Freezing Tolerance Research Articles

Multi-Objective Real-Time Optimal Energy Management Strategy Considering Energy Efficiency and Flexible Torque Response for a Dual-Motor Four-Drive Powertrain

To exhaust the potential of energy efficiency and dynamic performance of the dual-motor four-drive powertrain, this study developed a multi-objective real-time optimal energy management strategy considering energy efficiency and flexible torque response. First, a theoretical analysis of energy loss and operating characteristics was performed to elucidate the energy-saving advantages and control challenges of the dual-motor four-drive powertrain. Second, an economic strategy based on the adaptive nonlinear particle swarm optimization (ANLPSO) and optimization freezing tolerance mechanism was devised to realize real-time optimal power distribution. Then, the pre-shifting recognition schedule and gradient torque recovery strategy were developed to achieve flexible torque response during gear shifting. Finally, smooth switching logic was created to assure a seamless transition between the two strategies. Numerous simulation results indicate that compared with the single-motor drive strategy, the proposed strategy can increase energy efficiency by 8.1%, 4.02%, and 9.49% under NEDC, WLTC, and CLTC, respectively. During shifting, the longitudinal acceleration and jerk of the proposed strategy are significantly superior to those of the original strategy, thereby enhancing the vehicle’s dynamic performance and ride comfort. The results of the drum experiment validate the efficacy of the proposed method for energy consumption optimization and torque coordination control in the actual vehicle environment.

Integration of a Frost Mortality Scheme Into the Demographic Vegetation Model FATES

AbstractFrost is damaging to plants when air temperature drops below their tolerance threshold. The set of mechanisms used by cold‐tolerant plants to withstand freezing is called “hardening” and typically take place in autumn to protect against winter damage. The recent incorporation of a hardening scheme in the demographic vegetation model FATES opens up the possibility to investigate frost mortality to vegetation. Previously, the hardening scheme was used to improve hydraulic processes in cold‐tolerant plants. In this study, we expand upon the existing hardening scheme by implementing hardiness‐dependent frost mortality into CLM5.0‐FATES to study the impacts of frost on vegetation in temperate and boreal sites from 1950 to 2015. Our results show that the original freezing mortality approach of FATES, where each plant type had a fixed freezing tolerance threshold—an approach common to many other dynamic vegetation models, was restricted to predicting plant type distribution. The main results emerging from the new scheme are a high autumn and spring frost mortality, especially at colder sites, and increasing mid‐winter frost mortality due to global warming, especially at warmer sites. We demonstrate that the new frost scheme is a major step forward in dynamically representing vegetation in ESMs by for the first time including a level of frost tolerance that is responding to the environment and includes some level of cost (implicitly) and benefit. By linking hardening and frost mortality in a land surface model, we open new ways to explore the impact of frost events in the context of global warming.

Biochemical changes after cold acclimation in Nordic red clover (Trifolium pratense L.) accessions with contrasting levels of freezing tolerance.

The ability to tolerate low freezing temperatures is an important component of winter survival and persistence of red clover. Cold acclimation (CA) allows plants to acquire higher levels of freezing tolerance. However, the biochemical responses to cold and the importance of such changes for the plant to acquire adequate freezing tolerance have not been investigated in red clover of Nordic origin, which has a distinct genetic background. To shed light on this, we selected five freezing tolerant (FT) and five freezing susceptible (FS) accessions and studied the effect of CA on the contents of carbohydrates, amino acids and phenolic compounds in the crowns. Among those compounds which increased during CA, FT accessions had higher contents of raffinose, pinitol, arginine, serine, alanine, valine, phenylalanine and one phenolic compound (a pinocembrin hexoside derivative) than FS accessions, suggesting a role for these compounds in the freezing tolerance in the selected accessions. These findings, together with a description of the phenolic profile of red clover crowns, significantly add to the current knowledge of the biochemical changes during CA and their role in freezing tolerance in Nordic red clover. This article is protected by copyright. All rights reserved.

