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1.
Food Chem ; 398: 133874, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35964567

RESUMO

The influence of ultrasound-assisted immersion freezing (UF), immersion freezing (IF), and air freezing (AF) on the protein oxidation, structure, and thermal stability of chicken breast during frozen storage was evaluated in this study. Compared to IF and AF samples, the UF samples had a lower carbonyl content, dityrosine content, and surface hydrophobicity of myofibrillar protein (MP) (P < 0.05), as well as a higher free amino group content and total and reactive sulfhydryl content (P < 0.05). Moreover, UF significantly delayed the deterioration of protein secondary and tertiary structures and the decrease in protein thermal stability during frozen storage (P < 0.05). Additionally, the UF samples at 180 days had similar protein structures and quality characteristics to the IF samples at 90 days or the AF samples at 60 days. Overall, UF treatment can effectively retard protein oxidation, protein structure deterioration, and protein thermal stability loss caused by frozen storage.


Assuntos
Galinhas , Proteínas , Animais , Congelamento , Interações Hidrofóbicas e Hidrofílicas , Estabilidade Proteica
2.
Food Chem ; 398: 133903, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35998485

RESUMO

To investigate the potential mechanisms by which cold storage affects the water-holding capacity (WHC) of beef through analysis of exudates using an untargeted metabolomics strategy. A total of 877 metabolites were detected in four groups of beef exudates that have been frozen for 1, 2, 4, and 6 days, of which, 278 were identified as differential metabolites (DMs). The metabolic pathways of the DMs analysed by KEGG pathway enrichment included ABC transporters, purine metabolism, biosynthesis of cofactors, protein digestion and absorption, and ferroptosis. Ferroptosis was identified during storage of beef, and the reduction in WHC of beef was accompanied by a ferroptosis process. In addition, six DMs were identified in the KEGG pathway of ferroptosis, and the process of cellular ferroptosis was dependent on the inhibition of glutathione metabolic processes. Overall, the ferroptosis of cells during beef storage had a negative impact on WHC, and the finding of ferroptosis complemented the post-slaughter apoptosis.


Assuntos
Ferroptose , Água , Animais , Bovinos , Congelamento , Glutationa , Metabolômica , Água/análise
3.
Food Chem ; 399: 134020, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36037694

RESUMO

The effect of freeze-thaw (F-T) cycles on the digestive and protein structural properties of chicken breasts during in vitro digestion was investigated. With F-T cycles increased, the hardiness, chewiness, and shear force of chicken breasts increased, whereas the digestibility decreased, and particle size of digestive samples increased was evidenced by laser particle size analyzer and confocal fluorescence microscopy. The digestibility of the fifth F-T cycle samples in pepsin and pepsin/trypsin decreased by 25.99% and 11.82% compared to fresh samples, respectively. During F-T cycles, the disruption of protein structure was confirmed by the α-Helix decrease, ß-sheet increase, the intrinsic tryptophan intensities decrease and a redshift in the maximum value. Therefore, F-T cycles destroyed protein structure and induced the protein aggregation, resulting in chicken that was difficult to digest in the simulated digestion. The phenomenon became more acute as the number of F-T cycles increased.


Assuntos
Galinhas , Pepsina A , Animais , Digestão , Congelamento , Carne/análise
4.
Braz. j. oral sci ; 21: e225757, jan.-dez. 2022. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1366215

RESUMO

Aim: This study aimed to evaluate the effect of frozen storage on the physical properties of a silicone-based test food material, highly used to evaluate the masticatory performance in research settings. Methods: A total of 1,666 silicone cubes of Optosil Comfort® with 5.6-mm edges were shaped and stored at -18°C. The cubes were subsequently tested for flexural strength (maximum force, displacement, stress, and strain) before breaking (n = 136), changes in weight and size (n = 170), and masticatory performance (n = 1360) at eight timepoints: immediately after cube preparation (baseline, no freezing), and 1, 2, 3 and 4 weeks, and 2, 4 and 6 months after frozen storage. The cubes were thawed 8 h before each assessment. Results: The maximum force, stress, maximum displacement, and deformation values for the cubes were not affected by freezing (P > 0.05). At all of the time points, the cubes exhibited similar weight (P = 0.366) and size (identical values). The masticatory performance for the cubes also showed no differences from baseline through 6 months (P = 0.061). Conclusion: Freezing Optosil Comfort® silicone cubes did not alter the physical and mechanical properties of the material, being suitable to optimize the assessment of masticatory parameters for research purposes


