Long-term Cold Exposure Research Articles

Cotranscriptional splicing is required in the cold to produce COOLAIR isoforms that repress Arabidopsis FLC

Plants use seasonal cold to time the transition to reproductive development. Short- and long-term cold exposure is registered via parallel transcriptional shutdown and Polycomb-dependent epigenetic silencing of the Arabidopsis thaliana major flowering repressor locus FLOWERING LOCUS C (FLC). The cold-induced antisense transcripts (COOLAIR) determine the dynamics of FLC transcriptional shutdown, but the thermosensory mechanisms are still unresolved. Here, through a forward genetic screen, we identify a mutation that perturbs cold-induced COOLAIR expression and FLC repression. The mutation is a hypomorphic allele of SUPPRESSORS OF MEC-8 AND UNC-52 1 (SMU1), a conserved subunit of the spliceosomal B complex. SMU1 interacts in vivo with the proximal region of nascent COOLAIR and RNA 3' processing/cotranscriptional regulators and enhances COOLAIR proximal intron splicing to promote specific COOLAIR isoforms. SMU1 also interacts with ELF7, an RNA Polymerase II Associated Factor (Paf1) component and limits COOLAIR transcription. Cold thus changes cotranscriptional splicing/RNA Pol II functionality in an SMU1-dependent mechanism to promote two different isoforms of COOLAIR that lead to reduced FLC transcription. Such cotranscriptional mechanisms are emerging as important regulators underlying plasticity in gene expression.

Immune response to cold exposure: Role of γδ T cells and TLR2-mediated inflammation.

The mammalian body possesses remarkable adaptability to cold exposure, involving intricate adjustments in cellular metabolism, ultimately leading to thermogenesis. However, cold-induced stress can impact immune response, primarily through noradrenaline-mediated pathways. In our study, we utilized a rat model subjected to short-term or long-term mild cold exposure to investigate systemic immune response during the cold acclimation. To provide human relevance, we included a group of regular cold swimmers in our study. Our research revealed complex relationship between cold exposure, neural signaling, immune response, and thermogenic regulation. One-day cold exposure triggered stress response, including cytokine production in white adipose tissue, subsequently activating brown adipose tissue, and inducing thermogenesis. We further studied systemic immune response, including the proportion of leukocytes and cytokines production. Interestingly, γδ T cells emerged as possible regulators in the broader systemic response, suggesting their possible contribution in the dynamic process of cold adaptation. We employed RNA-seq to gain further insights into the mechanisms by which γδ T cells participate in the response to cold. Additionally, we challenged rats exposed to cold with the Toll-like receptor 2 agonist, showing significant modulation of immune response. These findings significantly contribute to understanding of the physiological acclimation that occur in response to cold exposure.

Cold tolerance of the mealybug parasitoid Anagyrus vladimiri

We investigated the lower thermal limits of Anagyrus vladimiri Triapitsyn (Hymenoptera: Encyrtidae), a natural enemy of mealybugs. Parasitoids were cooled to measure supercooling points and the lower lethal temperature LLT50. To investigate survival after long-term cold exposure, parasitoid adults and eggs, larvae, and pupae within their host mummy were gradually acclimated. Adults were then exposed for three days to 7 °C, 5 °C, 3 °C, and 1 °C, and immatures for varying durations to 5, 1, and − 4 °C. Parasitoids were investigated for survival and reproduction. To assess the impact of fluctuating temperature, parasitoid pupae were subjected to daily warming to 10 °C from baseline temperatures of 5 °C, 1 °C, and − 4 °C during four-day-cold exposure. Finally, eggs, pupae and adults were exposed to winter conditions in Switzerland in a semi-field setup. The LLT50 was − 17.24 °C for adults and 0.94 °C for pupae. Both values were above the supercooling points. No adult survived three days at 3 °C and lower. Likewise, no emergence occurred from eggs or larvae exposed for four days and longer to 1 °C or seven days to 5 °C. Pupae were cold-hardier surviving seven days at 5 °C and three days at 1 °C. Parasitoids surviving cold exposure were still able to reproduce. Daily warming decreased emergence of cold exposed pupae at a baseline temperature of 1 °C but not at 5 °C and − 4 °C. No eggs, pupae and adults survived winter conditions in the semi-field experiment. We thus consider A. vladimiri a chill-susceptible species with very limited cold-tolerance of the investigated population and low chances of survival during winter in Northern Switzerland.