Osmotic and metabolic responses to cold acclimation and acute cold challenge in a freeze avoidant lizard, Podarcis siculus

Ectotherms survive exposure to subzero temperatures through freeze tolerance or freeze avoidance. Among vertebrate ectotherms, glucose is commonly used as a cryoprotectant in freeze tolerant strategies and as an osmolyte in freeze avoidant strategies, while also functioning as a metabolic substrate. Whereas some lizard species are capable of both freeze tolerance and freeze avoidance, Podarcis siculus is limited to freeze avoidance through supercooling. We hypothesized that, even in a freeze-avoidant species such as P. siculus, plasma glucose would accumulate with cold acclimation and would increase in response to acute exposure to subzero temperatures. To investigate this, we tested whether plasma glucose concentration and osmolality would increase in response to a subzero cold challenge before and after cold acclimation. In addition, we examined the relationship between metabolic rate, cold acclimation, and glucose by measuring metabolic rate during the cold challenge trials. We found that plasma glucose increased during the cold challenge trials, and that the increase was more pronounced after cold acclimation. However, baseline plasma glucose decreased throughout cold acclimation. Interestingly, total plasma osmolality did not change, and the increase in glucose only slightly altered freezing point depression. Metabolic rate during the cold challenge decreased after cold acclimation, and changes in respiratory exchange ratio suggest an increased relative use of carbohydrates. Overall, our findings demonstrate an important role for glucose in the response of P. siculus to an acute cold challenge, thus adding evidence for glucose as an important molecule for overwintering ectotherms that use freeze avoidant strategies.

Versatile Quasi‐Solid Ionic Conductive Elastomer Inspired by Desertification Control Strategy for Soft Iontronics

AbstractIonic conductors, such as hydrogels, ionogels, and eutectogels, have attained considerable research interest in various advanced application scenarios. However, such ionic conductors still suffer from the restriction of inherent liquid compositions, which may leak or evaporate. Herein, inspired by the control strategy of desertification caused by soil erosion, a novel internal‐external dual enhancement design strategy, i.e., increasing the interaction between the filler itself and its matrix, is proposed to firmly embed the deep eutectic solvent (DES) into polyurethane (PU) to prevent liquid leakage, such that the prepared ionic conductive elastomers (PU‐DESs) are quasi‐solid. The PU‐DESs exhibit marvelous versatility including high stretchability, tensile strength, toughness, self‐healing efficiency, antibacterial ability, ionic conductivity, and excellent freezing tolerance. More intriguingly, benefiting from their quasi‐solid feature, PU‐DESs are endowed with long‐term environmental stability. Thanks to these superb versatile features, PU‐DESs are further successfully applied in the wearable sensor and triboelectric nanogenerator (TENG) for monitoring human motions and converting mechanical energy into electrical energy, breaking away from the limitations of previous most soft iontronics such as liquid leakage or evaporation and weak mechanical strength. Hence, this study establishes an effective material design strategy for various soft iontronics demanding environmental stability and durability.

Histone H3 and H4 Modifications Point to Transcriptional Suppression as a Component of Winter Freeze Tolerance in the Gall Fly Eurosta solidaginis.

The goldenrod gall fly (Eurosta solidaginis) is a well-studied model of insect freeze tolerance. In situations of prolonged winter subzero temperatures, larvae of E. solidaginis accept ice penetration throughout extracellular spaces while protecting the intracellular environment by producing extreme amounts of glycerol and sorbitol as cryoprotectants. Hypometabolism (diapause) is implemented, and energy use is reprioritized to essential pathways. Gene transcription is one energy-expensive process likely suppressed over the winter, in part, due to epigenetic controls. The present study profiled the prevalence of 24 histone H3/H4 modifications of E. solidaginis larvae after 3-week acclimations to decreasing environmental temperatures (5 °C, -5 °C and -15 °C). Using immunoblotting, the data show freeze-mediated reductions (p < 0.05) in seven permissive histone modifications (H3K27me1, H4K20me1, H3K9ac, H3K14ac, H3K27ac, H4K8ac, H3R26me2a). Along with the maintenance of various repressive marks, the data are indicative of a suppressed transcriptional state at subzero temperatures. Elevated nuclear levels of histone H4, but not histone H3, were also observed in response to both cold and freeze acclimation. Together, the present study provides evidence for epigenetic-mediated transcriptional suppression in support of the winter diapause state and freeze tolerance of E. solidaginis.

Involvement of CBF in the fine-tuning of litchi flowering time and cold and drought stresses.

