Accumulation Of Polymers Research Articles

The occurrence and degradation of aquatic plastic litter based on polymer physicochemical properties: A review

The whereabouts of the overwhelming majority of plastic estimated to enter the environment is unknown. This study’s aim was to combine information about the environmental occurrence and physicochemical properties of widespread polymers to predict the fate of aquatic plastic litter. Polyethylene and polypropylene are common in the surface layer and shorelines; polyester and cellulosic fibres in sewage treatment works, estuarine and deep-sea sediments. Overall, non-buoyant polymers are underrepresented on the ocean surface. Three main explanations are proposed for the missing plastic. The first is accumulation of both buoyant and non-buoyant polymers in sewage treatment works, river and estuarine sediments and along shorelines. The second is settling of non-buoyant polymers into the deep-sea. The third is fragmentation of both buoyant and non-buoyant polymers into particles smaller than captured by existing experimental methods. Some isolation techniques may overrepresent larger, buoyant particles; methodological improvements are needed to capture the full size-range of plastic litter. When microplastics fragment they become neutrally-buoyant, thus nanoplastics are potentially widely dispersed in aquatic systems, both horizontally and vertically. Ultimately, over decades or longer, plastics are potentially solubilized and subsequently biodegraded. The rates at which these processes apply to plastic litter in different environmental compartments remain largely unknown.

Enhanced production of lactate-based polyesters in Escherichia coli from a mixture of glucose and xylose by Mlc-mediated catabolite derepression

Lignocellulose-utilizing biorefinery is a promising strategy for the sustainable production of value-added products such as bio-based polymers. Simultaneous consumption of glucose and xylose in Escherichia coli was achieved by overexpression of the gene encoding Mlc, a multiple regulator of glucose and xylose uptake. This catabolite derepression gave the enhancement in the production of poly (15mol% lactate-co-3-hydroxybutyrate), up to 65% from 50% (wild-type strain) in the cellular contents, of the Mlc-overexpressing strain of E.coli on a mixture of glucose and xylose as carbon sources. Microscopic analysis indicated that the Mlc-overexpressing strain showed the enlargement of cell volume in the presence and absence of polymer production, consequently making an expanded volumetric space available for enhanced polymer accumulation. The enhanced polymer production by the catabolite derepression was also reproducible using the biomass, Miscanthus×giganteus (hybrid Miscanthus), which was cultivated in the farm of Hokkaido University.

Electro-Active Polymer Based Soft Tactile Interface for Wearable Devices

This paper reports soft actuator based tactile stimulation interfaces applicable to wearable devices. The soft actuator is prepared by multi-layered accumulation of thin electro-active polymer (EAP) films. The multi-layered actuator is designed to produce electrically-induced convex protrusive deformation, which can be dynamically programmable for wide range of tactile stimuli. The maximum vertical protrusion is and the output force is up to 255 mN. The soft actuators are embedded into the fingertip part of a glove and front part of a forearm band, respectively. We have conducted two kinds of experiments with 15 subjects. Perceived magnitudes of actuator's protrusion and vibrotactile intensity were measured with frequency of 1 Hz and 191 Hz, respectively. Analysis of the user tests shows participants perceive variation of protrusion height at the finger pad and modulation of vibration intensity through the proposed soft actuator based tactile interface.

An update on coating/manufacturing techniques of microneedles.

Recently, results have been published for the first successful phase I human clinical trial investigating the use of dissolving polymeric microneedles… Even so, further clinical development represents an important hurdle that remains in the translation of microneedle technology to approved products. Specifically, the potential for accumulation of polymer within the skin upon repeated application of dissolving and coated microneedles, combined with a lack of safety data in humans, predicates a need for further clinical investigation. Polymers are an important consideration for microneedle technology-from both manufacturing and drug delivery perspectives. The use of polymers enables a tunable delivery strategy, but the scalability of conventional manufacturing techniques could arguably benefit from further optimization. Micromolding has been suggested in the literature as a commercially viable means to mass production of both dissolving and swellable microneedles. However, the reliance on master molds, which are commonly manufactured using resource intensive microelectronics industry-derived processes, imparts notable material and design limitations. Further, the inherently multi-step filling and handling processes associated with micromolding are typically batch processes, which can be challenging to scale up. Similarly, conventional microneedle coating processes often follow step-wise batch processing. Recent developments in microneedle coating and manufacturing techniques are highlighted, including micromilling, atomized spraying, inkjet printing, drawing lithography, droplet-born air blowing, electro-drawing, continuous liquid interface production, 3D printing, and polyelectrolyte multilayer coating. This review provides an analysis of papers reporting on potentially scalable production techniques for the coating and manufacturing of microneedles.

