Microplastics (MPs) are emerging globally distributed pollutants of aquatic environments, and little is known about their fate at drinking water treatment plants (DWTPs), which provide a barrier ...preventing MPs from entering water for human consumption. This study investigated MPs ≥ 1 μm in raw and treated water of two DWTPs that both lie on the same river, but the local quality of water and the treatment technology applied differ. In the case of the more complex DWTP, MPs were analysed at 4 additional sampling sites along the treatment chain. The content of MPs varied greatly between the DWTPs. There were 23 ± 2 and 14 ± 1 MPs L−1 in raw and treated water, respectively, at one DWTP, and 1296 ± 35 and 151 ± 4 MPs L−1 at the other. Nevertheless, MPs comprised only a minor proportion (<0.02%) of all detected particles at both DWTPs. With regard to size and shape of MPs, the majority (>70%) were smaller than 10 μm, and only fragments and fibres were found, while fragments clearly prevailed. The most frequently occurring materials were cellulose acetate, polyethylene terephthalate, polyvinyl chloride, polyethylene, and polypropylene. Much higher total removal of MPs was achieved at the DWTP with a higher initial MP load and more complicated treatment (removal of 88% versus 40%); coagulation-flocculation-sedimentation, deep-bed filtration through clay-based material, and granular activated carbon filtration contributed to MP elimination by 62%, 20%, and 6%, respectively. Additionally, results from this more complex DWTP enabled to observe relationships between the removal efficiency and size and shape of MPs, particularly in the case of the filtration steps.
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•MPs ≥ 1 μm were analysed at different stages of drinking water treatment at two DWTPs.•Scanning electron microscopy and micro-Raman spectroscopy were employed.•MP content ranged from <20 to >1200 L−1, while fragments <10 μm always prevailed.•The number of MPs varied both between the DWTPs and along the treatment chain.•Current water treatment technology is capable of removing almost 90% of MPs ≥ 1 μm.
Main conclusions
Low temperature decreases PSII damage in vivo, confirming earlier in vitro results. Susceptibility to photoinhibition differs among Arabidopsis accessions and moderately decreases ...after 2-week cold-treatment. Flavonols may alleviate photoinhibition.
The rate of light-induced inactivation of photosystem II (PSII) at 22 and 4 °C was measured from natural accessions of
Arabidopsis thaliana
(Rschew, Tenela, Columbia-0, Coimbra) grown under optimal conditions (21 °C), and at 4 °C from plants shifted to 4 °C for 2 weeks. Measurements were done in the absence and presence of lincomycin (to block repair). PSII activity was assayed with the chlorophyll
a
fluorescence parameter
F
v
/
F
m
and with light-saturated rate of oxygen evolution using a quinone acceptor. When grown at 21 °C, Rschew was the most tolerant to photoinhibition and Coimbra the least. Damage to PSII, judged from fitting the decrease in oxygen evolution or
F
v
/
F
m
to a first-order equation, proceeded more slowly or equally at 4 than at 22 °C. The 2-week cold-treatment decreased photoinhibition at 4 °C consistently in Columbia-0 and Coimbra, whereas in Rschew and Tenela the results depended on the method used to assay photoinhibition. The rate of singlet oxygen production by isolated thylakoid membranes, measured with histidine, stayed the same or slightly decreased with decreasing temperature. On the other hand, measurements of singlet oxygen from leaves with Singlet Oxygen Sensor Green suggest that in vivo more singlet oxygen is produced at 4 °C. Under high light, the PSII electron acceptor
Q
A
was more reduced at 4 than at 22 °C. Singlet oxygen production, in vitro or in vivo, did not decrease due to the cold-treatment. Epidermal flavonols increased during the cold-treatment and, in Columbia-0 and Coimbra, the amount correlated with photoinhibition tolerance.
•Heat stress effects on yield parameters: more pronounced particularly at DC 61.•Main drought stress effect on chlorophyll content: Bohemia at DC 75, Tobak at DC 61.•Response of photosynthetic ...parameters were more pronounced than yield parameters.
