Comparative metal oxide nanoparticle toxicity using embryonic zebrafish

AbstractEngineered metal oxide nanoparticles (MO NPs) are finding increasing utility in the medical field as anticancer agents. Before validation of in vivo anticancer efficacy can occur, a better understanding of whole-animal toxicity is required. We compared the toxicity of seven widely used semiconductor MO NPs made from zinc oxide (ZnO), titanium dioxide, cerium dioxide and tin dioxide prepared in pure water and in synthetic seawater using a five-day embryonic zebrafish assay. We hypothesized that the toxicity of these engineered MO NPs would depend on physicochemical properties. Significant agglomeration of MO NPs in aqueous solutions is common making it challenging to associate NP characteristics such as size and charge with toxicity. However, data from our agglomerated MO NPs suggests that the elemental composition and dissolution potential are major drivers of toxicity. Only ZnO caused significant adverse effects of all MO particles tested, and only when prepared in pure water (point estimate median lethal concentration=3.5–9.1mg/L). This toxicity was life stage dependent. The 24h toxicity increased greatly (∼22.7 fold) when zebrafish exposures started at the larval life stage compared to the 24h toxicity following embryonic exposure. Investigation into whether dissolution could account for ZnO toxicity revealed high levels of zinc ion (40–89% of total sample) were generated. Exposure to zinc ion equivalents revealed dissolved Zn2+ may be a major contributor to ZnO toxicity

Emerging and legacy plasticisers in coastal and estuarine environments: a review

The occurrence of plastic waste in the environment is an emerging and ongoing concern. In addition to the physical impacts of macroplastics and microplastics on organisms, the chemical effects of plastic additives such as plasticisers have also received increasing attention. Research concerning plasticiser pollution in estuaries and coastal environments has been a particular focus, as these environments are the primary entry point for anthropogenic contaminants into the wider marine environment. Additionally, the conditions in estuarine environments favour the sedimentation of suspended particulate matter, with which plasticisers are strongly associated. Hence, estuary systems may be where some of the highest concentrations of these pollutants are seen in freshwater and marine environments. Recent studies have confirmed emerging plasticisers and phthalates as pollutants in estuaries, with the relative abundance of these compounds controlled primarily by patterns of use, source intensity, and fate. Plasticiser profiles are typically dominated by mid-high molecular weight compounds such as DnBP, DiBP, and DEHP. Plasticisers may be taken up by estuarine and marine organisms, and some phthalates can cause negative impacts in marine organisms, although further research is required to assess the impacts of emerging plasticisers. This review provides an overview of the processes controlling the release and partitioning of emerging and legacy plasticisers in aqueous environments, in addition to the sources of plasticisers in estuarine and coastal environments. This is followed by a quantitative analysis and discussion of literature concerning the (co-)occurrence and concentrations of emerging plasticisers and phthalates in these environments. We end this review with a discussion the fate (degradation and uptake by biota) of these compounds, in addition to identification of knowledge gaps and recommendations for future research

Molecular and morphophysiological responses cocoa leaves with different concentrations of anthocyanin to variations in light levels

Theobroma cacao gives higher yield when cultivated in full sun under irrigation system with fertilization, because is a species little conservative in relation the efficiency of water use. On the other hand, T. cacao is usually cultivated under shade conditions in ‘Cabruca’ and agroforestry systems but with low yield. It has been observed under field conditions that the genotypes of T. cacao with high concentration of anthocyanins in young leaves are more tolerant to high irradiance stress when grown in full sun. The accumulation of flavonoids or other UVabsorbing compounds in the leaf epidermis is one of the most important mechanisms to screening out UV-B radiation. The aim of this study was to evaluate the effects of different levels of light on three clonal cacao genotypes (‘Catongo’, SCA-6 and SJ-2), contrasting in relation to accumulation of anthocyanin levels in young leaves, by evaluations of photosynthesis, activity of guaiacol peroxidase (GPX), chloroplastid pigment contents and vacuolar (anthocyanins) flavonoids contents, anatomical characteristics and gene expression of the leaf. In summary, (i) the anthocyanins contents in leaf level did not provide protection against photoinhibition in T. cacao, (ii) the ‘Catongo’ and SJ-2 genotypes showed greater phenotypic plasticity to the morphology and the chloroplastidic pigment contents in the leaf, while the SCA-6 genotype allocated more in the flavonoids content and hsp70 gene expression; (iii) the relative expression of the genes psbA and psbO, did not vary between genotypes under irradiance stress

