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1.
J Environ Qual ; 49(1): 97-105, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016356

RESUMO

Cover crops are often recommended as a best management practice to reduce erosion, weed pressure, and nutrient loss. However, cover crops may be sources of phosphorus (P) to runoff water after termination. Two greenhouse trials were conducted to determine the effects of cover crop species, termination method, and time after termination on water-extractable P (WEP) release from crop biomass. Treatments were structured in a 3 × 3 × 3 factorial and arranged in a randomized complete block design with six replicates. Treatments included three cover crop species (triticale [× Triticosecale; Triticum × Secale 'Trical'], rapeseed [Brassica napus L. 'Winfred'], and crimson clover [Trifolium incarnatum L.]); three termination methods (clipping, freezing, and herbicide); and three WEP extraction times (1, 7, and 14 d after termination). Rapeseed consistently resulted in the least WEP when exposed to the same method of termination and at the same extraction time as the other species. For both trials, terminating crop tissue via freezing increased concentrations of WEP compared with other termination methods. The WEP release from cover crop tissue increased as the time after extraction increased, but the effect was greater for herbicide- and freeze-terminated cover crops and less for clipping-terminated cover crops. Future studies on WEP release from cover crops should pay close attention to the effects of extraction timing. Producers may be able to reduce P loss from cover crop tissue by selecting cover crop species with low WEP and minimizing the amount of biomass exposed to freezing conditions.


Assuntos
Agricultura , Fósforo , Biomassa , Produtos Agrícolas , Congelamento
2.
J Environ Qual ; 49(3): 700-711, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016390

RESUMO

Increased phosphorus (P) availability under flooded, anaerobic conditions may accelerate P loss from soils to water bodies. Existing knowledge on P release to floodwater from flooded soils is limited to summer conditions and/or room temperatures. Spring snowmelt runoff, which occurs under cold temperatures with frequent freeze-thaw events, is the dominant mode of P loss from agricultural lands to water bodies in the Canadian Prairies. This research examined the effects of temperature on P dynamics under flooded conditions in a laboratory study using five agricultural soils from Manitoba, Canada. The treatments were (a) freezing for 1 wk at -20 °C, thawing and flooding at 4 ± 1 °C (frozen, cold); (b) flooding unfrozen soil at 4 ± 1 °C (unfrozen, cold); and (c) flooding unfrozen soil at 20 ± 2 °C (warm). Pore water and surface water were collected weekly over 8 wk and analyzed for dissolved reactive phosphorus (DRP), pH, calcium, magnesium, iron (Fe), and manganese (Mn). Soils under warm flooding showed enhanced P release with significantly higher DRP concentrations in pore and surface floodwater compared with cold flooding of frozen and unfrozen soils. The development of anaerobic conditions was slow under cold flooding with only a slight decrease in Eh, whereas under warm flooding Eh declined sharply, favoring reductive dissolution reactions releasing P, Fe, and Mn. Pore water and floodwater DRP concentrations were similar between frozen and unfrozen soil under cold flooding, suggesting that one freeze-thaw event prior to flooding had minimal effect on P release under simulated snowmelt conditions.


Assuntos
Fósforo/análise , Solo , Anaerobiose , Canadá , Congelamento , Temperatura
3.
J Environ Qual ; 49(2): 314-323, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016430

