Combined effects of polyethylene microplastics and natural stressors on Chironomus riparius life-history traits.

Several studies have shown that ingestion of microplastics causes adverse effects in aquatic organisms, including sediment-dwelling invertebrates. Most studies focus on evaluating the effects of plastic particles alone without testing the mediating effects of different natural stressors and thus lacking realistic exposure scenarios. The present study addresses the interactive effects of exposure to polyethylene microplastics (PE-MPs; 2.5 g/kg) in the midge Chironomus riparius life history traits under different temperatures (15, 20 and 25 °C), a salinity gradient (0, 1 and 3 g L-1 sodium chloride - NaCl) and different levels of food (0.5, 0.25 and 0.125 mg macerated fish food larva-1day-1). By the analyses of linear models and independent action models applied to different life-history traits, such as larval growth, development time and imagoes body weight, the present work reveals that under temperatures lower than 20 °C or severe food shortage (<0.25 mg macerated fish food larva-1day-1), microplastics' effects can be stronger than those observed at standard toxicity test conditions (20 °C and 0.5 mg food larva-1day-1). Additionally, we also found that, in general, toxicity induced by PE-MPs to C. riparius larvae was reduced under warmer temperature (25 °C) and salinity. As observed, MPs toxicity can be mediated by natural stressors, which underlines the importance of co-exposure studies. In this sense, these results contribute to a more accurate risk assessment of microplastics. Despite the complex interactions between microplastics and natural factors here tested, were not found evidence that the deleterious effects of PE-MPs on C. riparius life cycle history are aggravated under increased temperature, food shortage, or salinisation of freshwaters.

Mechanisms influencing the impact of microplastics on freshwater benthic invertebrates: Uptake dynamics and adverse effects on Chironomus riparius.

Chironomids inhabit freshwater benthic ecosystems which are prone to microplastic contamination. This work aimed at understanding the factors and mechanisms influencing microplastic uptake and related adverse effects on Chironomus riparius, by exploring an extensive project database, conducting a literature review, and performing an agent-based model to explore trends in data. Results reveal that high concentrations of small microplastics fill the gut of fourth instar C. riparius (99.7 %). Ingested microplastics had an average size of 38-61 µm, presenting slower elimination rates than undigested organic or mineral particles. Ingestion rates of microplastics depend mainly on encounter rates, and therefore on available concentrations, until reaching a plateau corresponding to the maximum gut volume. Short-term toxicity of microplastics seems to result from damage to gut epithelium, with inflammatory reactions, production of reactive oxygen species, and a negative energy balance exacerbated by the lack of food (organic matter). Long-term toxicity is characterized by a reduction in larval body length and increase in mean time to emergence, seemly from increased energy costs rather than a decrease in nutrient absorption. Wild chironomids already present microplastics in their guts and environmental concentrations in hotspots may already exceed no effect concentrations. Therefore, environmental exposure to microplastics may induce adverse effects to wild C. riparius in freshwater benthic ecosystems, which could compromise their ecologic role as deposit-feeders (e.g., reducing their nutrient cycling ability) and key-stone species in aquatic food webs.

Trophic inferences of blue shark (Prionace glauca) in the Mexican Pacific from stable isotope analysis in teeth.

RATIONALE: Isotopic analysis of biogenic tissues such as teeth of elasmobranchs has been well recognized as an important method to interpret present and past environmental conditions. However, few studies on shark teeth have focused their attention on making trophic inferences or reconstruction of diet. METHODS: We analyzed the carbon (δ(13)C) and nitrogen (δ(15)N) isotope composition of the tooth crown and root from blue sharks Prionace glauca caught in southern Baja California using a continuous-flow system by means of an elemental analyzer combined with a Delta Plus XL mass spectrometer, to describe their feeding ecology, considering sex and maturity stage. RESULTS: Significant differences in δ(13)C values for tooth root were found between immature and mature males, with depleted values of (13)C in immature individuals. No statistical differences were found between maturity stages in females for both the C and N isotopes in any part of the tooth, which suggests that females were consuming the same prey in the same area. In addition, we observed significant differences in δ(15)N values between the tooth crown and root. CONCLUSIONS: Isotopic analysis in the tooth crown (dentin) and root may represent a new tool to describe the feeding ecology of different species of elasmobranchs, showing dietary change over a short timescale.