SCD1 sustains brown fat sympathetic innervation and thermogenesis during the long-term cold exposure

Brown fat adipose tissue (BAT) is a therapeutic potential target to improve obesity, diabetes and cold acclimation in mammals. During the long-term cold exposure, the hyperplastic sympathetic network is crucial for BAT the maintain the highly thermogenic status. It has been proved that the sympathetic nervous drives the thermogenic activity of BAT via the release of norepinephrine. However, it is still unclear that how the thermogenic BAT affects the remodeling of the hyperplastic sympathetic network, especially during the long-term cold exposure. Here, we showed that following long-term cold exposure, SCD1-mediated monounsaturated fatty acid biosynthesis pathway was enriched, and the ratios of monounsaturated/saturated fatty acids were significantly up-regulated in BAT. And SCD1-deficiency in BAT decreased the capacity of cold acclimation, and suppressed long-term cold mediated BAT thermogenic activation. Furthermore, by using thermoneutral exposure and sympathetic nerve excision models, we disclosed that SCD1-deficiency in BAT affected the thermogenic activity, depended on sympathetic nerve. In mechanism, SCD1-deficiency resulted in the unbalanced ratio of palmitic acid (PA)/palmitoleic acid (PO), with obviously higher level of PA and lower level of PO. And PO supplement efficiently reversed the inhibitory role of SCD1-deficiency on BAT thermogenesis and the hyperplastic sympathetic network. Thus, our data provided insight into the role of SCD1-mediated monounsaturated fatty acids metabolism to the interaction between thermogenic activity BAT and hyperplastic sympathetic networks, and illustrated the critical role of monounsaturated fatty acids biosynthetic pathway in cold acclimation during the long-term cold exposure.

Morphology of the heart during the period of progressive growth in conditions of prolonged exposure to low temperatures

Annotation. The aim of the research is to study the cardiac morphology during the period of growth under prolonged exposure to low temperatures. The main group consisted of outbred white rats (260 males and 190 females) undergoing active development, aged 4 weeks at the beginning of the experiment, and was kept in a room with an air temperature of +4±1 °C. The control group of animals was kept in a room with an air temperature of +20±10 °C. The experiment lasted for sixteen weeks. Research methods: macromorphometric study of the heart, histological study of paraffin sections, and ultrastructural study. Micromorphometric study was performed on semi-thin sections stained with 0.1% solution of toluidine blue at an ocular magnification of 10 and objective of 90, using a multi-purpose test system of short segments (Weibel grid) and an automatic analyzer of microscopic images “Integral-2MT”. PAS stain by A.L.Shabadash was used to detect glycogen, and the number of glycogen granules per unit area was counted on electronograms at a magnification of 20000 using a 1 cm2 area square. The stereological study of the electronograms was carried out at a magnification of 8000 using a Weibel grid. The statistical processing of the obtained results was carried out using the SPSS statistical program package, STATISTICA v. 10.0. It was found that the adaptation of the myocardium to the cold occurs according to the universal mechanism of adaptation to various extreme conditions associated with a deficit of energy metabolism. Therefore, the effect of cold can be regarded as non-specific. Based on the conducted research, the following stages of the adaptation process are defined: 1) short-term stress reaction (first 5 days); 2) myocardial hypertrophy (from 2nd to 6th weeks); 3) long-term, stable adaptation (more than 6 weeks). Morphological criteria for myocardial adaptation to long-term cold exposure have been identified: 1) physiological hypertrophy of the myocardium, mainly of the right ventricle; 2) the energy reserve of cardiomyocytes in the form of mitochondrial hyperplasia and glycogen accumulation. We plan to study the microcirculatory bed of the myocardium during the adaptation of the body to prolonged action of low temperature in the future.

