Cold Survival Research Articles

Comparative study of Tris Turmeric, Tris Turmeric Dimethyl Sulfoxide and Tris Turmeric Ethylene glycol extenders on the cryosurvivability, sperm resistance, in- vivo fertility and antioxidant status in buffalo bull semen

The freeze-thaw process leads to structural and functional damage due to excessive accumulation of reactive oxygen species (ROS). The addition of exogenous antioxidants to sperm diluents is of great importance to overcome oxidative damage during freezing. The purpose of this study was to explore the effects of three diluents Tris Turmeric, Tris Turmeric Dimethyl Sulfoxide and Tris Turmeric Ethylene glycol on the cold survival ability of buffalo sperm. Semen was collected from five local adult male buffalo breeds. A base diluent of Tris-citric acid-fructose (TCF) was prepared, adding 20% whole egg yolk (TCFY). The Tris extender without turmeric, without DMSO, and without EG was kept as a control. Other extenders are Tris containing turmeric TT (100 ml/5 ml Tris), Tris containing turmeric dimethyl sulfoxide TTD (100 ml/5 ml Tris + 1.5% DMSO) and Tris containing turmeric and ethylene glycol TTE EG (100 ml/5 ml Tris + 1.5% EG). Semen samples were added and a pure sperm concentration of 60 × 106/ml was achieved. Frozen buffalo sperm after thawing showed significant improvements in all research parameters of the three breeding samples compared to the control. Tris Turmeric Ethylene was the type that best improved sperm survival under frozen conditions, followed by Tris Turmeric and Tris Turmeric Dimethyl Sulfoxide compared to the control. A significant decrease in sperm motility after thawing was evident as usage time increased in all expanders. There was a significant increase in total antioxidant content (TAC) and insignificant change in malondialdehyde (MDA) of the diluent used compared to the control. Conception rate (CR) was higher in Tris Turmeric Ethylene glycol (65.2%), followed by Tris Turmeric (60.3%) and Tris Turmeric Dimethyl Sulfoxide (55.9%) compared to the control (36, 7%). It can be concluded that Tris Turmeric Ethylene Glycol is considered the best agent for improving cold survival and sperm fertility, followed by Tris Turmeric and Tris Turmeric Dimethyl Sulfoxide.

Regulation of spikelet developmental responses to chilling and freezing stress mediated by differential sugar metabolism in winter wheat

Spring cold stress poses a great threat to wheat reproductive growth, leading to compromised spike development and grain yield. There are two types of cold stress i.e. chilling stress (CS, above zero) and freezing stress (FS, below zero). However, it is unclear whether there is a difference in the mechanism of CS and FS in regulating spikelet development. This study aimed to unravel the underlying regulation in determining the difference for wheat spikelet exposed to CS at 2 °C and FS at −2°C by integrative analyses of transcriptome, metabolome, and physiology. Delayed floret development and shrunken cellular morphology in both CS and FS were observed, even malformation and degradation of anther cells occurred in FS. Kyoto Encyclopedia of gene and genomes (KEGG) analyses revealed that the most abundantly enriched pathways are phytohormone biosynthesis, starch and sucrose metabolism, and phenylpropanoid biosynthesis. Further physiological assays related to the identified pathways were performed. Compared to CS, the signal of abscisic acid (ABA), salicylic acid (SA) and jasmonic acid (JA) was more pronounced, and the signal of auxin (IAA) and gibberellin (GA) was inhibited further in FS. In addition, the contents of glucose, fructose and trehalose were elevated in CS, owing to greater activities of cell wall invertase and sucrose synthase, while the hexose content was decreased owing to lower activities of such enzymes in FS, concomitantly, flavonoid barely changed in CS, but it dramatically amounted in FS. Taken together, the glucose and trehalose pathway, along with induced ABA and SA signal were intensified in CS to maintain growth, while greater flavonoid and promoted JA synthesis were induced in FS for cold survival. Understanding the molecular of growth-defense under cold stress would provide a foundation for the development of breeding strategies.

11. Cold survival and pathogenicity of Yersinia enterocolitica BT4 strains isolated from pigs and genetically close or not to strains isolated from human cases

11. Cold survival and pathogenicity of Yersinia enterocolitica BT4 strains isolated from pigs and genetically close or not to strains isolated from human cases

Floxuridine supports UPS independent of germline signaling and proteostasis regulators via involvement of detoxification in C. elegans.

