Short-term partitioning of Cd recently taken up between sunflowers organs (<Emphasis Type="Italic">Helianthus annuus</Emphasis>) at flowering and grain filling stages: effect of plant transpiration and allometry

Aims

This work concentrated on understanding the allocation of Cd recently taken up between the organs of sunflower at early and middle reproductive growth stages. The roles of transpiration and allometry were investigated.

Methods

Sunflowers were grown hydroponically in greenhouse, being exposed to low concentrations of Cd (pCd²⁺ = 11.03). At flower bud and grain filling stages, plants were exposed for three days to ¹¹¹Cd and at the same time, subjected or not to fans to increase the transpiration. The partitioning of ¹¹¹Cd between plant organs measured by high resolution ICP-MS was then modelled.

Results

Although the use of fans increased the plant water uptake and transpiration by about 20%, there were no significant effects on the partitioning of recent Cd. Most of the recent Cd was recovered in roots (60%) and only 2.8% were found in seeds (0.8% for the husk and 2.0% for the almonds). The sequestration of recent Cd in a plant organ was successfully explained by its biomass and except for leaves, by the biomass of other organs acting as competitive sinks.

Conclusions

This work proposes a modelling approach for the partitioning of the labelled Cd between plant organs in sunflower.

     

Rock geochemistry induces stress and starvation responses in the bacterial proteome

Interactions between microorganisms and rocks play an important role in Earth system processes. However, little is known about the molecular capabilities microorganisms require to live in rocky environments. Using a quantitative label‐free proteomics approach, we show that a model bacterium (Cupriavidus metallidurans CH34) can use volcanic rock to satisfy some elemental requirements, resulting in increased rates of cell division in both magnesium‐ and iron‐limited media. However, the rocks also introduced multiple new stresses via chemical changes associated with pH, elemental leaching and surface adsorption of nutrients that were reflected in the proteome. For example, the loss of bioavailable phosphorus was observed and resulted in the upregulation of diverse phosphate limitation proteins, which facilitate increase phosphate uptake and scavenging within the cell. Our results revealed that despite the provision of essential elements, rock chemistry drives complex metabolic reorganization within rock‐dwelling organisms, requiring tight regulation of cellular processes at the protein level. This study advances our ability to identify key microbial responses that enable life to persist in rock environments.     

Evidence for different,host‐dependent functioning of Rx against both wild‐type and recombinant Pepino mosaic virus

The potato Rx gene provides resistance against Pepino mosaic virus (PepMV) in tomato; however, recent work has suggested that the resistance conferred may not be durable. Resistance breaking can probably be attributed to multiple mutations observed to accumulate in the capsid protein (CP) region of resistance‐breaking isolates, but this has not been confirmed through directed manipulation of an infectious PepMV clone. The present work describes the introduction of two specific mutations, A‐T78 and A‐T114, into the coat protein minimal elicitor region of an Rx‐controlled PepMV isolate of the EU genotype. Enzyme‐linked immunosorbent assay (ELISA) and phenotypic evaluation were conducted in three Rx‐expressing and wild‐type solanaceous hosts: Nicotiana benthamiana, Nicotiana tabacum and Solanum lycopersicum. Mutation A‐T78 alone was sufficient to confer Rx‐breaking activity in N. benthamiana and S. lycopersicum, whereas mutation A‐T114 was found to be associated, in most cases, with a secondary A‐D100 mutation to break Rx‐mediated resistance in S. lycopersicum. These results suggest that the need for a second, fitness‐restoring mutation may be dependent on the PepMV mutant under consideration. Both mutations conferred Rx breaking in S. lycopersicum, whereas neither conferred Rx breaking in N. tabacum and only A‐T78 allowed Rx breaking in N. benthamiana, suggesting that Rx may function in a different manner depending on the genetic background in which it is present.     

Cascade‐Type Prelithiation Approach for Li‐Ion Capacitors

An industry‐relevant method for pre‐lithiation of lithium‐ion capacitors to balance the first charge irreversibility is demonstrated, which addresses the prime bottleneck for their market integration. Based on a composite positive electrode that integrates pyrene monomers and an insoluble lithiated base, Li₃PO₄, a “cascade‐type” process involving two consecutive irreversible reactions is proposed: i) oxidative electropolymerization of the pyrene moieties releases electrons and protons; ii) protons are captured by Li₃PO₄ and exchanged for a stoichiometric amount of Li⁺ into the electrolyte. (¹H, ¹⁹F, and ³¹P) NMR spectroscopy, operando X‐ray diffraction, and Raman spectroscopy support this mechanism. By decoupling the irreversible source of lithium ions from electrons, the cascade‐type pre‐lithiation allows the simultaneous enhancement of the capacity of the positive electrode, thanks to p‐doping of the resulting polymer. Remarkably, the proton scavenging properties of Li₃PO₄ also boost the polymerization process, which enables a 16% increase in capacity without detrimental effect on power properties and cyclability. Full cells integrating a cheap carbon black based negative electrode, show much‐improved capacity of 17 mAh g^‐1_electrodes (44 F g^‐1_electrodes, 3–4.4 V) and excellent stability over 2200 cycles at 1 A g^‐1. Thanks to its versatile chemistry and flexibility this approach in principle can be applied to any kind of ion‐battery.     