Assuntos
Humanos , Masculino , Adulto , Elastômeros de Silicone , Teste de Materiais/métodos , Fenômenos Físicos , Congelamento , Resistência à Flexão , Mastigação , Fatores de Tempo
5.
Food Res Int ; 160: 111709, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36076405

RESUMO

In this study, we investigated the effect of fat aggregate size and percentage on fat network formation and, ultimately, on the melting properties of ice cream. To control fat destabilization degree and fat network formation, we varied fat and emulsifier content, and blended coconut oil with milk fat, obtaining three different sample series varying in: 1) fat content, 2) fat aggregate size, and 3) fat aggregate percentage. The degree of fat destabilization in terms of aggregate size and the percentage was measured by light scattering techniques. The distribution of the fat around the air cells and in the unfrozen serum phase was calculated based on the measured overrun. Overall, a similar overrun was found in the three series of ice cream. The fat percentage in the remaining phase was measured to verify how much fat and what type of fat aggregates were present in the fat network. The results show that fat destabilization degree is relatively more important than fat content in determining the melting behavior of ice cream with low overrun. Clear relations between different fat destabilization parameters and ice cream melting behavior were established, indicating that the melting behavior of ice cream is related to specific properties of the fat network. Controlling fat destabilization in the unfrozen ice cream phase may be used to alter the properties of ice cream, and could contribute as a fat reduction strategy in ice cream.


Assuntos
Sorvetes , Óleo de Coco , Emulsificantes , Congelamento
6.
PLoS One ; 17(9): e0274682, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36112572

RESUMO

The study aimed to delineate the robustness of the culture-based and molecular biology methods to assess the total bacterial concentration and Campylobacter jejuni (C. jejuni) quantification in caecal content, analysed as fresh or after being stored immediately at ultra-low (-80°C) temperature at different time points (for 3, 7, 14, 28 and 62 days post collection). The caecal content was collected from birds that were artificially colonised with C. jejuni (in-vivo), and quantification was performed using both colony-forming unit (CFU) and qPCR. The results showed that storage time affected the output of culture-based analyses but mostly did not alter concentration retrieved via qPCR. After an initial ~4.5 log10 reduction in CFU observed from fresh (day 0) to frozen samples, bacterial concentration retrieved with culture-based methods seemed to be constant in samples frozen for 3 to 62 days, indicating a possible threshold for C. jejuni loss of viability due to effect of storage temperature. Ranking order analyses, revealed that the molecular biology technique was able to attribute somewhat the same relative C. jejuni concentrations to the samples analysed via qPCR. However, day 0 measurements from culture-based methods were associated with the absence of or negatively weak correlations with the rest of the time points, but ranking order was maintained from day 3 onwards. On the other hand, ranking order correlations were less constant when measuring total bacterial concentration through qPCR. The study suggests that if biological samples can't be analysed as fresh (immediately after collection) and have to be stored prior to analysis, then storage at -80°C samples be recommended to avoid the temporal-dependent effects on C. jejuni concentrations. In addition, irrespective of the method of analysis, an initial loss of CFU must be factored in when interpreting the results obtained from frozen samples.


