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1.
Planta ; 253(6): 124, 2021 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-34014374

RESUMO

MAIN CONCLUSION: Anatomical, metabolic and microbial factors were identified that contribute to sequential freezing in wheat leaves and likely contribute to supercooling in the youngest leaves and potentially meristematic regions. Infrared thermography (IR) has been used to observe wheat leaves freezing independently and in an age-related sequence with older leaves freezing first. To determine mechanisms that might explain this sequence of freezing several analytical approaches were used: (1) The size of xylem vessels, in proximity to where freezing initiated, was measured to see if capillary freezing point depression explained sequential freezing. The sequence of freezing in the four youngest leaves was correlated, with the largest vessels freezing first. (2) Carbohydrate and amino acids were analyzed to determine if solute concentrations as well as interactions with membranes explained the freezing sequence. Sucrose was highly correlated to the freezing sequence for all leaves suggesting a prominent role for this sugar as compared to other simple sugars and fructans. Among individual free amino acids proline and serine were correlated to the freezing sequence, with younger leaves having the highest concentrations. (3) Microflora within and on leaf surfaces were determined to measure potential freezing initiation. Levels of bacteria and fungi were correlated to the freezing sequence for all leaves, and species or genera associated with high ice nucleation activity were absent in younger leaves. Moisture content and transcript expression of ice binding proteins were also measured. As expected, our results show that no single mechanism explains the freezing sequence observed via infrared analyses. While these multiple mechanisms are operative at different levels according to the leaf age, they seem to converge when it comes to the protection of vital meristematic tissues. This provides potential phenotypic characters that could be used by breeders to develop more winter-hardy genotypes.


Assuntos
Gelo , Triticum , Congelamento , Folhas de Planta , Triticum/genética , Xilema
3.
Nat Commun ; 12(1): 2675, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33976148

RESUMO

Developing molecules that emulate the properties of naturally occurring ice-binding proteins (IBPs) is a daunting challenge. Rather than relying on the (limited) existing structure-property relationships that have been established for IBPs, here we report the use of phage display for the identification of short peptide mimics of IBPs. To this end, an ice-affinity selection protocol is developed, which enables the selection of a cyclic ice-binding peptide containing just 14 amino acids. Mutational analysis identifies three residues, Asp8, Thr10 and Thr14, which are found to be essential for ice binding. Molecular dynamics simulations reveal that the side chain of Thr10 hydrophobically binds to ice revealing a potential mechanism. To demonstrate the biotechnological potential of this peptide, it is expressed as a fusion ('Ice-Tag') with mCherry and used to purify proteins directly from cell lysate.


Assuntos
Proteínas Anticongelantes/genética , Técnicas de Visualização da Superfície Celular/métodos , Mutação , Peptídeos Cíclicos/genética , Aminoácidos/química , Aminoácidos/genética , Aminoácidos/metabolismo , Proteínas Anticongelantes/química , Proteínas Anticongelantes/metabolismo , Sequência de Bases , Sítios de Ligação/genética , Cristalização , Interações Hidrofóbicas e Hidrofílicas , Gelo , Simulação de Dinâmica Molecular , Peptídeos Cíclicos/química , Peptídeos Cíclicos/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos
4.
Sci Total Environ ; 779: 146316, 2021 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-34030258

RESUMO

Spillages at sea of diluted bitumen (dilbit) from oil sands have received little attention until now. To our best knowledge, there are no reports on the impact of a severe exposure to dilbit on the Blue mussel (Mytilus edulis). In this study, adult Blue mussels were exposed to one conventional crude oil (Heidrun) and two dilbits (Cold Lake Blend and Access Western Blend) for a period of 7 days in an ice-covered environment and then maintained for three months until the spawning season. The exposed mussels were monitored for aromatic hydrocarbon bioaccumulation, physiological energetic budget, cellular stress, byssus production and gametogenesis. In spring, spawning was induced to characterize breeding success. Bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) was detected after three days of exposure, with higher concentrations of PAHs associated to the conventional oil (5.49 ± 0.12 µg·g-1 d.w.) compared to both dilbits (0.91 ± 0.02 µg·g-1; 0.51 ± 0.03 µg·g-1 d.w.). Despite a fast depuration rate and a good resilience of the exposed mussels, significant negative effects were observed at the cellular, physiological and fitness levels, especially in offspring. Our results suggest a higher toxicity of the diluted bitumen compared to the conventional crude despite the lower bioaccumulation of total PAHs. Dilbit treatments caused evident negative transgenerational effects on unexposed F1 generation.