Low-temperature and circadian signals are integrated by the sigma factor SIG5

Chloroplasts are a common feature of plant cells and aspects of their metabolism, including photosynthesis, are influenced by low-temperature conditions. Chloroplasts contain a small circular genome that encodes essential components of the photosynthetic apparatus and chloroplast transcription/translation machinery. Here, we show that in Arabidopsis, a nuclear-encoded sigma factor that controls chloroplast transcription (SIGMA FACTOR5) contributes to adaptation to low-temperature conditions. This process involves the regulation of SIGMA FACTOR5 expression in response to cold by the bZIP transcription factors ELONGATED HYPOCOTYL5 and ELONGATED HYPOCOTYL5 HOMOLOG. The response of this pathway to cold is gated by the circadian clock, and it enhances photosynthetic efficiency during long-term cold and freezing exposure. We identify a process that integrates low-temperature and circadian signals, and modulates the response of chloroplasts to low-temperature conditions.

Association of Prenatal and Postnatal Exposures to Warm or Cold Air Temperatures With Lung Function in Young Infants

Little is known about long-term associations of early-life exposure to extreme temperatures with child health and lung function. To investigate the association of prenatal and postnatal heat or cold exposure with newborn lung function and identify windows of susceptibility. This population-based cohort study (SEPAGES) recruited pregnant women in France between July 8, 2014, and July 24, 2017. Data on temperature exposure, lung function, and covariates were available from 343 mother-child dyads. Data analysis was performed from January 1, 2021, to December 31, 2021. Mean, SD, minimum, and maximum temperatures at the mother-child's residence, estimated using a state-of-the-art spatiotemporally resolved model. Outcome measures were tidal breathing analysis and nitrogen multiple-breath washout test measured at 2 months of age. Adjusted associations between both long-term (35 gestational weeks and first 4 weeks after delivery) and short-term (7 days before lung function test) exposure to ambient temperature and newborn lung function were analyzed using distributed lag nonlinear models. A total of 343 mother-child pairs were included in the analyses (median [IQR] maternal age at conception, 32 [30.0-35.2] years; 183 [53%] male newborns). A total of 246 mothers and/or fathers (72%) held at least a master's degree. Among the 160 female newborns (47%), long-term heat exposure (95th vs 50th percentile of mean temperature) was associated with decreased functional residual capacity (-39.7 mL; 95% CI, -68.6 to -10.7 mL for 24 °C vs 12 °C at gestational weeks 20-35 and weeks 0-4 after delivery) and increased respiratory rate (28.0/min; 95% CI, 4.2-51.9/min for 24 °C vs 12 °C at gestational weeks 14-35 and weeks 0-1 after delivery). Long-term cold exposure (5th vs 50th percentile of mean temperature) was associated with lower functional residual capacity (-21.9 mL; 95% CI, -42.4 to -1.3 mL for 1 °C vs 12 °C at gestational weeks 15-29), lower tidal volume (-23.8 mL; 95% CI, -43.1 to -4.4 mL for 1 °C vs 12 °C at gestational weeks 14-35 and weeks 0-4 after delivery), and increased respiratory rate (45.5/min; 95% CI, 10.1-81.0/min for 1 °C vs 12 °C at gestational weeks 6-35 and weeks 0-1 after delivery) in female newborns as well. No consistent association was observed for male newborns or short-term exposure to cold or heat. In this cohort study, long-term heat and cold exposure from the second trimester until 4 weeks after birth was associated with newborn lung volumes, especially among female newborns.