Enthesis Healing Is Dependent on Scaffold Interphase Morphology-Results from a Rodent Patellar Model.

The use of multiphasic scaffolds to treat injured tendon-to-bone entheses has shown promising results in vitro. Here, we used two versions of a biphasic silk fibroin scaffold to treat an enthesis defect created in a rat patellar model in vivo. One version presented a mixed transition between the bony and the tendon end of the construct (S-MT) while this transition was abrupt in the second version (S-AT). At 12 weeks after surgery, the S-MT scaffold promoted better healing of the injured enthesis, with minimal undesired ossification of the insertion area. The expression of tenogenic and chondrogenic markers was sustained for longer in the S-MT-treated group and the tangent modulus of the S-MT-treated samples was similar to the native tissue at 12 weeks while that of the S-AT-treated enthesis was lower. Our study highlights the important role of the transition zone of multiphasic scaffolds in the treatment of complex interphase tissues such as the tendon-to-bone enthesis.

Microplastics in freshwater sediments: Effects on benthic invertebrate communities and ecosystem functioning assessed in artificial streams.

The high levels of microplastics (MPs) found in freshwaters, particularly in riverine sediments, may impose a threat to the macroinvertebrate communities with possible consequences at ecosystem-level. The present study aimed to assess the effects of a mixture of different sizes of polyethylene microplastics (PE-MPs) on the composition and structure of macroinvertebrate communities and key-functions, such as primary production and leaf litter decomposition. MPs were mixed in the sediment at three different concentrations (0.1, 1, and 10 g kg-1) already found in freshwater sediments to enhance the relevance of the work. After eight days of exposure to PE-MPs, the observed changes in macroinvertebrate community structure were mostly due to the reduction in the abundance of deposit-feeders and grazers that were reduced by ca 31-50% and 34-39%, in the two highest MPs concentrations respectively, in comparison with the control treatment after 8 days of exposure. MPs internal concentrations were detected only in organisms exposed to plastic particles within artificial streams with chironomids and mayflies presenting higher MPs internal levels (average of 115 particles/individual found in chironomids, 166/individual for Baetis sp. and 415 particles/individual for Ephemerella sp.) suggesting higher ingestion of plastic microparticles. Nevertheless, the alterations in the community structure did not translate into impairments in the functional endpoints analysed, leaf litter decomposition and primary production, that were expected due to possible sub-lethal effects (e.g., feeding inhibition) on detritivores and grazers. This study represents one of the few assessments of MPs effects on freshwater benthic macroinvertebrate community structure and the first that simultaneously considered ecosystem-level functional endpoints. Further research combining different microplastics and longer exposure periods are needed to raise knowledge on potential ecological consequences of MPs to freshwaters.

Efficient healing of large osseous segmental defects using optimized chemically modified messenger RNA encoding BMP-2.

Large segmental osseous defects heal poorly. Recombinant, human bone morphogenetic protein-2 (rhBMP-2) is used clinically to promote bone healing, but it is applied at very high doses that cause adverse side effects and raise costs while providing only incremental benefit. We describe a previously unexplored, alternative approach to bone regeneration using chemically modified messenger RNA (cmRNA). An optimized cmRNA encoding BMP-2 was delivered to critical-sized femoral osteotomies in rats. The cmRNA remained orthotopically localized and generated BMP locally for several days. Defects healed at doses ≥25 µg of BMP-2 cmRNA. By 4 weeks, all animals treated with 50 µg of BMP-2 cmRNA had bridged bone defects without forming the massive callus seen with rhBMP-2. Moreover, such defects recovered normal mechanical strength quicker and initiated bone remodeling faster. cmRNA regenerated bone via endochondral ossification, whereas rhBMP-2 drove intramembranous osteogenesis; cmRNA provides an innovative, safe, and highly translatable technology for bone healing.

Suborganismal responses of the aquatic midge Chironomus riparius to polyethylene microplastics.