Litchi (Litchi chinensis) is an economically important fruit tree in southern China and is widely cultivated in subtropical regions. However, irregular flowering attributed to inadequate floral induction leads to a seriously fluctuating bearing. Litchi floral initiation is largely determined by cold temperatures, whereas the underlying molecular mechanisms have yet to be identified. In this study, we identified four CRT/DRE BINDING FACTORS (CBF) homologs in litchi, of which LcCBF1, LcCBF2 and LcCBF3 showed a decrease in response to the floral inductive cold. A similar expression pattern was observed for the MOTHER OF FT AND TFL1 homolog (LcMFT) in litchi. Furthermore, both LcCBF2 and LcCBF3 were found to bind to the promoter of LcMFT to activate its expression, as indicated by the analysis of yeast-one-hybrid (Y1H), electrophoretic mobility shift assays (EMSA), and dual luciferase complementation assays. Ectopic overexpression of LcCBF2 and LcCBF3 in Arabidopsis caused delayed flowering and increased freezing and drought tolerance, whereas overexpression of LcMFT in Arabidopsis had no significant effect on flowering time. Taken together, we identified LcCBF2 and LcCBF3 as upstream activators of LcMFT and proposed the contribution of the cold-responsive CBF to the fine-tuning of flowering time.

High-Efficiency and Recyclable Green Molten Salt Hydrate Solvent for Cellulose Hydrogels with High Conductivity and Freeze Tolerance

Cellulose, as a sustainable biomass material, has aroused wide attention and has been extensively employed in functional biomaterials. However, due to the strong intra/intermolecular interactions, the dissolution problem has significantly limited its applications. Although different kinds of solvents have been developed, most of them still cannot equilibrate dissolution, recyclability, and functional material preparation, simultaneously. In this work, an efficient and recyclable green solvent─molten salt hydrate (calcium chloride hexahydrate-lithium chloride, CHLH)─was prepared with excellent dissolving ability (high solubility of 7.0 wt %) for cellulose at a low dissolution temperature. Moreover, the CHLH showed good stability and storage properties. The dissolved cellulose could be stored in a solid state at a wide range of temperatures (<65 °C) for more than 3 months while remaining stable. Meanwhile, CHLH exhibited excellent recycling properties. After 5 dissolving–recovering cycles, the recycled CHLH still maintained stable dissolution performance and a high recovery of 92%. More importantly, the advantages of CHLH made the prepared cellulose hydrogel integrate good flexibility, ionic conductivity, and freezing tolerance. When used as a strain sensor, it could not only detect body movements but also identify the motion direction, which would have broad application prospects in flexible electronic devices.

Palmitoylation mediates the proteolysis of seed storage proteins during the cooling process in hydrated lettuce seeds (Lactuca sativa)

AbstractPalmitoyl-protein thioesterase (PPT), involved in the fatty acid synthesis and the de-palmitoylation of protein, was induced under ecological cooling treatment in hydrated lettuce seeds. However, there was no significant difference in fatty acid levels between the control and the cooled samples. To further study the function of PPT, 2-bromopalmitic acid (2-Bp), an inhibitor of protein palmitoylation, was applied during the imbibition of hydrated lettuce seeds, which was followed by slow-cooling treatment (−3°C h−1). The application of 2-Bp (1 mM) significantly increased the survival rate of seeds from 6.70% (control imbibition) to 22.67% (2-Bp imbibition) after slow cooling to −20°C. Differential scanning calorimetry (DSC) analysis indicated that 2-Bp led to earlier onset of ice crystals in the endosperm than the control group. Two-dimensional electrophoresis (2D) confirmed that 2-Bp could promote the hydrolysis of seed globulins and the accumulation of globulin peptides with small molecular weights. High-efficiency hydrolysis of globulin induced by mercaptoethanol improved the freezing tolerance of hydrated lettuce seeds and led to the accumulation of small globulin peptides, which further proved the positive function of small globulin polypeptides in enhancing the freezing tolerance of hydrated lettuce seeds. DSC of small globulin peptides showed that the smaller the molecular weight, the earlier the appearance of ice crystals and the higher the enthalpy of heat release. For the smallest peptides, the 2-Bp-4 in 2-Bp group exhibited higher enthalpy in exothermic peak than the control group (c-4). In conclusion, the hydrolysis of seed globulins and accumulation of small-molecule globulin peptides could be the major reason for improving the freezing tolerance of hydrated seeds after de-palmitoylation treatment.

LncRNA MtCIR2 positively regulates plant-freezing tolerance by modulating CBF/DREB1 gene clusters.