Extended lifespan and sex-specific fertility loss in cold-acclimated flies of the sibling species Drosophila buzzatii and Drosophila koepferae

Survival and reproduction are the core elements of Darwinian fitness. In the context of a fixed energy budget, organisms tend to allocate resources in order to maximize one at the expense of the other, in what has been called the lifespan-reproduction trade-off. Reproductive arrest and extended lifespan are common responses to low temperatures in many insects including fruit flies. In this study, we aim to understand the overwintering strategy of two closely-related Drosophila species with contrasting distribution ranges. We compared survival, lifespan, ovarian maturation, and reproductive output (fecundity and fertility) of virgin and mated adults of both Drosophila buzzatii and Drosophila koepferae after long-term cold exposure at dormancy-inducing conditions (10 °C, 10:14 L:D) and controls (25 °C, 12:12 L:D). Virgin flies of D. buzzatii showed the longest lifespan (averaging 102 days) under dormancy-inducing conditions. Cold-induced reproductive arrest preserves reproductive capacity mainly in virgin females that mated after reproductive dormancy, indicating that males were much more susceptible to fertility loss than females, in both species. Notably, females of D. buzzatii were capable of protecting stored sperm from cold damage and produced viable progeny. Even if, in D. buzzatii, fertility of flies mated after the cold-exposure was extremely low, cold temperature likely sterilized D. koepferae males, indicating that cold carry-over effects are stronger for the species with the shorter lifespan. Such species-specific effects of low temperature over fitness likely contributed to the divergence of these closely-related species and to the spread of D. buzzatii into cooler environments.

Effect of Long-Term Adaptation to Cold and Short-Term Cooling on the Expression of the TRPM2 Ion Channel Gene in the Hypothalamus of Rats

The present study is aimed to elucidate the possible involvement of the thermosensitive TRPM2 ion channel in changing of the temperature sensitivity of the hypothalamus after different cold exposures-long-term adaptation to cold and short-term cooling. Quantitative RT-PCR was used to study the expression of the gene of thermosensitive TRPM2 ion channel in the hypothalamus in the groups of control (kept for 5 weeks at +20 to +22 °C) and cold-adapted (5 weeks at +4 to +6 °C) rats, as well as in the groups of animals which were subjected to acute cooling (rapid or slow) with subsequent restoration of body temperature to the initial level. It has been shown that after long-term adaptation to cold, the decrease in the Trpm2 gene expression was observed in the hypothalamus, while a short-term cooling does not affect the expression of the gene of this ion channel. Thus, long-term adaptation to cold results in the decrease in the activity not only of the TRPV3 ion channel gene, as shown earlier, but also of the Trpm2 gene in the hypothalamus. The overlapping temperature ranges of the functioning of these ion channels and their unidirectional changes during the adaptation of the homoeothermic organism to cold suggest their functional interaction. The decrease in the Trpm2 gene expression may indicate the participation of this ion channel in adaptive changes in hypothalamic thermosensitivity, but only as a result of long-term cold exposure and not of a short-term cooling. These processes occurring at the genomic level are one of the molecular mechanisms of the adaptive changes.

Circulating Microparticles Are Differentially Increased in Lowlanders and Highlanders with High Altitude Induced Pulmonary Hypertension during the Cold Season.

The role of microparticles (MPs) and cold in high altitude pulmonary hypertension (HAPH) remains unexplored. We investigated the impact of long-term cold exposure on the pulmonary circulation in lowlanders and high-altitude natives and the role of MPs. Pulmonary hemodynamics were evaluated using Doppler echocardiography at the end of the colder and warmer seasons. We further examined the miRNA content of MPs isolated from the study participants and studied their effects on human pulmonary artery smooth muscle (hPASMCs) and endothelial cells (hPAECs). Long-term exposure to cold environment was associated with an enhanced pulmonary artery pressure in highlanders. Plasma levels of CD62E-positive and CD68-positive MPs increased in response to cold in lowlanders and HAPH highlanders. The miRNA-210 expression contained in MPs differentially changed in response to cold in lowlanders and highlanders. MPs isolated from lowlanders and highlanders increased proliferation and reduced apoptosis of hPASMCs. Further, MPs isolated from warm-exposed HAPH highlanders and cold-exposed highlanders exerted the most pronounced effects on VEGF expression in hPAECs. We demonstrated that prolonged exposure to cold is associated with elevated pulmonary artery pressures, which are most pronounced in high-altitude residents. Further, the numbers of circulating MPs are differentially increased in lowlanders and HAPH highlanders during the colder season.

ChREBP-regulated lipogenesis is not required for the thermogenesis of brown adipose tissue.