Recorte circular de cenas computacionais aplicado na separação de íris humana

O reconhecimento de padrões da íris humana é um processo não invasivo e que permite a extracção de características individuais. A localização e separação da íris do restante da imagem é fundamental para o bom desempenho dos métodos desenvolvidos nesta área. O isolamento da íris costuma ser um processo que exige a varredura da imagem e a comparação da localização de cada um de seus pixels. Como esta possui formato arredondado, o recorte de cenas computacionais, com janela de corte circular, pode ser aplicado nas imagens de íris para fazer este isolamento. No entanto, encontrar os limites de uma janela de visualização é um processo exigente computacionalmente, principalmente para estruturas de dados do tipo bitmap, que devem ser processadas pixel a pixel. Na tentativa de reduzir o processamento para tornar viável a aplicação na separação de íris, este trabalho usa os conceitos de hashing e a equação da circunferência para definir os pontos da imagem original bitmap pertencentes a uma área de visualização circular, sem a necessidade de percorrer todos os pixels da mesma. Apresenta-se o resultado da aplicação deste método para a separação da íris humana em imagens bitmap, sem a necessidade de comparar a localização de todos os seus pixels

Spatial and temporal dynamics of the abundance of crustose calcareous algae on the southernmost coral reefs of the western Atlantic (Abrolhos Bank, Brazil)

Crustose calcareous algae (CCA) constitute one of the main reef builders on the Abrolhos Bank, Brazil. Once CCA taxonomy is locally understood, differences in growth-forms may be useful for the delimitation of taxa using characteristics such as the presence or absence of surface protuberances. Here, growth-forms were used to identify and quantify the most common CCA taxa on the shallow reefs (3-10 m) of the Abrolhos Bank to determine possible changes in the CCA community over a period of 10 years, and the ecological significance of CCA to local reefs was interpreted. The CCA assemblages were surveyed from 2006-2015 by using fixed photoquadrats at four sites in the inner (10-20 km from the mainland) and mid-shelf reefs (40-75 km from the mainland). The five most common CCA taxa were Pneophyllum conicum, the Lithophyllum kaiserii / Lithophyllum sp. complex, Melyvonnea erubescens, the Hydrolithon boergesenii / Porolithon onkodes complex and Peyssonelia sp. The overall mean CCA cover on the reefs was 20%. A comparison with a previous monitoring study in the same region indicated that the CCA cover nearly doubled from 2003-2008 to 2006-2015. This study reveals that the coral-killing species P. conicum dominated CCA flora on the shallow Abrolhos reefs in the last decade, and the local specific abundance of CCA slightly fluctuated over time and was species-and site-specific. The information obtained in this study contributes to the understanding of the ecology of the key calcifying components of the Abrolhos reefs and provides a useful baseline for exploring the responses of CCA to future environmental changes.PELDMudancas Climaticas scientific programmes of the Brazilian National Science Agency (CNPq)Brazilian IODP Program (CAPES/MEC)P&D Program ANP/BrasoilFAPERJDiretoria Pesquisa Cient, Inst Pesquisas, Jardim Bot Rio De Janeiro, Rua Pacheco Leao 915, BR-22460030 Rio De Janeiro, RJ, BrazilUniv Fed Rio de Janeiro, Inst Biol, BR-21941599 Rio De Janeiro, RJ, BrazilUniv Fed Espirito Santo, Dept Oceanog, Ave Fernando Ferrari 514, BR-29090600 Vitoria, ES, BrazilUniv Fed Sao Paulo, Inst Mar, Campus Baixada Santista, BR-11030400 Santos, SP, BrazilUniv Fed Paraiba, Ctr Ciencias Aplicadas & Educ, Campus 4 Litoral Norte, BR-58297000 Rio Tinto, PB, BrazilUniv Fed Sao Paulo, Inst Mar, Campus Baixada Santista, BR-11030400 Santos, SP, BrazilANP/Brasoil: 48610.011015/2014-55Web of Scienc

Gate-Controlled Ionization and Screening of Cobalt Adatoms on a Graphene Surface

We describe scanning tunneling spectroscopy (STS) measurements performed on individual cobalt (Co) atoms deposited onto backgated graphene devices. We find that Co adatoms on graphene can be ionized by either the application of a global backgate voltage or by the application of a local electric field from a scanning tunneling microscope (STM) tip. Large screening clouds are observed to form around Co adatoms ionized in this way, and we observe that some intrinsic graphene defects display a similar behavior. Our results provide new insight into charged impurity scattering in graphene, as well as the possibility of using graphene devices as chemical sensors.Comment: 19 pages, 4 figure

Simulating temporal evolution of pressure in two-phase flow in porous media

We have simulated the temporal evolution of pressure due to capillary and viscous forces in two-phase drainage in porous media. We analyze our result in light of macroscopic flow equations for two-phase flow. We also investigate the effect of the trapped clusters on the pressure evolution and on the effective permeability of the system. We find that the capillary forces play an important role during the displacements for both fast and slow injection rates and both when the invading fluid is more or less viscous than the defending fluid. The simulations are based on a network simulator modeling two-phase drainage displacements on a two-dimensional lattice of tubes.Comment: 12 pages, LaTeX, 14 figures, Postscrip

