FePO4 NANOPARTILCES AS SOURCE OF NUTRIENTS: EFFECTS ON THE PLANT-SOIL SYSTEM AND EVI-DENCE FOR A SAFE AND SUSTAINABLE NANO-FERTILIZATION

In the last decade, nanotechnology became a consistent part of the technological progress in modern agriculture, with applications in agri-food technology, nano-biosensoring, plant defence and plant nutrition. Nanomaterials which can provide one or more macro/micro-nutrient to the plant are commonly referred as nanofertilizers. Nevertheless, in the scientific literature there are still few evidence of a successful utilization of nanomaterials as fertilizers. In a previous work, it has been shown that iron phosphate (FePO4) nanoparticles (NPs) can provide either iron (Fe) or phosphate (P) to plants grown in hydroponic. The present study is aimed to highlight the effect of FePO4 NPs used as nanofertilizer in the whole plant-soil system, and to determine if they can represent a safe and effective alternative to conventional fertilizers. To investigate the plant early transcriptomic responses to FePO4 NPs exposure, microarray expression analyses have been performed in maize and cucumber roots grown in hydroponic for 24 hours. Responses of the plants treated with FePO4 NPs were shown to be associated mainly to biotic and abiotic stress, cell wall modulation and regulation of transcription, and triggered a different pattern of responses that was dependent on the nano-size. To evaluate the possibility to apply FePO4 NPs to the soil as fertilizer, two different bare soils were treated. Soil enzyme activities, CO2 respiration and DGGE analyses showed that there was not negative impact of FePO4 NPs onto soil microbial community and metabolic functions, neither toxic effects. Further, FePO4 NPs provided available P in bare soil in respect to triple superphosphate (TSP), even though the efficacy was dependent on the soil characteristics. Moreover, FePO4 NPs represented a source of available P for plant, which grown in soil in controlled condition without significant differences in respect to TSP, although P availability in the bare soil resulted lower for NPs than TSP. Microbial community associated to rhizosphere was not negatively affected by NPs and a stimulatory effect on enzyme activity was observed. In this work it was shown that FePO4 NPs can be applied to the soil without any negative consequence for the environment, enhancing plant growth and providing nutrients. These results encourage the hypothesis that the nanoparticulate nature of fertilizers could contribute to rationalize the chemical inputs in agriculture and increasing nutrient use efficienc

Effects of C/N and N sources on sugar level, light energy dissipation and Nitrate Reductase in Arabidopsis

Carbon (C) and nitrogen (N), among many others, are essential elements for plant metabolism and growth. The environment conditions such as CO2, light availability, diurnal cycles, seasonal effect and biotic or abiotic stresses and many others, modulate the availability of carbon and nitrogen. So, the crosstalk named as ‘C/N balance’ is central for the regulation of plant growth and development. From previous experiments it is known that stressful C/N condition affects a large amount of aspects of plant metabolism. In the work from Huarancca Reyes et al., 2016, several physiological aspects resulted affected by unbalanced C/N ratio. Light dissipation was different under C/N stressful condition depending on the timing if compared with time zero. Change of C/N balance could also modulate the phosphorylation status of many enzymes which may modify their activity, subcellular localization, stability or even signal transduction. In addition, also total soluble sugar level was modulated depending on change of C/N balance. Since differences in C/N affect these parameters, in this project we checked if different sources of N had different effects when stressful condition was due to an unbalanced C/N ratio. In the previous work NH4NO3 was used as N source, and measurement of fluorescence, soluble sugar and enzymes activity were conducted on seedlings after 0,5; 2 and 24 hours after transfer in C/N medium. Here, since plant can assimilate N through different sources, NO3- and NH4+ were separately provided in C/N medium analyzing the same time course. In this work, we investigated on light energy dissipation, total soluble sugars level and Nitrate Reductase (NR) activity under stressful C/N condition (200 mM glucose/0,3 mM NO3- or NH4+) compared with control condition (100 mM glucose/30 mM NO3- or NH4+). We found that treated plants accumulated more total soluble sugars (TSS) if compared with control and, in the long period (after 24 hours), TSS was higher with NH4+ in the medium. Light energy dissipation in control plants increased, while in treated plants decreased with no significant differences between the two sources of nitrogen, except at 30 minutes after treatment where in control condition dissipation was higher, but then returned similar. Nitrate reductase actual activity was the result of an interaction between activity, activation state and protein level. This activity decreased starting from time zero in both treated and control samples, even if NH4+ as nitrogen source in control medium seemed to delay the reduction of NR total activity; by contrast, NR total activity showed a peak at 2 hours after treatment with NO3- , and at 30 minutes with NH4+. In conclusion, our data shows that low concentration of N affects NR that remains active to work as more as possible to use the low N available, but in different time depending on the source of N. When nitrate is applied, NR actual activity is rapidly decreased, but after 2 h of treatment it has a peak due to its low availability. By contrast, with ammonium in the medium the actual activity of NR is not affected, since nitrate is missing. NR is a dissipation channel of energy in excess derived from photosynthesis, therefore its activity when nitrate is missing could affect photosynthesis when N is low in the medium

