Antarctic sea anemones are dominant benthic predators, yet their molecular adaptive strategies to polar environments remain poorly understood. Urticinopsis antarctica is one of the most abundant Antarctic actiniarians, but until now it has lacked any integrated molecular characterisation This study provides the first comprehensive analysis combining de novo transcriptomics with histological and cytological observations to investigate immune and stress-response mechanisms in this azooxanthellate anthozoan. Gene Ontology and Pfam-based analyses revealed a broad and evolutionarily conserved innate immune repertoire, including Toll-like receptor, NF-κB, JAK-STAT and NOD-like receptor pathways, together with numerous transcripts of pattern-recognition domains such as TIR, NACHT, LRR and C-type lectins. Integration with signal peptide prediction demonstrated a significant enrichment of immune- and stress-related genes within the secretome, indicating a strong bias toward extracellular defence strategies. Histological analyses revealed a typical a diploblastic organization with abundant cnidocytes, mucous cells and migratory amoeboid cells, consistent with an epithelial-centred immune system. The absence of algal symbionts was confirmed at both molecular and tissue levels. Together, these findings indicate that U. antarctica maintains a complex, flexible immune and stress-response architecture despite extreme thermal stability and resource limitation. This new molecular and cellular baseline establishes U. antarctica as a valuable reference for understanding resilience, cold adaptation, and the evolution of immunity in polar anthozoans, and provides a foundation for future functional and experimental work on the responses of Antarctic benthic species to environmental change.

Hibernation is an amazing survival skill that some animals use to cope with natural challenges, and cold is the main stimulus. While most hibernation studies focus on long-term cold adaptation mechanisms, the rapid physiological adjustments triggered by short-term cold exposure may also be key components in the initiation of hibernation. This study focused on 20 Chinese Moccasin (Deinagkistrodon acutus), divided into two groups: an active group (n = 10) and a short-term cold exposure group (n = 10). Using serum biochemistry, serum antioxidant measurements, and liver transcriptome technology, the study explored the effects of short-term cold exposure on snake serum lipids, antioxidant capacity, and apoptosis. The results showed that the levels of cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were significantly lower in cold exposure snakes compared to the active group, whereas total bile acid was higher in the cold exposure group; serum antioxidant indicators glutathione peroxidase, superoxide dismutase, and total antioxidant capacity were lower in cold exposure snakes than in active snakes, whereas the concentration of malondialdehyde was higher in cold exposure snakes. The liver transcriptome revealed that more pro-apoptotic genes were upregulated in active snakes, whereas there were more upregulated anti-apoptotic genes in cold exposure snakes, and the ratio of anti-apoptotic to pro-apoptotic genes was significantly higher in cold exposure snakes than in active snakes. This study not only elucidates the physiological effects of short-term cold exposure on snakes but also advances our understanding of the adaptive mechanisms underlying the transition from activity to hibernation in ectothermic animals.

Proteomic analysis reveals the mechanism of cold tolerance in black porgy (Acanthopagrus schlegelii) via ribosome hibernation, metabolic remodeling, and antioxidant coordination.

We determined the complete genome sequence of Pseudomonas sp. PAMC25886 from alpine glacier cryoconite. The genome comprises a single circular chromosome of 7,035,536 bp with 61.2% G + C content and 6,409 protein-coding genes. This genome provides insight into aromatic compound degradation and cold adaptation in polar environments.

Metabolomics analysis reveals potential response mechanisms to cold stress in Altay sheep.

Sea buckthorn (Hippophae rhamnoides L.) is a typical cold-tolerant woody plant enriched in serotonin (5-hydroxytryptamine, 5-HT), yet the molecular basis of its chilling adaptation remains largely unclear. Here, we show that the exogenous application of serotonin significantly enhanced seedling growth and survival under 4 °C stress. Chilling stress markedly induced the expression of HrT5H1, a key gene encoding an enzyme involved in serotonin biosynthesis. Y1H, dual-luciferase reporter, and EMSA assays demonstrated that the bZIP transcription factor HrHY5 directly binds to and activates the HrT5H1 promoter. Overexpression of HrHY5 or HrT5H1 in tobacco and sea buckthorn hairy roots promoted endogenous serotonin accumulation, alleviated ROS damage, and improved cold tolerance. These findings establish the HrHY5-HrT5H1 regulatory module as a key mechanism underlying serotonin-mediated chilling resistance, providing new insights into the molecular basis of cold adaptation in woody plants.

