The intensifying production and release into the environment as well as the increasing potential in agricultural applications make the relationship between plants and nickel nanoparticles (Ni NPs) a relevant and timely topic. The aim of this review is to give an overview and discuss the latest findings about the relationship of Ni NPs and plants. Ni NPs can be synthesized using phytochemicals derived from plant parts in an environmentally friendly manner. There are several ways for these nanoparticles to enter plant cells and tissues. This can be demonstrated through various imaging and chemical mapping approaches (e.g., transmission electron microscopy, X-ray fluorescence spectroscopy etc.). NiO NPs affect plants at multiple levels, including subcellular, cellular, tissue, organ, and whole-plant levels. However, the effects of Ni NPs on plants’ ecological partners (e.g., rhizobiome, pollinators) remain largely unknown despite their ecotoxicological significance. The main cause of the Ni NPs-triggered damages is the reactive oxygen species imbalance as a consequence of the modulation of antioxidants. In non-tolerant plants, the toxicity of NiO NPs can be mitigated by exogenous treatments such as the application of silicon, salicylic acid, or jasmonic acid, which induce defense mechanisms whereas Ni-hypertolerant plant species possess endogenous defense systems, such as cell wall modifications and nitrosative signaling against NiO NP stress. Research highlights the role of Ni NPs in managing fungal diseases, showcasing their antifungal properties against specific pathogens. Due to the essentiality of Ni, the application of Ni NPs as nanofertilizers might be promising and has recently started to come into view.

The industrial application and environmental release of nickel oxide NPs (NiO NPs) is increasing, but the details of their relationship with plants are largely unknown. In this work, the cellular, tissue, organ, and molecular level responses of three ecotypes of Ni hyperaccumulator Odontarrhena lesbiaca grown in the presence of high doses of NiO NP (250 mg/L and 500 mg/L) were studied. All three ecotypes showed a similar accumulation of Ni in the presence of nano Ni, and in the case of NiO NPs, the root -to -shoot Ni translocation was slighter compared to the bulk Ni. In all three ecotypes, the walls of the root cells effectively prevented internalization of NiO NPs, providing cellular defense against Ni overload. Exposure to NiO NP led to an increase in cortex thickness and the deposition of lignin-suberin and pectin in roots, serving as a tissue -level defense mechanism against excessive Ni. Exposure to NiO NP did not modify or cause a reduction in some biomass parameters of the Ampeliko and Loutra ecotypes, while it increased all parameters in Olympos. The free salt form of Ni exerted more negative effects on biomass production than the nanoform, and the observed effects of NiO NPs can be attributed to the release of Ni ions. Nitric oxide and peroxynitrite levels were modified by NiO NPs in an ecotype -dependent manner. The changes in the abundance and activity of S-nitrosoglutathione reductase protein triggered by NiO NPs suggest that the enzyme is regulated by NiO NPs at the post -translational level. The NiO NPs slightly intensified protein tyrosine nitration, and the slight differences between the ecotypes were correlated with their biomass production in the presence of NiO NPs. Overall, the Odontarrhena lesbiaca ecotypes exhibited tolerance to NiO NPs at the cellular, tissue, organ/organism and molecular levels, demonstrating various defense mechanisms and changes in the metabolism of reactive nitrogen species metabolism and nitrosative protein modification.

Recently, there has been a great interest in melanoma and stromal cell-to-cell interactions behind the progressive behavior of melanoma. By in vitro co-culturing and using sequential seeding conditions imitating the niche properties, the gained hybrid variants are visualized by high content fluorescent microscopy. The co-culture experiment applied a consecutive seeding order of the primarily plated HDF-RFP-ZeoR fibroblast monolayer as the "soil" and the delayed spreading of the UACC 257-GFP-NeoR melanoma cells as the "seeds". Using only the single zeocin selection provides double advantages in eliminating the parental melanoma cells and preserving the zeocin resistant fibroblast as stroma to elongate the lifespan of the rare hybrid cells. The observed heterotypic interactions underwent detailed morphological analysis and classification in vitro, followed by ex vivocharacterization of human melanoma tissue samples. The morphology of the identified interactions included cell internalization, living cell-in-cell structures, intermediate hybrids, transient and definitive myofibroblast-like or resting fibroblast-like variants. The heterotypic melanoma-fibroblast interactions are classified as mainly defensive cancer cannibalism by the stromal cells, which may result in a paradoxical heterotypic cell fusion showing melanoma-to-stromal cell mimicry. The resulted definitive hybrids gained stromal phenotype indistinguishable from the surrounding stromal parental cells. The study strengthens the complexity of the cancer-stromal interactions in the cancer niche providing new fields on histopathologic diagnostics as well as on cancer-microenvironment research.