Biopolymer dynamics driven by helical flagella

Microbial flagellates typically inhabit complex suspensions of polymeric material which can impact the swimming speed of motile microbes, filter-feeding of sessile cells, and the generation of biofilms. There is currently a need to better understand how the fundamental dynamics of polymers near active cells or flagella impacts these various phenomena, in particular the hydrodynamic and steric influence of a rotating helical filament on suspended polymers. Our Stokesian dynamics simulations show that as a stationary rotating helix pumps fluid along its long axis, polymers migrate radially inwards while being elongated. We observe that the actuation of the helix tends to increase the probability of finding polymeric material within its pervaded volume. This accumulation of polymers within the vicinity of the helix is stronger for longer polymers. We further analyse the stochastic work performed by the helix on the polymers and show that this quantity is positive on average and increases with polymer contour length.

Particle Growth during the Polymerization of Olefins on Supported Catalysts. Part 2: Current Experimental Understanding and Modeling Progresses on Particle Fragmentation, Growth, and Morphology Development

AbstractThe morphology of the growing polymer particles is important in olefin polymerisation on supported catalysts. It has a significant impact on the rate of mass and energy transport, and consequently on the polymerisation rate, comonomer incorporation, and the molecular weight distribution. The ability to quantify the evolution of morphology during the polymerisation process à priori would therefore be quite useful. The morphology itself is a direct product of the fragmentation step and concurrent/subsequent expansion of the particle, both caused by the build‐up and dissipation of hydraulic forces due to the accumulation of polymer in the particle. It is influenced by the initial morphology of the support, as well as the reaction conditions and local polymer properties. The single particle models developed to describe the morphology evolution in a growing particle are reviewed here. The main assumptions, abilities, and limitations of the models are evaluated and the issues which face developing a completely predictive model are finally discussed. Despite some very interesting attempts at morphology modelling in recent years, significant progress still needs to be made in order to develop a fully predictive model of the sort.

Endoplasmic reticulum stress regulates oxygen-glucose deprivation-induced parthanatos in human SH-SY5Y cells via improvement of intracellular ROS.

Endoplasmic reticulum (ER) stress has been demonstrated to regulate neuronal death caused by ischemic insults via activation of apoptosis, but it still remains unclear whether ER stress participates in regulation of parthanatos, a new type of programmed cell death characterized by PARP-1 overactivation and intracellular accumulation of PAR polymer. we used oxygen-glucose deprivation (OGD) and human SH-SY5Y cells to simulate neuronal damage caused by ischemia. Oxygen-glucose deprivation induced time-dependent death in SH-SY5Y cells, which was accompanied with upregulation of PARP-1, accumulation of PAR polymer, decline of mitochondrial membrane potentials and nuclear translocation of AIF. Pharmacological inhibition of PARP-1 with its specific inhibitor 3AB rescued OGD-induced cell death, as well as prevented PAR polymer accumulation, mitochondrial depolarization, and AIF translocation into nucleus. Similar results could be found when PARP-1 was genetically knocked down with SiRNA. These indicated that OGD triggered parthanatos in SH-SY5Y cells. Then, we found inhibition of overproduction of ROS with antioxidant NAC attenuated obviously OGD-induced parthanatos in SH-SY5Y cells, suggesting ROS regulated OGD-induced parthanatos. Additionally, OGD also induced upregulation of ER stress-related proteins. Mitigation of ER stress with chemical chaperone 4-PBA or trehalose suppressed significantly OGD-induced overproduction of ROS, PARP-1 upregulation, PAR polymer accumulation, and nuclear accumulation of AIF, and cell death in SH-SY5Y cells. Endoplasmic reticulum stress regulates OGD-induced parthanatos in human SH-SY5Y cells via improvement of intracellular ROS.