Emerging evidence suggests that long noncoding RNAs (lncRNAs) are involved in regulation of plant response to environmental stress. CBF/DREB1s are highly conserved transcription factors that regulate response to cold stress in plants. However, very few lncRNAs were found to regulate expression of CBFs and cold tolerance in plant. Here, we identified a cold-responsive long intergenic noncoding RNA (MtCIR2) of CBF/DREB1 genes that were located in a major freezing tolerance QTL region of legume Medicago truncatula. We found that response of MtCIR2 transcription was more rapid than that of MtCBF/DREB1s during cold treatment. MtCIR2 positively regulated M. truncatula freezing tolerance, such that overexpression of MtCIR2 led to higher survival rate and lower cell membrane damage than wild-type plants, while mutation of MtCIR2 rendered the mutants more sensitive to cold stress. In addition, expression levels of MtCBF/DREB1s were up-regulated in the MtCIR2 overexpressing lines and down-regulated in the mutants. Among the MtCIR2-regulated genes, the strongest enriched genes were those involved in polysaccharide metabolic processes. In addition, we demonstrated that overexpression of MtCIR2 led to increases in contents of soluble sugars. These results highlight that MtCIR2 positively regulates tolerance to freezing by regulating MtCBF/DREB1s expression and glycometabolism in M. truncatula.

Cloning and Functional Characterization of Cold-Inducible MYB-like 17 Transcription Factor in Rapeseed (Brassica napus L.).

Rapeseed (Brassica napus L.) is an important crop for edible oil, vegetables, and biofuel. Rapeseed growth and development require a minimum temperature of ~1-3 °C. Notably, frost damage occurs during overwintering, posing a serious threat to the productivity and yield of rapeseed. MYB proteins are important transcription factors (TFs) in plants, and have been proven to be involved in the regulation of stress responses. However, the roles of the MYB TFs in rapeseed under cold stress conditions are yet to be fully elucidated. To better understand the molecular mechanisms of one MYB-like 17 gene, BnaMYBL17, in response to low temperature, the present study found that the transcript level of BnaMYBL17 is induced by cold stress. To characterize the gene's function, the 591 bp coding sequence (CDS) from rapeseed was isolated and stably transformed into rapeseed. The further functional analysis revealed significant sensitivity in BnaMYBL17 overexpression lines (BnaMYBL17-OE) after freezing stress, suggesting its involvement in freezing response. A total of 14,298 differentially expressed genes relative to freezing response were found based on transcriptomic analysis of BnaMYBL17-OE. Overall, 1321 candidate target genes were identified based on differential expression, including Phospholipases C1 (PLC1), FCS-like zinc finger 8 (FLZ8), and Kinase on the inside (KOIN). The qPCR results confirmed that the expression levels of certain genes showed fold changes ranging from two to six when compared between BnaMYBL17-OE and WT lines after exposure to freezing stress. Furthermore, verification indicated that BnaMYBL17 affects the promoter of BnaPLC1, BnaFLZ8, and BnaKOIN genes. In summary, the results suggest that BnaMYBL17 acts as a transcriptional repressor in regulating certain genes related to growth and development during freezing stress. These findings provide valuable genetic and theoretical targets for molecular breeding to enhance freezing tolerance in rapeseed.

Lysine and threonine supplementation promotes postharvest quality of Volvariella volvacea mushroom during low-temperature preservation via maintenance of the citrate cycle

Volvariella volvacea, the edible straw mushroom, is popular among consumers; however, its freshness is difficult to maintain at 4 °C. Spray treatment with the ubiquitin-binding enzyme E2 (UBEV2) inhibitor L345-0044 maintained the freshness of V. volvacea during storage at 4 °C for 48 h. Inhibitor treatment enhanced the ability of V. volvacea to resist cold stress by inducing overexpression of genes involved in protein translation, protein turnover, N-glycan biosynthesis, and lysine metabolism. Overexpression of saccharopine dehydrogenase genes, which participate in lysine metabolism in yeast, enhanced freezing tolerance. Anti-freezing experiments showed that the addition of l-lysine or l-threonine improved the quality of V. volvacea at 4 °C with stable soluble sugar levels, as lysine or threonine metabolism produced acetyl-CoA for maintaining the citrate cycle. Our findings revealed that supplementation with l-lysine or l-threonine prolonged the preservation time of V. volvacea for more than 24 h via maintenance of the citrate cycle.

Integrated Full-Length Transcriptome and Metabolome Profiling Reveals Flavonoid Regulation in Response to Freezing Stress in Potato.

