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Tricresyl phosphate isomers exert estrogenic effects via G protein-coupled estrogen receptor-mediated pathways Texte intégral
2020
Ji, Xiaoya | Li, Na | Ma, Mei | Rao, Kaifeng | Yang, Rong | Wang, Zijian
Tricresyl phosphates (TCPs), as representative aromatic organophosphate flame retardants (OPFRs), have received much attention due to their potential neurotoxicity and endocrine-disrupting effects. However, the role of estrogen receptor α (ERα) and G protein-coupled estrogen receptor (GPER) in their estrogen disrupting effects remains poorly understood. Therefore, in this study, three TCP isomers, tri-o-cresyl phosphate (ToCP), tri-m-cresyl phosphate (TmCP) and tri-p-cresyl phosphate (TpCP), were examined for their activities on ERα by using two-hybrid yeast assay, and action on GPER by using Boyden chamber assay, cAMP production assay, calcium mobilization assay and molecular docking analysis. The results showed that three TCP isomers were found to act as ERα antagonists. Conversely, they had agonistic activity on GPER to promote GPER-mediated cell migration of MCF7 cells and SKBR3 cells. Both ToCP and TpCP activated GPER-mediated cAMP production and calcium mobilization, whereas TmCP had different mode of action, it only triggered GPER-mediated calcium mobilization, as evidenced by using the specific GPER inhibitor (G15) and GPER overexpressing experiments. Molecular docking further revealed that the way of interaction of TmCP and TpCP with GPER was different from that of ToCP with GPER, and higher activity of ToCP in activating GPER-mediated pathways might be associated with the alkyl substitution at the ortho position of the aromatic ring. Our results, for the first time, found a new target, GPER, for TCPs exerting their estrogen-disrupting effects, and demonstrated complex estrogen-disrupting effects of three TCP isomers involved their opposite activities toward ERα and GPER.
Afficher plus [+] Moins [-]Response of isoprene emission from poplar saplings to ozone pollution and nitrogen deposition depends on leaf position along the vertical canopy profile Texte intégral
2020
Yuan, Xiangyang | Li, Shuangjiang | Feng, Zhaozhong | Xu, Yansen | Shang, Bo | Fares, Silvano | Paoletti, Elena
We investigated isoprene (ISO) emission and gas exchange in leaves from different positions along the vertical canopy profile of poplar saplings (Populus euramericana cv. ‘74/76’). For a growing season, plants were subjected to four N treatments, control (NC, no N addition), low N (LN, 50 kg N ha⁻¹year⁻¹), middle N (MN, 100 kg N ha⁻¹year⁻¹), high N (HN, 200 kg N ha⁻¹year⁻¹) and three O₃ treatments (CF, charcoal-filtered ambient air; NF, non-filtered ambient air; NF + O₃, NF + 40 ppb O₃). Our results showed the effects of O₃ and/or N on standardized ISO rate (ISOᵣₐₜₑ) and photosynthetic parameters differed along with the leaf position, with larger negative effects of O₃ and positive effects of N on ISOᵣₐₜₑ and photosynthetic parameters in the older leaves. Expanded young leaves were insensitive to both treatments even at very high O₃ concentration (67 ppb as 10-h average) and HN treatment. Significant O₃ × N interactions were only found in middle and lower leaves, where ISOᵣₐₜₑ declined by O₃ just when N was limited (NC and LN). With increasing light-saturated photosynthesis and chlorophyll content, ISOᵣₐₜₑ was reduced in the upper leaves but on the contrary increased in middle and lower leaves. The responses of ISOᵣₐₜₑ to AOT40 (accumulated exposure to hourly O₃ concentrations > 40 ppb) and PODY (accumulative stomatal uptake of O₃ > Y nmol O₃ m⁻² PLA s⁻¹) were not significant in upper leaves, but ISOᵣₐₜₑ significantly decreased with increasing AOT40 or PODY under limited N supply in middle leaves but at all N levels in lower leaves. Overall, ISOᵣₐₜₑ changed along the vertical canopy profile in response to combined O₃ and N exposure, a behavior that should be incorporated into multi-layer canopy models. Our results are relevant for modelling regional isoprene emissions under current and future O₃ pollution and N deposition scenarios.
Afficher plus [+] Moins [-]Wetland soil microplastics are negatively related to vegetation cover and stem density Texte intégral
2020
Helcoski, Ryan | Yonkos, Lance T. | Sanchez, Alterra | Baldwin, Andrew H.
