N-glucosyltransferase GbNGT1 from ginkgo complements the auxin metabolic pathway

As auxins are among the most important phytohormones, the regulation of auxin homeostasis is complex. Generally, auxin conjugates, especially IAA glucosides, are predominant at high auxin levels. Previous research on terminal glucosylation focused mainly on the O-position, while IAA-N-glucoside and IAA-Asp-N-glucoside have been neglected since their discovery in 2001. In our study, IAA-Asp-N-glucoside was found to be specifically abundant (as high as 4.13 mg/g) in the seeds of 58 ginkgo cultivars. Furthermore, a novel N-glucosyltransferase, termed GbNGT1, was identified via differential transcriptome analysis and in vitro enzymatic testing. It was found that GbNGT1 could catalyze IAA-Asp and IAA to form their corresponding N-glucosides. The enzyme was demonstrated to possess a specific catalytic capacity toward the N-position of the IAA-amino acid or IAA from 52 substrates. Docking and site-directed mutagenesis of this enzyme confirmed that the E15G mutant could almost completely abolish its N-glucosylation ability toward IAA-Asp and IAA in vitro and in vivo. The IAA modification of GbNGT1 and GbGH3.5 was verified by transient expression assay in Nicotiana benthamiana. The effect of GbNGT1 on IAA distribution promotes root growth in Arabidopsis thaliana.

Alternative oxidase1a and 1d limit proline-dependent oxidative stress and aid salinity recovery in Arabidopsis

A link between Pro catabolism and mitochondrial reactive oxygen species production has been established across eukaryotes and in plants increases in leaf respiration rates have been reported following Pro exposure. Here we investigated how alternative oxidases (AOXs) of the mitochondrial electron transport chain accommodate the large, atypical flux resulting from Pro catabolism and limit oxidative stress during Pro breakdown in mature Arabidopsis leaves. Following Pro treatment, AOX1a and AOX1d accumulate at transcript and protein levels, with AOX1d approaching the level of the typically dominant AOX1a isoform. We therefore sought to determine the function of both AOX isoforms under Pro respiring conditions. Oxygen consumption rate measurements in aox1a and aox1d leaves suggested these AOXs can functionally compensate for each other to establish enhanced AOX catalytic capacity in response to Pro. Generation of aox1a.aox1d lines showed complete loss of AOX proteins and activity upon Pro treatment, yet respiratory induction in response to Pro was still possible via the cytochrome pathway. However, aox1a.aox1d leaves suffered increased levels of oxidative stress and damage during Pro metabolism compared to WT or the single mutants. During recovery from salt stress, when high rates of Pro catabolism occur naturally, photosynthetic rates in aox1a.aox1d recovered slower than WT or the single aox lines, showing that both AOX1a and AOX1d are beneficial for cellular metabolism during Pro drawdown following osmotic stress. This work provides physiological evidence of a beneficial role for AOX1a but also the less studied AOX1d isoform in allowing safe catabolism of alternative respiratory substrates like Pro.

Tumor-killing nanoreactors fueled by tumor debris can enhance radiofrequency ablation therapy and boost antitumor immune responses

Radiofrequency ablation (RFA) is clinically adopted to destruct solid tumors, but is often incapable of completely ablating large tumors and those with multiple metastatic sites. Here we develop a CaCO3-assisted double emulsion method to encapsulate lipoxidase and hemin with poly(lactic-co-glycolic acid) (PLGA) to enhance RFA. We show the HLCaP nanoreactors (NRs) with pH-dependent catalytic capacity can continuously produce cytotoxic lipid radicals via the lipid peroxidation chain reaction using cancer cell debris as the fuel. Upon being fixed inside the residual tumors post RFA, HLCaP NRs exhibit a suppression effect on residual tumors in mice and rabbits by triggering ferroptosis. Moreover, treatment with HLCaP NRs post RFA can prime antitumor immunity to effectively suppress the growth of both residual and metastatic tumors, also in combination with immune checkpoint blockade. This work highlights that tumor-debris-fueled nanoreactors can benefit RFA by inhibiting tumor recurrence and preventing tumor metastasis.

Antimicrobial and catalytic applications of TiO2 nanoparticles prepared from titanium(IV)-Schiff base complexes as precursor

Attempts have been made to synthesis titanium dioxide (TiO2) nanoparticles using titanium (IV) complexes of Schiff base (TiOL) as a precursor where Schiff base ligand (L) act as a dibasic tetradentate one. TiO2 nanoparticles were synthesized by the direct calcination of titanium complexes at 500 °C for 3 hours. The analytical tools such as FT-IR, XRD, EDS, and SEM provided evidences in favor of the formation of TiO2 nanoparticles. Antimicrobial study showed that all prepared TiO2 nanoparticles have inhibition capacity on the growth against selected plant pathogenic fungi as well as some selected human pathogenic bacteria. Moreover, these TiO2 nanoparticles have catalytic capacity for the remarkable degradation (54.0%) of organic dye (Mordent brown 48) as well as industrial dye solutions.