Retrogenes, which formed via retrotransposon-mediated processes, are important drivers of genetic innovation and adaptive evolution. Although most plant genomes harbor abundant LTR retrotransposons that facilitate retrogene formation, studies on retrogenes in wild plants remain limited. Crucihimalaya himalaica, a close relative of Arabidopsis thaliana endemic to the Qinghai-Tibet Plateau (QTP) region, provides a valuable model for investigating plant adaptation to high-altitude environments. We report an updated high-quality, chromosome-level genome assembly of C. himalaica (scaffold N50: 30.99Mb) and transcriptomic data under cold stress. We identified 240 retrogenes (90% with complex structures), predominantly located in gene-rich regions, and found that LTR retrotransposons are more abundant in the upstream regions of C. himalaica retrogenes than in those of Arabidopsis thaliana. Under cold stress, retrogenes were significantly more likely to be differentially expressed compared to background genes, with 89.6% of them displaying expression patterns distinct from their parental genes. These differentially expressed retrogenes were evolutionarily older, under stronger purifying selection, and enriched in carbohydrate metabolism, transmembrane transport, and calcium-mediated signaling. Functional assays in A. thaliana demonstrated that mutants of C. himalaica retrogenes homologs exhibited enhanced freezing tolerance, likely via cell wall remodeling. The recently formed retrogene XMJChr05g02504 exhibited structural divergence, cold-induced expression, and signatures of positive selection, suggesting functional innovation of retrogene potentially contributing to C. himalaica's adaptation to the cold environment of QTP region. Our study provides a high-quality genome assembly of C. himalaica and reveals the evolutionary dynamics and roles of retrogenes, offering new insights into the genetic mechanisms underlying plant adaptation to high-altitude environments.

Qingke (hull-less barley), a staple crop on the Qinghai-Xizang Plateau, has evolved unique stress tolerance mechanisms. Cold stress damages plants through ice formation and oxidative stress, triggering antioxidant systems and stress-related gene expression. Long non-coding RNAs (lncRNAs) are known to regulate these responses. Physiological analysis revealed a dynamic defense strategy: antioxidant systems (SOD/POD) activated early (12h), shifting to osmotic regulation (soluble protein) later (48h). Membrane damage (MDA/conductivity) increased under stress but showed repair during recovery. Transcriptome profiling identified a core set of 317 differentially expressed genes enriched in catalytic and stress-response functions. Early stress (12h) predominantly involved hormone (jasmonate) and pathogen defense pathways. Later (48h), protein synthesis (ribosome) and secondary metabolism (phenylpropanoid) were upregulated. Recovery (24h) activated carbon metabolism and fatty acid degradation. Furthermore, specific lncRNAs (e.g., LNC_003210) were identified as potential regulators of photosynthesis-related genes. Qingke adapts to cold through phased physiological responses (antioxidant defense, osmoregulation) and dynamic metabolic reprogramming. LNC_003210 may play a key role in cold adaptation by regulating photosynthesis.

Medicago varia Martyn. exhibited enhanced cold tolerance that was correlated with coordinated adjustments in root xylem structure, modulation of cell wall components, and reprogramming of secondary metabolism, suggesting an integrated adaptive mechanism linking structure, composition, and metabolism. Alfalfa, as one of the most valuable perennial forage crops, is cultivated worldwide. However, its productivity is being threatened by extreme cold events. This study tried to understand the mechanisms of Medicago varia Martyn. (MvM) and Medicago sativa L. (MS) to combat cold climate through chemical, anatomical, spectral, and metabolic analysis. The results showed that MvM had higher content of neutral detergent soluble (74.60%) and soluble proteins (0.15mg/g), yet lower content of cellulose (10.45%) as compared to MS. Additionally, fourier transform infrared spectroscopy analysis also confirmed differences in functional groups associated with cellulose, hemicellulose, and lignin between MS and MvM. The smaller diameter and higher density of vessel in MvM were consistent with anatomical traits predicted to enhance hydraulic safety under freeze-thaw stress. Metabolomic profiling identified 831 and 604 differentially accumulated metabolites in MvM roots at flowering and senescence stages, with significant enrichment in pathways related to isoflavonoid biosynthesis, arginine/proline metabolism, and tryptophan metabolism. Key metabolites, such as Calceolarioside B, hydroxytyrosol, and Medicarpin, were markedly up-regulated in MvM. Hierarchical clustering highlighted species-specific accumulation of phenylpropanoids and alkaloids in MvM. These findings suggested that the enhanced cold tolerance of MvM might involve in coordinated structural adjustments in root xylem, modulation of cell wall composition, and reprogramming of secondary metabolism. This study provided new insights into the integrative mechanisms of cold adaptation in alfalfa and supported the development of cold-resistant varieties for cultivation in high-latitude regions.