Production of the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with varied composition using different nitrogen sources with Haloferax mediterranei

The extreme haloarchaea Haloferax mediterranei accumulates poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) without the need for specific precursors. In this study, growth kinetics and PHBV synthesis were characterised under nitrogen-excess and nitrogen-limiting conditions in ammonium and, for the first time, nitrate. With excess nitrogen, ammonium and nitrate cultures generated 10.7g/L biomass containing 4.6wt%PHBV and 5.6g/L biomass with 9.3wt% PHBV, respectively. Copolymer composition varied with the nitrogen source used: PHBV from ammonium cultures had 16.9mol% 3-hydroxyvalerate (HV), while PHBV from nitrate cultures contained 12.5mol% HV. Nitrogen limitation was achieved with carbon-to-nitrogen (C/N) molar ratios of 25 or higher. Nitrogen limitation reduced biomass generation and polymer concentration, but polymer accumulation increased to 6.6 and 9.4% for ammonium and nitrate, respectively, with C/N 42. PHBV composition was also affected and cultures with lower C/N ratios produced richer HV polymers. Copolymer formation was not a uniform process: HV was only detected after a minimum accumulation of 0.45g/L PHB and lasted for a maximum of 48h. The understanding of copolymer synthesis and the influence of culture conditions such as the nitrogen source will help in designing novel strategies for the production of PHBV with more regular structure and material properties.

HPMA‐PEG Surfmers and Their Use in Stabilizing Fully Biodegradable Polymer Nanoparticles

AbstractThe most adopted methods to produce polymer nanoparticles (NPs) for medical and pharmaceutical applications use surfactants that are toxic and physically adsorbed to the NPs, with the risk of desorption and insurgence of side effects. A valid alternative is represented by the use of surfmers, reactive surfactants that are chemically linked to the polymer chains, thus avoiding the release of toxic species. In this case, the lack of biodegradable surfmers introduces the concern of polymer accumulation into the body. In this work, biodegradable, poly(ethylene glycol) (PEG)ylated N‐(2‐hydroxypropyl) methacrylamide (HPMA) based surfmers are synthesized and used to stabilize lipophilic NPs. In particular, the NP core is made from a macromonomer comprising a poly(lactic acid) (PLA) chain functionalized with HPMA double bond. The NP forming polymer chains are then constituted by a uniform poly(HPMA) backbone that is biocompatible and water soluble and hydrolysable PEG and PLA pendants assuring the complete degradability of the polymer. The stability provided to these NPs by the synthesized surfmers is studied in the cases of both emulsion free radical polymerization and solution free radical polymerization followed by the flash nanoprecipitation of the obtained amphiphilic copolymers.

Evolutionary and functional characterization of leucoanthocyanidin reductases from Camellia sinensis

Main conclusionLARs promoted the biosynthesis of catechin monomers and inhibited their polymerization. The accumulation of catechin monomers and polymers was increased by up-regulating the expression ofNtLARandNtANRs in CsMYB5b transgenic tobacco.Tea is rich in polyphenolic compounds, and catechins are the major polyphenols in tea. The biosynthesis of polyphenols is closely related to the expression of the leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) genes. In this paper, an evolutionary analysis and functional characterization of three CsLARs were performed. The phylogenetic tree showed that plant LARs could be grouped into three, including gymnosperms, monocotyledons and dicotyledons (clusters I and II). The eighth amino acid residue in a conserved LAR-specific motif is changeable due to a transversion (G → T) and transition (G → C) that occur in the corresponding codon. Therefore, plant LARs can be classified as G-type, A-type and S-type LARs due to this variable amino acid residue. Although (2R, 3S)-trans-flavan-3-ols were the products of recombinant CsLARs proteins expressed in Escherichia coli, both (2R, 3S)-trans and (2R, 3R)-cis-flavan-3-ols were detected in tobacco overexpressing CsLARs. However, a butanol/HCl hydrolysis assay indicated that overexpression of the CsLARs caused a decrease in polymerized catechins. A hybridization experiment with CsLARc + AtPAP1 also showed that no polymers other than epicatechin, catechin and glycoside were detected, although the accumulation of anthocyanins was markedly decreased. CsMYB5b promoted the biosynthesis of both flavan-3-ols and proanthocyanidins (PAs). Therefore, LARs promoted the biosynthesis of catechin monomers and inhibited their polymerization. The accumulation of catechin monomers and polymers was increased by up-regulating the expression of the NtLAR and NtANRs in CsMYB5b transgenic tobacco.