Assuntos
Mytilus edulis , Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Animais , Hidrocarbonetos , Gelo , Campos de Petróleo e Gás , Petróleo/análise , Petróleo/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Poluentes Químicos da Água/toxicidade
5.
Food Chem ; 353: 129104, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-33730666

RESUMO

The effect of ice structuring protein (ISP) on the gelling properties of myofibrillar protein from quick-frozen pork patty during frozen storage was investigated by determining and comparing protein solubility, turbidity and gel properties. Protein solubility was increased by 10.23% and turbidity was decreased after ISP treated. The gel whiteness and strength of myofibrillar protein from patty with ISP were 8.38% and 13.70% higher than that of the control after frozen for 180 days. And the addition of ISP could weaken the influence of frozen storage on water mobility and reduce the water loss. Furthermore, ISP retrained the decrease in the maximum elastic (G') value and loss factor (tan δ) value of samples. Through observing by scanning electron microscope (SEM), ISP retarded the destruction of gel microstructure and maintained the relatively complete tissue of gel. These findings confirmed the importance of ISP in myofibrillar protein gel quality assurance of pork patty during frozen storage.


Assuntos
Carne de Porco/análise , Proteínas/química , Animais , Congelamento , Gelo , Solubilidade , Suínos
6.
Food Res Int ; 140: 109849, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33648167

RESUMO

A recent trend of environmental sustainability has induced many coffee providers to offer alternatives to plastic straws. There has been little research regarding consumer perception of these alternative drinking conditions. This study aimed to determine differences in consumer perception of iced coffee beverages (without ice cubes) between plastic straw and alternative drinking conditions. Brewed samples of medium roast ground coffee beans blend were cooled down and served at 5 °C in the five drinking conditions using different straw materials (plastic, paper, or stainless steel), sippy cup lid, or no lid. Seventy-five consumers rated attribute intensities and acceptances of iced coffee beverages in all five drinking conditions. The results showed that both the mean hedonic ratings of flavor, mouthfeel, or overall impression and the mean amount consumers were willing to pay (US$) for iced coffee beverages were greater in the sippy-cup lid condition than in the paper straw condition. After analyzing consumer comments of the drinking conditions, it was also found that the sippy-cup lid condition induced a more pleasant drinking experience than the paper straw condition. Notably, no significant differences between the plastic and alternative drinking conditions were observed in attribute intensity, acceptance, and monetary value perception of iced coffee beverages. In conclusion, this study shows that consumer experience and acceptability of iced coffee beverages can vary with drinking conditions. Therefore, the coffee industry and sensory professionals should consider not only sensory aspects of coffee, but also drinking conditions to improve consumer experience with coffee beverages.


Assuntos
Café , Gelo , Bebidas , Comportamento do Consumidor , Percepção
7.
Food Res Int ; 140: 109850, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33648168

RESUMO

Mongolian cheese is non-fermented cheese, which easily deteriorates during storage because of hydrolysis. The freezing points of sucrose and sucrose-free cheese were measured -5.16 °C and -4.29 °C, respectively. Ice-storage temperatures of -2 °C and -4 °C were used and 0 °C was used as reference temperature. In this study, the changes of proteolytic indexes (PI) and total viable counts (TVC) of cheese at different ice-temperatures during storage were studied. The PIs of all treatments increased over storage time, which conformed to the Arrhenius first-order kinetic model. The shelf lives of sucrose and sucrose-free cheese were predicted. In addition, -4 °C effectively suppressed the increases in TVC and PIs. The split-split-plot design was applied in comparing the effects of cheese type, the storage time and storage temperature on PI. Storage time was the most important factor followed by cheese type and storage temperature.


Assuntos
Queijo , Queijo/análise , Gelo , Cinética , Proteólise , Temperatura
8.
Cryobiology ; 99: 28-39, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33529683

RESUMO

Ice-binding proteins (IBPs) inhibit the growth of ice through surface adsorption. In some freeze-resistant fishes and insects, circulating IBPs serve as antifreeze proteins to stop ice growth by lowering the freezing point. Plants are less able to avoid freezing and some use IBPs to minimize the damage caused in the frozen state by ice recrystallization, which is the growth of large ice grains at the expense of small ones. Here we have accurately and reproducibly measured the ice recrystallization inhibition (IRI) activity of over a dozen naturally occurring IBPs from fishes, insects, plants, and microorganisms using a modified 'splat' method on serial dilutions of IBPs whose concentrations were determined by amino acid analysis. The endpoint of IRI, which was scored as the lowest protein concentration at which no recrystallization was observed, varied for the different IBPs over two orders of magnitude from 1000 nM to 5 nM. Moreover, there was no apparent correlation between their IRI levels and reported antifreeze activities. IBPs from insects and fishes had similar IRI activity, even though the insect IBPs are typically 10x more active in freezing point depression. Plant IBPs had weak antifreeze activity but were more effective at IRI. Bacterial IBPs involved in ice adhesion showed both strong freezing point depression and IRI. Two trends did emerge, including that basal plane binding IBPs correlated with stronger IRI activity and larger IBPs had higher IRI activity.


