Cadmium and arsenic-induced-stress differentially modulates Arabidopsis root architecture, peroxisome distribution, enzymatic activities and their nitric oxide content

In plant cells, cadmium (Cd) and arsenic (As) exert toxicity mainly by inducing oxidative stress through an imbalance between the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), and their detoxification. Nitric oxide (NO) is a RNS acting as signalling molecule coordinating plant development and stress responses, but also as oxidative stress inducer, depending on its cellular concentration. Peroxisomes are versatile organelles involved in plant metabolism and signalling, with a role in cellular redox balance thanks to their antioxidant enzymes, and their RNS (mainly NO) and ROS. This study analysed Cd or As effects on peroxisomes, and NO production and distribution in the root system, including primary root (PR) and lateral roots (LRs). Arabidopsis thaliana wild-type and transgenic plants enabling peroxisomes to be visualized in vivo, through the expression of the 35S-cyan fluorescent protein fused to the peroxisomal targeting signal1 (PTS1) were used. Peroxisomal enzymatic activities including the antioxidant catalase, the H2O2-generating glycolate oxidase, and the hydroxypyruvate reductase, and root system morphology were also evaluated under Cd/As exposure. Results showed that Cd and As differently modulate these activities, however, catalase activity was inhibited by both. Moreover, Arabidopsis root system was altered, with the pollutants differently affecting PR growth, but similarly enhancing LR formation. Only in the PR apex, and not in LR one, Cd more than As caused significant changes in peroxisome distribution, size, and in peroxisomal NO content. By contrast, neither pollutant caused significant changes in peroxisomes size and peroxisomal NO content in the LR apex

Jasmonic acid methyl ester induces xylogenesis and modulates auxin-induced xylary cell identity with NO Involvement

In Arabidopsis basal hypocotyls of dark-grown seedlings, xylary cells may form from the pericycle as an alternative to adventitious roots. Several hormones may induce xylogenesis, as Jasmonic acid (JA), as well as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) auxins, which also affect xylary identity. Studies with the ethylene (ET)-perception mutant ein3eil1 and the ET-precursor 1-aminocyclopropane-1-carboxylic acid (ACC), also demonstrate ET involvement in IBA-induced ectopic metaxylem. Moreover, nitric oxide (NO), produced after IBA/IAA-treatments, may affect JA signalling and interact positively/negatively with ET. To date, NO-involvement in ET/JA-mediated xylogenesis has never been investigated. To study this, and unravel JA-effects on xylary identity, xylogenesis was investigated in hypocotyls of seedlings treated with JA methyl-ester (JAMe) with/without ACC, IBA, IAA. Wild-type (wt) and ein3eil1 responses to hormonal treatments were compared, and the NO signal was quantified and its role evaluated by using NO-donors/scavengers. Ectopic-protoxylem increased in the wt only after treatment with JAMe(10 μM), whereas in ein3eil1 with any JAMe concentration. NO was detected in cells leading to either xylogenesis or adventitious rooting, and increased after treatment with JAMe(10 μM) combined or not with IBA(10 μM). Xylary identity changed when JAMe was applied with each auxin. Altogether, the results show that xylogenesis is induced by JA and NO positively regulates this process. In addition, NO also negatively interacts with ET-signalling and modulates auxin-induced xylary identity

Exploiting the photoactivity of bacterial reaction center to investigate liposome dynamics

Charge recombination kinetics of bacterial photosynthetic protein Reaction Center displays an exquisite sensitivity to the actual occupancy of ubiquinone-10 in its QB-binding site. Here, we have exploited such phenomenon for assessing the growth and the aggregation/fusion of phosphocholine vesicles embedding RC in their membrane, when treated with sodium oleate