RESUMO

Soil freeze-thaw cycles (FTCs) profoundly influence biophysical conditions and modify biogeochemical processes across many northern-hemisphere and alpine ecosystems. How FTCs will contribute to global processes in seasonally snow-covered ecosystems in the future is of particular importance as climate change progresses and winter snowpacks decline. Our understanding of these contributions is limited because there has been little consideration of inter- and intrayear variability in the characteristics of FTCs, in part due to a limited appreciation for which of these characteristics matters most with respect to a given biogeochemical process. Here, we introduce the concept of effective FTCs: those that are most likely linked to changes in key soil processes. We also propose a set of parameters to quantify and characterize effective FTCs using standard field soil temperature data. To put these proposed parameters into effective practice, we present FTCQuant, an R package of functions that quantifies FTCs based on a set of user-defined parameter criteria and, importantly, summarizes the individual characteristics of each FTC counted. To demonstrate the utility of these new concepts and tools, we applied the FTCQuant package to re-analyze data from two published studies to help explain over-winter changes to N2 O emissions and wet-aggregate stability. We found that effective FTCs would be defined differently for each of these response variables and that effective FTCs provided a 76 and 33% increase in model fit for wet-aggregate stability and cumulative N2 O emission, respectively, relative to conventional FTC quantification methods focusing on fluctuations around 0 °C. These results demonstrate the importance of identifying effective FTCs when scaling soil processes to regional or global levels. We hope our contributions will inform future deductions, hypothesis generation, and experimentation with respect to expected changes in freeze-thaw cycling globally.


Assuntos
Ecossistema , Solo , Mudança Climática , Congelamento , Neve
4.
J Environ Qual ; 49(2): 404-416, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016431

RESUMO

Biogeochemical processes in northern peatland ecosystems are influenced by seasonal temperature fluctuations that are changing with the climate. Methylmercury (MeHg), commonly produced in peatlands, affects downstream waters; therefore, it is important to understand how temperature transitions affect mercury (Hg) dynamics. We investigated how the freeze-thaw cycle influences belowground peat pore water total Hg (THg), MeHg, and dissolved organic carbon (DOC). Four large, intact peat columns were removed from an ombrotrophic peat bog and experimentally frozen and thawed. Pore water was sampled across seven depths in the peat columns during the freeze-thaw cycle and analyzed for THg, MeHg, and DOC concentrations. Freezing results showed increased concentrations of THg below the ice layers and limited change in MeHg concentrations. During thawing, THg concentrations significantly increased, whereas MeHg concentrations decreased. Limited bromide movement and depth decreases in THg and DOC concentrations were associated with increased bulk density and degree of humification in the peat. The experiment demonstrates the effects of the freeze-thaw cycle on Hg concentrations in northern peatlands. Changes to freeze-thaw cycles with climate change may exacerbate Hg cycling and transport processes in peatland environments.


Assuntos
Mercúrio/análise , Compostos de Metilmercúrio , Ecossistema , Congelamento , Solo
5.
Int J Nanomedicine ; 15: 6263-6277, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32922002

RESUMO

Background: Nowadays, smart synthesized nanostructures have attracted wide attention in the field of stem cell nanotechnology due to their effect on different properties of stem cells. Methods: GFc7 growth nanofactor was synthesized based on nanochelating technology as an iron-containing copper chelator nanocomplex. The effect of this nanocomplex on the expansion and differentiation of hematopoietic stem cells (HSCs) as well as its performance as a cryoprotectant was evaluated in the present study. Results: The results showed that the absolute count of CD34+ and CD34+CD38- cells on days 4, 7, 10 and 13; the percentage of lactate dehydrogenase enzyme on the same days and CD34+CXCR4 population on day 10 were significantly increased when they were treated with GFc7 growth nanofactor in a fetal bovine serum (FBS)-free medium. This medium also led to delayed differentiation in HSCs. One noticeable result was that CD34+CD38- cells cultured in an FBS medium were immediately differentiated into CD34+CD38+ cells, while CD34+CD38- cells treated with GFc7 growth nanofactor in FBS medium did not show such an immediate significant differentiation. De-freezing GFc7-treated CD34+ cells, which were already frozen according to cord blood bank protocols, showed a higher percentage of cell viability and a larger number of colonies according to colony-forming cell assay as compared to control. Conclusion: It can be claimed that treating HSCs with GFc7 growth nanofactor leads to quality and quantity improvement of HSCs, both in terms of expansion in vitro and freezing and de-freezing processes.