Various insults can trigger innate immune activation through pattern recognition receptors(PRRs) in different cell types. These can leave lasting epigenetic changes, and affected cells undergo cellular reprogramming, resulting in altered responsiveness to subsequent encounters. This is an adaptive response of the innate immune system called innate immune memory(IIM). We were interested in whether Cutibacterium acnes (C. acnes) may initiate similar events in keratinocytes. We used C. acnes for primary training, and after five days of rest, Pam3Csk4 (TLR1/2 agonist) for secondary induction in normal human epidermal keratinocyte (NHEK) and HaCaT cells. The mRNA expression of several immune-related genes (e.g., TNFa, IL-8, SOCS1, TNFAIP3, TNIP1) increased in Pam3Csk4-induced trained HaCaT cells, compared to Pam3Csk4-induced, untrained ones, suggestive of innate training-like IIM processes. Expression differences were also observed in NHEK cells, but their direction was not the same in cells originating from different body parts. We found statistically significantly higher TNFa levels in cells from the breast region (NHEK-B), but lower ones in abdominal (NHEK-A) samples, indicative of innate training vs., tolerance events, respectively. The global 5-methylcytosine (5-mC) content of the genomic DNA isolated from these samples was higher in control (untrained, uninduced) NHEK-B cells compared to NHEK-A ones even after the 5 days of resting. Previous C. acnes treatment led to a marked and sustained decrease in NHEK-A cultures and no changes in NHEK-B ones. Members of our microbiota may modify keratinocyte immune events and through that profoundly affects the cutaneous immune responses in vitro and possibly in vivo. Epigenetic differences of NHEK cells representing different skin regions may arise due to the variations in the inhabiting microbiota composition.

In addition to their beneficial effects on plant physiology, multi-walled carbon nanotubes (MWCNTs) are harmful to plants in elevated concentrations. This study compared the effects of two doses of MWCNT (10 and 80 mg/L) in Brassica napus and Solanum lycopersicum seedlings focusing on nitro-oxidative processes. The presence of MWCNTs was detectable in the root and hypocotyl of both species. Additionally, transmission electron microscopy analysis revealed that MWCNTs are heavily transformed within the root cells forming large aggregates. The uptake of MWCNTs negatively affected root viability and root cell proliferation of both species, but more intense toxicity was observed in S. lycopersicum compared to B. napus. The presence of MWCNT triggered more intense protein carbonylation in the relative sensitive S. lycopersicum, where increased hydrogen peroxide levels were observed. Moreover, MWCNT exposure increased the level of physiological protein tyrosine nitration which was more intense in S. lycopersicum where notable peroxynitrite accumulation occurred. These suggest for the first time that MWCNT triggers secondary nitro-oxidative stress which contributes to its toxicity. Moreover, the results indicate that the extent of the nitro-oxidative processes is associated with the extent of MWCNT toxicity.

Fusarium graminearum and F. culmorum cause the most widespread wheat disease Fusarium head blight (FHB). The present study describes that the Fusarium inoculation of the wheat spikes caused systemic changes in the key elements of the antioxidant/detoxification defence system in the flag leaf during the grain filling period in wheat lines differing in biotic stress susceptibility to explore changes in some components of the response. According to our data, the inoculation with both F. graminearum and F. culmorum at the anthesis changed significantly the activities of superoxide dismutase (SOD) and guaiacol peroxidase (POD) enzymes, as well as the glutathione transferase (GST) activity in the flag leaves of the selected wheat lines approx. two weeks later after the infection. In silico approach supported the expressional up-regulation of various GST genes upon Fusarium infection. Based on our results, GST sequences TaGSTF26 and TaGSTU120 were among the series of important stress response genes, which were transcriptionally up-regulated, thus possibly playing a role in the systemic response to Fusarium infection, where TaGSTF26 might have an important role in the successful defence. These GSTs can serve as effective markers of the detoxification process for breeders and plant protection in the future.