Assuntos
Campylobacter jejuni , Galinhas , Animais , Campylobacter jejuni/genética , Galinhas/microbiologia , Técnicas de Cultura , Congelamento , Biologia Molecular
7.
Biochem Biophys Res Commun ; 628: 98-103, 2022 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-36084557

RESUMO

A cryoprotectant known as ice-binding protein (IBP) is thought to facilitate the cold survival of plants, insects, and fungi. Here, we prepared a genetically modified Caenorhabditis elegans strain to synthesize fish-derived IBPs in its body wall muscles and examined whether the antifreeze activity modification of this IBP by point mutation affects the cold tolerance of this worm. We chose a 65-residue IBP identified from notched-fin eelpout, for which the replacement of the 20th alanine residue (A20) modifies its antifreeze activity. These mutant proteins are denoted A20L, A20G, A20T, A20V, and A20I along with the wild-type (WT) protein. We evaluated the survival rate (%) of the transgenic C. elegans that synthesized each IBP mutant following 24 h of preservation at -5, +2, and +5 °C. Significantly, a dramatic improvement in the survival rate was detected for the worms synthesizing the activity-enhanced mutants (A20T and A20I), especially at +2 °C. In contrast, the rate was not improved by the expression of the defective mutants (A20L, A20G, WT and A20V). The survival rate (%) probably correlates with the antifreeze activity of the IBP. These data suggest that IBP protects the cell membrane by employing its ice-binding mechanism, which ultimately improves the cold tolerance of an IBP-containing animal.


Assuntos
Proteínas Anticongelantes , Gelo , Alanina/genética , Animais , Proteínas Anticongelantes/química , Proteínas Anticongelantes/genética , Proteínas Anticongelantes/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Transporte/metabolismo , Proteínas de Peixes/genética , Congelamento , Proteínas Mutantes/metabolismo , Mutação , Compostos Organotiofosforados
8.
Cells ; 11(17)2022 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-36078076

RESUMO

When coral species become extinct, their genetic resources cannot be recovered. Coral cryobanks can be employed to preserve coral samples and thereby maintain the availability of the samples and increase their potential to be restocked. In this study, we developed a procedure to determine coral species-specific requirements for cryobank freezing through determining suitable cryoprotective agents (CPAs), CPA concentrations, equilibration times, holding durations, viability rates, and cell amounts for banked coral cells, and we established the first ever coral cell cryobank. Coral cells, including supporting and gland cells, epidermal nematocysts, Symbiodiniaceae and symbiotic endoderm cells (SEC) were found from the extracted protocol. Approximately half of the corals from the experimental corals consisted of spindle and cluster cells. Gastrodermal nematocysts were the least common. The overall concentration of Symbiodiniaceae in the coral cells was 8.6%. Freezing using DMSO as a CPA was suitable for approximately half of the corals, and for the other half of species, successful cell cryopreservation was achieved using MeOH and EG. EG and DMSO had similar suitabilities for Acanthastrea, Euphyllia, Favites, Lobophyllia, Pavona, Seriatopora, and Turbinaria, as did EG and MeOH for Acropora, Echinopyllia, and Sinularia and MeOH and DMSO for Platygyra after freezing. At least 14 straws from each species of coral were cryobanked in this study, totaling more than 1884 straws (0.5 mL) with an average concentration of 6.4 × 106 per mL. The results of this study may serve as a framework for cryobanks worldwide and contribute to the long-term conservation of coral reefs.


Assuntos
Antozoários , Animais , Criopreservação/métodos , Crioprotetores/farmacologia , Dimetil Sulfóxido/farmacologia , Congelamento
9.
Cells ; 11(17)2022 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-36078098

RESUMO

Mesenchymal stem cells (MSCs) manifest vast opportunities for clinical use due both to their ability for self-renewal and for effecting paracrine therapeutic benefits. At the same time, difficulties with non-recurrent generation of large numbers of cells due to the necessity for long-term MSC expansion ex vivo, or the requirement for repeated sampling of biological material from a patient significantly limits the current use of MSCs in clinical practice. One solution to these problems entails the creation of a biobank using cell cryopreservation technology. This review is aimed at analyzing and classifying literature data related to the development of protocols for the cryopreservation of various types of MSCs and tissue-engineered structures. The materials in the review show that the existing techniques and protocols for MSC cryopreservation are very diverse, which significantly complicates standardization of the entire process. Here, the selection of cryoprotectors and of cryoprotective media shows the greatest variability. Currently, it is the cryopreservation of cell suspensions that has been studied most extensively, whereas there are very few studies in the literature on the freezing of intact tissues or of tissue-engineered structures. However, even now it is possible to develop general recommendations to optimize the cryopreservation process, making it less traumatic for cells.