Assuntos
Citoproteção , Células-Tronco Hematopoéticas/citologia , Nanopartículas/química , ADP-Ribosil Ciclase 1/metabolismo , Antígenos CD34/metabolismo , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Ensaio de Unidades Formadoras de Colônias , Difusão Dinâmica da Luz , Congelamento , Regulação da Expressão Gênica , Humanos , Nanopartículas/ultraestrutura , Receptores CXCR4/metabolismo
6.
Ecotoxicol Environ Saf ; 204: 111005, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32738624

RESUMO

Freezing temperatures is an important stressor in the arctic regions and has a significant influence on the population dynamics and geographic distribution of terrestrial invertebrates. Toxic metals in the environment can interfere with protective cold-acclimation responses of organisms. It is therefore important to evaluate the combined effects of cold stress and environmental contaminants. Here, we aimed to investigate the effects of Hg (HgCl2) on various physiological aspects of freeze-tolerance in the earthworm (Enchytraeus albidus). We measured the levels of the cryoprotectant glucose, the glycogen content (source of glucose molecules for cryoprotection and fuel for metabolism), and changes in the composition of membrane phospholipid fatty acids (PLFA) as an indicator of lipid peroxidation. Freezing at -6 °C had no effect on survival in uncontaminated soil, however, survival of freezing in Hg contaminated soil was clearly reduced, especially at extended exposure times. Thus, the LC50 value in frozen soil decreased from 8.3 mg Hg kg-1 (when exposed for 17 days) to only 4.2 mg Hg kg-1 after 36 days' exposure indicating that combined effects of Hg and freezing became larger at prolonged exposure times. Hg caused a depletion of glycogen reserves (almost 50% at 12 mg kg-1 dry soil), but despite this effect worms were able to maintain a constant cryoprotectant level (about 0.12 mg glucose mg-1 dry weight) at all Hg concentrations. Hg had clear negative effects on the proportion of unsaturated PLFAs, which could be an indication of lipid peroxidation. Since a high proportion of unsaturated fatty acids in the membrane is important for invertebrate freeze-tolerance, our results suggest that the negative effect of Hg on freeze-tolerance in E. albidus is related to degraded membrane functionality at low temperature.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Congelamento , Cloreto de Mercúrio/efeitos adversos , Oligoquetos/efeitos dos fármacos , Animais , Crioprotetores/farmacologia , Relação Dose-Resposta a Droga , Ácidos Graxos/metabolismo , Glucose/farmacologia , Glicogênio/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Mercúrio/efeitos adversos
7.
Environ Monit Assess ; 192(9): 559, 2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32747987

RESUMO

This article aims to analyze the dynamics of freezing and thawing of Antarctic lakes located in ice-free areas on Nelson Island and Fildes Peninsula, where response to changes in air temperature and precipitation rates occur rapidly, during the period from July 2016 to December 2018. In these places, which are difficult to access, remote sensing is an important alternative, especially considering the use of active remote sensors such as the Synthetic Aperture Radar (SAR), which has less restriction regarding the presence of clouds over the study area. Three backscatter thresholds were defined (σ) for the identification of the physical state of the water of the lakes of the study region, applied in Sentinel 1A SAR (S1A) images under Horizontal Horizontal (HH) polarization and Interferometric Wide (IW) imaging mode. These images, along with the air temperature data obtained by the Interim Re-Analysis (ERA-Interim) atmospheric reanalysis model, provided the evidence for the interpretation of the freezing and thawing periods of the lakes. The thresholds applied for the definition of the physical state of the lake water were greater than - 14 dB for frozen water, between - 14 and - 17 dB for the surface, with up to 60% of their frozen area, and less than - 17 dB for open water. The temporal analysis revealed that the lakes start to thaw in October, become completely thawed in February, and freeze again in March. Nevertheless, it can be said that the S1A satellite allows a satisfactory identification of the liquid and solid phases of the water in the lakes of the study region.