The exact pathogenesis of acne-related post-inflammatory hyperpigmentation (PIH) is unknown. It is thought that epidermal inflammation induces the release of arachidonic acid and its oxidation products, leading to melanocyte activation and pigment production. Cutibacterium acnes (C. acnes) contributes to keratinocyte inflammation in acne pathogenesis. In severe cases inflamed sebaceous follicles may be ruptured, thereby bacteria and their metabolites can reach the melanocytes in the basal epidermal layer. We aimed to investigate whether, in addition to inducing epidermal immune activation, C. acnes may also directly affects melanocytes, thus contributing to PIH development. In our study we established C. acnes-treated normal human melanocyte and melanocyte-keratinocyte co-cultures and analyzed the properties of melanocyte immune activation and melanogenesis. We observed that direct C. acnes treatment increased the mRNA expression level of tumor necrosis factor alpha and the secreted protein levels of interleukin 6 and 8, together with the mRNA levels of tyrosinase and dopachrome tautomerase, playing roles in melanin biosynthesis. Tyrosinase enzyme activities and the intracellular melanin levels were also elevated, which we confirmed using real-time RT-PCR, L-DOPA staining, direct melanin measurement, and silver-nitrate staining. Based on our results, we propose that C. acnes or bacterial components may directly interact with melanocytes during the formation of severe acne lesions due to the disruption of intact follicles. They may induce melanocyte immune activation and increased melanogenesis, contributing to PIH symptoms.

Due to their release into the environment, zinc oxide nanoparticles (ZnO NPs) may come in contact with plants. In elevated concentrations, ZnO NPs induce reactive oxygen species (ROS) production, but the metabolism of reactive nitrogen species (RNS) and the consequent nitro-oxidative signalling has not been examined so far. In this work, Brassica napus and Brassica juncea seedlings were treated with chemically synthetized ZnO NPs (∼8 nm, 0, 25 or 100 mg/L). At low dose (25 mg/L) ZnO NP exerted a positive effect, while at elevated concentration (100 mg/L) it was toxic to both species. Additionally, B. juncea was more tolerant to ZnO NPs than B. napus. The ZnO NPs could enter the root cells due to their small (∼8 nm) size which resulted in the release of Zn2+ and subsequently increased Zn2+ content in the plant organs. ZnO NPs disturbed superoxide radical and hydrogen peroxide homeostasis and modulated ROS metabolic enzymes (NADPH oxidase, superoxide dismutase, ascorbate peroxidase) and non-enzymatic antioxidants (ascorbate and glutathione) inducing similar changes in oxidative signalling in both Brassica species. The homeostasis of RNS (nitric oxide, peroxynitrite and S-nitrosoglutathione) was also altered by ZnO NPs; however, changes in nitrosative signalling proved to be different in the examined species. Moreover, ZnO NPs triggered changes in protein carbonylation and nitration. These results suggest that ZnO NPs induce changes in nitro-oxidative signalling which may contribute to ZnO NP toxicity. Furthermore, difference in ZnO NP tolerance of Brassica species is more likely related to nitrosative than to oxidative signalling.

A körforgásos gazdaság célkitűzéseinek megvalósítása nagymértékben függ a hulladékkezelési feladatok logisztikai problémáinak megoldásától. A közösségi közlekedés területén bekövetkező automatizálás és digitalizáció hozzájárul az adott járműállomány gyors lecserélődéséhez, ezért szükséges megoldani a leselejtezett eszközök hatékony kezelését. Jelen cikk keretében bemutatásra kerül a körforgásos gazdasági modellnek megfelelő járműbontó kapacitásigény-felmérése a közúti közösségi közlekedési eszközök tekintetében. Majd egy járműbontó külső és belső logisztikai folyamatait érintő tervezési és fejlesztési eszközök kerülnek ismertetésre.