Nitric oxide alleviates cadmium- but not arsenic-induced damages in rice roots

Nitric oxide (NO) has signalling roles in plant stress responses. Cadmium (Cd) and arsenic (As) soil pollutants alter plant development, mainly the root-system, by increasing NO-content, triggering reactive oxygen species (ROS), and forming peroxynitrite by NO-reaction with the superoxide anion. Interactions of NO with ROS and peroxynitrite seem important for plant tolerance to heavy metal(oid)s, but the mechanisms underlying this process remain unclear. Our goal was to investigate NO-involvement in rice (Oryza sativa L.) root-system after exposure to Cd or As, to highlight possible differences in NO-behaviour between the two pollutants. To the aim, morpho-histological, chemical and epifluorescence analyses were carried out on roots of different origin in the root-system, under exposure to Cd or As, combined or not with sodium nitroprusside (SNP), a NO-donor compound. Results show that increased intracellular NO levels alleviate the root-system alterations induced by Cd, i.e., inhibition of adventitious root elongation and lateral root formation, increment in lignin deposition in the sclerenchyma/endodermis cell-walls, but, even if reducing As-induced endodermis lignification, do not recover the majority of the As-damages, i.e., enhancement of AR-elongation, reduction of LR-formation, anomalous tissue-proliferation. However, NO decreases both Cd and As uptake, without affecting the pollutants translocation-capability from roots to shoots. Moreover, NO reduces the Cd-induced, but not the As-induced, ROS levels by triggering peroxynitrite production. Altogether, results highlight a different behaviour of NO in modulating rice root-system response to the toxicity of the heavy metal Cd and the metalloid As, which depends by the NO-interaction with the specific pollutant

Caracterización superficial de pigmentos sobre artefactos paleolíticos de la zona de los Montes Albanos (Roma, Italia) por microscopía óptica y espectroscopía raman

Preliminary results of the characterization of red pigmentations on paleolithic artefacts from the southern area of Montes Albanos (Rome, Italy) are presented. The set of materials consists of three decorated rounded pebblestones and a cortical flint blade typologically attributable to the Upper Paleolithic (Final Epigravetense, 14,000-12,000 cal BP). The findings were observed with optical microscope Nikon SMZ 1000/800 with magnifications of 1x to 6.3x. In two pebblestones, one decorated with parallel engravings, residues of ocher were detected in association with traces of use. In the third one, stained red dye was observed to form geometric patterns. Finally, reddish pigmentations were located on the cortical dorsal surface of a flint blade. To characterize chemically the coloring agent detected, macro-microscopically, Raman spectroscopy was used, a technique that allowed the study of the nature of the residues and the detection of additional organic materials whose presence must be related to post-depositional contaminations produced by the manipulation or/and surface exposure of artifacts

Cadmium and arsenic affect root development in Oryza sativa L. negatively interacting with auxin

Cadmium (Cd) and arsenic (As), non essential, but toxic, elements for animals and plants are frequently present in paddy fields. Oryza sativa L., a staple food for at least the half of world population, easily absorbs As and Cd by the root, and in this organ the pollutants evoke consistent damages, reducing/modifying the root system. Auxins are key hormones in regulating all developmental processes, including root organogenesis. Moreover, plants respond to environmental stresses, such as those caused by Cd and As, by changing levels and distribution of endogenous phytohormones. Even though the effects of Cd and As on the roots have been investigated in some species, it remains necessary to deepen the knowledge about the cross-talk between these toxic elements and auxin during root formation and development, in particular in agronomically important plants, such as rice. Hence, the research goal was to investigate the interactions between Cd and As, alone or combined, and auxin during the development of rice roots. To reach the aim, morphological, histological and histochemical analyses were carried out on seedlings, exposed or not to Cd and/or As, belonging to the wild type and transgenic lines useful for monitoring indole-3-acetic acid (IAA) localization, i.e., OsDR5:GUS, and IAA cellular influx and efflux, i.e., OsAUX1:GUS and OsPIN5b:GUS. Moreover, the transcript levels of the YUCCA2 and ASA2, IAA biosynthetic genes were also monitored in Cd and/or As exposed wild type seedlings. The results highlight that As and Cd affect cyto-histology and morphology of the roots. In particular, they alter the lateral root primordia organization and development with negative consequences on root system architecture. This is due to a disturbance of IAA biosynthesis and transport, as indicated by the altered expression of both ASA2 and YUCCA2 biosynthetic genes, and AUX1 and PIN5b transporter genes