Assuntos
Lagos , Radar , Regiões Antárticas , Monitoramento Ambiental , Congelamento , Ilhas
8.
Nat Commun ; 11(1): 4182, 2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32826882

RESUMO

Living in a group allows individuals to decrease their defenses, enabling other beneficial behaviors such as foraging. The detection of a threat through social cues is widely reported, however, the safety cues that guide animals to break away from a defensive behavior and resume alternate activities remain elusive. Here we show that fruit flies display a graded decrease in freezing behavior, triggered by an inescapable threat, with increasing group sizes. Furthermore, flies use the cessation of movement of other flies as a cue of threat and its resumption as a cue of safety. Finally, we find that lobula columnar neurons, LC11, mediate the propensity for freezing flies to resume moving in response to the movement of others. By identifying visual motion cues, and the neurons involved in their processing, as the basis of a social safety cue this study brings new insights into the neuronal basis of safety in numbers.


Assuntos
Comportamento Animal , Drosophila/fisiologia , Neurônios/fisiologia , Segurança , Comportamento Social , Animais , Sinais (Psicologia) , Feminino , Congelamento
9.
Gene ; 761: 145039, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32777527

RESUMO

The wood frog (Rana sylvatica) can tolerate full body freezing in winter. As a protective response, wood frogs dehydrate their cells and accumulate large quantities of glucose as an intracellular cryoprotectant. Freezing causes ischemia since blood delivery to organs is interrupted. Fascinatingly, wood frogs can tolerate dehydration, extreme hyperglycemia, and anoxia independently of freezing. In response to low oxygen levels, wood frogs strategically reduce their metabolic rates and allocate the finite amount of intracellular fuel available to pro-survival processes while reducing or interrupting all others. In this study, the involvement of advanced glycation end products (AGEs) and the high mobility group box 1 (HMGB1) protein in activating RAGE (AGE receptor) were investigated. The results show that freezing, anoxia and dehydration induced the expression of total HMGB1 and its acetylation in the heart. RAGE levels were induced in response to all stress conditions, which resulted in differential regulation of the ETS1 transcription factor. While the nuclear localization of total ETS1 was not affected, the DNA binding activity of total and its active form increased in response to freezing and dehydration but not in response to anoxia. Current results indicate that ETS1 acts as a transcriptional activator for peroxiredoxin 1 in response to freezing but acts as a transcriptional repressor of several nuclear-encoded mitochondrial genes in response to all stresses. Altogether, current results show that the HMGB1/RAGE axis may activate ETS1 and that this activation could result in both transcriptional activation and/or repression in a stress-dependent manner.


Assuntos
Mitocôndrias/metabolismo , Miocárdio/metabolismo , Ranidae/metabolismo , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Animais , Desidratação/metabolismo , Congelamento , Glucose/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Produtos Finais de Glicação Avançada/fisiologia , Proteína HMGB1/metabolismo , Proteína HMGB1/fisiologia , Coração/fisiologia , Hipóxia/metabolismo , Oxigênio/metabolismo , Ranidae/genética , Receptor para Produtos Finais de Glicação Avançada/fisiologia , Estresse Fisiológico/fisiologia
10.
J Chromatogr A ; 1627: 461416, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823114

RESUMO

Animal feeds are often reported to be contaminated with chemical residues, and when present above the maximum legal limit, these compounds can cause harmful effects to consumers of animal produce. Thus, animal feed safety is an important regulatory concern. The aim of this study was to optimise a multiresidue method for the simultaneous analysis of multi-class pesticides and a number of frequently used veterinary drugs using LC-MS/MS and GC-MS/MS. The method was validated in a range of feed matrices, including maize feed, poultry feed and mixed feed concentrate. The optimised sample preparation workflow involved extraction of feeds (5 g) with ethyl acetate (10 mL), followed by a freezing step (at -20°C) used for eliminating the matrix co-extractives. The extract was further cleaned by dispersive solid phase extraction with a combination of primary secondary amine, C18 and florisil sorbents. From the cleaned-extract, an aliquot was analysed by GC-MS/MS, while another portion of it was solvent-exchanged to acetonitrile:water (50:50) and then analysed by LC-MS/MS. This method effectively minimised the matrix interferences. A total of 192 pesticides was analysed by GC-MS/MS within a runtime of 22 min. The LC-MS/MS method was validated for 187 compounds including 17 veterinary drugs. For most of the compounds, the limit of quantification (LOQ) was 0.01 mg/kg. The recoveries at LOQ and higher levels ranged between 70% and 120%, with precision-RSDs of < 20%. The method provided a precise analysis in a wide range of market-feed samples. As shown, the method is suitable for regulatory and commercial testing purposes.


