Days Of Cold Stress Research Articles

Dietary alpha-lipoic acid boosts growth, immune-antioxidant traits, behavior, and transcriptomes of antioxidant, apoptosis, and immune-related genes to combat cold stress in Nile tilapia (Oreochromis niloticus)

Water temperature is a major environmental factor affecting fish activity, physiology, behavior, and growth. Alpha lipoic acid (ALA) has garnered much attention lately as an aqua feed supplement because of its antioxidant effects. Thus, this study aimed to assess the effect of dietary ALA on performance, hematological and immunological indices, behavior and oxidative stress, apoptosis, and genetic inflammation in Oreochromis niloticus following 60 days of cold stress. Two hundred forty fish were divided into four groups (15 fish/replicate, N = 60 fish/group). The control (CNT) and ALA groups were reared at 25 °C and fed a basal diet without any supplementation or a basal diet containing 600 mg ALA/kg diet, respectively. The cold water-stressed group (CWS) and ALA + CWS groups were reared at 18 °C and fed basal and basal diets containing ALA, respectively. The results revealed that dietary ALA supplementation significantly improved feed utilization and growth in fish. ALA also mitigated CWS-induced microcytic hypochromic anemia and hyperlipidemia. Moreover, ALA supplementation considerably enhanced the antioxidant status and boosted intestinal α amylase, lipase, protease, and serum acetylcholinesterase activity of CWS-exposed fish. Besides, ALA supplementation significantly reversed CWS-induced upregulation of proinflammatory genes, pro-apoptotic genes, heat shock protein, and proliferating cell nuclear antigen or downregulation of superoxide dismutase and catalase gene expressions in liver and spleen tissues. Furthermore, ALA supplementation reduced CWS-induced histopathological alterations in fish liver, spleen, and intestine. We can conclude that ALA (600 mg/kg diet) could be recommended as an aqua feed supplement to boost growth, antioxidant capacity, and immunity and attenuate inflammatory and apoptotic reactions of fish reared under CWS-induced.

Gene Profiling of the Ascorbate Oxidase Family Genes under Osmotic and Cold Stress Reveals the Role of AnAO5 in Cold Adaptation in Ammopiptanthus nanus.

The uplift of the Qinghai Tibet Plateau has led to a drastic change in the climate in Central Asia, from warm and rainy, to dry and less rainfall. Ammopiptanthus nanus, a rare evergreen broad-leaved shrub distributed in the temperate desert region of Central Asia, has survived the drastic climate change in Central Asia caused by the uplift of the Qinghai-Tibet Plateau. Ascorbate oxidase (AO) regulates the redox status of the apoplast by catalyzing the oxidation of ascorbate acid to dehydroascorbic acid, and plays a key role in the adaptation of plants to environmental changes. Analyzing the evolution, environmental response, and biological functions of the AO family of A. nanus is helpful for understanding how plant genome evolution responds to climate change in Central Asia. A total of 16 AOs were identified in A. nanus, all of which contained the ascorbate oxidase domain, most of which contained transmembrane domain, and many were predicted to be localized in the apoplast. Segmental duplication and tandem duplication are the main factors driving the gene amplification of the AO gene family in A. nanus. Gene expression analysis based on transcriptome data and fluorescence quantitative PCR, as well as enzyme activity measurements, showed that the expression levels of AO genes and total enzyme activity decreased under short-term osmotic stress and low-temperature stress, but the expression of some AO genes (AnAO5, AnAO13, and AnAO16) and total enzyme activity increased under 7 days of cold stress. AnAO5 and AnAO11 are targeted by miR4415. Further functional studies on AnAO5 showed that AnAO5 protein was localized in the apoplast. The expression of AnAO5 in yeast cells and the transient expression in tobacco enhanced the tolerance of yeast and tobacco to low-temperature stress, and the overexpression of AnAO5 enhanced the tolerance of Arabidopsis seedlings to cold stress. Our research provides important data for understanding the role of AOs in plant adaptation to environmental change.

Oxtr/TRPV1 expression and acclimation of skeletal muscle to cold-stress in male mice.