Evidence of high Ca uptake by cyanobacteria forming intracellular CaCO3 and impact on their growth

Several species of cyanobacteria biomineralizing intracellular amorphous calcium carbonates (ACC) were recently discovered. However, the mechanisms involved in this biomineralization process and the determinants discriminating species forming intracellular ACC from those not forming intracellular ACC remain unknown. Recently, it was hypothesized that the intensity of Ca uptake (i.e., how much Ca was scavenged from the extracellular solution) might be a major parameter controlling the capability of a cyanobacterium to form intracellular ACC. Here, we tested this hypothesis by systematically measuring the Ca uptake by a set of 52 cyanobacterial strains cultured in the same growth medium. The results evidenced a dichotomy among cyanobacteria regarding Ca sequestration capabilities, with all strains forming intracellular ACC incorporating significantly more calcium than strains not forming ACC. Moreover, Ca provided at a concentration of 50 μM in BG‐11 was shown to be limiting for the growth of some of the strains forming intracellular ACC, suggesting an overlooked quantitative role of Ca for these strains. All cyanobacteria forming intracellular ACC contained at least one gene coding for a mechanosensitive channel, which might be involved in Ca influx, as well as at least one gene coding for a Ca²⁺/H⁺ exchanger and membrane proteins of the UPF0016 family, which might be involved in active Ca transport either from the cytosol to the extracellular solution or the cytosol toward an intracellular compartment. Overall, massive Ca sequestration may have an indirect role by allowing the formation of intracellular ACC. The latter may be beneficial to the growth of the cells as a storage of inorganic C and/or a buffer of intracellular pH. Moreover, high Ca scavenging by cyanobacteria biomineralizing intracellular ACC, a trait shared with endolithic cyanobacteria, suggests that these cyanobacteria should be considered as potentially significant geochemical reservoirs of Ca.     

Knockout of receptor for advanced glycation end‐products attenuates age‐related renal lesions

Pro‐aging effects of endogenous advanced glycation end‐products (AGEs) have been reported, and there is increasing interest in the pro‐inflammatory and ‐fibrotic effects of their binding to RAGE (the main AGE receptor). The role of dietary AGEs in aging remains ill‐defined, but the predominantly renal accumulation of dietary carboxymethyllysine (CML) suggests the kidneys may be particularly affected. We studied the impact of RAGE invalidation and a CML‐enriched diet on renal aging. Two‐month‐old male, wild‐type (WT) and RAGE^?/? C57Bl/6 mice were fed a control or a CML‐enriched diet (200 μg CML/g_food) for 18 months. Compared to controls, we observed higher CML levels in the kidneys of both CML WT and CML RAGE^?/? mice, with a predominantly tubular localization. The CML‐rich diet had no significant impact on the studied renal parameters, whereby only a trend to worsening glomerular sclerosis was detected. Irrespective of diet, RAGE^?/? mice were significantly protected against nephrosclerosis lesions (hyalinosis, tubular atrophy, fibrosis and glomerular sclerosis) and renal senile apolipoprotein A‐II (ApoA‐II) amyloidosis (p < 0.001). A positive linear correlation between sclerosis score and ApoA‐II amyloidosis score (r = 0.92) was observed. Compared with old WT mice, old RAGE^?/? mice exhibited lower expression of inflammation markers and activation of AKT, and greater expression of Sod2 and SIRT1. Overall, nephrosclerosis lesions and senile amyloidosis were significantly reduced in RAGE^?/? mice, indicating a protective effect of RAGE deletion with respect to renal aging. This could be due to reduced inflammation and oxidative stress in RAGE^?/? mice, suggesting RAGE is an important receptor in so‐called inflamm‐aging.     

Chelate-assisted phytoextraction of lead using Fagopyrum esculentum: laboratory vs. field experiments

Abstract

The development of more sustainable remediation techniques has been receiving greater attention, as an alternative to soil excavation plan in urban gardens. An in situ phytoextraction experiment with buckwheat (Fagopyrum esculentum) was performed with a 5?mmol kg^?1 citric acid (CA) application. Joint experiments under laboratory conditions were conducted using various cultivars of F. esculentum in two soils with a Pb contamination of either geogenic or anthropogenic origin and various chelate concentrations. Results show that a minimum dose of 50?mmol kg^?1 of CA is required to lower soil pH and raise the concentration of mobile Pb–CaCl₂ for both soils. Consequently, Pb shoot uptake is increased from 6.3 to 8.9 times depending on soil type. Phytoextraction efficiency is found to be 1.3 to 2.0 times higher in the anthropogenic contaminated soil than in the soil with geogenic Pb. A scale effect has also been identified since Pb root accumulation under laboratory conditions was 2.4 times higher than in the field experiment. Despite an increase in the Pb extraction rate with CA, buckwheat appears to lack the efficiency needed to remove Pb in moderately contaminated soils. The calculated remediation period would last 166?years to remove the mobile Pb fraction.     

Synthesis and biological evaluation of 3-amino-, 3-alkoxy- and 3-aryloxy-6-(hetero)arylpyridazines as potent antitumor agents

Various 3-amino-, 3-aryloxy- and alkoxy-6-arylpyridazines have been synthesized by an electrochemical reductive cross-coupling between 3-amino-, 3-aryloxy- or 3-alkoxy-6-chloropyridazines and aryl or heteroaryl halides. In vitro antiproliferative activity of these products was evaluated against a representative panel of cancer cell lines (HuH7, CaCo-2, MDA-MB-231, HCT116, PC3, NCI-H727, HaCaT) and oncogenicity prevention of the more efficient derivatives was highlighted on human breast cancer cell line MDA-MB 468-Luc prior establishing their interaction with p44/42 and Akt-dependent signaling pathways.