Enhancement of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) accumulation in Arxula adeninivorans by stabilization of production

BackgroundIn recent years the production of biobased biodegradable plastics has been of interest of researchers partly due to the accumulation of non-biodegradable plastics in the environment and to the opportunity for new applications. Commonly investigated are the polyhydroxyalkanoates (PHAs) poly(hydroxybutyrate) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHB-V). The latter has the advantage of being tougher and less brittle. The production of these polymers in bacteria is well established but production in yeast may have some advantages, e.g. the ability to use a broad spectrum of industrial by-products as a carbon sources.ResultsIn this study we increased the synthesis of PHB-V in the non-conventional yeast Arxula adeninivorans by stabilization of polymer accumulation via genetic modification and optimization of culture conditions. An A. adeninivorans strain with overexpressed PHA pathway genes for β-ketothiolase, acetoacetyl-CoA reductase, PHAs synthase and the phasin gene was able to accumulate an unexpectedly high level of polymer. It was found that an optimized strain cultivated in a shaking incubator is able to produce up to 52.1% of the DCW of PHB-V (10.8 g L−1) with 12.3%mol of PHV fraction. Although further optimization of cultivation conditions in a fed-batch bioreactor led to lower polymer content (15.3% of the DCW of PHB-V), the PHV fraction and total polymer level increased to 23.1%mol and 11.6 g L−1 respectively. Additionally, analysis of the product revealed that the polymer has a very low average molecular mass and unexpected melting and glass transition temperatures.ConclusionsThis study indicates a potential of use for the non-conventional yeast, A. adeninivorans, as an efficient producer of polyhydroxyalkanoates.

Complete factorial design to adjust pH and sugar concentrations in the inoculum phase of Ralstonia solanacearum to optimize P(3HB) production.

Poly(3-hydroxybutyrate) (P(3HB)) is a biodegradable plastic biopolymer that accumulates as lipophilic inclusions in the cytoplasm of some microorganisms. The biotechnological process by which P(3HB) is synthesized occurs in two phases. The first phase involves cell growth in a complex culture medium, while the second phase involves polymer accumulation in the presence of excess carbon sources. As such, the efficiency of the second phase depends on the first phase. The aim of this study was to evaluate culture media with different concentrations of sucrose and glucose and different pH values in the inoculum phase of Ralstonia solanacearum RS with the intention of identifying methods by which the biomass yield could be increased, subsequently enhancing the yield of P(3HB). The culture medium was formulated according to the experimental planning type of central composite rotational design 22. The independent variables were pH and sugar concentration (sucrose and glucose), and the dependent variables were OD600nm, dry cell weight (DCW), and P(3HB) yield. The highest cell growth, estimated by the OD600nm (20.6) and DCW (5.35) values, was obtained when sucrose was used in the culture medium at a concentration above 35 g.L-1 in combination with an acidic pH. High polymer (45%) accumulation was also achieved under these conditions. Using glucose, the best results for OD600nm (12.5) and DCW (2.74) were also obtained at acidic pH but with a sugar concentration at the minimum values evaluated. Due to the significant accumulation of polymer in the cells that were still in the growth phase, the accumulating microorganism P(3HB) Ralstonia solanacearum RS can be classified as having type II metabolism in relation to the polymer accumulation phase, which is different from other Ralstonia spp. studied until this time.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production from biodiesel by-product and propionic acid by mutant strains of Pandoraea sp.

Pandoraea sp. MA03 wild type strain was subjected to UV mutation to obtain mutants unable to grow on propionic acid (PA) but still able to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] from glycerol and PA at high 3HV yields. In shake flask experiments, mutant prp25 was selected from 52 mutants affected in the propionate metabolism exhibiting a conversion rate of PA into 3HV units of 0.78 g g-1 . The use of crude glycerol (CG) plus PA or valeric acid resulted in a copolymer with 3HV contents varying from 21.9 to 30 mol% and 22.2 to 36.7 mol%, respectively. Fed-batch fermentations were performed using CG and PA and reached a 3HV yield of 1.16 g g-1 , which is 86% of the maximum theoretical yield. Nitrogen limitation was a key parameter for polymer accumulation reaching up to 63.7% content and 18.1 mol% of 3HV. Henceforth, mutant prp25 is revealed as an additional alternative to minimize costs and support the P(3HB-co-3HV) production from biodiesel by-products. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1077-1084, 2017.