The ubiquitin-proteasome system (UPS) is critical for maintaining proteostasis, influencing stress resilience, lifespan, and thermal adaptability in organisms. In Caenorhabditis elegans, specific proteasome subunits and activators, such as RPN-6, PBS-6, and PSME-3, are associated with heat resistance, survival at cold (4°C), and enhanced longevity at moderate temperatures (15°C). Previously linked to improving proteostasis, we investigated the impact of sterility-inducing floxuridine (FUdR) on UPS functionality under proteasome dysfunction and its potential to improve cold survival. Our findings reveal that FUdR significantly enhances UPS activity and resilience during proteasome inhibition or subunit deficiency, supporting worms' normal lifespan and adaptation to cold. Importantly, FUdR effect on UPS activity occurs independently of major proteostasis regulators and does not rely on the germ cells proliferation or spermatogenesis. Instead, FUdR activates a distinct detoxification pathway that supports UPS function, with GST-24 appearing to be one of the factors contributing to the enhanced activity of the UPS upon knockdown of the SKN-1-mediated proteasome surveillance pathway. Our study highlights FUdR unique role in the UPS modulation and its crucial contribution to enhancing survival under low-temperature stress, providing new insights into its mechanisms of action and potential therapeutic applications.

Paleoclimatic and paleogeographic significance of the early Santonian ice-rafted dropstones in the Songliao Basin, NE China

Two ice-rafted dropstones were discovered in the Yaojia Formation (early Santonian) of wells Ao14 and F247 in the Songliao Basin, northeastern China. The dropstone from well Ao14 was further studied using computed tomography (CT) scanning, sporopollen, carbon and oxygen isotope, and zircon U–Pb isotope analyses. The results show that the dropstone is composed of quartz monzonite and has an age of 178.0 ± 3.3 Ma. Based on the bedrock age analysis around the Songliao Basin, it is suggested that the dropstone in well Ao14 may have originated from the Zhangguangcai Range. The palynoflora assemblage indicates a mixed survival of cold and warm palynomorphs. The carbon and oxygen isotope compositions of the synsedimentary calcareous clasts surrounding the dropstone exhibit obvious negative biases, suggesting that glacier meltwater flowed into the paleo-lake, probably due to the significant topographic height difference between the Songliao Basin and adjacent areas during the early Santonian. Additionally, it can be inferred that coastal mountains formed in the Zhangguangcai Range area, which is located southeast of the Songliao Basin, and the dropstones derived from this region. During the cold season, the dropstones may be transported to the edge of Songliao Lake by avalanche and mixed with carbonate debris. As the seasons changed, the lake ice broke into pieces and carrying the dropstones and carbonate debris into the deep lake area. The present research provides direct evidence of a brief global cold event and the presence of high mountains in the southeastern Songliao Basin during the early Santonian in the Cretaceous greenhouse world.

Cold-induced FOXO1 nuclear transport aids cold survival and tissue storage

Cold-induced injuries severely limit opportunities and outcomes of hypothermic therapies and organ preservation, calling for better understanding of cold adaptation. Here, by surveying cold-altered chromatin accessibility and integrated CUT&Tag/RNA-seq analyses in human stem cells, we reveal forkhead box O1 (FOXO1) as a key transcription factor for autonomous cold adaptation. Accordingly, we find a nonconventional, temperature-sensitive FOXO1 transport mechanism involving the nuclear pore complex protein RANBP2, SUMO-modification of transporter proteins Importin-7 and Exportin-1, and a SUMO-interacting motif on FOXO1. Our conclusions are supported by cold survival experiments with human cell models and zebrafish larvae. Promoting FOXO1 nuclear entry by the Exportin-1 inhibitor KPT-330 enhances cold tolerance in pre-diabetic obese mice, and greatly prolongs the shelf-life of human and mouse pancreatic tissues and islets. Transplantation of mouse islets cold-stored for 14 days reestablishes normoglycemia in diabetic mice. Our findings uncover a regulatory network and potential therapeutic targets to boost spontaneous cold adaptation.

