomorus sierra), fresh dolphinfish (Coryphaena hippurus), fresh tilapia (Gerres cinereus), and fresh bullseye puffer (Sphoeroides annulatus). Mercury (µg g-1 wet weight) ranged from 0.01 (dolphinfish) to 0.23 (bullseye puffer); Se ranged from 0.12 to 0.25. EPA + DHA ranged from 1.16 to 10.72 mg g-1. Intake of EPA + DHA was comparable or above the recommended daily intake; Hg intake was below the reference dose but Se intake was below than recommended values for the different population groups. Considering the HBVSe, fishery products had positive values; i.e., they are healthy food items. According to the interaction of Hg and Se and the rate of fishery product consumption, the risk for consumers is below one percent.
Assuntos
Mercúrio , Selênio , Animais , Ácidos Graxos , Peixes , Mercúrio/análise , México , Medição de Risco , Alimentos Marinhos , Selênio/análise , AtumRESUMO
Zebrafish (Danio rerio) is a well-established vertebrate model in ecotoxicology research that responds to a wide range of xenobiotics such as pesticides, drugs, and endocrine-disrupting compounds. The epigenome can interact with the environment and transform internal and/or external signals into phenotypic responses through changes in gene transcription. Environmental exposures can also generate epigenetic variations in offspring even by indirect exposure. In this review, we address the advantages of using zebrafish as an experimental animal model to study transgenerational epigenetic processes upon exposure to xenobiotics. We focused mostly on DNA methylation, although studies on post-translational modifications of histones, and non-coding RNAs related to xenobiotic exposure in zebrafish are also discussed. A revision of the methods used to study epigenetic changes in zebrafish revealed the relevance and reproducibility for epigenetics-related research. PubMed and Google Scholar databases were consulted for original research articles published from 2013 to date, by using six keywords: zebrafish, epigenetics, exposure, parental, transgenerational, and F2. From 499 articles identified, 92 were considered, of which 14 were selected as included F2 and epigenetic mechanisms. Current knowledge regarding the effect of xenobiotics on DNA methylation, histone modifications, and changes in non-coding RNAs expressed in F2 is summarized, along with key experimental design considerations to characterize transgenerational effects.
RESUMO
The aim of this study was to determine the potential fertilizing of spermatozoa from the epididymal tail in different periods of time post-orchiectomy (P-OQ). Therefore, the study was approached in two stages. In the first stage, the orchiectomy was performed in 30 adult pigs. The testicles were stored at 5.00 ËC in physiological saline solution for 5, 24, 48, 72, 96 and 120 hr. The spermatozoa were obtained by backflushing the vas deferens. The spermogram and fluorometric study were performed for each sample to evaluate the exposure of phosphatidyl-serine (PS) and acrosome reaction (AR). The second stage included the fertilization test, 16 prepubertal sows were selected, after synchronizing the oestrous cycle and the post-cervical artificial insemination was performed with the refrigerated sperm samples from each P-OQ time. The percentage of live sperm remained without significant changes until 96 hr P-OQ. An increase in the percentage of spermatozoa that showed a PS exposure was observed. The premature AR was evident after 72 hr. Considering that the artificial insemination was performed ensuring a minimum number of live sperms, no significant differences were observed in the number of embryos and corpora lutea. The results indicated that pig sperm collected from the epididymal tail P-OQ and stored for 5 and up to 72 hr at 5.00 ËC had viable characteristics and maintained their fertilization ability. However, there was an increase in the loss of phospholipid asymmetry of the plasma membrane as time increased (72 and 96 hr), therefore, sperm viability was decreased.
RESUMO
Glyphosate [N-(phosphonomethyl)glycine] is the active ingredient in widely used broad-spectrum herbicides. Even though the toxicity mechanism of this herbicide in vertebrates is poorly understood, evidence suggests that glyphosate is an endocrine disruptor capable of producing morphological anomalies as well as cardiotoxic and neurotoxic effects. We used the zebraï¬sh model to assess the effects of early life glyphosate exposure on the development of cartilage and bone tissues and organismal responses. We found functional alterations, including a reduction in the cardiac rate, significant changes in the spontaneous tail movement pattern, and defects in craniofacial development. These effects were concomitant with alterations in the level of the estrogen receptor alpha osteopontin and bone sialoprotein. We also found that embryos exposed to glyphosate presented spine deformities as adults. These developmental alterations are likely induced by changes in protein levels related to bone and cartilage formation.
Assuntos
Osso e Ossos/efeitos dos fármacos , Anormalidades Craniofaciais/induzido quimicamente , Glicina/análogos & derivados , Herbicidas/toxicidade , Teratogênicos/toxicidade , Animais , Osso e Ossos/anormalidades , Anormalidades Craniofaciais/metabolismo , Anormalidades Craniofaciais/veterinária , Embrião não Mamífero/anormalidades , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/metabolismo , Receptor alfa de Estrogênio/metabolismo , Feminino , Proteínas de Peixes/metabolismo , Glicina/toxicidade , Frequência Cardíaca/efeitos dos fármacos , Locomoção/efeitos dos fármacos , Masculino , Osteopontina/metabolismo , Sialoglicoproteínas/metabolismo , Peixe-Zebra/anormalidades , Peixe-Zebra/metabolismo , GlifosatoRESUMO
A pesticide characterization is presented for two highly technified valleys in northwest Mexico: Culiacan Valley (CV) in Sinaloa and Yaqui Valley (YV) in Sonora. Approximately 250,000 kg of active ingredients are used every year, half of which are considered highly hazardous pesticides. Legacy pesticides are still present in the soils of these valleys. The aim of the present study was to identify and quantify a wide variety of pesticides in soils and correlate their concentrations with historical and current use. Agricultural soils from both valleys were sampled and analyzed using accelerated solvent extraction and subsequent quantification by gas chromatography with selective detectors. The most frequently detected pesticides (mean, µg g-1) in CV were organochlorines (0.1967), organophosphates (0.0928), synthetic pyrethroids (0.2565), organonitrogen (0.0552), and miscellaneous pesticides (0.1851). In YV, the most frequently detected pesticides were organochlorines (0.8607), organophosphates (0.0001), synthetic pyrethroids (0.0124), and miscellaneous pesticides (0.0009). The pesticides were more diverse in CV compared to those of YV, which was based on the types of crops produced. Both locations presented highly hazardous pesticides, including concentrations above the action levels established by the Canadian Soil Quality Guide. A follow-up risk assessment is recommended to assess potential effects.