The Tianshan Mountains, which host two native subspecies of western honeybees, represent the easternmost natural distribution limit of Apis mellifera. The managed Xinjiang black honeybee (XJ), introduced a century ago and designated as a Chinese National Animal Genetic Resource, has expanded rapidly under anthropogenic management. However, this expansion simultaneously threatens populations of native subspecies Apis mellifera sinisxinyuan and Apis mellifera pomonella. Herein, we performed the first whole-genome resequencing of the XJ population and analyzed whole-genome data from 19 XJ workers and 172 global A. mellifera samples to clarify the evolutionary history of XJ and evaluate its interactions with native bees. Population structure and phylogenomic analyses showed that XJ clustered within C lineage but formed a divergent clade distinct from other C lineage subspecies, with the closest affinity to Apis mellifera carnica (FST = 0.053). Despite higher inbreeding than other C lineage subspecies, XJ displayed comparatively higher genetic diversity (Θπ = 2.15 × 10-3) and heterozygosity (0.0028) than other C lineage populations (0.0015), although XJ's value falls within the global range of A. mellifera. This genetic pattern can be attributed to substantial introgression (~10%-15%) from the M lineage, specifically from the native A. m. sinisxinyuan. TreeMix and F-branch analysis identified significant gene flow from A. m. sinisxinyuan into the ancestral population of the XJ. Functional enrichment analysis suggested that genes within introgressed regions are involved in cold adaptation and foraging efficiency, and independent transcriptome validation confirmed differential expression of key candidate genes (e.g., LOC552291/MCM4) within these introgressed regions. Overall, our findings indicate that XJ represents an introduced population that has undergone regional adaptation, facilitated by the introgression of potentially adaptive alleles from native taxa. This case underscores the need for conservation strategies balancing management of economically valuable populations with protection of native lineages from genetic swamping and ecological competition.

Comparative genomics provides insights into the cold adaptation of endophytic fungi associated with Deschampsia antarctica.

A hierarchical ScMYB11L–ScZAT1–ScDREB1A module defines a derepression pathway for cold-response regulation in sugarcane

Plants adapt to winter through two key strategies: vernalization, which enables flowering after prolonged cold, and cold acclimation, which enhances freezing tolerance. Although both require long-term cold perception, how they are integrated remains unclear. We identify the cytosolic chaperonin TCP1 Ring Complex (TRiC)/Chaperonin Containing TCP1 (CCT) complex as a critical upstream regulator of both processes in Arabidopsis. A missense mutation in CCT8 impairs vernalization and freezing tolerance, with reduced expression of VERNALIZATION INSENSITIVE 3 (VIN3) and C-REPEAT BINDING FACTORs (CBFs), central regulators of these processes. TRiC is required for the accumulation of REVEILLE (RVE) transcription factors, core components of the circadian oscillator. In particular, RVE8 activates VIN3 and CBF expression by binding their promoters. Genetic and biochemical evidence shows that TRiC promotes RVE abundance during cold exposure, thereby contributing to VIN3-associated epigenetic silencing of FLOWERING LOCUS C and CBF-dependent freezing tolerance. VIN3 expression is also circadian-regulated and preferentially induced by cold during the subjective day, revealing circadian gating. These findings uncover a TRiC-RVE-VIN3/CBF regulatory framework linking circadian signaling with seasonal cold adaptation, and show how a core protein-folding machinery modulates transcription factors to coordinate developmental processes and stress responses in winter.