Microplastics are a complex group of ubiquitous environmental contaminants of emerging concern. These particles degrade slowly, release plasticizers, and can be transferred between trophic levels. In aquatic systems, they have been identified suspended in the water column, along shorelines, and within sediment. However, the abundance and distribution of microplastics in vegetated wetlands, which are transitional ecosystems between terrestrial and aquatic environments, are poorly understood. Here we describe the spatial distribution of soil microplastics in habitats of varying vegetation density in an urban tidal wetland. Samples were wet-sieved, organic matter was oxidized using hydrogen peroxide, and microplastics separated under a dissecting microscope, counted, and weighed. A fraction (n = 175) were analyzed via FTIR for validation. Positive microplastics identification was 81%–93%. Dominant polymers were polystyrene (29%) and polyethylene and synthetic rubber (both 8%). Average microplastic number to a 5-cm depth (23,200 ± 2,500 m−2 or 1,270 ± 150 kg−1) varied between habitat types, where mudflat, channel edge, and drift line habitats all had significantly more total microplastics than the interior of dense stands of vegetation, suggesting that emergent wetland plants are a highly effective filter of microplastics. Microfibers were about eight times as abundant as microfragments, and fibers and fragments differed in their distribution patterns, with microfibers most abundant in vegetation-free mudflats and microfragments in vegetated channel edges. Our results demonstrate that vegetated wetlands are important locations for microplastic accumulation and that wetland vegetation and hydrodynamics affect spatial distribution of microplastics between habitats.
Afficher plus [+] Moins [-]Effects of co-exposure to 900 MHz radiofrequency electromagnetic fields and high-level noise on sleep, weight, and food intake parameters in juvenile rats Texte intégral
2020
Bosquillon de Jenlis, Aymar | Del Vecchio, Flavia | Delanaud, Stéphane | Bach, Véronique | Pelletier, Amandine
Electrohypersensitive people attribute various symptoms to exposure of radiofrequency electromagnetic fields (RF-EMF); sleep disturbance is the most frequently cited. However, laboratory experiments have yielded conflicting results regarding sleep alterations. Our hypothesis was that exposure to RF-EMF alone would lead to slight or non-significant effects but that co-exposure to RF-EMFs and other environmental constraints (such as noise) would lead to significant effects.3-week-old male Wistar rats (4 groups, n = 12 per group) were exposed for 5 weeks to continuous RF-EMF (900 MHz, 1.8 V/m, SAR = 30 mW/kg) in the presence or absence of high-level noise (87.5 dB, 50–20000 Hz) during the rest period. After 5 weeks of exposure, sleep (24 h recording), food and water intakes, and body weight were recorded with or without RF-EMF and/or noise. At the end of this recording period, sleep was scored during the 1 h resttime in the absence of noise and of RF-EMF exposure.Exposure to RF-EMF and/or noise was associated with body weight gain, with hyperphagia in the noise-only and RF-EMF + noise groups and hypophagia in the RF-EMF-only group. Sleep parameters recording over 24 h highlighted a higher frequency of active wakefulness in the RF-EMF-only group and a lower non-rapid eye movement/rapid eye movement sleep ratio during the active period in the noise-only group. There were no differences in sleep duration in either group. During the 1-h, constraint-free sleep recording, sleep rebound was observed in the noise-only group but not in the RF-EMF-only and RF-EMF + noise groups.Our study showed effects of RF-EMF, regardless of whether or not the animals were also exposed to noise. However, the RF-EMF + noise group presented no exacerbation of those effects. Our results did not support the hypothesis whereby the effects of RF-EMF on physiological functions studied are only visible in animals exposed to both noise and RF-EMF.
Afficher plus [+] Moins [-]Metro station free drinking water fountain- A potential “microplastics hotspot” for human consumption Texte intégral
2020
Shruti, V.C. | Pérez-Guevara, Fermín | Kutralam-Muniasamy, Gurusamy
Microplastics have become an inevitable component of our environment. Worldwide, free public fountains are common and one of the best sources of drinking water which are being installed with one of the viewpoints of reducing single-use plastics bottle consumption. However, the state of knowledge on how microplastics might be affecting in those free public drinking fountains is unknown. In this study, free drinking water fountains from 42 metro stations in Mexico City were being looked into for the occurrence of microplastics and investigated their shape type, size, abundance, distribution, polymer composition and surface morphology. Microplastics were detected in all the samples analyzed. The results revealed the significant abundance of microplastics ranging from 5 ± 2 to 91 ± 14 L⁻¹ in drinking water with an overall average of 18 ± 7 microplastics L⁻¹. Transparent fibers (69%) were predominant in the identified microplastics followed by blue (24%) and red colored (7%) fibers. The most frequent microplastics dimensions ranged between 0.1 and 1 mm which is approximately 75% of the total microplastics. Micro-Raman spectroscopy analysis indicated that microplastics contained in drinking water were mainly polyesters (poly (trimethylene terephthalate)) and epoxy resin suggesting the possible contribution of wastewater discharges for microplastics contamination. Thus, this study findings show that free public drinking water fountains are potential microplastics hotspot for human consumption and provide useful references for mitigation measures.