Assuntos
Células-Tronco Mesenquimais , Proliferação de Células , Criopreservação/métodos , Congelamento , Humanos , Células-Tronco Mesenquimais/metabolismo , Engenharia Tecidual
10.
Nat Commun ; 13(1): 4957, 2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36104329

RESUMO

Sea-level rise projections rely on accurate predictions of ice mass loss from Antarctica. Climate change promotes greater mass loss by destabilizing ice shelves and accelerating the discharge of upstream grounded ice. Mass loss is further exacerbated by mechanisms such as the Marine Ice Sheet Instability and the Marine Ice Cliff Instability. However, the effect of basal thermal state changes of grounded ice remains largely unexplored. Here, we use numerical ice sheet modeling to investigate how warmer basal temperatures could affect the Antarctic ice sheet mass balance. We find increased mass loss in response to idealized basal thawing experiments run over 100 years. Most notably, frozen-bed patches could be tenuously sustaining the current ice configuration in parts of George V, Adélie, Enderby, and Kemp Land regions of East Antarctica. With less than 5 degrees of basal warming, these frozen patches may begin to thaw, producing new loci of mass loss.


Assuntos
Mudança Climática , Camada de Gelo , Regiões Antárticas , Congelamento , Elevação do Nível do Mar
11.
Biopreserv Biobank ; 20(4): 374-383, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35984941

RESUMO

Cryopreservation of spermatogonial stem cells (SSCs) is an important method to restore and maintain fertility in preadolescent children suffering from cancer. For protection of SSCs from cryoinjury, various antioxidant agents have been used. The aim of this study was to assess the antiapoptotic and antioxidant effects of melatonin in frozen-thawed SSCs. SSCs were isolated from testes of neonatal mice (3-6 days old) and their purities were measured by flow cytometry with promyelocytic leukemia zinc finger protein. After culturing, the cells were frozen in two groups (1) control and (2) melatonin (100 µM) and stored for 1 month. Finally, the cell viability, colonization rate, expression of Bcl-2 and BAX gene, and intracellular reactive oxygen species (ROS) were evaluated after freezing-thawing. Melatonin increased the viability and colonization of SSCs and Bcl-2 gene expression. It also diminished BAX gene expression and intracellular ROS. The results of this study show that melatonin with antioxidant and antiapoptotic effects can be used as an additive for freezing and long-term storage of cells and infertility treatment in the clinic.


Assuntos
Antioxidantes , Melatonina , Espermatogônias , Animais , Animais Recém-Nascidos , Antioxidantes/farmacologia , Apoptose , Proliferação de Células , Criopreservação/métodos , Congelamento , Masculino , Melatonina/farmacologia , Camundongos , Estresse Oxidativo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Espécies Reativas de Oxigênio , Espermatogônias/efeitos dos fármacos , Células-Tronco/efeitos dos fármacos , Proteína X Associada a bcl-2
12.
Reprod Biol Endocrinol ; 20(1): 123, 2022 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-35974356