Nitrate reductase modulation in response to changes in C/N balance and nitrogen source in Arabidopsis

Environmental cues modulate carbon (C) and nitrogen (N) balance which are essential elements for plant metabolism and growth. In Arabidopsis, photochemical efficiency of PSII, phosphorylation status and localization of many enzymes, and total soluble sugars level resulted affected by unbalanced C/N ratio. Since differences in C/N affect these parameters, here we checked whether different sources of N have different effects when high C/N ratio was imposed. NO3- and NH4+ were separately provided in C/N medium. We investigated the effects on photochemical efficiency of PSII, total soluble sugars level and nitrate reductase activity under stressful C/N condition compared with control condition. We found that treated plants accumulated more total soluble sugars when compared with control. Photochemical efficiency of PSII did not show significant differences between the two sources of nitrogen after 24 h. Nitrate reductase actual activity was the result of a combination among activity, activation state and protein level. This activity constantly decreased starting from time zero in control condition; by contrast, nitrate reductase actual activity showed a peak at 2 h after treatment with NO3- , and at 30 min with NH4+. This, according with the total soluble sugars results, can be explained by the existence of a crosstalk between the sugars in excess and low nitrate in the medium, that blocks the activity of nitrate reductase in stressful sugar condition until the plant is adapted to the stress

Neurorehabilitation

The logistics of neurorehabilitation of this group of patients differ based on their unique clinical status. Disorders of consciousness (DOC) after severe acquired brain injury (ABI) include coma, vegetative state (VS), and minimally conscious state (MCS). Coma is primarily assessed via the Glasgow Coma Scale (GCS) [1] in the acute phase, whereas the Disability Rating Scale (DRS) [2], Levels of Cognitive Function (LCF) [3], Glasgow Outcome Scale (GOS), and Glasgow Outcome Scale-Extended (GOS-E) [4, 5] are the most commonly used scales in the post-acute phase

Development of a multisite model for Ni(II) ion in solution from thermodynamic and kinetic data

Force-field parameters are developed for a multisite model of Ni(II) ions to be used in molecular dynamics simulations combined to enhanced sampling methods. The performances of two charge-partitioning schemes are validated by taking into account structural, thermodynamic, and kinetic observables. One of the two models, featuring partial charges on the dummy atoms only, matches both Ni(II) free energy of solvation and water exchange rates. Such model is particularly suited to study complexation events at a fully dynamic description. \ua9 2017 Wiley Periodicals, Inc

Protein Tunnels: The Case of Urease Accessory Proteins

Transition metals are both essential micronutrients and limited in environmental availability. The Ni­(II)-dependent urease protein, the most efficient enzyme known to date, is a paradigm for studying the strategies that cells use to handle an essential, yet toxic, metal ion. Urease is a virulence factor of several human pathogens, in addition to decreasing the efficiency of soil organic nitrogen fertilization. Ni­(II) insertion in the urease active site is performed through the action of three essential accessory proteins: UreD, UreF, and UreG. The crystal structure of the UreD-UreF-UreG complex from the human pathogen <i>Helicobacter pylori</i> (<i>Hp</i>UreDFG) revealed the presence of tunnels that cross the entire length of both UreF and UreD, potentially able to deliver Ni­(II) ions from UreG to apo-urease. Atomistic molecular dynamics simulations performed on the <i>Hp</i>UreDFG complex in explicit solvent and at physiological ionic conditions demonstrate the stability of these protein tunnels in solution and provide insights on the trafficking of water molecules inside the tunnels. The presence of different alternative routes across the identified tunnels for Ni­(II) ions, water molecules, and carbonate ions, all involved in urease activation, is highlighted here, and their potential role in the urease activation mechanism is discussed