Freshwater riverbeds are a major repository of microplastics (MPs) from inland activities. Benthic macroinvertebrates that live in close contact with sediments seem to ingest a considerable amount of such plastic particles. The effects of MPs on life-history traits are relatively well-known, but the suborganismal mechanisms underlying such effects remain unclear. This study addressed the potential effects of low-density polyethylene (LDPE) MPs on Chironomus riparius larvae at cellular and molecular levels. Fourth instar C. riparius larvae were exposed to 0.025 and 2.5 g/kg LDPE of dry sediment (sizes: <32 and 32-45 µm; with irregular shape) under laboratory conditions for 48 h. These short-term exposures to environmental concentrations of LDPE MPs induced changes in the energy reserves (mostly by decreasing carbohydrates and increasing lipids), increased antioxidant and detoxification responses (tGSH, CAT, and GST), and induced increases in the activity of AChE (related to neurotransmission). In addition, at the gene level, exposure to MPs modified mRNA levels of InR, Dis, EcR, Dronc, Met (endocrine system), Def (immune system), PARP, ATM, NLK, and Decay (DNA repair), generating important alterations in the C. riparius development and response to unfavorable situations. This study provides new evidence of the effects of LDPE MPs at the suborganismal level, filling the gap in knowledge regarding the mechanisms underlying the toxicity of MPs and spotlighting gene expression analyses as early indicators of MP toxicity in C. riparius which were confirmed by Integrated biomarker response analyses highlighting the gene expression as sensible and useful endpoints for LPDE pollution in freshwaters. These results, coupled with previous investigations on responses at the organismal level, emphasizes the potential adverse effects of LDPE MPs on C. riparius, which may compromise freshwater benthic communities, considering its ecological role within these habitats.

Oxidative damage and decreased aerobic energy production due to ingestion of polyethylene microplastics by Chironomus riparius (Diptera) larvae.

Riverine sediments are major sinks of microplastics from inland anthropogenic activities, imposing a threat to freshwater benthic invertebrates. This study investigated the ingestion of three size-classes (SC) of irregularly shaped polyethylene microplastics (PE-MPs; SC I: 32-63 µm; II: 63-250 µm; III: 125-500 µm) after 48 h by dipteran larvae (detritivore/collector) Chironomus riparius, and the consequent effects on neurotransmission, energy allocation and oxidative stress. The tested PE-MPs concentrations (1.25; 5; 20 g kg-1) were within the range of concentrations reported in riverbanks from highly urbanised areas (1 - 9 g kg-1), except for 20 g kg-1 representing the worst-case scenario. After exposure to SC I, larvae presented high amounts (up to ∼2400 particles/organism) of PE-MPs in their guts, with an average size-range of 30-60 µm. In the SC II and III, larvae presented PE-MPs of higher diameter (up to 125 µm) and a visible gut obstruction. The high number of particles in the larval gut (SC I) and/or difficulties for their egestion (SC I, II and III) induced oxidative damage and reduced aerobic energy production. In addition, larvae exposed to SC II and III revealed depletion in their total lipid reserves as a consequence of lacking nutrients, and the ones exposed to SC III presented a decrease in their detoxification capacity. These results highlight that freshwater detritivores with low selective feeding behaviour (e.g., chironomids) are more prone to ingest microplastics, with potentially adverse effects on cellular metabolism, redox status and antioxidant-detoxification defences. These harmful effects at lower levels of the biological organisation may ultimately affect organisms' physiology and fitness.

Immune response triggered by the ingestion of polyethylene microplastics in the dipteran larvae Chironomus riparius.

The activation of insects' immune system due to the ingestion of microplastics (MPs) has only been evidenced by the upregulation of specific genes. The activation of phenoloxidase (PO) system is one of the primary responses involved in insects' innate immunity when facing parasites and pathogens, and ingestion of MPs can trigger a similar process. This study aimed at addressing the activities of basal PO and total PO (PO+ prophenoloxidase - proPO), in Chironomus riparius larvae (a model species in ecotoxicology) exposed to sediments spiked with polyethylene microplastics (PE-MPs; size-range 32-63 µm; concentrations: 1.25; 5; to 20 g kg-1) for 48 h. The ingestion of PE-MPs by larvae triggered a significant increase of basal PO activity at 5 and 20 g PE-MPs kg-1, by 26% and 29%, respectively, whereas total PO increased significantly in the latter (+48%), suggesting de novo synthesis of proPO by organisms. Considering the particle size, the immune response's activation is probably linked to damage in the epithelial cells of the gut lumen. This research work provides the first evidence on the activation of the insect's innate immune system after ingestion of MPs and underlines the PO activity as a good indicator of the immune response induced by MPs' ingestion.