ObjectivesBrown adipose tissue (BAT) plays a critical role in energy expenditure by uncoupling protein 1 (UCP1)-mediated thermogenesis and represents an important therapeutic target for metabolic diseases. Carbohydrate response element-binding protein (ChREBP) is a key transcription factor regulating de novo lipogenesis, and its activity is associated with UCP1 expression and thermogenesis in BAT. However, the exact physiological role of endogenous ChREBP in BAT thermogenesis remains unclear.MethodsWe used the Cre/LoxP system to generate ChREBP BAT-specific knockout mice, and examined their BAT thermogenesis under acute cold exposure and long-term cold acclimation. Gene expression was analyzed at the mRNA and protein levels, and lipogenesis was examined by 3H-H2O incorporation assay.ResultsThe mice lacking ChREBP specifically in BAT displayed a significant decrease in the expression levels of lipogenic genes and the activity of de novo lipogenesis in BAT after cold exposure, with UCP1 expression decreased under thermoneutral conditions or after acute cold exposure but not chronic cold acclimation. Unexpectedly, BAT-specific ChREBP deletion did not significantly affect body temperature as well as local temperature or morphology of BAT after acute cold exposure or chronic cold acclimation. Of note, ChREBP deletion mildly aggravated glucose intolerance induced by a high-fat diet.ConclusionsOur work indicates that ChREBP regulates de novo lipogenesis in BAT and glucose tolerance, but is not required for non-shivering thermogenesis by BAT under acute or long-term cold exposure.

Long-term intermittent cold exposure affects peri-ovarian adipose tissue and ovarian microenvironment in rats

Long-term intermittent cold exposure affects peri-ovarian adipose tissue and ovarian microenvironment in rats

The effect of long-term cold acclimation on redox state and antioxidant defense in the high-altitude frog, Nanorana pleskei.

Cold hardiness is a key determinant of the distribution and abundance of ectothermic animals, and thermal acclimation can strongly influence stress tolerance phenotypes. However, the effect of cold acclimation on oxidative stress and antioxidant defenses is still not well understood. Here, we investigated the effects of long-term cold exposure (30 days at 4°C in darkness versus 30 days at 20°C in natural light) on the redox state and antioxidant defenses of the high-altitude frog, Nanorana pleskei, indigenous to the Tibetan plateau. We found that cold acclimation, under conditions mimicking winter, led to a significant increase in the ratio of oxidized glutathione (GSSG) to its reduced form (GSH) in liver and skeletal muscle tissues, suggesting that cold exposure induced oxidative stress in this species. Furthermore, malondialdehyde (MDA) contents were significantly augmented in heart, liver and muscle, indicating cold-related oxidative damage in these tissues. In the brain, GST activity, total antioxidant capacity (T-AOC), and vitamin C content showed a significant reduction after cold acclimation. In liver, an apparent decrease was also observed in the activities of SOD and GST, as well as T-AOC, whereas CAT and GPX activities showed a prominent increase in cold-acclimated groups. In kidney, there was a significant decrease in most antioxidant enzyme activities except for SOD and GST activity. In skeletal muscle, the activity of SOD, CAT, GR as well as T-AOC significantly decreased but GPX activity showed a significant increase in cold-acclimated frogs. These findings indicate that, in general, cold acclimation induces a suppression of the antioxidant defense system. Overall, our present study systematically describes the responses of antioxidant defenses to long-term cold acclimation and these findings contribute to extending the current understanding of the mechanisms of cold tolerance in high-altitude frogs.

Natural temperature fluctuations promote COOLAIR regulation of FLC.