RESUMO

BACKGROUND: The previous model-based cost-effectiveness analyses regarding elective oocyte cryopreservation remained debatable, while the usage rate may influence the cost per live birth. The aim of this study is to disclose the usage and cost-effectiveness of the planned cryopreserved oocytes after oocyte thawing in real-world situations. METHODS: This was a retrospective single-center observational study. Women who electively cryopreserved oocytes and returned to thaw the oocytes were categorized as thawed group. The oocytes were fertilized at our center and the sperm samples for each individual was retrieved from their respective husbands. Clinical outcomes were traced and the cumulative live birth rate per thawed case was calculated. The costs from oocyte freezing cycles to oocyte thawing, and embryo transfer cycles were accordingly estimated. The cumulative cost per live birth was defined by the cumulative cost divided by the live births per thawed case. RESULTS: We recruited 645 women with 840 oocyte retrieval cycles for elective oocyte freezing from November 2002 to December 2020. The overall usage rate was 8.4% (54/645). After the storage duration exceeded ten years, the probabilities of thawing oocytes were 10.6%, 26.6%, and 12.7% from women who cryopreserved their oocytes at the age ≤ 35 years, 36-39 years, and ≥ 40 years, respectively (P = 0.304). Among women who thawed their oocytes, 31.5% (17/54) of women achieved at least one live birth. For the age groups of ≤ 35 years, 36-39 years, and ≥ 40 years, the cumulative live birth rates per thawed case were 63.6%, 42.3%, and 17.6%, respectively (P = 0.045), and the cumulative costs for one live birth were $11,704, $17,189, and $35,642, respectively (P < 0.001). CONCLUSIONS: The overall usage rate was 8.4% in our cohort. The cumulative live birth rate was greatest in the youngest group and the cumulative cost per live birth was highest in the oldest group, which was threefold greater than that in the group aged ≤ 35 years. The findings added to the limited evidence of the usage rate in real-world situations, which could hopefully aid future analysis and decision-making in public health policy and for women willing to preserve fertility. TRIAL REGISTRATION: None.


Assuntos
Recuperação de Oócitos , Sêmen , Análise Custo-Benefício , Criopreservação , Feminino , Fertilização In Vitro , Congelamento , Humanos , Nascido Vivo/epidemiologia , Masculino , Oócitos , Gravidez , Taxa de Gravidez , Estudos Retrospectivos
13.
Theriogenology ; 190: 65-72, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-35963122

RESUMO

Sperm cryopreservation is the most common procedure used to establish germplasm banks for endangered species - but sometimes sperm cells cannot be obtained. In such cases, freezing testicular tissue may be the only option. The testes contains germ cells at different stages of differentiation, including spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa, among which differences in cryoresistance might be expected. The present work compares the viability and DNA integrity of 'rounded' cells, and of elongated spermatids and spermatozoa, from the dog and wild boar, following the cryopreservation of testicular tissue by slow freezing or vitrification. Cell viability was analyzed by PI/SYBR14 staining, and DNA integrity via the TUNEL technique. For wild boar, no significant differences were seen between the two methods with respect to the percentage of viable cells, nor in the percentage of cells with DNA damage. In the dog, the percentage of viable rounded germ cells (65.0 ± 2.4%) was higher (P < 0.05) after vitrification than after slow freezing (45.1 ± 6.7%). No difference was found between the two methods in terms of the viability of elongated cells. For rounded cells, the percentage of intact DNA was greater (P < 0.05) after vitrification (90.5 ± 2.1%) than after slow freezing (42.6 ± 11.0%), while for elongated spermatids and spermatozoa it was higher (P < 0.05) after slow freezing (66.9 ± 6.1%) than after vitrification (50.7 ± 4.5%). Thus, the response to cryopreservation is cell type-, cryopreservation type-, and species-dependent. Vitrification would appear to be the most appropriate method for preserving dog testicular tissue given the associated high cell viability and low degree of DNA fragmentation, while in wild boar, either method might be used.