Cranial vault lymphoma: a systematic review of five patients.

Bone involvement is a common finding in many types of lymphoma (Clin Oncol 9(3): 195-196, 1997). However, cranial vault affliction has been regarded as an exceedingly rare presentation, particularly in the case of primary lymphoma (J Neurosurg 108(5): 1018-1020, 2008). Our objective is to describe a series of five immunocompetent patients with histologically confirmed cranial vault lymphoma (CVL), and to conduct a systematic review of the current literature. Our review points out identical imaging patterns in most of the lesions for all reported CVL cases, despite their different histological subtypes. This typical pattern can be seen on computed tomography (CT) scans and magnetic resonance imaging (MRI) as an expansive tumor that affects all three compartments of the cranial vault, including the scalp, skull bone, and pachymeninges, even in the absence of osteolysis. We argue that the absence of osteolysis might enhance diagnostic capability. In the appropriate clinical setting, these features represent important disease characteristics that may help with an earlier diagnosis. Large B-cell lymphoma was the most common subtype of primary CVL.

PDMS Based Hybrid Sol-Gel Materials for Sensing Applications in Alkaline Environments: Synthesis and Characterization.

Nowadays, concrete degradation is a major problem in the civil engineering field. Concrete carbonation, one of the main sources of structures' degradation, causes concrete's pH to decrease; hence, enabling the necessary conditions for corrosion reinforcement. An accurate, non-destructive sensor able to monitor the pH decrease resistant to concrete conditions is envisaged by many researchers. Optical fibre sensors (OFS) are generally used for concrete applications due to their high sensitivity and resistance to external interferences. Organic-inorganic hybrid (OIH) films, for potential functionalization of OFS to be applied in concrete structures, were developed. Polydimethylsiloxane (PDMS) based sol-gel materials were synthesized by the formation of an amino alcohol precursor followed by hydrolysis and condensation. Different ratios between PDMS and (3-aminopropyl)triethoxysilane (3-APTES) were studied. The synthesized OIH films were characterized by Fourier-transformed infrared spectroscopy (FTIR), UV-Vis spectroscopy, electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA). The OIH films were doped with phenolphthalein (Phph), a pH indicator, and were characterized by UV-Vis and EIS. FTIR characterization showed that the reaction between both precursors, the hydrolysis and the condensation reactions occurred successfully. UV-Vis characterization confirmed the presence of Phph embedded in the OIH matrices. Dielectric and thermal properties of the materials showed promising properties for application in contact with a high alkaline environment.

Synthesis, Optical and Electrical Characterization of Amino-alcohol Based Sol-gel Hybrid Materials.

This manuscript describes the synthesis and characterization of five new organic-inorganic hybrid (OIH) sol-gel materials that were obtained from a functionalized siloxane 3-glycidoxypropyltrimethoxysilane (GPTMS) by the reaction with the new Jeffamine®, namely three different diamines, i.e., EDR-148, RFD-270, and THF-170, a secondary diamine, i.e., SD-2001, and a triamine, i.e., T-403. The OIH sol-gel materials were characterized by UV-visible absorption spectrophotometry, steady-state photoluminescence spectroscopy, and electrochemical impedance spectroscopy. The reported OIH sol-gel materials showed that, with the exception of the samples prepared with Jeffamine® SD-2001, the transmittance values ranged between 61% and 79%. Regarding the capacitance data, the values reported changed between 0.008 and 0.013 nF cm-2. Due to their optical and electrical properties these new OIH materials show promising properties for applications as support films in an optical sensor area such as fiber sensor devices. Studies to assess the chemical stability of the OIH materials in contact with cement pastes after 7, 14, and 28 days were also performed. The samples prepared with THF-170 and GPTMS, when compared to the samples prepared with RFD-270 and T-403, exhibited improved behavior in the cement paste (alkaline environment), showing promising properties for application as support film in optical fiber sensors in the civil engineering field.

A New Non-invasive Technique for Measuring 3D-Oxygen Gradients in Wells During Mammalian Cell Culture.