Assuntos
Ração Animal/análise , Cromatografia Líquida/métodos , Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Drogas Veterinárias/análise , Animais , Congelamento , Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Resíduos de Praguicidas/análise , Reprodutibilidade dos Testes , Solventes/química , Água/química
11.
J Chromatogr A ; 1625: 461238, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709314

RESUMO

In the present study, a novel strategy based on unidirectional freezing and atom transfer radical polymerization combined with activator regenerated by electron transfer (ARGET-ATRP) was applied to synthesizing orderly macroporous monolithic column with restricted-access (RA) property in a 1000µL pipette tip. The RA column was composed of hydrophobic inner column (poly(styrene-co-ethylene glycol dimethacrylate) and hydrophilic outer layer (poly-hydroxyethyl methacrylate chain) which was grafted on the hydrophobic surface by means of the second ARGET-ATRP reaction. The as-prepared RA monolithic tip was connected to a 2mL syringe for directly extracting magnolol and honokiol from rat plasma just by manually pushing operation. The surface morphology and chemical composition of the column were characterized by scanning electronic microscope, infrared spectroscopy and X-ray photoelectron spectroscopy respectively. The determined results of evaluation experiments based on the optimized solid phase extraction conditions showed that the RA column possessed good protein exclusion power, extraction recovery and reusability. The constructed RA-SPE-HPLC/UV method for simultaneously analyzing magnolol and honokiol in rat plasma was validated with quality control (QC) samples at four concentration levels. Good precision (RSDs, 3.39~11.16%) and acceptable accuracy (relative recoveries, 89.52%~108.42%) were obtained for intra- and inter-day assays. The determined results of real rat plasma as well as the standard-addition samples demonstrated the developed method with good accuracy and precision. It can be extrapolated from the experimental results that this simple and cost-efficient RA-SPE method is also suitable for directly extracting other hydrophobic constituents in biological body fluid for therapeutic drug monitoring or pharmacokinetic study.


Assuntos
Compostos de Bifenilo/sangue , Cromatografia Líquida de Alta Pressão/métodos , Lignanas/sangue , Metacrilatos/química , Polietilenoglicóis/química , Animais , Compostos de Bifenilo/isolamento & purificação , Compostos de Bifenilo/normas , Cromatografia Líquida de Alta Pressão/normas , Congelamento , Interações Hidrofóbicas e Hidrofílicas , Lignanas/isolamento & purificação , Lignanas/normas , Controle de Qualidade , Ratos , Reprodutibilidade dos Testes , Extração em Fase Sólida
12.
Huan Jing Ke Xue ; 41(5): 2177-2187, 2020 May 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608835

RESUMO

To isolate the aerobic denitrification bacteria suitable for water quality in the low-temperature period of Baiyangdian Lake, a water quality investigation and bioinformatics analysis of the aerobic denitrification bacterial community were carried out using a MiSeq high-throughput sequencing technique based on napA. Moreover, α-diversity, ß-diversity, and network analyses were also carried out. The results showed significant differences in the water quality of different sampling sites in Baiyangdian Lake, and the estuary area exhibited the highest nitrogen concentration. α-diversity exhibited significant differences (P<0.05), and the abundance and diversity of ZZD and BH were the lowest. The operational taxonomic units of the water body mainly belonged to Proteobacteria (α-Proteobacteria, ß-Proteobacteria, and γ-Proteobacteria). Meanwhile, Venn diagram analysis indicated the community of aerobic denitrification bacteria exhibited significant differences, and variance inflation factor and redundancy analysis showed that temperature, dissolved oxygen, ammonia, nitrate, dissolved total phosphorus, and redox potential were the main environmental factors. Network analysis showed that symbiotic relationships accounted for a major proportion of the microbial network. Mantel test analysis shows that temperature, redox potential, nitrate, ammonia, dissolved total phosphorus, and iron and manganese are the key factors affecting the evolution of modular community structure. From all the results, the MiSeq high-throughput sequencing technique based on the napA gene was an effective tool to explore the changes of aerobic denitrification bacterial community structure, which could supply a reference to isolate the "directional-accurate-efficient" aerobic denitrification bacterial agent in the future.