Effective Implementation of Urban Agendas through Urban Action Structures (UAS): The Case of the Basque Country

Cities are the main contributors to pollution, resource consumption and social inequalities. Therefore, they should play a key role in the path towards a more sustainable scenario in line with SDGs and different Urban Agendas. However, there are still difficulties in their implementation and citizen can play a central role. This paper presents the Urban Action Structures (UAS), understood as entities with a catalytic capacity with respect to innovative urban policies. Methodologically, firstly, a prospective analysis from regional to international level has been developed, making it possible to identify innovative lines of action in the field of sustainable cities. Secondly, the study has focused on identifying and studying UAS that can make it possible to implement the lines of action previously identified. This paper has shown that there are already social structures that can be understood as UAS, since they implement actions aligned with the priorities of the Urban Agenda for the Basque Country and, therefore, of the SDGs. The research concludes that UAS can play a key role in facilitating the implementation of Urban Agendas. Hence, urban policies should favor the generation of UAS, in order to promote long-term urban development and to foster a more sustainable spatial planning.

Catalytic Conversion of n-C7 Asphaltenes and Resins II into Hydrogen Using CeO2-Based Nanocatalysts

This study focuses on evaluating the volumetric hydrogen content in the gaseous mixture released from the steam catalytic gasification of n-C7 asphaltenes and resins II at low temperatures (<230 °C). For this purpose, four nanocatalysts were selected: CeO2, CeO2 functionalized with Ni-Pd, Fe-Pd, and Co-Pd. The catalytic capacity was measured by non-isothermal (from 100 to 600 °C) and isothermal (220 °C) thermogravimetric analyses. The samples show the main decomposition peak between 200 and 230 °C for bi-elemental nanocatalysts and 300 °C for the CeO2 support, leading to reductions up to 50% in comparison with the samples in the absence of nanoparticles. At 220 °C, the conversion of both fractions increases in the order CeO2 < Fe-Pd < Co-Pd < Ni-Pd. Hydrogen release was quantified for the isothermal tests. The hydrogen production agrees with each material’s catalytic activity for decomposing both fractions at the evaluated conditions. CeNi1Pd1 showed the highest performance among the other three samples and led to the highest hydrogen production in the effluent gas with values of ~44 vol%. When the samples were heated at higher temperatures (i.e., 230 °C), H2 production increased up to 55 vol% during catalyzed n-C7 asphaltene and resin conversion, indicating an increase of up to 70% in comparison with the non-catalyzed systems at the same temperature conditions.

Dramatic changes in mitochondrial substrate use at critically high temperatures: a comparative study using Drosophila

ABSTRACTEctotherm thermal tolerance is critical to species distribution, but at present the physiological underpinnings of heat tolerance remain poorly understood. Mitochondrial function is perturbed at critically high temperatures in some ectotherms, including insects, suggesting that heat tolerance of these animals is linked to failure of oxidative phosphorylation (OXPHOS) and/or ATP production. To test this hypothesis, we measured mitochondrial oxygen consumption rate in six Drosophila species with different heat tolerance using high-resolution respirometry. Using a substrate–uncoupler–inhibitor titration protocol, we examined specific steps of the electron transport system to study how temperatures below, bracketing and above organismal heat limits affect mitochondrial function and substrate oxidation. At benign temperatures (19 and 30°C), complex I-supported respiration (CI-OXPHOS) was the most significant contributor to maximal OXPHOS. At higher temperatures (34, 38, 42 and 46°C), CI-OXPHOS decreased considerably, ultimately to very low levels at 42 and 46°C. The enzymatic catalytic capacity of complex I was intact across all temperatures and accordingly the decreased CI-OXPHOS is unlikely to be caused directly by hyperthermic denaturation/inactivation of complex I. Despite the reduction in CI-OXPHOS, maximal OXPHOS capacity was maintained in all species, through oxidation of alternative substrates – proline, succinate and, particularly, glycerol-3-phosphate – suggesting important mitochondrial flexibility at temperatures exceeding the organismal heat limit. Interestingly, this failure of CI-OXPHOS and compensatory oxidation of alternative substrates occurred at temperatures that correlated with species heat tolerance, such that heat-tolerant species could defend ‘normal’ mitochondrial function at higher temperatures than sensitive species. Future studies should investigate why CI-OXPHOS is perturbed and how this potentially affects ATP production rates.

Enhancing The Photocatalytic Conversion Of Pt(IV) Substrates By Flavoprotein Engineering

Our recent work demonstrates that certain flavoproteins can catalyze the redox activation of Pt(IV) prodrug complexes under light irradiation. Herein, we used site directed mutagenesis on the mini Singlet Oxygen Generator (mSOG) to modulate the photocatalytic activity of this flavoprotein towards two model Pt(IV) substrates. Among the prepared mutants, Q103V mSOG displayed enhanced catalytic efficiency as a result of its longer triplet excited state lifetime. This study shows, for the first time, that protein engineering can improve the catalytic capacity of a protein towards metal-containing substrate.