Despite of its essentiality, nickel (Ni) in excess is toxic for plants partly due to the overproduction of reactive oxygen species (ROS) and the consequent increase in oxidative stress signalling. However, in Ni-stressed plants little is known about the signal transduction of reactive nitrogen species (RNS) and protein tyrosine nitration as the protein-level consequence of increased RNS formation. Our experiments compared the nickel accumulation and tolerance, the redox signalling and the protein nitration in the agar-grown Arabidopsis thaliana and Brassica juncea exposed to Ni (50 μM nickel chloride). Studying GUS-tagged Arabidopsis lines (ARR5::GUS, ACS8::GUS and DR5::GUS) revealed that Ni-increased lateral root (LR) emergence, and concomitantly reduced LR initiation were accompanied by elevated levels of auxin, cytokinin, and ethylene in the LRs or in upper root parts, whereas Ni-induced primary root shortening is related to decreased auxin, and increased cytokinin and ethylene levels. These suggest the Ni-induced disturbance of hormonal balance in the root system. Results of the comparative study showed that weaker Ni tolerance of A. thaliana was coupled with a Ni-induced increase in RNS, ROS, and hydrogen sulfide levels, as well as with an increase in redox signalling and consequent increment of protein nitration. However, in relative Ni tolerant B. juncea, redox signalling (except for peroxynitrite) was not modified, and Ni-induced intensification of protein tyrosine nitration was less pronounced. Data collectively show that the better Ni tolerance of Brassica juncea may be related to the capability of preventing the induction of redox signalling and consequently to the slighter increase in protein nitration.

Accumulation of heavy metals such as zinc (Zn) disturbs the metabolism of reactive oxygen (e.g. hydrogen peroxide, H2O2) and nitrogen species (e.g. nitric oxide, NO; S-nitrosoglutathione, GSNO) in plant cells; however, their signal interactions are not well understood. Therefore, this study examines the interplay between H2O2 metabolism and GSNO signaling in Arabidopsis. Comparing the Zn tolerance of the wild type (WT), GSNO reductase (GSNOR) overexpressor 35S::FLAG-GSNOR1 and GSNOR-deficient gsnor1-3, we observed relative Zn tolerance of gsnor1-3, which was not accompanied by altered Zn accumulation capacity. Moreover, in gsnor1-3 plants Zn did not induce NO/S-nitrosothiol (SNO) signaling, possibly due to the enhanced activity of NADPH-dependent thioredoxin reductase. In WT and 35S::FLAG-GSNOR1, GSNOR was inactivated by Zn, and Zn-induced H2O2 is directly involved in the GSNOR activity loss. In WT seedlings, Zn resulted in a slight intensification of protein nitration detected by Western blot and protein S-nitrosation observed by resin-assisted capture of SNO proteins (RSNO-RAC). LC-MS/MS analyses indicate that Zn induces the S-nitrosation of ascorbate peroxidase 1. Our data collectively show that Zn-induced H2O2 may influence its own level, which involves GSNOR inactivation-triggered SNO signaling. These data provide new evidence for the interplay between H2O2 and SNO signaling in Arabidopsis plants affected by metal stress.

Termites depend on their gut microbes for digestion of complex polysaccharides of wood into simpler molecules. Cellulose is a major polymeric carbohydrate present in the wood which is broken down to simpler byproducts through metabolic steps by the hindgut microbes. Termite gut microbes also produce gases during the cellulose degradation process, of which methane is the major product. Gut microbes belong to three major groups, namely, bacteria, archaea and protozoa. They show a mutualistic relationship and typically convert 95% of cellulose into simple sugars within 24 h. More than 200 species of microbes form this community, producing different types of wood-busting enzymes, mainly cellulases, cellubiases, hemicellulases, glucosidases and gluconases, during wood degradation. Studies suggest that lower termites utilize both endogenous and protozoal enzymes for cellulose digestion, while higher termites acquire enzymes from their diet instead of protozoal enzymes. Some termite species change their feeding habits with seasonal variations. These affect gut microbes population and therefore are responsible for enhancing their survival under changed environmental conditions.