Afficher plus [+] Moins [-]Characterisation of hyper tolerant Bacillus firmus L-148 for arsenic oxidation Texte intégral
2020
Bagade, Aditi | Nandre, Vinod | Paul, Dhiraj | Patil, Yugendra | Sharma, Nisha | Giri, Ashok | Kodam, Kisan
Groundwater arsenic pollution causes millions of deaths worldwide. Long term natural and anthropogenic activities have increased arsenic levels in groundwater causing higher threats of arsenic exposure. Arsenic hyper-tolerant Firmicute Bacillus firmus L-148 was isolated from arsenic limiting Lonar lake soil, which tolerated more than 3 M arsenic and could oxidize 75 mM arsenite [As(III)] in 14 days. It oxidized As(III) in presence of heavy metals and had unusual pH optima at 9.2. B. firmus L-148 was studied at the biochemical, protein, genomic and transcript level for understanding its arsenic oxidizing machinery. The proteomic and transcript analysis exhibited the presence of ars and aio operon and supported the inducible nature of ars operon. Robust, hyper-tolerant, fast As(III) oxidizing, least nutrient requiring and multi-metal resistance qualities of the strain were used in microcosm studies for bioremediation. Artificial groundwater mimicking microcosm with 75 mM As(III) was developed. Modulation of carbon source, iron and multi metals affected growth and As(III) oxidation rate. The As(III) oxidation was recorded to be 77% in 15 days in presence of sodium acetate and Fe ions. This microcosm study can be explored for bioremediation of arsenic contaminated water and followed by precipitation using other methods.
Afficher plus [+] Moins [-]Sludge retention time affects the microbial community structure: A large-scale sampling of aeration tanks throughout China Texte intégral
2020
Sun, Chenxiang | Zhang, Bing | Chen, Zhan | Qin, Wentao | Wen, Xianghua
Microbial communities in activated sludge (AS) have a significant influence on the functions and stability of aeration tanks in wastewater treatment plants (WWTPs). The microbial community structure is affected by various factors, among which operational parameters outcompeted as the key factors in shaping its structure. However, as an important operational parameter of aeration tank, the mechanisms by which sludge retention time (SRT) affect community properties remain unclear. In this study, 144 AS samples from aeration tanks of 48 full-scale WWTPs operating under different SRT conditions were examined via high-throughput Illumina-MiSeq sequencing technology. The results indicated that SRT significantly affected the diversity, composition, assembly, and co-occurrence patterns of the microbial community in aeration tanks. Moreover, our results provided clear evidence that the microbial communities in aeration tanks operating under SRT of 10–20 days have the highest biodiversity, the lowest stochastic processes influence, the more stable molecular ecological network structure, the lowest risks of filamentous sludge bulking and enhanced nitrogen removal potential. The microbial communities could be more stable and resilient to disturbance when aeration tanks were operated under this SRT condition. The findings of this study provided a reference for the optimization of aeration tanks from an of microbial community perspective.
Afficher plus [+] Moins [-]Multisensory pollution: Artificial light at night and anthropogenic noise have interactive effects on activity patterns of great tits (Parus major) Texte intégral
2020
Dominoni, Davide | Smit, Judith A.H. | Visser, Marcel E. | Halfwerk, Wouter
Urbanisation is increasing globally at a rapid pace. Consequently, wild species face novel environmental stressors associated with urban sprawl, such as artificial light at night and noise. These stressors have pervasive effects on the behaviour and physiology of many species. Most studies have singled out the impact of just one of these stressors, while in the real world they are likely to co-occur both temporally and spatially, and we thus lack a clear understanding of the combined effect of anthropogenic stressors on wild species. Here, we experimentally exposed captive male great tits (Parus major) to artificial light at night and 24 h noise in a fully factorial experiment. We then measured the effect of both these stressors on their own and their combination on the amount and timing of activity patterns. We found that both light and noise affected activity patterns when presented alone, but in opposite ways: light increased activity, particularly at night, while noise reduced it, particularly during the day. When the two stressors were combined, we found a synergistic effect on the total activity and the nighttime activity, but an antagonistic effect on daytime activity. The significant interaction between noise and light treatment also differed among forest and city birds. Indeed, we detected a significant interactive effect on light and noise on daytime, nighttime, dusktime and offset of activity of urban birds, but not of forest birds. These results suggest that both artificial light at night and anthropogenic noise can drive changes in activity patterns, but that the specific impacts depend on the habitat of origin. Furthermore, our results demonstrate that co-occurring exposure to noise and light can lead to a stronger impact at night than predicted from the additive effects and thus that multisensory pollution may be a considerable threat for wildlife.