Simulating a hybridization event of a range-expanding sexual cannibal (Argiope bruennichi)

Abstract Hybridization plays an important role in animal speciation. Mediterranean populations of the Palaearctic wasp spider Argiope bruennichi have recently undergone a range expansion northwards. Adaptation to colder winters was facilitated by introgressed alleles derived from Asian populations, hence the resulting hybrids were able to expand geographically. Argiope bruennichi exhibits a highly complex mating system that includes strong sexual conflict and predisposes the species to behaviours that could facilitate directed hybridization and hybrid stabilization. To test this, we simulated a hybridization event with European and Asian spiders and a backcrossing event with southern and northern European spiders by conducting mate choice experiments and mating trials. We found pronounced differences in the cannibalism and monopolization successes between the populations. Asian male spiders were more successful in monopolizing European females than their European conspecifics and more successful than European males with Asian females. This would have led to an increased proportion of these specific offspring in the hybrid population. Our results suggest the mating system as a driving factor in the directional hybridization of Asian males and European females and the establishment of new northern European populations of A. bruennichi. We found no influences of the mating system on the stabilization of the resulting hybrid populations, probably owing to cold survival adaptations being a more important factor.

Patulin removal in fruit-based products using probiotics and potential probiotics

<p>Patulin (PAT) is a prevalent mycotoxin frequently found in fruit and its derivatives, such as apple, pear, and juices. Despite worldwide attempts to diminish the levels of PAT at every stage of the fruit production process, its contamination rate remains high. This mycotoxin is worrisome due to its potential adverse impacts on human health. Eating PAT-contaminated fruit can lead to acute and chronic health issues. It is established, by the Joint FAO/WHO, a maximum tolerable daily intake for PAT at 0.4 µg/kg/day. Therefore, monitoring for PAT contamination is essential for the safe consumption of fruits and fruit-related products such as juices, purees, ciders, jams, marmalades, vinegar, and dried fruits. PAT has physiochemical properties that enable its survival in cold, hypoxic, acidic, or high-temperature conditions. Ideally, detoxification procedures should aim to reduce the level of toxins to safe levels whilst preserving the nutritional and palatable values of the treated commodity. There are several physical, chemical, and biological techniques available for PAT detoxification. However, while physical and chemical methods can remove PAT, they may also lower the nutrient quality and organoleptic properties of the food. Biological detoxification is an effective, environmentally friendly, easy, and cost-effective method, as established by existing research. It has proven efficacy in food safety research and regulatory compliance programs. Probiotics have been studied for their potential to reduce PAT in foods via different mechanisms (such as adsorption, degradation, and transformation), as well as all their health-beneficial effects. In this review, the reduction of PAT in fruit-based products using probiotics or potential probiotics is widely discussed.<strong></strong></p>

Factors that influence measurements of sweet cherry (Prunus avium) flower bud cold hardiness obtained using differential thermal analysis

Differential thermal analysis (DTA) is a technique commonly used to evaluate the cold hardiness of plant organs that supercool as a means for cold survival. The aim of this study was to evaluate the effect of different pretest bud storage conditions, cooling rates, and bud excision techniques on dormant sweet cherry flower bud low temperature exotherms (LTEs) measured using DTA. Furthermore, this study compared cold hardiness estimates made using DTA and controlled freezing tests. We determined that buds stored at warmer temperatures (12.5 °C and room temperature) for 2–6 h prior to DTA or transported to the lab in a moist environment underwent biologically relevant changes in their apparent sensitivity to cold, as indicated by LTEs produced at warmer temperatures. The DTA cooling rate also significantly affected LTEs, with faster cooling resulting in the production of LTEs at warmer temperatures. Overall, LTEs were comparable among buds with varying amounts of plant material remaining attached to the bud base. It is important to note that the region directly subtending the primordia was always left intact on the buds being compared. This study demonstrated that overall, DTA and controlled freezing tests resulted in comparable measures of cold hardiness. The findings presented in this study are pertinent to researchers interested in conducting cold hardiness measurements in sweet cherry and highlight that consistency in DTA pretest conditions and bud preparation are required to achieve reliable LTE results that can be compared among studies.

Complete genome sequence of a winter season Vibrio facilitates discovery of a novel subclade of cold-adapted species in the albus clade.

In temperate marine climate zones, seasonal changes in water temperature contribute to distinct populations of warm- and cold-water vibrios. We report here the complete genome sequence (BUSCO score=94.8) of the novel strain Vibrio sp. VB16 isolated in late winter from the intertidal zone near Virginia Beach, Virginia, USA with the ability to form colonies at 4 °C. The 5.2 Mbp genome is composed of a large (3.6 Mbp) and small (1.6 Mbp) chromosome. Based on paired average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH), V. sp. VB16 is the same species as V. sp. UBA2437 from a North Sea tidal flat and is closely related to V. sp. DW001 from Antarctic sea ice. Our phylogenomic and bioinformatic analyses placed VB16, UBA2437 and DW001 into a cold-tolerant subclade within the albus clade, along with two non-cold-tolerant subclades. Orthovenn analysis indicated that VB16 and its other albus clade members shared 1544 gene orthologue clusters, including clusters for biosynthesis of polar flagella and tight adhesion pili that predict multiple lifestyles, either free-living or as an opportunistic pathogen within a marine eukaryotic host. The cold-tolerant subclade shared 552 orthologue proteins, including genes known to promote survival in cold or freezing temperatures, such as the eicosapentaenoic acid biosynthetic gene cluster, syp exopolysaccharide gene cluster and novel giant proteins with ice-binding domains. This subclade represents a group of psychrotolerant or 'moderate psychrophile' winter season Vibrio species. The discovery of this subclade opens the door for experimental work on the physiological features, virulence potential and ecological importance of this subclade.