Heat waves and drought periods are expected to become more frequent due to climate change. This may cause a critical decline in future crop yields. However, insufficient knowledge of the interactive effects of high temperature and drought stress at specific growth stages is the cause of numerous uncertainties in modeling impacts of climate change on field crop growth and yield. Hence, the aim of this study was to investigate the effects of interactions between the short-term exposure (3 and 7 days) of two winter wheat genotypes to elevated temperature and drought stress on yield formation and photosynthetic parameters. Winter wheat plants grown under ambient conditions were subjected to four temperature regimes (with maxima at 26, 32, 35 and 38 °C) and drought in growth chambers at three critical growth stages (beginning of stem elongation – DC 31, beginning of anthesis – DC 61, and medium milk ripe – DC 75). The response of yield formation parameters was obviously modulated by variety and growth stage. Grain number was more affected by drought at DC 31 and by the temperature at DC 61. Grain weight per spike was reduced by drought stress similarly at all growth stages, but the results indicated the increasing sensitivity of this parameter to a temperature at the later growth stage. Although yield parameters only changed slightly with the length of heat and drought stress, the photosynthetic parameters were strongly affected, particularly by longer drought and the interactive effect of high temperature and drought stress. Higher temperature significantly increased the negative impact of drought on CO2 assimilation rate. Photosynthetic parameters were less affected by combined high temperatures and drought stress at DC 61 as compared to other growth stages investigated. The larger effect at the later growth stage (DC 75) can be attributed to induced senescence, among other factors, particularly in the Bohemia variety. The Tobak variety appears to be more tolerant to combined high temperatures and drought stress in terms of photosynthetic parameters. Based on the relationships between heat degree-days (HDD) and grain weight per spike we demonstrated the potential of HDD to integrate length and intensity of heat stress at different growth stages, particularly for estimation effects on yield parameters. It can be summarized that although the short-term combination of high temperatures and drought causes significant reductions in photosynthetic parameters, the impact on yield formation is much lower, indicating fast recovery of photosynthetic processes and compensation in yield formation parameters.
Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on ...germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 – 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.
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•δ-HCH influences the germination success rate of Alnus glutinosa seeds.•Germination efficiency changes are progeny-dependent.•Alder seedling uptake of δ-HCH did not exceed 2.52% of the pollutant dose.•Alder seedling’s presence enhanced the effectiveness of δ-HCH removal by 20.85–35.89%.•Alder seedling’s hormones concentrations changed both negatively and positively to some extent during the exposure to δ-HCH.
6-Diazo-5-oxo-l-norleucine (DON) is a glutamine antagonist with robust anticancer efficacy; however, its therapeutic potential was hampered by its biodistribution and toxicity to normal tissues, ...specifically gastrointestinal (GI) tissues. To circumvent DON’s toxicity, we synthesized a series of tumor-targeted DON prodrugs designed to circulate inert in plasma and preferentially activate over DON in tumor. Our best prodrug 6 (isopropyl 2-(6-acetamido-2-(adamantane-1-carboxamido)hexanamido)-6-diazo-5-oxohexanoate) showed stability in plasma, liver, and intestinal homogenates yet was readily cleaved to DON in P493B lymphoma cells, exhibiting a 55-fold enhanced tumor cell-to-plasma ratio versus that of DON and resulting in a dose-dependent inhibition of cell proliferation. Using carboxylesterase 1 knockout mice that were shown to mimic human prodrug metabolism, systemic administration of 6 delivered 11-fold higher DON exposure to tumor (target tissue; AUC0–t = 5.1 nmol h/g) versus GI tissues (toxicity tissue; AUC0–t = 0.45 nmol h/g). In summary, these studies describe the discovery of a glutamine antagonist prodrug that provides selective tumor exposure.
•Interactive effects of water deficit and N nutrition were studied in winter wheat.•Production and physiological parameters were measured in field experiment.•Spectral reflectance and thermal imaging ...were used to estimate wheat responses.•Spectral indices providing estimation of responses to N and water deficit were found.•Grain protein content and its estimation are affected by water availability.