Afficher plus [+] Moins [-]Can atmospheric pollutants influence menstrual cycle function? Texte intégral
2020
Giorgis-Allemand, L. | Thalabard, J.C. | Rosetta, L. | Siroux, V. | Bouyer, J. | Slama, R.
A few experimental studies suggest that atmospheric pollutants could affect the endocrine system, and in particular stress hormones and the hypothalamic-hypophyseal-ovarian axis, which could in turn influence menstrual cycle function. We aimed to study the possible short-term effects of atmospheric pollutants on the length of the follicular and luteal phases and on the duration of the menstrual cycle in humans. To do so, from a nation-wide study on couples’ fecundity, we recruited 184 women not using contraception who collected urine samples at least every other day during one menstrual cycle, from which a progesterone metabolite was assayed, allowing estimation of the duration of the follicular and luteal phases of the cycle. Atmospheric pollution (nitrogen dioxide and particulate matter with an aerodynamical diameter below 10 μm, PM₁₀) levels were estimated from a dispersion model with a 1-km resolution combined with permanent monitoring stations measurements, allowing to estimate exposures in the 30-day, 1–10 and 11-30-day periods before the start of the menstrual cycle. Regression models allowed to quantify the change in cycle duration associated with atmospheric pollutants and adjusted for potential confounders. Follicular phase duration increased on average by 0.7 day (95% confidence interval, CI, 0.2; 1.3) for each increase by 10 μg/m³ in NO₂ concentration averaged over the 30 days before the cycle and by 1.6 day (95% CI, 0.3; 2.9) for each increase by 10 μg/m³ in PM₁₀. There was no strong evidence of associations of exposures in this time window with luteal phase or with total menstrual cycle durations (p > 0.2). Exposures in the 1–10 day period before the cycle start were also associated with increased follicular phase duration. This study is one of the first prospective studies to suggest short-term alterations in follicular phase duration following atmospheric pollutants exposure.
Afficher plus [+] Moins [-]Bacterial foraging facilitates aggregation of Chlamydomonas microsphaera in an organic carbon source-limited aquatic environment Texte intégral
2020
Zhao, Ranran | Chen, Guowei | Liu, Li | Zhang, Wei | Sun, Yifei | Li, Baoguo | Wang, Gang
Microalgal aggregation is a key to many ecosystem functions in aquatic environments. Yet mechanistic understanding of microalgae aggregation, especially the interactions with ubiquitous bacteria populations, remains elusive. We reported an experimental study illustrating how the emerging bacterial populations interacted with a model microalga (Chlamydomonas microsphaera) cells and the consequent aggregation patterns. Results showed that the emergence of bacterial populations significantly stimulated C. microsphaera aggregation. Both bacterial and C. microsphaera motilities were remarkably excited upon coculturing, with the mean cell velocity being up to 2.67 and 1.80 times of those of separate bacterial and C. microsphaera cultures, respectively. The stimulated bacterial and C. microsphaera cell velocity upon coculturing would likely provide a mechanism for enhanced probability of cell-cell collisions that led to amplified aggregation of C. microsphaera population. Correlation analysis revealed that bacterial resource foraging (for polysaccharides) was likely a candidate mechanism for stimulated cell motility in an organic carbon source-limited environment, whereby C. microsphaera-derived polysaccharides serve as the sole organic carbon source for heterotrophic bacteria which in turns facilitates bacteria-C. microsphaera aggregation. Additional analysis showed that bacterial populations capable of successive decomposing algal-derived organic matters dominated the cocultures, with the top five abundant genera of Brevundimonas (24.78%), Shinella (17.94%), Sphingopyxis (11.62%), Dongia (5.82%) and Hyphomicrobium (5.45%). These findings provide new insights into full understanding of microalgae-bacteria interactions and consequent microbial aggregation characteristics in aquatic ecosystems.
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