Assuntos
Proteínas de Transporte , Gelo , Animais , Proteínas Anticongelantes/metabolismo , Criopreservação/métodos , Cristalização , Peixes , Congelamento , Insetos
9.
Nat Commun ; 12(1): 1183, 2021 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-33608518

RESUMO

Ice-nucleation active (INA) bacteria can promote the growth of ice more effectively than any other known material. Using specialized ice-nucleating proteins (INPs), they obtain nutrients from plants by inducing frost damage and, when airborne in the atmosphere, they drive ice nucleation within clouds, which may affect global precipitation patterns. Despite their evident environmental importance, the molecular mechanisms behind INP-induced freezing have remained largely elusive. We investigate the structural basis for the interactions between water and the ice-nucleating protein InaZ from the INA bacterium Pseudomonas syringae. Using vibrational sum-frequency generation (SFG) and two-dimensional infrared spectroscopy, we demonstrate that the ice-active repeats of InaZ adopt a ß-helical structure in solution and at water surfaces. In this configuration, interaction between INPs and water molecules imposes structural ordering on the adjacent water network. The observed order of water increases as the interface is cooled to temperatures close to the melting point of water. Experimental SFG data combined with molecular-dynamics simulations and spectral calculations show that InaZ reorients at lower temperatures. This reorientation can enhance water interactions, and thereby the effectiveness of ice nucleation.


Assuntos
Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/metabolismo , Temperatura Baixa , Água/química , Atmosfera , Proteínas da Membrana Bacteriana Externa/genética , Óxido de Deutério , Congelamento , Gelo , Simulação de Dinâmica Molecular , Plantas/microbiologia , Pseudomonas syringae/metabolismo
10.
Cryobiology ; 99: 20-27, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33545147

RESUMO

Cooling rate is a critical parameter affecting the success of cell cryopreservation. Fast cooling can result in intracellular ice formation (IIF), while slow cooling can bring solution effects injury, both are detrimental to the cells. Whilst most of the studies have investigated how IIF affects cells, solution effects injury has received little attention. Here, we studied the solution effects injury of human T lymphocytes by cryomicroscopy and tested the osmoprotective ability of some frequently used cryoprotective agents (CPAs) such as dimethyl sulfoxide (DMSO), glycerol, trehalose, urea and l-proline. We further investigated the relationship between cell volume, latent heat and solution effects cell injury. We found that solution effects injury during interrupted slow cooling was caused by high concentration of the extracellular solution rather than eutectic formation and solutes precipitation. DMSO, glycerol and trehalose can protect cells from solution effects injury, while l-proline and urea cannot under the same condition. The cell volume and latent heat are not crucial for causing solution effects injury in cells. This work confirms that high osmotic pressure, rather than eutectic formation, leads to cell injury. It also suggests that cell volume and latent heat may not be a key factor for explaining solution effects injury and its prevention in the cryopreservation of human T lymphocytes.


Assuntos
Criopreservação , Gelo , Criopreservação/métodos , Crioprotetores/farmacologia , Dimetil Sulfóxido/farmacologia , Congelamento , Humanos , Linfócitos T
11.
Artigo em Inglês | MEDLINE | ID: mdl-33419196

RESUMO

The use of slip-resistant winter footwear is crucial for the prevention of slips and falls on ice and snow. The main objective of this paper is to evaluate a mechanical testing method to determine footwear slip resistance on wet and dry ice surfaces and to compare it with the human-centred test method introduced by researchers at KITE (Knowledge, Innovation, Talent, Everywhere)-Toronto Rehabilitation Institute-University Health Network. Phase 1 of this study assessed the repeatability and reproducibility of the mechanical method by evaluating ten different occupational winter boots using two SATRA Slip resistance testers (STM 603, SATRA Technology Centre, Kettering, UK). One tester is located in Toronto and one in Montreal. These boots were chosen based on the needs of the IRSST (Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail, Montréal, Quebec, Canada), who were primarily interested in providing safe winter footwear for police, firefighters and municipal workers. In Phase 2, the results of the human-centred test approach were compared with the mechanical results. In Phase 3, two of these boots with conflicting results from the previous phases were tested using a second human-centred method. In Phase 1, the mechanical testing results obtained in the two labs showed a high linear correlation (>0.94) and good agreement on both ice surfaces; however, they revealed a bias (~0.06) between the two labs on the dry ice condition. The mechanical and human-centred tests (phase 2) were found to be better correlated in the wet ice condition (R = 0.95) compared to the dry ice condition (R = 0.34). Finally, the rating of the footwear slip resistance based on the number of slips counted in phase 3 was consistent with the rating by the human-centred test method (phase 2), but not the mechanical method (phase 1). The findings of this study provide a better understanding of the limitations of the SATRA ice tray for measuring footwear slip resistance and demonstrate that the mechanical method must be further refined to make it more comparable to the human-centred methods to achieve better agreement with real-world performance.


