The ‘europium anomaly’ in plants: facts and fiction

Rare earth elements (REEs) and normalized REE pattern determined in plant and soil samples represent powerful tools to trace biogeochemical processes during weathering, soil genesis and processes in the rhizosphere, and thus publications reporting rare earth elements and normalized REE pattern in soil systems and plants are increasing rapidly. Generally, a normalized REE pattern allow for the recognition of an anomalous concentrations of an individual REE. In the literature anomalies are predominantly reported/focused for/on the redox-sensitive elements cerium (Ce) and europium (Eu) that can shift their oxidation state during interactions with organic and inorganic soil phases and biological processes affecting the elements’ mobility in soil and uptake by plants. Thus positive Eu anomalies in plants are often interpreted as a consequence of reduction of Eu3+ to Eu2+ in the rhizosphere followed by a preferential uptake of Eu2+. However, due to an analytical artefact in ICP-MS analysis, a false Eu anomaly may be reported. This can be avoided by using a barium (Ba) interference correction. We draw attention to the possibility of this problem and to being aware of potential occurrence when Eu anomalies are reported. Finally, we recommend (i) including information on how this potential problem was dealt with in the Materials and Methods section of articles and (ii) how to implement FAIR principles in the section (including data availability on an open repository).

Ecotoxicological effects of silver nanoparticles in marine mussels

In the marine bioindicator species M. galloprovincialis Lam we predicted toxicity and bioaccumulation of 5 nm alkane-coated and 50 nm uncoated silver nanoparticles (AgNPs) along with Ag+, as a function of the actual dose level. We generated a time persistence model of silver concentration in seawater and used the Area Under the Curve (AUC) as independent variable in hazard assessment. This approach allowed us to evaluate unbiased ecotoxicological endpoints for acute (survival) and chronic toxicity (byssal adhesion). Logistic regression analysis rendered LC5096h values of 0.68 ± 0.08; 1.00 ± 0.20; 1.00 ± 0.42 mg h L-1 respectively for Ag+, 5 nm and 50 nm AgNP posing no evidence the silver form is a necessary variable to predict the survival outcome. By contrast, for byssal adhesion regression analysis revealed a much higher toxicological potential of Ag+ vs AgNPs, 0.0021 ± 0.0009; 0.053 ± 0.016; 0.021 (no computable error for 50 nm AgNP) mg h L-1, and undoubtedly confirmed a role of the silver form. Bioaccumulation was higher for Ag+ > 5 nm AgNP > 50 nm AgNP reflecting a parallel with the preferential uptake route / target organ. We, eventually, provided a full range of toxicological endpoints to derive risk quotients.

Competing Sorption of Se(IV) and Se(VI) on Schwertmannite

Schwertmannite (SHM) is a naturally occurring mineral that has been shown to effectively scavenge oxyanions from contaminated water. In this study, Fourier-transform infrared spectroscopy and X-ray absorption spectroscopy techniques in combination with wet-chemical techniques were used to study the competitive sorption of Se(IV) and Se(VI) at pH 3. The experiments were conducted with three types of schwertmannite obtained from oxidative synthesis, biogenic synthesis and high-pressure compaction at different initial Se concentrations and mixing ratios for 48 h and 56 days, respectively. A threshold value for the uptake mechanisms was identified, which reflects the amount of easily exchangeable sulphate (~0.5 mmol/g). At adsorbate concentrations below this threshold, an inner-sphere corner-sharing bidentate binuclear complex forms upon exchange with sulphate. At higher concentrations, both oxyanions become bound to SHM through co-occurrence of mainly inner-sphere and partly outer-sphere corner-sharing bidentate binuclear complexes with Fe(III) containing surface sites. Single species experiments clearly indicate a higher affinity of SHM for Se(IV). However, in mixed species experiments, competitive sorption occurs with equal or even preferential uptake of Se(VI) at concentrations much lower than the threshold value, presumably due to geometrical similarity between selenate and sulphate, and increasing preference for Se(IV) at high Se concentrations.

Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions

In order to better constrain calcium cycling in natural soil and in soil used for agriculture, we present the δ44/40Ca values measured in rainwater, groundwater, plants, soil, and bedrock samples from a representative karst forest in SW China. The δ44/40Ca values are found to differ by ≈3.0‰ in the karst forest ecosystem. The Ca isotope compositions and Ca contents of groundwater, rainwater, and bedrock suggest that the Ca of groundwater primarily originates from rainwater and bedrock. The δ44/40Ca values of plants are lower than that of soils, indicating the preferential uptake of light Ca isotopes by plants. The distribution of δ44/40Ca values in the soil profiles (increasing with soil depth) suggests that the recycling of crop-litter abundant with lighter Ca isotope has potential effects on soil Ca isotope composition. The soil Mg/Ca content ratio probably reflects the preferential plant uptake of Ca over Mg and the difference in soil maturity. Light Ca isotopes are more abundant in mature soils than nutrient-depleted soils. The relative abundance in the light Ca isotope (40Ca) is in the following order: farmland > burnt grassland > forests > grassland > shrubland. Our results further indicate that biological fractionation in a soil–plant system is a vital factor for Ca–geochemical transformations in soil surface systems.

Towards Smart Drug Delivery: Exploration Of A Molecularly Imprinted Polymer Network

The current study explores the concept of Molecular Imprinting Technology (MIT) and evaluates the ability of a molecularly imprinted hydrogel polymer (MIP) to preferentially uptake the template drug propranolol from aqueous solution. The extent of the molecular affinity and recognition was challenged by introducing a secondary competing structure during uptake. The release of propranolol as a response to environmental stimuli was investigated. The MIP was synthesized with copolymers methyl methacrylate (MMA) and N,N-dimethyl acrylamide (DMAA). Morphology was studied by scanning electron microscopy (SEM), ptake, displacement, and release experiments were studied by fluorescence spectroscopy. The SEM studies did not indicate the presence of molecularly imprinted cavities. The MIPs demonstrated preferential uptake in comparison to the non-imprinted (NIP) counterpart. The displacement studies revealed that uptake by the MIP is not very selective. The release studies demonstrated that ropranolol release can be tailored to respond to environmental stimuli such as temperature and, especially, pH.