Cold stress impairs plant growth and development, resulting in crop failure. Cultivated potato (Solanum tuberosum L.) is sensitive to freezing, while its wild relative, S. commersonii, has a strong freezing tolerance. To decipher the anti-freezing mechanism of CM, we carried out a transcriptomic and metabolomic analysis of an anti-freezing variety of CM (a type of S. commersonii) and a freeze-sensitive variety of DM (a type of Solanum tuberosum L.). A total of 49,232 high-quality transcripts from 12,811 gene loci, including 46,772 coding sequences and 2018 non-coding RNAs, were identified. KEEG enrichment analysis of differentially expressed genes (DEGs) between the two varieties showed that the flavonoid biosynthesis pathway was strongly induced by freezing stress, which was proven by flavonoid metabolome analysis. Consistent with the accumulation of more flavonoids, nearly all the pathway genes were significantly upregulated in CM than those in DM. The transcript levels of two chalcone synthase (CHS-1) isoforms and four isoforms of flavonoid 3'-hydroxylase (F3'H-1) were confirmed by qRT-PCR. Co-expression analysis identified one Myb-related and three UGTs (UDP-glycosyltransferase) that were significantly upregulated in CM during freezing stress. Our findings support that the flavonoid pathway was significantly enhanced by freezing stress and the greater accumulation ofglycosylatedflavonoids in resistant types than that of sensitive types, maybe accounting for the increased freezing tolerance of freeze-resistant potato varieties.

A genome-wide association study of freezing tolerance in red clover (Trifolium pratense L.) germplasm of European origin.

Improvement of persistency is an important breeding goal in red clover (Trifolium pratense L.). In areas with cold winters, lack of persistency is often due to poor winter survival, of which low freezing tolerance (FT) is an important component. We conducted a genome wide association study (GWAS) to identify loci associated with freezing tolerance in a collection of 393 red clover accessions, mostly of European origin, and performed analyses of linkage disequilibrium and inbreeding. Accessions were genotyped as pools of individuals using genotyping-by-sequencing (pool-GBS), generating both single nucleotide polymorphism (SNP) and haplotype allele frequency data at accession level. Linkage disequilibrium was determined as a squared partial correlation between the allele frequencies of pairs of SNPs and found to decay at extremely short distances (< 1 kb). The level of inbreeding, inferred from the diagonal elements of a genomic relationship matrix, varied considerably between different groups of accessions, with the strongest inbreeding found among ecotypes from Iberia and Great Britain, and the least found among landraces. Considerable variation in FT was found, with LT50-values (temperature at which 50% of the plants are killed) ranging from -6.0°C to -11.5°C. SNP and haplotype-based GWAS identified eight and six loci significantly associated with FT (of which only one was shared), explaining 30% and 26% of the phenotypic variation, respectively. Ten of the loci were found within or at a short distance (<0.5 kb) from genes possibly involved in mechanisms affecting FT. These include a caffeoyl shikimate esterase, an inositol transporter, and other genes involved in signaling, transport, lignin synthesis and amino acid or carbohydrate metabolism. This study paves the way for a better understanding of the genetic control of FT and for the development of molecular tools for the improvement of this trait in red clover through genomics assisted breeding.

Acquisition of Freezing Tolerance of Resurrection Species from Gesneriaceae, a Comparative Study.

Resurrection plants have the unique ability to restore normal physiological activity after desiccation to an air-dry state. In addition to their desiccation tolerance, some of them, such as Haberlea rhodopensis and Ramonda myconi, are also freezing-tolerant species, as they survive subzero temperatures during winter. Here, we compared the response of the photosynthetic apparatus of two other Gesneriaceae species, Ramonda serbica and Ramonda nathaliae, together with H. rhodopensis, to cold and freezing temperatures. The role of some protective proteins in freezing tolerance was also investigated. The water content of leaves was not affected during cold acclimation but exposure of plants to -10 °C induced dehydration of plants. Freezing stress strongly reduced the quantum yield of PSII photochemistry (Y(II)) and stomatal conductance (gs) on the abaxial leaf side. In addition, the decreased ratio of Fv/Fm suggested photoinhibition or sustained quenching. Freezing-induced desiccation resulted in the inhibition of PSII activity, which was accompanied by increased thermal energy dissipation. In addition, an increase of dehydrins and ELIPs was detected, but the protein pattern differed between species. During recovery, the protein abundance decreased and plants completely recovered their photosynthetic activity. Thus, our results showed that R. serbica, R. nathaliae, and H. rhodopensis survive freezing stress due to some resurrection-linked traits and confirmed their freezing tolerance.