Oxygen tension plays an important role in overall cell function and fate, regulating gene expression, and cell differentiation. Although there is extensive literature available that supports the previous statement, little information is to be found about accurate O2 measurements during culture. In fact, O2 concentration at the cell layer during culture is commonly assumed to be equal to that of the incubator atmosphere. This assumption does not consider oxygen diffusion properties, cell type, cell density, media composition, time in culture nor height of the cell culture medium column. In this study, we developed a non-invasive, optical sensor foil-based technique suitable for measuring the 3D oxygen gradient that is formed during cell culture as a result of normal cell respiration. For this propose, we created a 3D printed ramp to which surface an oxygen optode sensor foil was attached. The ramps were positioned inside the culture wells of 24 well plate prior cell seeding. This set up in conjunction with the VisiSens TD camera system allows to investigate the oxygen gradient formation during culture. Cultivation was performed with three different initial cell densities of the cell line A549 that were seeded on the plate containing the ramps with the oxygen sensors. The O2 gradient obtained after 96 h of culture showed significantly lower O2 concentrations closer to the bottom of the well in high cell density cultures compared to that of lower cell density cultures. Furthermore, it was very interesting to observe that even with low cell density culture, oxygen concentration near the cell layer was lower than that of the incubator atmosphere. The obtained oxygen gradient after 96 h was used to calculate the oxygen consumption rate (OCR) of the A549 cells, and the obtained value of ~100 fmol/h/cell matches the OCR value already reported in the literature for this cell line. Moreover, we found our set up to be unique in its ability to measure oxygen gradient formation in several wells of a cell culture plate simultaneously and in a non-invasive manner.

The Diels-Alder cycloaddition reaction in the functionalization of carbon nanofibers.

Carbon nanofibres were functionalized by a Diels-Alder cycloaddition reaction of 1,3-butadiene, generated in situ from sulfolene. The experimental conditions were selected on the basis of a differential scanning calorimetry (DSC) study on the reagents and the functionalization was confirmed by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Analysis performed on the surface of the functionalized material by X-ray photoelectron spectroscopy (XPS) and FT-IR using the Attenuated Total Reflectance (ATR) technique indicates that the carbonyl and sulfoxide groups are present on the surface of the functionalized material. The acidic surface of the functionalized nanofiber suggests the presence of carboxylic acid and possibly sulfonic acid groups.

Ingestion of small-sized and irregularly shaped polyethylene microplastics affect Chironomus riparius life-history traits.

Microplastics (MPs) are emerging contaminants of freshwater ecosystems. Once in aquatic systems, most of these plastic particles undergo processes of fragmentation, biofouling, and sedimentation, resulting in increased concentrations of smaller sized and irregularly-shaped particles in the sediment. High levels of MPs in freshwater sediments can denote a potential threat to benthic and sediment-dwelling organisms such as dipteran larvae. This study evaluates the ecotoxicological effect of three pools of irregularly-shaped polyethylene (PE) microplastics (pools containing 90% of the particles within 32-63 µm (size-class A), 63-250 µm (size-class B) and 125-500 µm (size-class C)), with concentrations ranging from 1.25 to 20 g Kg-1 sediment, on the dipteran Chironomus riparius life-history traits. After ten days of exposure, larvae ingested PE particles typically in the 32-63 µm range, even when 90% of the particles possessed higher size (i.e., in size-classes B and C) and the larvae mandible allowed the ingestion of such bigger-sized particles. Thus, the number of ingested particles was higher in size-class A, followed by B and C, and led to a significant reduction with similar magnitude on larval growth (Lowest Observed Effect Concentrations (LOEC) = 2.5 g Kg-1 sediment DW) and a significant delay on imagoes emergence (e.g., LOEC = 1.5 g Kg-1 sediment DW for females). The results from this study show that the ingestion and persistence of small-sized polyethylene microplastics caused significant impairments on life-history traits of C. riparius. Considering their role on freshwater food-webs and the potential persistence of small-sized PE particles in their larval gut, these results also point for the potential adverse effects of small-sized microplastics at the community and ecosystem level.

An Improved, Chemically Modified RNA Encoding BMP-2 Enhances Osteogenesis In Vitro and In Vivo.