Keratinocytes are important gatekeepers of our body, forming a complex barrier. They distinguish between friendly microbes and harmful invaders and initiate effective immune responses if necessary. Tight regulation of these innate immune events are crucial, as they may quickly become deleterious, if not properly controlled. We aimed to analyze the regulation of innate immune reactions of keratinocytes initiated upon the recognition of Cutibacterium acnes (C. acnes) bacterium. We identified TNIP1 as a factor exhibiting negative regulatory effects on C. acnes-induced TLR signaling pathways. Transcriptional regulation of this gene is complex, JNK and MAPKK-dependent signaling pathways are important for basal TNIP1 expression, whereas C. acnes-induced expression changes diminish in response to JNK, MAPKK, NF-κB and p38 inhibition. The promoter region of TNIP1 also contains functional retinoic acid response elements (RARE) and all-trans retinoic acid (ATRA) treatment significantly increased TNIP1 protein expression levels. As a consequence, C. acnes-induced mRNA expression of TLR-2 and the pro-inflammatory TNFα and CCL5 decreased, TLR-4 and CXCL8 levels increased, whereas TLR3 and IL-6 mRNAs were not affected by the treatment. C. acnes is a key member of the postadolescent cutaneous microbiome of healthy skin, but also inducing innate immune and inflammatory events in acne pathogenesis in teenagers. Retinoids, apart from their know effects (decreasing sebaceous gland size and sebum secretion, leading to the control of C. acnes load) may attenuate C. acnes-induced inflammation by directly affecting TNIP1 expression and also by attenuating TLR2 expression and signaling.

Selenium phytotoxicity involves processes like reactive nitrogen species overproduction and nitrosative protein modifications. This study evaluates the toxicity of two selenium forms (selenite and selenate at 0 µM, 20 µM, 50 µM and 100 µM concentrations) and its correlation with protein tyrosine nitration in the organs of hydroponically grown Indian mustard (Brassica juncea L.). Selenate treatment resulted in large selenium accumulation in both Brassica organs, while selenite showed slight root-to-shoot translocation resulting in a much lower selenium accumulation in the shoot. Shoot and root growth inhibition and cell viability loss revealed that Brassica tolerates selenate better than selenite. Results also show that relative high amounts of selenium are able to accumulate in Brassica leaves without obvious visible symptoms such as chlorosis or necrosis. The more severe phytotoxicity of selenite was accompanied by more intense protein tyrosine nitration as well as alterations in nitration pattern suggesting a correlation between the degree of Se forms-induced toxicities and nitroproteome size, composition in Brassica organs. These results imply the possibility of considering protein tyrosine nitration as novel biomarker of selenium phytotoxicity, which could help the evaluation of asymptomatic selenium stress of plants.

At high concentrations, selenium (Se) exerts phytotoxic effects in non-tolerant plant species partly due to the induction of nitro-oxidative stress; however, these processes are not fully understood. In order to obtain a more accurate view of the involvement of nitro-oxidative processes in plant Se sensitivity, this study aims to characterize and compare Se-triggered changes in reactive oxygen (ROS) and nitrogen species (RNS) metabolism and the consequent protein tyrosine nitration as a marker of nitrosative stress in the non-accumulator Astragalus membranaceus and the Se hyperaccumulator Astragalus bisulcatus. The observed parameters (Se accumulation, microelement homeostasis, tissue-level changes in the roots, germination, biomass production, root growth and cell viability) supported that A. membranaceus is Se sensitive while the hyperaccumulator A. bisulcatus tolerates high Se doses. We first revealed that in A. membranaceus, Se sensitivity coincides with the Se-induced disturbance of superoxide metabolism, leading to its accumulation. Furthermore, Se increased the production or disturbed the metabolism of RNS (nitric oxide, peroxynitrite and S-nitrosoglutathione), consequently resulting in intensified protein tyrosine nitration in sensitive A. membranaceus. In the (hyper)tolerant and hyperaccumulator A. bisulcatus, Se-induced ROS/RNS accumulation and tyrosine nitration proved to be negligible, suggesting that this species is able to prevent Se-induced nitro-oxidative stress.