Towards Smart Drug Delivery: Exploration Of A Molecularly Imprinted Polymer Network

The current study explores the concept of Molecular Imprinting Technology (MIT) and evaluates the ability of a molecularly imprinted hydrogel polymer (MIP) to preferentially uptake the template drug propranolol from aqueous solution. The extent of the molecular affinity and recognition was challenged by introducing a secondary competing structure during uptake. The release of propranolol as a response to environmental stimuli was investigated. The MIP was synthesized with copolymers methyl methacrylate (MMA) and N,N-dimethyl acrylamide (DMAA). Morphology was studied by scanning electron microscopy (SEM), ptake, displacement, and release experiments were studied by fluorescence spectroscopy. The SEM studies did not indicate the presence of molecularly imprinted cavities. The MIPs demonstrated preferential uptake in comparison to the non-imprinted (NIP) counterpart. The displacement studies revealed that uptake by the MIP is not very selective. The release studies demonstrated that ropranolol release can be tailored to respond to environmental stimuli such as temperature and, especially, pH.

Stimulation of vascular organoids with SARS-CoV-2 antigens increases endothelial permeability and regulates vasculopathy

ObjectiveThrombotic complications and vasculopathy have been extensively associated with severe COVID-19 infection, however the mechanisms by which endotheliitis is induced remain poorly understood. Here we investigate vascular permeability in the context of SARS-CoV-2-mediated endotheliitis in patient samples and a vascular organoid model.Methods and ResultsWe report the presence of the Spike glycoprotein in pericytes associated with pericyte activation and increased endothelial permeability in post-mortem COVID-19 lung autopsies. A pronounced decrease in the expression of the adhesion molecule VE-cadherin is observed in patients with thrombotic complications. Interestingly, fibrin-rich thrombi did not contain platelets, did not colocalize with tissue factor and have heterogenous levels of Von Willebrand factor, suggesting a biomarker-guided therapy might be required to target thrombosis in severe patients. Using a 3D vascular organoid model, we observe that ACE2 is primarily expressed in pericytes adjacent to vascular networks, consistent with patient data, indicating a preferential uptake of the S glycoprotein by these cells. Exposure of vascular organoids to SARS-CoV-2 or its antigens, recombinant trimeric Spike glycoprotein and Nucleocapsid protein, reduced endothelial cell and pericyte viability as well as CD144 expression with no additive effect upon endothelial activation via IL-1β.ConclusionsOur data suggest that pericyte uptake of SARS-CoV-2 or Spike glycoprotein contributes to vasculopathy by altering endothelial permeability increasing the risk of thrombotic complications.

Manganese distribution in the Mn-hyperaccumulator Grevillea meisneri from New Caledonia

• Grevillea meisneri, an endemic New Caledonian Mn-hyperaccumulator, is used in rehabilitation of degraded mining sites on the island. Large-scale programs require transplanting nursery-grown seedlings, but effects of the nursery environment on Mn tolerance of transplants and their capacity to hyper-accumulate Mn are unknown, slowing rehabilitation efforts.• We studied tissue-level distribution of Mn and other elements in different tissues of G. meisneri using micro-X-Ray Fluorescence spectroscopy (μXRF), comparing nursery-grown plants transplanted into the site and sampled seven years later, and similar-sized plants that had grown spontaneously in the site. • Mirroring patterns in other Mn-hyperaccumulators, Mn was preferentially accumulated in leaves but was also present in roots. Concentrations were highest in leaf epidermal tissues, in cortex and vascular tissues of stems and primary roots, and in phloem and pericycle-endodermis of parent cluster roots. Although abundant in soil, Ni was absent from all tissues of G. meisneri. Ca was always co-localised with Mn. Preferential uptake of Mn vs Ni in roots implies as-yet-uncharacterized specific Mn-transporters, while Ca and Mn co-localisation suggests shared transport pathways. • No differences were observed in concentration and distribution of Mn in transplanted and spontaneously-growing plants. Nursery-grown transplants should be highly suitable for large-scale, high-throughput rehabilitation programs.

Nutrient supplementation experiments with saltern microbial communities implicate utilization of DNA as a source of phosphorus

All environments including hypersaline ones harbor measurable concentrations of dissolved extracellular DNA (eDNA) that can be utilized by microbes as a nutrient. However, it remains poorly understood which eDNA components are used, and who in a community utilizes it. For this study, we incubated a saltern microbial community with combinations of carbon, nitrogen, phosphorus, and DNA, and tracked the community response in each microcosm treatment via 16S rRNA and rpoB gene sequencing. We show that microbial communities used DNA only as a phosphorus source, and provision of other sources of carbon and nitrogen was needed to exhibit a substantial growth. The taxonomic composition of eDNA in the water column changed with the availability of inorganic phosphorus or supplied DNA, hinting at preferential uptake of eDNA from specific organismal sources. Especially favored for growth was eDNA from the most abundant taxa, suggesting some haloarchaea prefer eDNA from closely related taxa. The preferential eDNA consumption and differential growth under various nutrient availability regimes were associated with substantial shifts in the taxonomic composition and diversity of microcosm communities. Therefore, we conjecture that in salterns the microbial community assembly is driven by the available resources, including eDNA.