Plants monitor many aspects of their fluctuating environments to help align their development with seasons. Molecular understanding of how noisy temperature cues are registered has emerged from dissection of vernalization in Arabidopsis, which involves a multiphase cold-dependent silencing of the floral repressor locus FLOWERING LOCUS C (FLC). Cold-induced transcriptional silencing precedes a low probability PRC2 epigenetic switching mechanism. The epigenetic switch requires the absence of warm temperatures as well as long-term cold exposure. However, the natural temperature inputs into the earlier transcriptional silencing phase are less well understood. Here, through investigation of Arabidopsis accessions in natural and climatically distinct field sites, we show that the first seasonal frost strongly induces expression of COOLAIR, the antisense transcripts at FLC Chamber experiments delivering a constant mean temperature with different fluctuations showed the freezing induction of COOLAIR correlates with stronger repression of FLC mRNA. Identification of a mutant that ectopically activates COOLAIR revealed how COOLAIR up-regulation can directly reduce FLC expression. Consistent with this, transgenes designed to knockout COOLAIR perturbed the early phase of FLC silencing. However, all transgenes designed to remove COOLAIR resulted in increased production of novel convergent FLC antisense transcripts. Our study reveals how natural temperature fluctuations promote COOLAIR regulation of FLC, with the first autumn frost acting as a key indicator of autumn/winter arrival.

Quantitative model analysis of the resting membrane potential in insect skeletal muscle: Implications for low temperature tolerance

Abiotic stressors, such as cold exposure, can depolarize insect cells substantially causing cold coma and cell death. During cold exposure, insect skeletal muscle depolarization occurs through a 2-stage process. Firstly, short-term cold exposure reduces the activity of electrogenic ion pumps, which depolarize insect muscle markedly. Secondly, during long-term cold exposure, extracellular ion homeostasis is disrupted causing further depolarization. Consequently, many cold hardy insects improve membrane potential stability during cold exposure through adaptations that secure maintenance of ion homeostasis during cold exposure. Less is known about the adaptations permitting cold hardy insects to maintain membrane potential stability during the initial phase of cold exposure, before ion balance is disrupted. To address this problem it is critical to understand the membrane components (channels and transporters) that determine the membrane potential and to examine this question the present study constructed a mathematical “charge difference” model of the insect muscle membrane potential. This model was parameterized with known literature values for ion permeabilities, ion concentrations and membrane capacitance and the model was then further developed by comparing model predictions against empirical measurements following pharmacological inhibitors of the Na+/K+ ATPase, Cl− channels and symporters. Subsequently, we compared simulated and recorded membrane potentials at 0 and 31 °C and at 10–50 mM extracellular [K+] to examine if the model could describe membrane potentials during the perturbations occurring during cold exposure. Our results confirm the importance of both Na+/K+ ATPase activity and ion-selective Na+, K+ and Cl− channels, but the model also highlights that additional electroneutral flux of Na+ and K+ is needed to describe how membrane potentials respond to temperature and [K+] in insect muscle. While considerable further work is still needed, we argue that this “charge difference” model can be used to generate testable hypotheses of how insects can preserve membrane polarization in the face of stressful cold exposure.

The Diverse Roles of FLOWERING LOCUS C in Annual and Perennial Brassicaceae Species.

Most temperate species require prolonged exposure to winter chilling temperatures to flower in the spring. In the Brassicaceae, the MADS box transcription factor FLOWERING LOCUS C (FLC) is a major regulator of flowering in response to prolonged cold exposure, a process called vernalization. Winter annual Arabidopsis thaliana accessions initiate flowering in the spring due to the stable silencing of FLC by vernalization. The role of FLC has also been explored in perennials within the Brassicaceae family, such as Arabis alpina. The flowering pattern in A. alpina differs from the one in A. thaliana. A. alpina plants initiate flower buds during vernalization but only flower after subsequent exposure to growth-promoting conditions. Here we discuss the role of FLC in annual and perennial Brassicaceae species. We show that, besides its conserved role in flowering, FLC has acquired additional functions that contribute to vegetative and seed traits. PERPETUAL FLOWERING 1 (PEP1), the A. alpina FLC ortholog, contributes to the perennial growth habit. We discuss that PEP1 directly and indirectly, regulates traits such as the duration of the flowering episode, polycarpic growth habit and shoot architecture. We suggest that these additional roles of PEP1 are facilitated by (1) the ability of A. alpina plants to form flower buds during long-term cold exposure, (2) age-related differences between meristems, which enable that not all meristems initiate flowering during cold exposure, and (3) differences between meristems in stable silencing of PEP1 after long-term cold, which ensure that PEP1 expression levels will remain low after vernalization only in meristems that commit to flowering during cold exposure. These features result in spatiotemporal seasonal changes of PEP1 expression during the A. alpina life cycle that contribute to the perennial growth habit. FLC and PEP1 have also been shown to influence the timing of another developmental transition in the plant, seed germination, by influencing seed dormancy and longevity. This suggests that during evolution, FLC and its orthologs adopted both similar and divergent roles to regulate life history traits. Spatiotemporal changes of FLC transcript accumulation drive developmental decisions and contribute to life history evolution.