Water and nitrogen (N) deficit are globally the most frequently limiting factors for agricultural crops, while both often occur together. To evaluate the interactive effects of water deficit and N nutrition on remote sensing data, rainout shelter field experiments were conducted in winter wheat during 2013–2014. Canopy spectral reflectance and infrared thermal imaging parameters were correlated to biochemical, physiological, morphological and production characteristics. Correlation analysis revealed that stomatal response to water deficit is best estimated using the NPCI (Normalized Pigment Chlorophyll Index) vegetation index and also by the CWSI (Crop Water Stress Index) thermal index. A variety of vegetation indices can be used to estimate grain yield, among which the best-performing is the Normalized Red Edge-Red Index (NRERI). That index shows the highest correlation irrespective of water deficit and N nutrition. Although none of the indices provided good detection of N content in plants, the total N uptake in wheat grain was reliably estimated by the TCARI/OSAVI (Transformed Chlorophyll Absorption Reflectance Index/Optimized Soil-Adjusted Vegetation Index). The results demonstrated that utilization of N for yield or grain protein formation was largely determined by water availability, and the relationships between vegetation indices and grain protein content thus have a distinct slope under water deficit. In summary, the spectral and thermal indices can provide satisfactory estimation, irrespective of interactions between water and N deficit, for grain yield, N uptake, and stomatal responses. However, when estimating the grain protein content, the water availability should be considered.
The glutamine antagonist 6-diazo-5-oxo-l-norleucine (DON) exhibits remarkable anticancer efficacy; however, its therapeutic potential is hindered by its toxicity to gastrointestinal (GI) tissues. We ...recently reported the discovery of DRP-104, a tumor-targeted DON prodrug with excellent efficacy and tolerability, which is currently in clinical trials. However, DRP-104 exhibits limited aqueous solubility, and the instability of its isopropyl ester promoiety leads to the formation of an inactive M1-metabolite, reducing overall systemic prodrug exposure. Herein, we aimed to synthesize DON prodrugs with various ester and amide promoieties with improved solubility, GI stability, and DON tumor delivery. Twenty-one prodrugs were synthesized and characterized in stability and pharmacokinetics studies. Of these,
,
-butyl-(
)-6-diazo-2-((
)-2-(2-(dimethylamino)acetamido)-3-phenylpropanamido)-5-oxo-hexanoate, showed excellent metabolic stability in plasma and intestinal homogenate, high aqueous solubility, and high tumor DON exposures and preserved the ideal tumor-targeting profile of DRP-104. In conclusion, we report a new generation of glutamine antagonist prodrugs with improved physicochemical and pharmacokinetic attributes.
Populus nigra is an important autochthonous woody plant that can be grown as a renewable energy source. The possibility of its improvement through intraspecific hybridization was tested. Differences ...in biomass production, growth parameters, Melampsora larici-populina rust resistance and drought tolerance were evaluated among 19 intraspecific hybrids from controlled crosses, 2 clones selected from natural populations and the “MAX 4” clone (P. nigra × P. maximowiczii). These P. nigra clones from controlled crosses were chosen from more than 2000 hybrid individuals whose parents were selected from natural populations in the Czech Republic. A field trial was set up in Pruhonice, Czech Republic (320 m a.s.l., 591 mm rainfall annually, mean annual temperature of 9.5 °C). The planting density was 6061 plants ha-1, and the plants were coppiced three times at 3-year intervals. The trial was irrigated only during its establishment. Among the clones, significant differences were found in all the evaluated traits over three rotations. An average dry matter yield of the best clone “MAX 4” was 12.8 t ha-1 yr-1 over three harvests. The best black poplar clone reached up to 9.4 t ha-1 yr-1 in three harvests. Rust resistance was constant over 9 years and high for the three P. nigra clones (two from controlled crosses and one from natural populations). Moreover, the best P. nigra clones from controlled crosses showed higher drought tolerance than the “MAX 4” clone. Breeding progress was confirmed, and most of the P. nigra clones from controlled crosses performed better than the clones selected from natural populations. The trial validated the suitability of natural populations for use as gene sources for intraspecific hybridization and as sources of clones with traits comparable with those of interspecific clones. These new P. nigra clones can replace allochthonous clones in areas where autochthonous P. nigra populations are threatened by introgression.