Assuntos
Sêmen , Vitrificação , Animais , Criopreservação/métodos , Criopreservação/veterinária , Cães , Congelamento , Masculino , Espermatozoides/metabolismo , Sus scrofa , Suínos
14.
Biopreserv Biobank ; 20(4): 311-316, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35984940

RESUMO

Long-term cryopreservation of human umbilical vein endothelial cells (HUVECs) is important and beneficial for a variety of biomedical research and applications. In this study, we investigated HUVEC's cryobiological characteristics and parameters that are indispensable for predicting and determining an optimal cooling rate to prevent lethal intracellular ice formation (IIF) and severe cell dehydration during the cryopreservation processes. The parameters include cell membrane hydraulic conductivity (i.e., cell membrane water permeability), Lp, cell membrane water permeability activation energy, Elp, and osmotically inactive volume of a cell Vb. Cryomicroscopy was used to study the IIF phenomena and cell volume excursion at various cooling rates, 1, 10, and 20°C/min, respectively, based on which the cryobiological parameters were determined using biophysical and mathematical models. Results from this research work laid an important cryobiological foundation for the optimization of HUVEC's cryopreservation conditions.


Assuntos
Congelamento , Células Endoteliais da Veia Umbilical Humana , Água , Transporte Biológico/fisiologia , Permeabilidade da Membrana Celular/fisiologia , Criopreservação , Desidratação , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Gelo , Água/metabolismo
15.
16.
Food Chem ; 397: 133751, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-35914456

RESUMO

The effects of 1, 3, 5 kV/cm electrostatic field (EF) and 2, 5, 8 mT static magnetic field (MF) on the quality of frozen broccoli and cauliflower (B and C) were studied. The freezing parameters were significantly improved by 3, 5 kV/cm EF or 8 mT MF treatment (P < 0.05), a maximum reduction of nucleation time and phase transition time by 20.14 % and 32.09 % was found in 5 kV/cm EF treated cauliflower. EF or MF treatment improved sample quality to some extent, the overall effect of 3 kV/cm EF was the best, which led to a maximum drip loss reduction of 64.3 % in cauliflower, accompanied by lower relative conductivity, higher ascorbic acid and less cell rupture. EF or MF did not significantly reduce the damage of the flavor. MF was less effective than EF in improving the quality of frozen B and C.


Assuntos
Brassica , Ácido Ascórbico , Congelamento , Campos Magnéticos , Eletricidade Estática
17.
Bioresour Technol ; 361: 127735, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35934248

RESUMO

The selectivity of alkali treatment (AT) for hemicellulose separation is reduced due to the alkali solubility of lignin. It was improved using freeze-thaw-assisted alkaline treatment (FT/AT). In this study, bamboo hemicellulose was separated via a one-step freeze-thaw-assisted alkali treatment (OFT/AT). The effects of freezing temperature, freezing time, alkali concentration, and treatment time on bamboo components were studied. The separation yield of hemicellulose was 73.26%, compared to 64.00% using conventional FT/AT. The separation of lignin and cellulose was inhibited as alkali concentration decreased from 7.0% to 5.0%. The extraction yield of hemicellulose increased from 46.35% to 56.12%. Structural analysis of extracted hemicellulose revealed the effective inhibition of the breakage of the xylose backbone and arabinose side chain of hemicellulose. This indicated that the molecular structure of extracted hemicellulose was relatively complete. It provides theoretical support for the efficient separation of hemicellulose by AT.


Assuntos
Álcalis , Lignina , Congelamento , Lignina/química , Polissacarídeos/química
18.
Water Res ; 222: 118950, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35964509