Low temperature remains a major bottleneck in silage fermentation, especially in cold regions and high-altitude areas. This study investigated the regulatory role of compatible solutes in enhancing the cold adaptation of Pediococcus pentosaceus OL77 and their synergistic application in oat silage under suboptimal temperatures (5°C-15°C). RT-qPCR analysis showed that expression of the cold shock protein gene CspP was sharply induced at 5°C, indicating its central role in cold-stress response. Exogenous trehalose and betaine significantly downregulated CspP expression, promoted bacterial growth, accelerated acid production, and enhanced metabolic stability. In silage trials, the OL77 + trehalose treatment resulted in improved lactic acid production, reduced ammonia nitrogen accumulation, and suppression of yeasts and molds across all tested temperatures. A random forest model identified 11 core variables critical for silage quality, highlighting the combined treatment as the most effective across all temperature conditions. These findings offer a robust theoretical and practical framework for enhancing low-temperature silage through synergistic application of compatible solutes and psychrophilic lactic acid bacteria and demonstrate the potential of machine learning in fermentation process optimization.IMPORTANCELow temperature is a major constraint on silage fermentation in cold and high-altitude regions. This study shows that trehalose improves the cold adaptation and fermentation performance of Pediococcus pentosaceus OL77, highlighting a practical strategy for improving oat silage quality under suboptimal temperatures.

Bolting height is a key genetic trait that affects the stress tolerance, environmental adaptation, and winter survival of Brassica napus winter rapeseed. It is particularly important for enhancing winter survival in the arid–frigid regions. This study aimed to elucidate the genetic relationship between bolting height and cold stress tolerance, thereby supporting breeding for enhanced cold tolerance. Ninety-five winter rapeseed accessions were used in this study. Through both spring and autumn sowing trials, the dynamic changes in bolting height under different environments were systematically analyzed, and the genetic stability of bolting height as well as its correlation with cold tolerance were clarified. Bolting height showed consistent variation trends between spring and autumn sowing trials, exhibiting high genetic stability. It displayed an extremely significant negative correlation with cold tolerance: genotypes with lower bolting height possessed stronger cold tolerance. The regulatory mechanism underlying low bolting and cold tolerance was revealed at cellular and molecular levels. Low bolting accessions exhibited flat and broad shoot apical meristems, with small and compact cells, a high nucleoplasmic ratio, and indistinct vacuoles. The gibberellin synthesis gene BnaA06g24070D was downregulated, while the key cold-tolerant gene BnCBF5 was upregulated. Exogenous hormone treatment preliminarily verified the causal regulatory effect of bolting height on cold tolerance. In both spring and autumn sowing trials, bolting height at the initial flowering stage showed an extremely significant positive correlation with vernalization index, with correlation coefficients of 0.80 and 0.78, respectively. Lower bolting height corresponded to a smaller vernalization index and stronger temperature sensitivity. Moreover, bolting height at the initial flowering stage showed an extremely significant negative correlation with comprehensive cold tolerance scores, with correlation coefficients of −0.77 and −0.80, respectively. Low-bolt materials had significantly higher overwintering rates and comprehensive cold tolerance scores, as well as a markedly lower semi-lethal temperature (LT50), compared with high-bolt accessions. Low-bolt accessions presented significantly prolonged bolting stage, bud stage, initial flowering stage, and whole growth durations, and their agronomic trait stability across years was significantly superior to that of high-bolt accessions. This study confirmed that low bolting height is a crucial breeding trait for the cold tolerance of winter rapeseed, and thus an important selection indicator for the cold tolerance improvement of winter rapeseed in arid–frigid regions in northern China.