1H-NMR analysis reveals cold acclimation induces homeoviscous adaptation in membranes from liver, but not in blood cells or skeletal muscle in the freeze tolerant Cope's gray treefrog

Cope’s gray treefrog Dryophytes chrysoscelis is a seasonally freeze tolerant anuran capable of repeatedly freezing and thawing as much as two-thirds of body water by accumulating and mobilizing cryoprotectants. In cold-acclimated D. chrysoscelis, RBCs are inherently freeze tolerant in vitro, suggesting that membrane composition may contribute to cellular freeze tolerance. The objective of this study is to compare the effects of cold acclimation on lipid profiles of membranes from liver, muscle, and blood cells, to assess the role of membrane composition in cellular and organismal freeze tolerance. It is hypothesized that membrane biochemical composition is tissue-specific and is sensitive to environmental fluctuation. Membranes were prepared from liver (N=7), skeletal muscle (N=7), and blood cells (WBCs, RBCs, and platelets) (N=5) collected from wild-caught male treefrogs that were either cold-acclimated (5°C, 8 hrs daylight) or maintained in warm conditions (22°C, 12 hrs daylight). Fatty acid characterization and cholesterol and triacylglycerol (TAG) content were evaluated using 1 H-NMR spectra collected in a 400 MHz Bruker Avance spectrometer. Principal component analysis demonstrated that membrane lipid profiles were tissue-specific, but distinct warm and cold profiles were detected only in liver. Fatty acids in liver membranes did not vary with acclimation state in chain length ( P=0.46), but total unsaturation was nearly 2-fold greater in cold compared with warm frogs ( P&lt;0.05). Monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids were elevated by 1.7-fold in cold frogs ( P&lt;0.05). Of the PUFA lipid species assessed, linoleic acid (LA) was more than doubled in cold frogs ( P&lt;0.05), while other Ω-3 and Ω-6 fatty acids did not vary between groups ( P&gt;0.5). TAG, free cholesterol, and esterified cholesterol were elevated by 2.5-fold, 2-fold, and 1.4-fold, respectively, in cold frogs (P&lt;0.05), while free cholesterol did not vary between groups ( P=0.38). In membranes from muscle and blood cells, neither fatty acid characterization nor TAG and cholesterol varied between warm and cold frogs, but trends suggested that MUFA ( P=0.10) and LA ( P=0.06) content in blood cells may be elevated in warm frogs. Overall, liver membranes are remodeled during cold acclimation, supporting the hypothesis that membrane composition is adapted to maintain cell function and integrity (i.e. homeoviscous adaptation). Specifically, elevated fatty acid unsaturation and cholesterol in liver likely contribute to cellular freeze tolerance and may support the central role of liver in mobilizing metabolites and cryoprotectants during cold acclimation. However, the absence of such changes (or even changes in the opposite direction) in muscle and blood cells indicates that additional environmental cues, such as exposure to freezing conditions, may be required to induce remodeling and/or that membrane lipid composition does not contribute to freeze tolerance in some tissues. This study was supported by a UD STEM Catalyst Grant awarded to CMK and JE, a Graduate Student Summer Fellowship and Dittrich-Spotila Research Fellowship awarded to EEY, and an NSF-MRI Grant awarded to JE and CMK that was supported by the Ohio Action Fund. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Highly robust and sensitive dual-network freeze-resistant organic hydrogel thermocells

Thermocells (TECs) are eco-friendly and ideal power-generation devices that sustainably convert waste heat into electricity to power wearable electronics. However, their poor mechanical properties, limited operating temperature, and low sensitivity limit their practical application. Hence, K3/4Fe(CN)6 and NaCl thermoelectric materials were introduced into a bacterial cellulose-reinforced polyacrylic acid double-network structure and permeated into a glycerol (Gly)/water binary solvent to prepare an organic thermoelectric hydrogel. The resulting hydrogel had a tensile strength of approximately 0.9 MPa and a stretched length of approximately 410 %; moreover, it worked stably even in the stretched/twisted state. Owing to the introduction of Gly and NaCl, the as-prepared hydrogel exhibited excellent freezing tolerance (− 22 °C). In addition, the TEC also demonstrated excellent sensitivity (~13 s). Good environmental stability and high sensitivity make this hydrogel TEC a promising candidate for thermoelectric power-generation/temperature-monitoring systems.