Assuntos
Desnitrificação , Lagos , Bactérias , Congelamento , Nitrogênio
13.
Proc Biol Sci ; 287(1931): 20201273, 2020 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-32693722

RESUMO

Many insects survive internal freezing, but the great complexity of freezing stress hinders progress in understanding the ultimate nature of freezing-induced injury. Here, we use larvae of the drosophilid fly, Chymomyza costata to assess the role of mitochondrial responses to freezing stress. Respiration analysis revealed that fat body mitochondria of the freeze-sensitive (non-diapause) phenotype significantly decrease oxygen consumption upon lethal freezing stress, while mitochondria of the freeze-tolerant (diapausing, cold-acclimated) phenotype do not lose respiratory capacity upon the same stress. Using transmission electron microscopy, we show that fat body and hindgut mitochondria swell, and occasionally burst, upon exposure of the freeze-sensitive phenotype to lethal freezing stress. By contrast, mitochondrial swelling is not observed in the freeze-tolerant phenotype exposed to the same stress. We hypothesize that mitochondrial swelling results from permeability transition of the inner mitochondrial membrane and loss of its barrier function, which causes osmotic influx of cytosolic water into the matrix. We therefore suggest that the phenotypic transition to diapause and cold acclimation could be associated with adaptive changes that include the protection of the inner mitochondrial membrane against permeability transition and subsequent mitochondrial swelling. Accumulation of high concentrations of proline and other cryoprotective substances might be a part of such adaptive changes as we have shown that freezing-induced mitochondrial swelling was abolished by feeding the freeze-sensitive phenotype larvae on a proline-augmented diet.


Assuntos
Congelamento , Insetos/fisiologia , Mitocôndrias , Aclimatação , Animais , Drosophilidae , Larva/fisiologia
14.
Food Chem ; 333: 127439, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32653686

RESUMO

Anthocyanin is derived from a flavylium cation structure, and it promotes health in humans and functions in plants as protection against environmental stress. The rapid analysis of anthocyanin structure and content is a critical challenge for improving fruit quality. In this study, the tomato cultivar Indigo Rose, which is a popular purple cultivated tomato used for breeding, was taken as an example for anthocyanin analysis. A rapid analysis method was developed to minimize anthocyanin loss from the fresh fruit. Four new anthocyanins were discovered in the tomato, and the structures of a total of 12 anthocyanins were determined. Among these, petunidin-3-(trans-p-coumaroyl)-rutinoside-5-glucoside and malvidin-3-(trans-p-coumaroyl)-rutinoside-5-glucoside were the main anthocyanins in Indigo Rose. The structural modifications of these anthocyanins were mainly glycosylation and acylation, and there were also hydroxylation and methylation. Our findings provide new insight into the biosynthesis pathway in tomato fruit.


Assuntos
Antocianinas/análise , Antocianinas/química , Lycopersicon esculentum/química , Espectrometria de Massas/métodos , Acilação , Antocianinas/metabolismo , Cromatografia Líquida de Alta Pressão , Análise de Alimentos/métodos , Congelamento , Frutas/química , Glicosilação , Estrutura Molecular
15.
Food Chem ; 332: 127385, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32623125

RESUMO

A promising way of processing Baltic herring, Clupea harengus membras, is turning the fish into boneless mince. However, Baltic herring is prone to lipid oxidation, which possesses a challenge for industrial applications. The aim of this work was to study the efficacy of press cakes from Finnish berries and a supercritical CO2 plant extract to limit lipid oxidation during frozen storage of Baltic herring mince and to determine the impact of these additions on consumer acceptance in a fish product. Peroxide value, formation of volatile oxidation products and loss of polyunsaturated fatty acids showed that the tested natural additives decreased oxidation to a greater or similar extent as conventional antioxidants during 10-month storage. While potential of berry press cakes and plant extracts as "green label antioxidants" was shown, consumer study indicated need for further research to reach both optimal antioxidative efficacy and sensory properties.