Assuntos
Gelo , Sapatos , Acidentes por Quedas , Canadá , Humanos , Quebeque , Reprodutibilidade dos Testes
12.
Chemistry ; 27(26): 7402-7407, 2021 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-33464680

RESUMO

Ice nucleation-active bacteria are the most efficient ice nucleators known, enabling the crystallization of water at temperatures close to 0 °C, thereby overcoming the kinetically hindered phase transition process at these conditions. Using highly specialized ice-nucleating proteins (INPs), they can cause frost damage to plants and influence the formation of clouds and precipitation in the atmosphere. In nature, the bacteria are usually found in aqueous environments containing ions. The impact of ions on bacterial ice nucleation efficiency, however, has remained elusive. Here, we demonstrate that ions can profoundly influence the efficiency of bacterial ice nucleators in a manner that follows the Hofmeister series. Weakly hydrated ions inhibit bacterial ice nucleation whereas strongly hydrated ions apparently facilitate ice nucleation. Surface-specific sum-frequency generation spectroscopy and molecular dynamics simulations reveal that the different effects are due to specific interactions of the ions with the INPs on the surface of the bacteria. Our results demonstrate that heterogeneous ice nucleation facilitated by bacteria strongly depends upon the nature of the ions, and specific ion-protein interactions are essential for the complete description of heterogeneous ice nucleation by bacteria.


Assuntos
Atmosfera , Gelo , Bactérias , Temperatura , Água
13.
Nat Commun ; 12(1): 570, 2021 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-33495440

RESUMO

Melting of the Greenland Ice Sheet is a leading cause of land-ice mass loss and cryosphere-attributed sea level rise. Blooms of pigmented glacier ice algae lower ice albedo and accelerate surface melting in the ice sheet's southwest sector. Although glacier ice algae cause up to 13% of the surface melting in this region, the controls on bloom development remain poorly understood. Here we show a direct link between mineral phosphorus in surface ice and glacier ice algae biomass through the quantification of solid and fluid phase phosphorus reservoirs in surface habitats across the southwest ablation zone of the ice sheet. We demonstrate that nutrients from mineral dust likely drive glacier ice algal growth, and thereby identify mineral dust as a secondary control on ice sheet melting.


Assuntos
Eutrofização/fisiologia , Camada de Gelo , Microalgas/crescimento & desenvolvimento , Minerais/metabolismo , Fósforo/metabolismo , Biomassa , Ecossistema , Congelamento , Geografia , Aquecimento Global , Groenlândia , Gelo , Microalgas/citologia , Microalgas/ultraestrutura , Microscopia Eletrônica de Varredura , Estações do Ano
15.
Methods Mol Biol ; 2180: 351-361, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32797420

RESUMO

Raman spectroscopy has been gaining in popularity for noninvasive analysis of single cells. Raman spectra and images deliver meaningful information regarding the biochemical, biophysical, and structural properties of cells in various states. Low-temperature Raman spectroscopy has been applied to verify the presence of ice inside a frozen cell and to illustrate the distribution of both penetrating and non-penetrating cryoprotectants. This chapter delineates Raman cryomicroscopic imaging of single cells as well as sample handling for spectroscopic measurements at subzero temperature. The experimental setup is depicted with a special emphasis on a custom-built temperature-controlled cooling stage. The use of Raman cryomicroscopic imaging is demonstrated using Jurkat cells cryopreserved in a sucrose solution. Moreover, strategies for determining intracellular ice formation (IIF) and analysis of sucrose partitioning across the cell membrane are presented.