IMPACT STATEMENT: The use of chemically modified RNA (cmRNA) with increased stability using translation initiator of short untranslated regions (TISU) offers the prospect of finally allowing us to unlock the potent osteogenic properties of BMP-2 in a clinically expedient manner. As noted, delivery of recombinant BMP-2 protein has had modest clinical efficacy, whereas gene delivery is effective but very difficult to translate into human clinical use. This study shows the great potential of cmRNA encoding BMP-2 with TISU in a long-bone critical-sized rat model.

Foraging habits and levels of mercury in a resident population of bottlenose dolphins (Tursiops truncatus) in Bocas del Toro Archipelago, Caribbean Sea, Panama.

A small and genetically isolated bottlenose dolphin (Tursiops truncatus) population resides year-round in the Bocas del Toro Archipelago-Panama (BDT). Photo-identification and genetic data showed that this dolphin population is highly phylopatric and is formed exclusively by individuals of the "inshore form". This study aimed to investigate the trophic ecology and mercury concentrations of bottlenose dolphins in BDT to assess their coastal habits. We collected muscle samples (n = 175) of 11 potential fish prey species, and skin samples from free-ranging dolphins in BDT (n = 37) and La Guajira-Colombia (n = 7) to compare isotopic niche width. Results showed that BDT dolphins have a coastal feeding habit, belong to the "inshore form" (δ13C = -13.05 ±â€¯1.89‰), and have low mercury concentrations (mean = 1637 ±â€¯1387 ng g-1dw). However, this element is biomagnified in the BDT food chain, showing a marginal dolphins health risk (RQ = 1.00). We call for a monitoring pollutant program and conservation strategies aimed to protect the dolphin population at BDT.

Standardization of (241)Am, (124)Sb and (131)I by live-timed anti-coincidence counting with extending dead time.

The National Metrology Laboratory for Ionizing Radiation (LNMRI)/Brazil has implemented a live-timed anti-coincidence system with extending dead time to complement the existing systems in its Radionuclide Laboratory for activity measurements of radioactive sources. In this new system, the proportional counter has been replaced by a liquid-scintillation-counter for alpha and beta detection. In order to test the performance of the new system, radioactive solutions of (131)I, (124)Sb and (241)Am have been standardized. In this work the measurement method, the results and the associated uncertainties are described and discussed.

Standardization of 67Ga, 51Cr and 55Fe by live-timed anti-coincidence counting with extending dead time.

In this work, the activity standardization of 51Cr, 55Fe and 67Ga by live-timed anti-coincidence counting with extending dead time is described. The difficulties of the method, the uncertainties of the results of the measurements and the comparison of these results with others measurement methods are discussed.

Eumelanin Nanoparticle-Incorporated Polyvinyl Alcohol Nanofibrous Composite as an Electroconductive Scaffold for Skeletal Muscle Tissue Engineering.

Eumelanins are melanocyte-derived natural pigments with inherent electrical cues and outstanding physicochemical properties, which enhance the electroconductivity of the synthetic polymeric scaffold, upon incorporation as nanoparticles. Electrospun nanofibrous meshes generated from such composite polymers are of great interest for muscle tissue engineering applications. In this study, we investigated the feasibility of fabricating nanofibrous scaffolds of polyvinyl alcohol (PVA) incorporated with eumelanin nanoparticles (EUNp) by electrospinning and further assessed their impact on myogenic differentiation of skeletal myoblasts. Morphological and physicochemical analysis of EUNp-PVA nanofibrous mesh showed uniform, bead-free, thermally stable, and randomly oriented nanofibers (450 ± 10 nm) with effective retention of the incorporated EUNp, without any chemical cross-reactivity. Voltammetric measurements of EUNp-PVA mesh exhibits stable electrical conductivity (∼4.0 S cm-1), which was undetectable in plain PVA meshes. In vitrocytocompatibility studies showed a significant increase in viability, proliferation, and metabolic activity of the seeded C2C12 myoblast on EUNp-PVA mesh compared to controls. Interestingly, EUNp-PVA nanofibers supported reorganization of the C2C12 myoblast, with comparatively longer and wider myotube-like structures formed. Our results suggest that an EUNp-PVA composite nanofibrous scaffold with inherent electroconductive properties of incorporated EUNp and topographical cues of PVA nanofibers could be an excellent biomaterial scaffold for skeletal muscle tissue engineering applications.