Duration of cold exposure defines the rate of reactivation of a perennial FLC orthologue via H3K27me3 accumulation

Vernalisation is the process in which long-term cold exposure makes plants competent to flower. In vernalisation of Arabidopsis thaliana, a floral repressor, AtFLC, undergoes epigenetic silencing. Although the silencing of AtFLC is maintained under warm conditions after a sufficient duration of cold, FLC orthologues are reactivated under the same conditions in perennial plants, such as A. halleri. In contrast to the abundant knowledge on cold requirements in AtFLC silencing, it has remained unknown how cold duration affects the reactivation of perennial FLC. Here, we analysed the dynamics of A. halleri FLC (AhgFLC) mRNA, H3K4me3, and H3K27me3 over 8 weeks and 14 weeks cold followed by warm conditions. We showed that the minimum levels of AhgFLC mRNA and H3K4me3 were similar between 8 and 14 weeks vernalisation; however, the maximum level of H3K27me3 was higher after 14 weeks than after 8 weeks vernalisation. Combined with mathematical modelling, we showed that H3K27me3 prevents a rapid increase in AhgFLC expression in response to warm temperatures after vernalisation, which controls AhgFT expression and the initiation of flowering. Thus, the duration of cold defines the rate of AhgFLC reactivation via the buffering function of H3K27me3 against temperature increase.

Response of Winter Wheat Seedlings Respiration to Long-Term Cold Exposure and Short-Term Daily Temperature Drops

The effects of a long-term (6-day) exposure to low positive temperature (4°С, LT treatment) and short-term (3 h per a day for 6 days) daily temperature drops to 4°С (DROP treatment) on leaf respiration in winter wheat (Triticum aestivum L., var. Moskovskaya 39) were studied under controlled conditions. In the case of the LT treatment, the respiration rate in the darkness (Rd) increased by 36%, while the DROP treatment only resulted in a tendency to such an increase. The influence of both DROP and LT treatments on the respiration rate in the light (Rl) and temperature sensitivity of Rd and Rl was insignificant. In contrast to the DROP treatment, the LT treatment increased the level of light-induced inhibition of plant respiration. In both LT- and DROP-treated plants, the rate of gross photosynthesis (Ag) measured at 12°С increased by 23 and 54%, respectively, as compared to the control plants. The DROP treatment did not affect the Rd/Ag and Rl/Ag ratios in plant leaves. The Rd/Ag value in LT-treated plants measured at 22°С was higher than in control plants, while the Rl/Ag value measured at 12°С was lower than in the control. The DROP treatment did not affect the sensitivity of respiration to salicylhydroxamic acid (SHAM), an inhibitor of the alternative respiratory pathway. The LT treatment increased the share of a SHAM-sensitive respiration in the total respiration of plant leaves by 25% on average, which indirectly indicates the activation of an alternative pathway of the electron transfer in the respiratory chain. Thus, a long-term continuous exposure of winter wheat seedlings to low positive temperatures provided a modifying effect on respiration manifested via changes in the respiratory rate, activity of the SHAM-sensitive respiration, and the ratio between respiration and gross photosynthesis. In the case of a short-term daily exposure to low temperature high respiration stability was observed.