RESUMO

Stormwater treatment systems remove and accumulate microplastics from surface runoff, but some of them can be moved downward to groundwater by natural freeze-thaw cycles. Yet, it is unclear whether or how microplastic properties such as density could affect the extent to which freeze-thaw cycles would move microplastics in the subsurface. To examine the transport and redistribution of microplastics in the subsurface by freeze-thaw cycles, three types of microplastics, with density smaller than (polypropylene or PP), similar to (polystyrene or PS), or greater than (polyethylene terephthalate or PET) water, were first deposited on the top of packed sand-the most common filter media used in infiltration-based stormwater treatment systems. Then the columns were subjected to either 23 h of drying at 22 °C (control) or freeze-thaw treatment (freezing at -20 °C for 6 h and thawing at 22 °C for 17 h) followed by a wetting event. The cycle was repeated 36 times, and the effluents were analyzed for microplastics. Microplastics were observed in effluents from the columns that were contaminated with PET and subjected to freeze-thaw cycles. Comparison of the distribution of microplastics in sand columns at the end of 36 cycles confirmed that freeze-thaw cycles could disproportionally accelerate the downward mobility of denser microplastics. Using a force balance model, we show that smaller microplastics (<50 µm) can be pushed at higher velocity by the ice-water interface, irrespective of the density of microplastics. However, plastic density becomes critical when the size of microplastics is larger than 50 µm. The coupled experimental studies and theoretical framework improved the understanding of why denser microplastics such as PET and PVC may move deeper into the subsurface in the stormwater treatment systems and consequently elevate groundwater pollution risk.


Assuntos
Microplásticos , Purificação da Água , Congelamento , Plásticos , Chuva , Areia , Água , Abastecimento de Água
19.
Int J Mol Sci ; 23(16)2022 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-36012703

RESUMO

Cold stress limits plant growth, development and yields, and the C-repeat binding factors (CBFs) function in the cold resistance in plants. However, how pomegranate CBF transcription factors respond to cold signal remains unclear. Considering the significantly up-regulated expression of PgCBF3 and PgCBF7 in cold-tolerant Punica granatum 'Yudazi' in comparison with cold-sensitive 'Tunisia' under 4 °C, the present study focused on the two CBF genes. PgCBF3 was localized in the nucleus, while PgCBF7 was localized in the cell membrane, cytoplasm, and nucleus, both owning transcriptional activation activity in yeast. Yeast one-hybrid and dual-luciferase reporter assay further confirmed that PgICE1 could specifically bind to and significantly enhance the activation activity of the promoters of PgCBF3 and PgCBF7. Compared with the wild-type plants, the PgCBF3 and PgCBF7 transgenic Arabidopsis thaliana lines had the higher survival rate after cold treatment; exhibited increased the contents of soluble sugar and proline, while lower electrolyte leakage, malondialdehyde content, and reactive oxygen species production, accompanying with elevated enzyme activity of catalase, peroxidase, and superoxide dismutase; and upregulated the expression of AtCOR15A, AtCOR47, AtRD29A, and AtKIN1. Collectively, PgCBFs were positively regulated by the upstream PgICE1 and mediated the downstream COR genes expression, thereby enhancing freezing tolerance.


Assuntos
Arabidopsis , Congelamento , Proteínas de Plantas , Romã (Fruta) , Fatores de Transcrição , Arabidopsis/genética , Arabidopsis/fisiologia , Temperatura Baixa , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas/fisiologia , Romã (Fruta)/genética , Regiões Promotoras Genéticas , Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologia
20.
Int J Mol Sci ; 23(15)2022 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-35955757

RESUMO

Hemicellulose is a major component of the complex biomass recalcitrance structure of fiber cell walls. Even though biomass recalcitrance protects plants, it affects the effective utilization of lignocellulosic biomass resources. Therefore, the separation and extraction of hemicellulose is very important. In this study, an improved two-step alkali pretreatment method was proposed to separate hemicellulose efficiently. Firstly, 16.61% hemicellulose was extracted from bamboo by the weak alkali treatment. Then, the physical freezing and the alkali treatment were carried out by freezing at -20 °C for 12.0 h and thawing at room temperature, heating to 80 °C, and treating with 5.0% sodium hydroxide for 90 min; the extraction yield of hemicellulose reached 73.93%. The total extraction yield of the two steps was 90.54%, and the molecular weight and purity reached 44,865 g·mol-1 and 89.60%, respectively. It provides a new method for breaking the biomass recalcitrance of wood fiber resources and effectively extracting hemicellulose.


Assuntos
Álcalis , Polissacarídeos , Biomassa , Carboidratos , Fibras na Dieta , Congelamento , Hidrólise , Polissacarídeos/química
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