Co-occurrence of macroplastics, microplastics, and legacy and emerging plasticisers in UK soils

Despite a theoretical link between plastic and plasticiser occurrence in the terrestrial environment, there are few empirical studies of the relationship between these contaminants in soils. We carried out a field study to assess the cooccurrence of plastic waste, and legacy and emerging plasticisers in UK soils (n = 19) from various land uses (woodlands, urban roadsides, urban parklands, landfill-associated). Surface plastics and soil microplastics were quantified and characterised using ATR-FTIR and μ-FTIR. Eight legacy (phthalate) and three emerging (adipate, citrate, trimellitate) plasticisers were quantified using GC–MS. Surface plastics were found at higher prevalence at landfillassociated and urban roadside sites, with levels significantly (2 orders of magnitude) greater than in woodlands. Microplastics were detected in landfill-associated (mean 12.3 particles g−1 dw), urban roadside (17.3 particles g−1dw) and urban parkland (15.7 particles g−1 dw) soils, but not in woodland soils. The most commonly detected polymers were polyethene, polypropene and polystyrene. Mean ∑plasticiser concentration in urban roadside soils (3111 ng g−1 dw) was significantly higher than in woodlands (134 ng g−1 dw). No significant difference was found between landfill-associated (318 ng g−1 dw) and urban parkland (193 ng g−1 dw) soils and woodlands. Di-n-butyl phthalate (94.7% detection frequency) and the emerging plasticiser trioctyl trimellitate (89.5%) were the most commonly detected plasticisers, with diethylhexyl phthalate (493 ng g−1 dw) and di-iso-decyl phthalate (96.7 ng g−1 dw) present at the highest concentrations. ∑plasticiser concentrations were significantly correlated with surface plastic (R2 = 0.23), but not with soil microplastic concentrations. Whilst plastic litter seems a fundamental source of plasticisers in soils, mechanisms such as airborne transport from source areas may be as important. Based on the data from this study, phthalates remain the dominant plasticisers in soils, but emerging plasticisers are already widespread, as reflected by their presence in all land uses studied

Purification, characterization and structural determination of UDP-N-acetylglucosamine pyrophosphorylase produced by Moniliophthora perniciosa

The enzyme UDP-N-acetylglucosamine pyrophosphorylase (PyroMp) from Moniliophthora perniciosa (CCMB 0257), a pathogenic fungal strain and the causative agent of the witches' broom disease in Theobroma cacao, was partially purified by precipitation with ammonium sulfate and gel filtration on Sephacryl S-200. The buffer for enzyme extraction was sodium phosphate, 0.050 mol L-1, pH 7.0, containing 1.0 mol L-1 NaCl. Response surface methodology (RSM) was used to determine the optimum pH and temperature conditions. Four different isoenzymes (PyroMp I, PyroMp II, PyroMp III and PyroMp IV) were obtained with optimal pH ranging from 6.9-8.4 and optimum temperature ranging from 28 to 68 °C. The 3D structure of pyrophosphorylase of M. perniciosa was determined by comparative modeling. The model obtained showed a good quality, possessing 78.6% of amino acids in energetically allowed regions. The model was then submitted for DM simulation and showed a good geometric quality (91.1% Ramachandran plot). The active site of the enzyme was found to be extremely well conserved. This model will be useful for developing new inhibitors against witches' broom disease.A enzima UDP-N-acetilglicosamina pirofosforilase de Moniliophthora perniciosa (CCMB 0257), o fungo patogênico causador da doença vassoura-de-bruxa do Theobroma cacao, foi parcialmente purificada por precipitação com sulfato de amônio e cromatografia de gel filtração em Sephacryl S-200. O tampão de extração da enzima foi o fosfato de sódio, 0,050 mol L-1, pH 7,0, contendo 1,0 mol L-1 de NaCl. A metodologia de superfície de resposta (MSR) foi usada para a obtenção do pH e temperatura ótima. Os resultados mostraram quatro diferentes isoenzimas (PyroMp I, PyroMp II, PyroMp III e PyroMp IV) que apresentaram pH ótimo na faixa de 6,9-8,4 e temperatura ótima variando entre 28 a 68 °C. A estrutura 3D de pirofosforilase de M. perniciosa foi obtida por modelagem comparativa. O modelo obtido mostrou uma boa qualidade, possuindo 78,6% de aminoácidos nas regiões energeticamente favoráveis. O modelo foi então submetido a simulações de dinâmica molecular (DM). O modelo apresentou uma boa qualidade geométrica após as simulações de DM (91,1% -gráfico de Ramachandran). A procura pelo sítio ativo da enzima mostrou que este é mantido extremamente conservado. Este modelo pode ser útil para desenvolvimento de inibidores contra a doença vassoura de bruxa.FINEPCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)CNPqFAPESBFIOCRUZ - Programa de Pós-Graduação em Biotecnologia UEF