SlSNAT1-dependent melatonin synthesis enhances tomato cold tolerance by promoting SlNCED1-mediated ABA accumulation, thereby strengthening antioxidant capacity, maintaining photosynthesis, and reducing ROS-induced membrane damage under cold stress. Cold stress limits greenhouse tomato growth by suppressing photosynthesis, promoting reactive oxygen species (ROS) accumulation, and disrupting membrane integrity, which ultimately reduces yield. Melatonin (MT) enhances plant stress tolerance, but its role in regulating cold adaptation in tomato remains unclear. Here, we used CRISPR/Cas9-generated SlSNAT1 mutants and VIGS-mediated SlNCED1-silenced plants to test how MT influences abscisic acid (ABA) biosynthesis and cold tolerance. The SlSNAT1 mutation markedly reduced endogenous MT, decreased the expression of ABA biosynthetic genes (SlNCED1/2), and increased the expression of ABA catabolic genes (SlCYP707A1/2), thereby weakening cold-induced ABA accumulation. Accordingly, the mutants showed higher membrane permeability and ROS levels, together with lower photosynthetic efficiency and reduced antioxidant enzyme activity under cold stress. SlNCED1 silencing further reduced ABA accumulation and antioxidant capacity. By contrast, exogenous MT partly restored ABA content, antioxidant enzyme activity, and photosynthetic performance, thereby alleviating cold injury. Correlation analysis showed that ABA content was positively associated with antioxidant activity, photosynthetic traits, and osmotic regulators, but negatively associated with ROS levels and membrane damage. MT synthesis mediated by SlSNAT1 promotes ABA accumulation, at least in part, by enhancing SlNCED1 expression. These findings clarify a mechanism underlying MT-ABA cross talk during cold stress and suggest a potential strategy to enhance cold tolerance in greenhouse tomato.

Morphometric characteristics of the winter hair coat were studied in Yakut horses of different age and sex groups (n=42) by clipping samples in the shoulder region, followed by measurement of hair length, density, mass, hair diameter, and medulla diameter.In winter, a longer and denser coat is formed, primarily due to the growth of fine undercoat-type hairs. Against the background of an overall decrease in the absolute diameter of the medulla, a significant increase in its relative proportion (77.7–84.1% of total hair diameter) was observed, indicating a functional restructuring of hair structure toward enhanced thermal insulation properties.In young horses, hair density per 1 cm² decreases with age (from 1653 to 1299 hairs/cm²) while hair thickness simultaneously increases, likely due to skin growth and stretching with a relatively stable number of hair follicles. Sexual dimorphism is evident in the highest hair density in stallions (1531 hairs/cm²), greater hair thickness in geldings (96.8 μm) and mares (78.0 μm) compared to stallions, as well as maximum medulla development in 18-month-old youngsters (84.1%) and working geldings (83.7%).Comparative analysis revealed that in Yakut horses the medulla is present and well-developed in all hair types (unlike in Yakut cattle — ~40% and reindeer — predominantly in guard hairs). The results suggest that the pronounced development of the medulla across all hair types represents one of the key morphological adaptations of the Yakut horse to extremely low temperatures (down to –70 °C), providing effective thermal insulation due to the trapped immobile air within the medulla.

Low temperature alters bacterial growth and surface-linked behaviors; however, the genetic role of the associated pilus systems in cold adaptation remains unclear. Here, we used the psychrotolerant tundra isolate Pseudomonas fragi D12 as a model to investigate the transcriptional responses and functional divergence of three fimbrial genes, fimA, fimC, and fimD, through a combination of transcriptome analysis and gene knockout/overexpression assays. RNA-seq analysis revealed that extreme cold stress (4°C) triggered a robust induction of the fim cluster and an adjacent regulatory module comprising an Arc-family DNA-binding protein and an EAL-domain phosphodiesterase. qRT-PCR confirmed the RNA-seq trends. Functional assays demonstrated distinct ecological roles; deletion of fimA increased swimming but reduced swarming, whereas overexpression of fimA led to an increase in swarming. fimC overexpression enhanced swimming, whereas fimC deletion decreased swarming. fimD deletion increased swimming and reduced swarming, while fimD overexpression suppressed swarming. Temperature-gradient experiments further showed that across the three temperatures examined (4°C, 15°C, and 30°C), motility and biofilm formation were the highest at 15°C. Transmission electron microscopy associated these behavioral changes with altered fimbrial density and organization, and growth-curve analysis indicated no major defects in planktonic proliferation. In combination, the data point to a fimbrial apparatus that is transcriptionally responsive to cold and may mechanically modulate the coupling of a single polar flagellum to liquid and solid interfaces, while the genomic context of fimACD remains compatible with local modulation of cyclic di-GMP signaling that has yet to be examined directly.IMPORTANCELow-temperature environments are widespread in nature; however, the genetic contributions of bacterial surface appendages to cold-associated behavioral adaptation remain poorly understood. Our work, using the psychrotolerant tundra isolate Pseudomonas fragi D12, offers a tractable example in which a single chaperone-usher fimbrial operon exerts a marked influence on how cells move and form biofilms across the three temperatures examined (4°C, 15°C, and 30°C). By combining transcriptomics, defined genetic changes, and imaging, we connect cold-inducible expression of the fimACD locus with altered fimbrial architecture, motility behavior, and biofilm robustness, while separating these effects from bulk growth. The results support a view in which fimbriae in a psychrotolerant bacterium operate as adjustable elements that influence when cells favor long-range swimming versus surface-associated growth. Such information may provide direct genetic and phenotypic evidence for functional specialization of the fimbrial system under cold stress, offering new insight into the molecular strategies that enable microbial survival in low-temperature habitats.