Active microbiota persist in dry permafrost and active layer from Elephant Head, Antarctica.

Dry permafrost is a challenging environment for microbial life due to cold, dry, and often oligotrophic conditions. In 2016, Elephant Head, Antarctica, was confirmed as the second site on Earth to contain dry permafrost. It is geographically distinct from the McMurdo Dry Valleys where dry permafrost has been studied previously. Here, we present the first study of the microbial activity, diversity, and functional potential of Elephant Head dry permafrost. Microbial activity was measured using radiorespiration assays with radiolabeled acetate as a carbon source at 5, 0, and -5°C. Low, but detectable, rates of microbial activity were measured in some samples at 0 and -5°C. This is distinct from previous studies of McMurdo Dry Valley dry permafrost which concluded that dry permafrost represents a cold-arid limit to life on the planet. The isolation of cold-adapted organisms from these soils, including one capable of subzero growth, further supports that the Elephant Head dry active layer and dry permafrost harbor viable microbial life, which may be active in situ. Metagenomic, 16S rRNA gene, and internal transcribed spacer and amplicon sequencing identified similar microbial communities to other Antarctic and cold environments. The Elephant Head microbial community appears to be adapted for survival in cold, dry, and oligotrophic conditions based on the presence of cold adaptation and stress response genes in the metagenomes. Together, our results show that dry permafrost environments do not exclude active microbial life at subzero temperatures, suggesting that the cold, dry soils of Mars may also not be as inhospitable as previously thought.

Oligogalactolipid production during cold challenge is conserved in early diverging lineages.

Severe cold, defined as a damaging cold beyond acclimation temperatures, has unique responses, but the signaling and evolution of these responses are not well understood. Production of oligogalactolipids, which is triggered by cytosolic acidification in Arabidopsis (Arabidopsis thaliana), contributes to survival in severe cold. Here, we investigated oligogalactolipid production in species from bryophytes to angiosperms. Production of oligogalactolipids differed within each clade, suggesting multiple evolutionary origins of severe cold tolerance. We also observed greater oligogalactolipid production in control samples than in temperature-challenged samples of some species. Further examination of representative species revealed a tight association between temperature, damage, and oligogalactolipid production that scaled with the cold tolerance of each species. Based on oligogalactolipid production and transcript changes, multiple angiosperm species share a signal of oligogalactolipid production initially described in Arabidopsis, namely cytosolic acidification. Together, these data suggest that oligogalactolipid production is a severe cold response that originated from an ancestral damage response that remains in many land plant lineages and that cytosolic acidification may be a common signaling mechanism for its activation.

The involvement of Antifreeze protein maxi-like and Cold-shock domain-containing protein genes in cold-induced larval diapause and cold-shock treatment of khapra beetle

The khapra beetle, Trogoderma granarium (Everts) (Coleoptera: Dermestideae), is a cosmopolitan and one of the most destructive pests of various stored grains and grain products. This pest is categorized as a quarantine threat in many countries. The larvae undergo diapause that lasts for several years depending on different stress conditions such as temperature, insecticidal applications, starvation, humidity, crowding, and fecal pellets. When conditions are favorable for the development, diapause terminates and the larva continues its development. In the present study, two cold-regulated genes Antifreeze protein maxi-like (TgAFP) and Cold-shock domain-containing protein E1 (TgCSDP) were identified in the cDNA library of T. granarium. Nucleotide sequences of two unigene cDNAs encoding TgAFP and TgCSDP were verified using RT-PCR and RACE-PCR amplifications. Transcriptional regulations of TgAFP and TgCSDP were examined in cold-induced diapause larvae, cold-shocked larvae, and at different developmental stages. Gene expression pattern of TgAFP revealed the highest mRNA levels during pre-diapause (25 °C) followed by the larvae exposed to 5 °C during the diapause phase. This can be attributable to the protective role of TgAFP against temperature fall. Significant upregulation of TgCSDP at 15 °C might indicate its probable chaperone role in toleration for cold-induced diapause. TgAFP level was downregulated after cold-shock treatment (CST), while it was slightly upregulated by recovery, indicating that it might confer tolerance for the recovery period (RP). The highest TgCSDP expression after the CST might suggest its involvement in response to acute CST. Low abundance of TgAFP expression in each developmental stage might suggest that 33 °C temperature does not induce the synthesis of TgAFP. Significant amount of TgCSDP levels in adults might indicate its putative role in development. These findings suggest that TgAFP and TgCSDP genes might be crucial for cold survival where the T. granarium undergoes its facultative diapause.