Many samples contain compounds with various numbers of two or more regular structural groups. Such “multidimensional” samples (according to the Giddings’ notation) are best separated in orthogonal ...chromatographic systems with different selectivities for the individual repeat structural groups, described by separation factors. Correlations between the repeat group selectivities characterize the degree of orthogonality and suitability of chromatographic systems for two-dimensional (2D) separations of two-dimensional samples. The range of the structural units in that can be resolved in a given time can be predicted on the basis of a model describing the repeat group selectivity in the first- and second-dimension systems. Two-dimensional liquid chromatographic system combining reversed-phase (RP) mode in the first dimension and normal-phase (NP) mode in the second dimension were studied with respect to the possibilities of in-line fraction transfer between the two modes. Hydrophilic interaction liquid chromatography (HILIC) with an aminopropyl silica column (APS) is more resistant than classical non-aqueous NP systems against adsorbent desactivation with aqueous solvents transferred in the fractions from the first, RP dimension to the second dimension. Hence, HILIC is useful as a second-dimension separation system for comprehensive RP–NP LC
×
LC. A comprehensive 2D RP–NP HPLC method was developed for comprehensive 2D separation of ethylene oxide–propylene oxide (EO–PO) (co)oligomers. The first-dimension RP system employed a 120
min gradient of acetonitrile in water on a C18 microbore column at the flow-rate of 10
μL/min. In the second dimension, isocratic HILIC NP with ethanol-dichloromethane-water mobile phase on an aminopropyl silica column at 0.5
mL/min was used. Ten microliter fractions were transferred from the RP to the HILIC NP system at 1
min switching valve cycle frequency.
Although plants are often exposed to atmospheric nanoparticles (NPs), the mechanism of NP deposition and their effects on physiology and metabolism, and particularly in combination with other ...stressors, are not yet understood. Exploring interactions between stressors is particularly important for understanding plant responses in urban environments where elevated temperatures can be associated with air pollution. Accordingly, 3-year-old spruce seedlings were exposed for 2 weeks to aerial cadmium oxide (CdO) NPs of environmentally relevant size (8–62 nm) and concentration (2 × 105 cm−3). While half the seedlings were initially acclimated to high temperature (35 °C) and vapour pressure deficit (VPD; 2.81 kPa), the second half of the plants were left under non-stressed conditions (20 °C, 0.58 kPa). Atomic absorption spectrometry was used to determine Cd content in needles, while gas and liquid chromatography was used to determine changes in primary and secondary metabolites. Photosynthesis-related processes were explored with gas-exchange and chlorophyll fluorescence systems. Our work supports the hypothesis that atmospheric CdO NPs penetrate into leaves but high temperature and VPD reduce such penetration due to stomatal closure. The hypothesis that atmospheric CdO NPs influences physiological and metabolic processes in plants was also confirmed. This impact strengthens with increasing time of exposure. Finally, we found evidence that plants acclimated to stress conditions have different sensitivity to CdO NPs compared to plants not so acclimated. These findings have important consequences for understanding impacts of global warming on plants and indicates that although the effects of elevated temperatures can be deleterious, this may limit other forms of plant stress associated with air pollution.
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•Penetration of CdO nanoparticles is modulated by factors driving stomatal openness.•CdO nanoparticles affect both physiology and metabolism in spruce seedlings.•Effects of CdO nanoparticles are strengthened with time of exposure.•Acclimation to high temperature alters sensitivity of spruce to CdO nanoparticles.
Temperature affects absorption of CdO nanoparticles by spruce seedlings from the air which subsequently influence both physiological and metabolic processes.
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