This study identified a novel psychrophilic marine microalga with a 'raphe-like' structure in the cell wall and rich in polyunsaturated fatty acids, revealing its cold adaptation mechanisms by integrated physiological and omics analysis. Microalgae are pivotal primary producers in global ecosystems, thriving across diverse habitats. However, the mechanisms that enable microalgae to thrive in cold environments remain poorly understood. In this study, a novel green microalga (designated LWD-1) was isolated from the Bohai Sea and phylogenetically classified as Chlamydomonas sp. through 18S rDNA sequencing and transcriptomic classification. Notably, a distinctive 'raphe-like' structure was observed across the entire cell wall of the LWD-1 strain, a novel morphological trait not previously reported in Chlorophyta. LWD-1exhibited optimal growth at 10°C, with strongly reduced growth above 15°C and showed lethality at 25°C. When cultivated at 10°C, LWD-1 exhibited enhanced photosynthetic efficiency, starch and triacylglycerol accumulation compared with the moderate temperature (20°C). Moreover, membrane lipids and polyunsaturated fatty acid (PUFA) content significantly increased in LWD-1 at 10°C compared with 20°C. Notably, the galactolipid sulfoquinovosyldiacylglycerol (SQDG) was the most abundant membrane lipid in LWD-1, which was significantly increased at 10°C compared to 20°C. Furthermore, transcriptomic analysis revealed that genes involved in carbon fixation, photosynthesis, glycerophospholipid biosynthesis and nitrogen metabolism were upregulated in LWD-1 at the lower temperature. In addition, we identified key genes involved in cold adaptation in LWD-1 through transcriptomic and proteomic analysis. Taken together, these results indicate that the novel psychrophilic green microalga LWD-1 is a promising platform for producing PUFA, oil and starch. This study also provides key insights into algal adaptation to cold environments.

This study investigated the adaptive mechanisms of silver pomfret in response to chronic low-temperature stress, focusing on the tissue-specific expression patterns of the key lipid metabolism gene scd1 and its central role in regulating hepatic apoptosis. A gradual cooling experiment (from 18 °C to 6 °C) was conducted to analyze the spatiotemporal expression profiles of ten lipid metabolism-related genes across six tissues. The results revealed that the most pronounced changes were observed in the heart, liver, and gills. The liver and heart rapidly activated genes involved in lipid breakdown and utilization from 16 to 12 °C for immediate energy supply, while gill tissue upregulated the pi3k/p450/srebp/scd1 pathway at 10 °C to remodel membrane lipids against sustained stress. Further in vitro hepatocyte experiments demonstrated that scd1 expression directly regulated cell survival and apoptosis under low temperatures. Knockdown of scd1 significantly promoted apoptosis, whereas its overexpression effectively suppressed it. Moreover, scd1 expression was intricately modulated by its upstream regulators srebp (positive regulation) and pparγ (showing potential negative feedback at specific temperatures). This study systematically elucidates the pivotal role of scd1-mediated lipid metabolic reprogramming in the cold adaptation of silver pomfret, providing a crucial theoretical foundation for deciphering the molecular mechanisms of cold tolerance and for breeding cold-resistant strains.