Assuntos
Cromatografia com Fluido Supercrítico/métodos , Produtos Pesqueiros/análise , Extratos Vegetais/química , Animais , Antioxidantes/química , Dióxido de Carbono/química , Ácidos Docosa-Hexaenoicos/análise , Ácido Eicosapentaenoico/análise , Peixes , Congelamento , Lipídeos/análise , Fenóis/análise , Compostos Orgânicos Voláteis/análise
16.
AAPS PharmSciTech ; 21(5): 173, 2020 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-32548717

RESUMO

Innovative strategies for periodontal regeneration have been the focus of research clusters across the globe for decades. In order to overcome the drawbacks of currently available options, investigators have suggested a novel concept of functionally graded membrane (FGM) templates with different structural and morphological gradients. Chitosan (CH) has been used in the past for similar purpose. However, the composite formulation of composite and tetracycline when cross-linked with glutaraldehyde have received little attention. Therefore, the purpose of the study was to investigate the drug loading and release characteristics of novel freeze gelated chitosan templates at different percentages of glutaraldehyde. These were cross-linked with 0.1 and 1% glutaraldehyde and loaded with doxycycline hyclate. The electron micrographs depicted porous morphology of neat templates. After cross-linking, these templates showed compressed ultrastructures. Computerized tomography analysis showed that the templates had 88 to 92% porosity with average pore diameter decreased from 78 to 44.9 µm with increasing concentration. Fourier transform infrared spectroscopy showed alterations in the glycosidic segment of chitosan fingerprint region which after drug loading showed a dominant doxycycline spectral composite profile. Interestingly, swelling profile was not affected by cross-linking either at 0.1 and 1% glutaraldehyde and template showed a swelling ratio of 80%, which gained equilibrium after 15 min. The drug release pattern also showed a 40 µg/mL of release after 24 h. These doxycycline-loaded templates show their tendency to be used in a functionally graded membrane facing the defect site.


Assuntos
Materiais Biocompatíveis/química , Quitosana/química , Reagentes para Ligações Cruzadas/química , Congelamento , Regeneração Tecidual Guiada Periodontal/métodos , Materiais Biocompatíveis/farmacocinética , Quitosana/farmacocinética , Reagentes para Ligações Cruzadas/farmacocinética , Liberação Controlada de Fármacos , Géis , Glutaral/química , Glutaral/farmacocinética , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
17.
J Vis Exp ; (159)2020 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-32478750

RESUMO

Drosophila serves as a useful model for assessing synaptic structure and function associated with neurodegenerative diseases. While much work has focused on neuromuscular junctions (NMJs) in Drosophila larvae, assessing synaptic integrity in adult Drosophila has received much less attention. Here we provide a straightforward method for dissection of the dorsal longitudinal muscles (DLMs), which are required for flight ability. In addition to flight as a behavioral readout, this dissection allows for the both DLM synapses and muscle tissue to be amenable to structural analysis using fluorescently labeled antibodies for synaptic markers or proteins of interest. This protocol allows for the evaluation of the structural integrity of synapses in adult Drosophila during aging to model the progressive, age-dependent nature of most neurodegenerative diseases.