Exploring cross-protective effects between cold and immune stress in Drosophila melanogaster

It is well established that environmental and biotic stressors like temperature and pathogens/parasites are essential for the life of small ectotherms. There are complex interactions between cold stress and pathogen infection in insects. Possible cross-protective mechanisms occur between both stressors, suggesting broad connectivity in insect stress responses. In this study, the functional significance of these interactions was tested, as well as the potential role of newly uncovered candidate genes, turandot. This was done using an array of factorial experiments exposing Drosophila melanogaster flies to a combination of different cold stress regimes (acute or chronic) and infections with the parasitic fungus Beauveria bassiana. Following these crossed treatments, phenotypic and molecular responses were assessed by measuring 1) induced cold tolerance, 2) immune resistance to parasitic fungus, and 3) activation of turandot genes. We found various responses in the phenotypic outcomes according to the various treatment combinations with higher susceptibility to infection following cold stress, but also significantly higher acute cold survival in flies that were infected. Regarding molecular responses, we found overexpression of turandot genes in response to most treatments, suggesting reactivity to both cold and infection. Moreover, maximum peak expressions were distinctly observed in the combined treatments (infection plus cold), indicating a marked synergistic effect of the stressors on turandot gene expression patterns. These results reflect the great complexity of cross-tolerance reactions between infection and abiotic stress, but could also shed light on the mechanisms underlying the activation of these responses.

Complete genome of Nakamurella sp. PAMC28650: genomic insights into its environmental adaptation and biotechnological potential

The mechanisms underlying the survival of bacteria in low temperature and high radiation are not yet fully understood. Nakamurella sp. PAMC28650 was isolated from a glacier of Rwenzori Mountain, Uganda, which species belonged to Nakamurella genus based on 16S rRNA phylogeny, ANI (average nucleotide identity), and BLAST Ring Image Generator (BRIG) analysis among Frankineae suborder. We conducted the whole genome sequencing and comparative genomics of Nakamurella sp. PAMC28650, to understand the genomic features pertaining to survival in cold environment, along with high UV (ultraviolet) radiation. This study highlights the role of polysaccharide in cold adaptation, mining of the UV protection-related secondary metabolites and other related to cold adaptation mechanism through different bioinformatics tools, and providing a brief overview of the genes present in DNA repair systems. Nakamurella sp. PAMC28650 contained glycogen and cellulose metabolism pathways, mycosporine-like amino acids and isorenieratene-synthesizing gene cluster, and a number of DNA repair systems. Also, the genome analysis showed osmoregulation-related genes and cold shock proteins. We infer these genomic features are linked to bacterial survival in cold and UV radiation.

Thermal tolerance responses of the two-spotted stink bug, Bathycoelia distincta (Hemiptera: Pentatomidae), vary with life stage and the sex of adults

Temperature tolerance is an essential component of insect fitness, and its understanding can provide a predictive framework for their distribution and abundance. The two-spotted stink bug, Bathycoelia distincta Distant, is a significant pest of macadamia. The main goal of this study was to investigate the thermal tolerance of B. distincta across different life stages. Thermal tolerance indices investigated included critical thermal maximum (CTmax), critical thermal minimum (CTmin), effects of acclimation on CTmax and CTmin at 20, 25, and 30 °C, and rapid heat hardening (RHH), and rapid cold hardening (RCH). The Kruskal-Wallis test was used to explore the effects of life stage and acclimation on CTmax and CTmin and Generalized Linear Models (GLM) for the probability of survival after pre-exposure to RHH at 41 °C for 2 h and RCH at −8 °C for 2 h. CTmax and CTmin varied significantly between life stages at all acclimation temperatures, but CTmin (3.5 °C) varied more than CTmax (2.1 °C). Higher acclimation temperatures resulted in larger variations between life stages for both CTmax and CTmin. A significant acclimation response was observed for the CTmax of instar 2 (1.7 °C) and CTmin of females (2.7 °C) across acclimation temperatures (20–30 °C). Pre-exposure significantly improved the heat and cold survival probability of instar 2 and the cold survival probability of instar 3 and males. The response between life stages was more variable in RCH than in RHH. Instar 2 appeared to be the most thermally plastic life stage of B. distincta. These results suggest that the thermal plastic traits of B. distincta life stages may enable this pest to survive in temperature regimes under the ongoing climate change, with early life stages (except for instar 2) more temperature sensitive than later life stages.