Neuroserpin polymers cause oxidative stress in a neuronal model of the dementia FENIB

The serpinopathies are human pathologies caused by mutations that promote polymerisation and intracellular deposition of proteins of the serpin superfamily, leading to a poorly understood cell toxicity. The dementia FENIB is caused by polymerisation of the neuronal serpin neuroserpin (NS) within the endoplasmic reticulum (ER) of neurons. With the aim of understanding the toxicity due to intracellular accumulation of neuroserpin polymers, we have generated transgenic neural progenitor cell (NPC) cultures from mouse foetal cerebral cortex, stably expressing the control protein GFP (green fluorescent protein), or human wild type, G392E or delta NS. We have characterised these cell lines in the proliferative state and after differentiation to neurons. Our results show that G392E NS formed polymers that were mostly retained within the ER, while wild type NS was correctly secreted as a monomeric protein into the culture medium. Delta NS was absent at steady state due to its rapid degradation, but it was easily detected upon proteasomal block. Looking at their intracellular distribution, wild type NS was found in partial co-localisation with ER and Golgi markers, while G392E NS was localised within the ER only. Furthermore, polymers of NS were detected by ELISA and immunofluorescence in neurons expressing the mutant but not the wild type protein. We used control GFP and G392E NPCs differentiated to neurons to investigate which cellular pathways were modulated by intracellular polymers by performing RNA sequencing. We identified 747 genes with a significant upregulation (623) or downregulation (124) in G392E NS-expressing cells, and we focused our attention on several genes involved in the defence against oxidative stress that were up-regulated in cells expressing G392E NS (Aldh1b1, Apoe, Gpx1, Gstm1, Prdx6, Scara3, Sod2). Inhibition of intracellular anti-oxidants by specific pharmacological reagents uncovered the damaging effects of NS polymers. Our results support a role for oxidative stress in the cellular toxicity underlying the neurodegenerative dementia FENIB.

Influence of the drying conditions on the particle distribution in particle-filled polymer films: Predictive simulation of the particle distribution during drying

For coating applications, particles are frequently added to a polymer solution, and then the dispersion is deposited onto a substrate and dried to make the composite coating. To engineer its microstructure, it is essential to understand how drying conditions and dispersion composition influence the distribution of components. In this work a 1D-simulation model is proposed to predict the component distribution during drying of a particle–polymer–solvent mixture not undergoing a phase change. It uses a quasi-binary approach to describe diffusion in the multicomponent system. Only binary and pure component data for solvent–polymer and particle dispersion systems are needed. Comparison of the model to others in the literature shows good agreement. The model was used to explore particle distribution during drying of a base case dispersion with an initial solvent, polymer, and particle contents of 95, 3.5, and 1.5 vol%, respectively. Under the conditions explored, the polymer remains uniformly distributed in the solvent phase during drying, but the particle distribution varies. Depending on the dominance of evaporation, particle sedimentation or diffusion, three different component distributions through the thickness occur: a particle-rich sediment at the bottom and polymer enriched layer on the top, a particle-rich layer on the top and polymer accumulation at the top or uniform distributions of particles and polymer. The different regimes are mapped as function of relevant dimensionless numbers. The effect of changing the solvent concentration and relative amounts of polymer and particles are explored.

Performances and Coating Morphology of a Siloxane-Based Hydrophobic Product Applied in Different Concentrations on a Highly Porous Stone

Many polymers, able to confer a hydrophobicity to treated surfaces, have been proposed for the restoration and conservation of civil and monumental buildings. Polysiloxanes, and their precursors, the silanes, have been frequently employed for stone protection. To avoid decay of the treated surfaces, the effectiveness and harmlessness of the treatment need to be carefully evaluated before application in the field. In this study, a commercial alkyl-siloxane was tested as a protective treatment on a highly porous stone, starting from water solutions with different contents of the product. The treatments have been devised to try to balance the requirements and the sustainability of the conservative actions. Sustainability, in terms of costs and environmental impact, is regarded as a key factor in the 21st century. Morphological observations of the stone surface, static contact angle and colour measurements, water vapour transmission test, and tests of water absorption were carried out to characterize the untreated and treated stones. A concentration below the minimum level suggested by the manufacturer was still able to act as a good barrier against water. More concentrated solutions produced polymer accumulation and coatings with extended cracks. The properties of the treated stone were affected by the presence of cracks in the coating.

Application of flow cytometry for monitoring the production of poly(3-hydroxybutyrate) by Halomonas boliviensis.