Assuntos
Envelhecimento/patologia , Drosophila melanogaster/fisiologia , Degeneração Neural/patologia , Sinapses/metabolismo , Esclerose Amiotrófica Lateral/patologia , Animais , Animais Geneticamente Modificados , Denervação , Dissecação , Congelamento , Humanos , Larva/metabolismo , Junção Neuromuscular/fisiologia , Coloração e Rotulagem , Tórax
18.
Food Chem ; 330: 127243, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32521403

RESUMO

The influences of konjac glucomannan (KGM) on the water distribution of frozen dough and steamed bread quaility made from frozen dough were addressed in this study. Low Field Nuclear Magnetic Resonance (LF-NMR) analysis demonstrated that the less tightly bound water of the dough was transferred to tightly bound water with the increase of KGM. Differential Scanning Calorimetry (DSC) showed that the freezable water of the frozen dough was transferred to non-freezable water with increasing the amount of KGM. DSC and LF-NMR results indicated the water state in the frozen dough was consistent. The addition of KGM enhanced the height and whiteness of steamed bread, but it decreased springiness, cohesiveness and resilience of steamed bread. As the KGM substitution rate increased, the hardness of steamed bread first decreased and then increased. The steamed bread with 1.5% of KGM showed the best quality.


Assuntos
Pão/análise , Mananas/química , Água/química , Varredura Diferencial de Calorimetria , Congelamento , Dureza , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular , Vapor
19.
Food Chem ; 328: 127113, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32474239

RESUMO

In view of the high polarity and ubiquitous occurrence of perchlorate, achieving an ultra-trace analysis has become a challenging task. The present study aimed to develop a simple and generic pretreatment protocol based on cold-induced liquid-liquid extraction to efficiently extract perchlorate from tea and dairy products and remarkably decrease potential matrix interferences and laborious cleanup. By optimizing the pretreatment conditions, the enrichment factor of perchlorate increased by 7.79 times under the compromise between the matrix effect and extraction recovery. The validated method presented satisfactory selectivity, linearity, accuracy, precision, and matrix effect, providing recoveries of 78.2%-106.2% with RSDr ranging from 1.2% to 7.9% and RSDR less than 10.7% for tea and dairy products. This pretreatment protocol depended only on shaking, freezing, and centrifugation in one step, without additional equipment or tedious operations, which will be explored to a greater extent in complex biological or food matrices.


Assuntos
Laticínios/análise , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Extração Líquido-Líquido/métodos , Percloratos/análise , Chá/química , Centrifugação/métodos , Análise Custo-Benefício , Análise de Alimentos/economia , Congelamento , Extração Líquido-Líquido/economia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores de Tempo
20.
Sci Total Environ ; 740: 140006, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32563873

RESUMO

Nitrous oxide (N2O) emissions from soils applied with livestock excreta have been widely reported previously. The highest N2O emissions from soils are also often reported during thawing periods in cold regions where soil freezing is common. However, the combined effects of cow urine application and freeze-thaw events on N2O emissions and the related enzyme activities are still not clear. Thus, we simulated a freeze-thaw event at -3 °C for 7 days, and then increased to 3 °C for 46 days using intact soil cores with cow urine (392 kg N ha-1). We compared the factors influencing the magnitudes of N2O emissions through soil microbial processes with and without the freeze-thaw event. Dicyandiamide (DCD), an inhibitor of nitrification, was added to investigate the significance of nitrification on N2O emissions. The N2O emission rates from the urine-applied soils peaked to approximately 1000 µg N2O-N m-2 h-1 immediately after the soils thawed. Soil freezing with urine application was significantly higher cumulative N2O emissions (537 mg N2O-N m-2), compared to non-frozen soils with urine (247 mg N2O-N m-2) during the incubation period (54 days). The effect of DCD application on N2O emissions was not clear during the freeze-thaw event, although nitrate production rates were reduced. After the freezing event, soil moisture (water-filled pore space) was significantly higher in the non-frozen soils compared to the frozen soils, due to a 9% decline in bulk density of frozen soils. Additionally, the impact of thawing on urease and denitrification enzyme activities was influenced by the urine application. Urine application increased the urease activity, while the freezing event decreased the magnitudes. The physical changes in the soils were also important controlling factors of the N2O emissions from cow urine-applied soils in cold regions.


Assuntos
Óxido Nitroso/análise , Solo , Agricultura , Animais , Bovinos , Feminino , Congelamento , Nitrificação
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