Rising floor and dropping ceiling: organ heterogeneity in response to cold acclimation of the largest extant amphibian.

Low temperature imposes strong selective pressure on ectotherms. To maximize their overall fitness under cold conditions, the ectotherms may either try to maintain their physiological activities through metabolic compensation or enter into metabolic depression; however, some species adopt both strategies to cope with different degrees of cold. Nevertheless, how these two seemingly opposite strategies are coordinated has rarely been elucidated. Here, we investigated the molecular strategy underlying the cold acclimation of Andrias davidianus, the largest extant amphibian, using multi-organ metabolomics and transcriptomics. The results showed remarkable organ heterogeneity in response to cold. While most organs showed transcriptional upregulation of metabolic processes, the heart exhibited downregulation. This heterogeneity explained the adaptive reorganization in resource allocation, which compensates for metabolic maintenance by compromising growth. Importantly, the cardiac function might constitute a ‘ceiling’ to constrain the space for compensation, especially under colder conditions. Additionally, the opposite transcriptional regulation of oxidative phosphorylation and other pathways might also shape the overall metabolic capacity under cold conditions. The heterogeneity in cold responses may have directed a shift in cold adaptive strategy from compensation to depression with a drop in temperature. These results provide a novel insight into the regulatory mechanisms underlying cold survival strategies of ectotherms.

A mutation to a fish ice-binding protein synthesized in transgenic Caenorhabditis elegans modulates its cold tolerance

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.

Ferritin-mediated iron detoxification promotes hypothermia survival in Caenorhabditis elegans and murine neurons

How animals rewire cellular programs to survive cold is a fascinating problem with potential biomedical implications, ranging from emergency medicine to space travel. Studying a hibernation-like response in the free-living nematode Caenorhabditis elegans, we uncovered a regulatory axis that enhances the natural resistance of nematodes to severe cold. This axis involves conserved transcription factors, DAF-16/FoxO and PQM-1, which jointly promote cold survival by upregulating FTN-1, a protein related to mammalian ferritin heavy chain (FTH1). Moreover, we show that inducing expression of FTH1 also promotes cold survival of mammalian neurons, a cell type particularly sensitive to deterioration in hypothermia. Our findings in both animals and cells suggest that FTN-1/FTH1 facilitates cold survival by detoxifying ROS-generating iron species. We finally show that mimicking the effects of FTN-1/FTH1 with drugs protects neurons from cold-induced degeneration, opening a potential avenue to improved treatments of hypothermia.

Cold and exogenous calcium alter Allium fistulosum cell wall pectin to depress intracellular freezing temperatures.

De-methyl esterification of homogalacturonan and subsequent cross-linking with Ca2+ is hypothesized to enhance the freezing survival of cold acclimated plants by reducing the porosity of primary cell walls. To test this theory, we collected leaf epidermal peels from non- (23/18 °C) and cold acclimated (2 weeks at 12/4 °C) Japanese bunching onion (Allium fistulosum L.). Cold acclimation enhanced the temperature at which half the cells survived freezing injury by 8 °C (LT50 =-20 °C), and reduced tissue permeability by 70-fold compared with non-acclimated epidermal cells. These effects were associated with greater activity of pectin methylesterase (PME) and a reduction in the methyl esterification of homogalacturonan. Non-acclimated plants treated with 50mM CaCl2 accumulated higher concentrations of galacturonic acid, Ca2+ in the cell wall, and a lower number of visible cell wall pores compared with that observed in cold acclimated plants. Using cryo-microscopy, we observed that 50mM CaCl2 treatment did not lower the LT50 of non-acclimated cells, but reduced the lethal intracellular ice nucleation to temperatures observed in cold acclimated epidermal cells. We postulate that the PME-homogalacturonan-mediated reduction in cell wall porosity is integral to intracellular freezing avoidance strategies in cold acclimated herbaceous cells.