In this study, a flow cytometry (FC) protocol was implemented to measure poly(3-hydroxybutyrate) (PHB) content in a halophilic bacterium, to have a faster and easier control of the process. The halophilic bacterium Halomonas boliviensis was stained with BODIPY 493/503 and analyzed using FC. Bacterial polymer accumulation induced by two different nutrient limitations during the operation of a 2 L bioreactor was studied using traditional gas chromatography (GC) analysis and FC. The application of this rapid and straightforward method is useful to obtain complex and precise information about PHB accumulation that could be used for the monitoring, control and optimization of the production of PHB. A clear correlation between the PHB concentration determined by GC and the fluorescence signal obtained from stained bacteria by using FC was observed. Additionally, the heterogeneity of bacterial population as a function of PHB content was measured. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:276-284, 2017.

Poly(3-hydroxybutyrate)/metribuzin formulations: characterization, controlled release properties, herbicidal activity, and effect on soil microorganisms.

Slow-release formulations of the herbicide metribuzin (MET) embedded in the polymer matrix of degradable poly-3-hydroxybutyrate [P(3HB)] in the form of microparticles, films, microgranules, and pellets were developed and tested. The kinetics of polymer degradation, MET release, and accumulation in soil were studied in laboratory soil microecosystems with higher plants. The study shows that MET release can be controlled by using different techniques of constructing formulations and by varying MET loading. MET accumulation in soil occurs gradually, as the polymer is degraded. The average P(3HB) degradation rates were determined by the geometry of the formulation, reaching 0.17, 0.12, 0.04, and 0.05mg/day after 60days for microparticles, films, microgranules, and pellets, respectively. The herbicidal activities of P(3HB)/MET formulations and commercial formulation Sencor Ultra were tested on the Agrostis stolonifera and Setaria macrocheata plants. The parameters used to evaluate the herbicidal activity were plant density and the weight of fresh green biomass measured at days 10, 20, and 30 after sowing. All P(3HB)/MET formulations had pronounced herbicidal activity, which varied depending on MET loading and the stage of the experiment. In the early phases of the experiment, the herbicidal effect of P(3HB)/MET formulations with the lowest MET loading (10%) was comparable with that of the commercial formulation. The herbicidal effect of P(3HB)/MET formulations with higher MET loadings (25 and 50%) at later stages of the experiment were stronger than the effect of Sencor Ultra.

The Polyphenol Oleuropein Aglycone Modulates the PARP1-SIRT1 Interplay: AnIn Vitro and In Vivo Study.

Poly(ADP-ribose) polymerase-1 (PARP1) activation contributes to the cascade of events initiated by amyloid-β (Aβ) peptide eventually leading to cell death in Alzheimer's disease brain. A significant accumulation of PAR polymers and increase of PARP1 expression were detected in the cortex at the early (3.5 months) and intermediate (6 months) stage of Aβ deposition in the TgCRND8 mouse model. Our previous data highlighted the beneficial effects of oleuropein aglycone (OLE), the main polyphenol found in the olive oil, against neurodegeneration both in cultured cells and in model organisms. Here we found that 8-week OLE treatment (50 mg/kg of diet) to 6-month-old TgCRND8 mice rescued to control values PARP1 activation and the levels of its product, PAR. In N2a neuroblastoma cells, PARP1 activation and PAR formation upon exposure to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were abolished by pretreatment for 24 h with either OLE (100μM) or PARP inhibitors. A significant reduction of the NAD+ content, compared to controls, was found in N2a cells exposed to MNNG (100μM) for 90 min; the latter was slightly attenuated by cell treatment for 24 h with PJ-34 or with OLE. In vitro and in vivo, the OLE-induced reduction of PARP1 activation was paralleled by the overexpression of Sirtuin1 (SIRT1), and, in vivo, by a decrease of NF-κB and the pro-apoptotic marker p53. In N2a cells, we also found that OLE potentiates the MNNG-induced increase of Beclin1 levels. In conclusion, our data show that OLE treatment counteracts neuronal damage through modulation of the PARP1-SIRT1 interplay.

English

PHA is a biodegradable and biocompatible natural thermoplastic produced from renewable bioresources and is hence attracting attention as a plastic material for use in the environment and medical fields. In the present study, the Lynisibacillus sp. strain UEA-20.171 was selected for production of polyhydroxyalkanoate (PHA) in bioreactor. The accumulation of polymer in the bacterium occurs when there is an imbalance in the concentration of nitrogen in relation to carbon (glucose). After the period of adaptation in mineral medium from 12 to 24 h, the cell division occurred from 12 to 24 h, and the formation of biopolymers from 36 to 48 h. It was observed that the polymer produced by the isolated UEA-20.171, was P(3HB). Key words: Polyhydroxyalkanoates, polyhydroxybutyrate, bioplastics, Lysinibacillus.