Assuntos
Membrana Celular/metabolismo , Temperatura Baixa , Criopreservação/métodos , Crioprotetores/farmacologia , Liofilização/métodos , Processamento de Imagem Assistida por Computador/métodos , Análise Espectral Raman/métodos , Membrana Celular/efeitos dos fármacos , Humanos , Gelo/análise , Células Jurkat , Transição de Fase
16.
Methods Mol Biol ; 2180: 191-201, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32797412

RESUMO

From early dry-ice-based freezers and passive coolers, cryopreservation devices have come a long way. With increasing interest in the field of cryobiology from new scientific applications, the importance of reliable, traceable, and reproducible cold chain devices is sure to increase, ensuring more precise cryopreservation and enabling better post-thaw outcomes, both for the user and for biological samples. As with any cryopreservation process, it is important to optimize each part of the cold chain for each lab's biological samples, cryocontainers used, and logistical restraints. In this chapter we describe how freezing technology can be used for cryopreservation of cells.


Assuntos
Criopreservação/métodos , Crioprotetores/metabolismo , Liofilização/métodos , Gelo/análise , Animais , Cristalização , Humanos
17.
Methods Mol Biol ; 2180: 221-269, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32797414

RESUMO

Quantitative information about the kinetics and cumulative probability of intracellular ice formation is necessary to develop minimally damaging freezing procedures for the cryopreservation of cells and tissues. Conventional cryomicroscopic assays, which rely on indirect evidence of intracellular freezing (e.g., opacity changes in the cell cytoplasm), can yield significant errors in the estimated kinetics. In contrast, the formation and growth of intracellular ice crystals can be accurately detected using temporally resolved imaging methods (i.e., video recording at sub-millisecond resolution). Here, detailed methods for the setup and operation of a high-speed video cryomicroscope system are described, including protocols for imaging of intracellular ice crystallization events and stochastic analysis of the ice formation kinetics in a cell population. Recommendations are provided for temperature profile design, sample preparation, and configuration of the video acquisition parameters. Throughout this chapter, the protocols incorporate best practices that have been drawn from two decades of experience with high-speed video cryomicroscopy in our laboratory.


Assuntos
Células/citologia , Criopreservação/métodos , Congelamento , Gelo/análise , Microscopia de Vídeo/instrumentação , Microscopia de Vídeo/métodos , Animais , Células/metabolismo , Cristalização , Humanos , Cinética
18.
Methods Mol Biol ; 2180: 271-283, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32797415

RESUMO

Ice recrystallization inhibition assays are used to screen for compounds that possess the ability to inhibit ice recrystallization. The most common of these assays are the splat cooling assay (SCA) and sucrose sandwich assay (SSA). These two assays possess similarities; however, they vary in their sample size, cooling rate, and the solution used to dissolve the analyte. In this chapter, both assay methods are described in detail, and we perform a direct comparison of the assays by evaluating the IRI activity of an antifreeze protein (AFP I). IRI activity is quantified by using ImageJ software to analyze ice crystals, and a quantitative value describing the efficiency of the inhibitor is generated. This analysis emphasizes the importance of choosing the right assay to measure IRI activity.


Assuntos
Proteínas Anticongelantes/metabolismo , Criopreservação/métodos , Crioprotetores/farmacologia , Congelamento , Ensaios de Triagem em Larga Escala/métodos , Gelo/análise , Animais , Bioensaio , Cristalização , Humanos , Transição de Fase
19.
Mater Sci Eng C Mater Biol Appl ; 119: 111584, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33321630

RESUMO

3D biopolymeric scaffolds often lack the biochemical cues and mechanical strength to encourage bone tissue regeneration. Chemical crosslinkers have been extensively used to impart strength, but have been found to be toxic at the site of implantation and possess a lacuna in physical strength. We attempted to address this by engineering a self-crosslinked polymer through the in-situ reduction of Graphene oxide (GO) in a gelatin cryogel (Gel-RGO) using ice as a template to create pores. Superior osteoinductive and antimicrobial properties were further endowed on the cryogel by incorporating silver nanoparticles decorated nanohydroxyapatite in the Gel-RGOAg@Hap(2%) cryogel. The optimized biocompatible cryogel favoured bone cell adhesion and its proliferation. The osteoconductive and osteoinductive potential of the cryogel was confirmed through biomineralization and differentiation of bone cells. In addition, these cryogels showed prolonged antimicrobial activity against S. aureus. This investigation exhibits the achievability/prospect of building up an ideal gelatin platform without the utilization of an outside crosslinking agent via manipulating the conditions of gelation. The superior crosslinking achieved between gelatin and GO, in addition to its ability to support bone formation and prevent infection make this cryogel an attractive candidate for bone tissue engineering applications.


Assuntos
Anti-Infecciosos , Nanopartículas Metálicas , Criogéis , Gelatina , Grafite , Gelo , Osteogênese , Porosidade , Prata/farmacologia , Staphylococcus aureus , Engenharia Tecidual , Tecidos Suporte
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