Long-term intermittent cold exposure regulates glucose homeostasis via intervening metabolism of adipose tissue in mice

Long-term intermittent cold exposure regulates glucose homeostasis via intervening metabolism of adipose tissue in mice

Effects of low-temperature stress on histone modification in ZF4 cells

PDF HTML阅读 XML下载 导出引用 引用提醒 低温压力对ZF4细胞组蛋白修饰的影响 DOI: 作者: 作者单位: 1. 水产种质资源发掘与利用教育部重点实验室, 上海海洋大学, 上海 201306;2. 水产科学国家级实验教学示范中心, 上海海洋大学, 上海 201306;3. 海洋生物科学国际联合研究中心, 中国科学技术部, 上海海洋大学, 上海 201306 作者简介: 姜蓬垒(1988-),男,博士研究生,研究方向为表观遗传学.E-mail:770163089@qq.com 通讯作者: 中图分类号: S917 基金项目: 国家自然科学基金项目（31372516，81770165）；上海市自然科学基金项目（13ZR1419500）；上海市教育委员会"东方学者"计划支持项目. Effects of low-temperature stress on histone modification in ZF4 cells Author: Affiliation: 1. Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education;Shanghai Ocean University, Shanghai 201306, China;2. National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China;3. International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Tech-nology, Shanghai 201306, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探索低温压力对斑马鱼细胞组蛋白修饰的影响，建立并优化使用斑马鱼（）成纤维细胞ZF4进行染色质免疫共沉淀（chromatin immunoprecipitation，ChIP）的条件。本研究分别优化了ChIP过程中裂解细胞所使用的NP-40浓度、超声破碎的时间，确定了最佳NP-40浓度为0.2%，超声时间为20 min。利用针对-actin启动子区域的引物，通过常规PCR初步验证ChIP实验是否成功。琼脂糖凝胶电泳结果显示，IgG组常规PCR产物基本无条带，H3K27me3组条带较暗，H3K4me3和H3K27ac组有较亮条带，初步说明实验可靠。使用正常培养（28℃）与长期低温驯化（18℃，30 d）的斑马鱼成纤维细胞ZF4作为实验材料，通过优化之后的ChIP技术进行实验。分别使用qPCR和ChIP-qPCR检测低温驯化对肿瘤坏死因子b（tumor necrosis factor b，基因经过低温驯化后上调，而ChIP-qPCR结果显示，基因启动子区域的H3K4me3、H3K27ac水平来调控基因的表达。本研究建立并优化的ChIP实验条件可以用来研究ZF4细胞组蛋白修饰变化，为下一步探索低温压力对斑马鱼细胞全基因组组蛋白修饰的影响奠定基础。 Abstract:Environmental stresses can regulate gene expression patterns by modulating histone activity. However, the effect of low-temperature stress on whole-genome histone modification in fish has not been reported. To explore the effect of low-temperature stress on histone modification in zebrafish () cells, the experimental conditions for chromatin immunoprecipitation (ChIP) were established and optimized. The optimum NP-40 concentration for lysing cells was 0.2%. The optimal time of sonication with a Covaris S220 to break the chromatin was 20 min. Primers targeting the -actin promoter region were used to perform routine PCR to verify the preliminary ChIP experiment results. Optimized experimental conditions resulted in a very low background, with nearly no IgG band in the agarose gel. Moreover, the lack of H3K27me3 in the -actin promoter region, accompanied by enriched H3K4me3 and H3K27ac, was observed as predicted. Zebrafish embryonic ZF4 fibroblasts cultured under normal condition (28℃) and cold-acclimated ZF4 cells under long-term cold exposure (18℃ for 30 days) were evaluated with the optimized ChIP protocol. The effect of cold acclimation on the expression of tumor necrosis factor tnfb promoter was detected by qPCR and ChIP-qPCR, respectively. The qPCR and ChIP-qPCR results showed that was upregulated after cold acclimation and that H3K4me3 and H3K27ac were enriched in the promoter region of , while enrichment of H3K27me3 showed no significant change. This suggests that cold pressure regulates expression by affecting H3K4me3 and H3K27ac levels in the promoter region of . In conclusion, the established and optimized ChIP method can be used to study histone modification in ZF4 cells and provides a foundation for further analysis of the effect of low-temperature stress on whole-genome histone modification in zebrafish cells. 参考文献 相似文献 引证文献