The human skin provides a physical barrier which separates our body from the external environment. Earlier we have shown that Propionibacterium acnes (P. acnes), a member of the cutaneous microbiota, may modulate the barrier properties of an in vitro cultured keratinocyte monolayer and a three dimensional organotypic skin (OS) model. Our aim was to perform a detailed, molecular analysis of these effects using the above in vitro models. For that, we used a confluent immortalised human keratinocyte (HPV-KER) cell culture kept in low or high Ca2+ ion-containing culturing media and an OS model. These were treated with P. acnes bacterium, and the expression changes of tight junction (TJ) proteins (claudin 1, 4 – CLDN1, 4; occluding – OCLN and zonula occludens 1 – ZO-1) were investigated with real time RT-PCR, western blot (WB) analysis and immunohistochemical staining. mRNA expression levels of TJ genes showed only slight changes upon bacterial treatment, suggesting that barrier changes were possibly not due to bacterially-induced transcriptional events. CLDN1 levels decreased, ZO-1 protein levels increased in the monolayer cultures independent of Ca2+ ion concentration. CLDN4 and OCLN protein levels increased upon bacterial treatment in the high Ca2+ HPV-KER cultures. IHC staining of OS models showed that protein expression of CLDN1 changed similarly to the monolayer cultures upon P. acnes treatment. CLDN4 and OCLN levels also increased in the granulosus and spinosus epidermis layers similarly to the low Ca2+ HPV-KER cultures. These results suggest that HPV-KER monolayers cultured under different conditions behaves similarly to various epidermal layers. In the studied in vitro models P. acnes may modulate the level and localization of TJ proteins and through that play a role in the maintenance of epidermal homeostasis.

Nitric oxide (NO) and related molecules (reactive nitrogen species) regulate diverse physiological processes mainly through posttranslational modifications such as protein tyrosine nitration (PTN). PTN is a covalent and specific modification of tyrosine (Tyr) residues resulting in altered protein structure and function. In the last decade, great efforts have been made to reveal candidate proteins, target Tyr residues and functional consequences of nitration in plants. This review intends to evaluate the accumulated knowledge about the biochemical mechanism, the structural and functional consequences and the selectivity of plants' protein nitration and also about the decomposition or conversion of nitrated proteins. At the same time, this review emphasizes yet unanswered or uncertain questions such as the reversibility/irreversibility of tyrosine nitration, the involvement of proteasomes in the removal of nitrated proteins or the effect of nitration on Tyr phosphorylation. The different NO producing systems of algae and higher plants raise the possibility of diversely regulated protein nitration. Therefore studying PTN from an evolutionary point of view would enrich our present understanding with novel aspects. Plant proteomic research can be promoted by the application of computational prediction tools such as GPS-YNO2 and iNitro-Tyr software. Using the reference Arabidopsis proteome, Authors performed in silico analysis of tyrosine nitration in order to characterize plant tyrosine nitroproteome. Nevertheless, based on the common results of the present prediction and previous experiments the most likely nitrated proteins were selected thus recommending candidates for detailed future research.

Propionibacterium acnes (P. acnes) is a member of the human skin microbiome, but it can also activate TLR signaling pathways and induce innate immune and inflammatory events in human epidermal keratinocytes. However, in healthy skin and during homeostatic conditions the bacterium does not provoke immune activation. This suggests a possible a mechanism, which may control the P. acnes-induced innate immune and inflammatory events in keratinocytes. TNFAIP3 was identified as negative regulator of NF-κB-dependent signaling pathways, thus we aimed to analyze whether this molecule has a role in the regulation of the P. acnes-induced TLR signaling pathway in keratinocytes. For that, we used a human immortalized keratinocyte cell line (HPV-KER) and different cell and molecular biological techniques, including siRNA-mediated silencing, luciferase reporter assay, real-time RT-PCR, western blot analysis and ELISA. Our results show that keratinocytes expressed TNFAIP3, and its mRNA and protein expression significantly and dose dependently increased after P. acnes treatment. An NF-κB inhibitor, SN50 abrogated the P. acnes-induced upregulation of TNFAIP3, which suggests a role for NF-κB in its transcriptional regulation. Attenuation of TNFAIP3 significantly increased the basal NF-κB promoter activity, also basal, and P. acnes-induced mRNA expression of TNFα, IL-1α, IL-6, CXCL8 and CCL5 inflammatory mediators. Next to this, TNFAIP3 silencing increased secreted CXCL8 and CCL5 levels. Based on our data, TNFAIP3 is a negative regulator in keratinocytes playing an important role in controlling the P. acnes-induced TLR signaling pathways, and through that the maintenance of the epidermal homeostasis.