The transcription factor MYB43 antagonizes with ICE1 to regulate freezing tolerance in Arabidopsis.

Previous discovering meticulously illustrates the post-translational modifications and protein stability regulation of ICE1 and their role in cold stress. However, the studies on the interaction of ICE1 with other transcription factors, and their function in modulation cold stress tolerance, as well as in the transition between cold stress and growth are largely insufficient. In this work, we found that maltose binding protein (MBP) 43 directly binds to the promoters of CBF genes to repress their expression, thereby negatively regulating freezing tolerance. Biochemical and genetic analyses showed that MYB43 interacts and antagonizes with ICE1 to regulate the expression of CBF genes and plant's freezing stress tolerance. PLEIOTROPIC REGULATORY LOCUS 1 (PRL1) accumulates under cold stress and promotes MYB43 protein degradation; however, when cold stress disappears, PRL1 restores normal protein levels, causing MYB43 protein to re-accumulate to normal levels. Furthermore, PRL1 positively regulates freezing tolerance by promoting degradation of MYB43 to attenuate its repression of CBF genes and antagonism with ICE1. Thus, our study reveals that MYB43 inhibits CBF genes expression under normal growth condition, while PRL1 promotes MYB43 protein degradation to attenuate its repression of CBF genes and antagonism with ICE1, and thereby to the precise modulation of plant cold stress responses.

Ocean acidification increases susceptibility to sub-zero air temperatures in ecosystem engineers and limit poleward range shifts.

Ongoing climate change has caused rapidly increasing temperatures, and an unprecedented decline in seawater pH, known as ocean acidification. Increasing temperatures are redistributing species towards higher and cooler latitudes which are most affected by ocean acidification. Whilst the persistence of intertidal species in cold environments is related to their capacity to resist sub-zero air temperatures, studies have never considered the interacting impacts of ocean acidification and freeze stress on species survival and distribution. Here, a full-factorial experiment was used to study whether ocean acidification increases mortality in subtidal Mytilus trossulus and subtidal M. galloprovincialis, and intertidal M. trossulus following sub-zero air temperature exposure. We examined physiological processes behind variation in freeze tolerance using 1H NMR metabolomics, analyses of fatty acids, and amino acid composition. We show that low pH conditions (pH = 7.5) significantly decrease freeze tolerance in both intertidal and subtidal populations of Mytilus spp. Under current day pH conditions (pH = 7.9), intertidal M. trossulus was more freeze tolerant than subtidal M. trossulus and subtidal M. galloprovincialis. Conversely, under low pH conditions, subtidal M. trossulus was more freeze tolerant than the other mussel categories. Differences in the concentration of various metabolites (cryoprotectants), or in the composition of amino acids and cell membrane phospholipid fatty acids could not explain the decrease in survival. These results suggest that ocean acidification can offset the poleward range expansions facilitated by warming, and that reduced freeze tolerance could result in a range contraction if temperatures become lethal at the equatorward edge.

Comprehensive Transcriptome Analysis of Responses during Cold Stress in Wheat (Triticum aestivum L.).

Wheat production is often impacted by pre-winter freezing damage and cold spells in later spring. To study the influences of cold stress on wheat seedlings, unstressed Jing 841 was sampled once at the seedling stage, followed by 4 °C stress treatment for 30 days and once every 10 days. A total of 12,926 differentially expressed genes (DEGs) were identified from the transcriptome. K-means cluster analysis found a group of genes related to the glutamate metabolism pathway, and many genes belonging to the bHLH, MYB, NAC, WRKY, and ERF transcription factor families were highly expressed. Starch and sucrose metabolism, glutathione metabolism, and plant hormone signal transduction pathways were found. Weighted Gene Co-Expression Network Analysis (WGCNA) identified several key genes involved in the development of seedlings under cold stress. The cluster tree diagram showed seven different modules marked with different colors. The blue module had the highest correlation coefficient for the samples treated with cold stress for 30 days, and most genes in this module were rich in glutathione metabolism (ko00480). A total of eight DEGs were validated using quantitative real-time PCR. Overall, this study provides new insights into the physiological metabolic pathways and gene changes in a cold stress transcriptome, and it has a potential significance for improving freezing tolerance in wheat.