The endophytic bacterial community of healthy and Xylella-infected olive sapwood

Endophytic bacteria are of biotechnological and agronomic interest as they promote plant healthiness by producing and secreting plant growth regulators, and antagonizing phytopathogens through the induction of resistance mechanisms, and the supply of nutritional elements. One of the factors that may influence the behavior of olive towards the ‘quick decline syndrome’ is the nature of the endophytic microbial community occurring in sapwood. Objectives of the research was to characterize the bacterial endophytic population occurring into the xylem of healthy and Xylellainfected olive trees by an isolation-dependent approach. Preliminary results indicate that under field conditions, the population level of cultivable endophytic bacteria is highly variable, being mainly affected by the host genotype, host age, and wilting severity. Among the different group are Pseudomonas, Bacillus, Lysinibacillus, Pantoea, Microbacterium, Stenotrophomonas, and Methylobacterium spp. Bacteria of the Methylobacetrium genus occupy the same ecological niche of X. fastidiosa subsp. pauca. It has been reported as potential biocontrol agent of the pathogen, being its population higher in citrus plant showing mild symptoms of variegated chlorosis. Further research is in progress to better characterize the different Methylobacterium strains, using both biochemical and molecular approaches, and to evaluate its activity in reducing the severity of olive quick decline syndrome

Atogepant for the Prevention of Episodic Migraine in Adults: A Systematic Review and Meta-Analysis of Efficacy and Safety

Introduction: The inhibition of the calcitonin gene-related peptide (CGRP) pathway has attracted interest in pharmacological research on migraine. Atogepant is a potent, selective, orally available antagonist of the CGRP receptor approved as a preventive treatment of episodic migraine. This systematic review with meta-analysis aims to evaluate the efficacy and safety of atogepant for the prevention of episodic migraine in adult patients. Methods: Randomized, placebo-controlled, single or double-blinded trials were identified through a systematic literature search (December week 4, 2021). Main outcomes included the changes from baseline in monthly migraine days and the incidence of adverse events (AEs) and treatment withdrawal due to AEs. Mean difference (MD) and risk ratio (RR) with 95% confidence intervals (95% CIs) were estimated. Results: Two trials were included, overall enrolling 1550 patients. A total of 408 participants were randomized to placebo, 314 to atogepant 10 mg, 411 to atogepant 30 mg, and 417 to atogepant 60 mg once daily. The mean age of the patients was 41.0 years and 87.7% were women. The reduction in the mean number of migraine days from baseline across the 12-week treatment period was significantly greater among patients treated with atogepant at either the daily dose of 10 mg (MD − 1.16, 95% CI − 1.60 to − 0.73, p < 0.001), 30 mg (MD − 1.15, 95% CI − 1.54 to − 0.76, p < 0.001), or 60 mg (MD − 1.20, 95% CI − 2.18 to − 0.22, p = 0.016) than with placebo. There were no differences in the occurrence of AEs and drug withdrawal due to AEs between atogepant and placebo groups. Constipation was more commonly observed in patients treated with atogepant at 30 mg/day than placebo (RR 5.19, 95% CI 2.00–13.46; p = 0.001). Treatment with atogepant at the daily dose of 60 mg was associated with a higher risk of constipation (RR 4.92, 95% CI 1.89–12.79; p = 0.001) and nausea (RR 2.73, 95% CI 1.47–5.06; p = 0.001) than placebo. Conclusion: Atogepant is an efficacious and overall well-tolerated treatment for the prevention of episodic migraine in adults

Comparative Raman Study of Organic-Free and Surfactant-Capped Rod-Shaped Anatase TiO2 Nanocrystals

Excitation of lattice vibrations in nanostructured anatase TiO2 frequently occurs at energy values differing from that found for the corresponding bulk phase. Particularly, investigations have long aimed at establishing a correlation between the low-frequency E-g(1) mode and the mean crystallite size on the basis of phonon-confinement models. Here, we report a detailed Raman study, supported by X-ray diffraction analyses, on anatase TiO2 nanocrystals with rod-shaped morphology and variable geometric parameters, prepared by colloidal wet-chemical routes. By examining the anomalous shifts of the E-g(1) mode in the spectra of surfactant-capped nanorods and in those of corresponding organic-free derivatives (obtained by a suitable thermal oxidative treatment), an insight into the impact of exposed facets and of the coherent crystalline domain size on Raman-active lattice vibrational modes has been gained. Our investigation offers a ground for clarifying the current lack of consensus as to the applicability of phonon-confinement models for drawing information on the size of surface-functionalized TiO2 nanocrystals upon analysis of their Raman features