We explored the involvement of oxytocin receptor (Oxtr)/transient-receptor-potential-vanilloid-1 (TRPV1) genes and oxytocin (Oxt) on the adaptation of skeletal muscle to cold stress challenge in mice. Oxtr expression in hypothalamic paraventricular (PVN), supraoptic nuclei (SON), and hippocampus (HIPP) were evaluated by immunohistochemistry in parallel with the measurement of circulating Oxt. The Oxtr and TRPV1 gene expressions in soleus (SOL) and tibialis anterior (TA) muscles were investigated by RT-PCR. Histological studies of the cardiac muscle after cold stress were also performed. Male mice (n = 15) were divided into controls maintained at room temperature (RT = 24°C), exposed to cold stress (CS) at T = 4°C for 6 h , and 5 days. Immunohistochemical studies showed that Oxtr protein expression increased by two-fold (P = 0.01) in PVN and by 1.5-fold (P = 0.0001) in HIPP after 6 h- and 5 days of CS but decreased by 2-fold (P = 0.026) in SON in 5 days. Both Oxtr and TRPV1 gene expression increased after 6 h and 5 days of CS in SOL and TA muscles. Oxtr vs TRPV1 gene expression in SOL and TA muscles evaluated by regression analysis was linearly correlated following CS at 6 h and 5 days but not at control temperature of 24 ± 1°C, supporting the hypothesis of coupling between these genes. The circulating levels of Oxt are unaffected after 6 h of CS but decreased by 0.2-fold (P = 0.0141) after 5 days-CS. This is the first report that Oxtr and TRPV1 expressions are upregulated in response to cold acclimation in skeletal muscle. The up-regulation of Oxtr in PVN and HIPP balances the decrease of circulating Oxt.

Effect of cold stress on polyamine metabolism and antioxidant responses in chickpea

Metabolic and genomic characteristics of polyamines (PAs) may be associated with the induction of cold tolerance (CT) responses in plants. Characteristics of PAs encoding genes in chickpea (Cicer arietinum L.) and their function under cold stress (CS) are currently unknown. In this study, the potential role of PAs along with the antioxidative defense systems were assessed in two chickpea genotypes (Sel96th11439, cold-tolerant and ILC533, cold-sensitive) under CS conditions. Six days after exposure to CS, the leaf H2O2 content and electrolyte leakage index increased in the sensitive genotype by 47.7 and 59 %, respectively, while these values decreased or remained unchanged, respectively, in the tolerant genotype. In tolerant genotype, the enhanced activity of superoxide dismutase (SOD) (by 50 %) was accompanied by unchanged activities of ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) as well as the accumulation of glutathione (GSH) (by 43 %) on the sixth day of CS. Higher levels of putrescine (Put) (322 %), spermidine (Spd) (45 %), spermine (Spm) (69 %) and the highest ratio of Put/(Spd + Spm) were observed in tolerant genotype compared to the sensitive one on the sixth day of CS. Gamma-aminobutyric acid (GABA) accumulation was 74 % higher in tolerant genotype compared to the sensitive one on the sixth day of CS. During CS, the activity of diamine oxidase (DAO) and polyamine oxidase (PAO) increased in tolerant (by 3.02- and 2.46-fold) and sensitive (by 2.51- and 2.8-fold) genotypes, respectively, in comparison with the respective non-stressed plants (normal conditions). The highest activity of DAO and PAO in the tolerant genotype was accompanied by PAs decomposition and a peak in GABA content on the sixth day of CS. The analysis of chickpea genome revealed the presence of five PAs biosynthetic genes, their chromosomal locations, and cis-regulatory elements. A significant increase in transcript levels of arginine decarboxylase (ADC) (24.26- and 7.96-fold), spermidine synthase 1 (SPDS1) (3.03- and 1.53-fold), SPDS2 (5.5- and 1.62-fold) and spermine synthase (SPMS) (3.92- and 1.65-fold) genes was detected in tolerant and sensitive genotypes, respectively, whereas the expression of ornithine decarboxylase (ODC) genes decreased significantly under CS conditions in both genotypes. Leaf chlorophyll and carotenoid contents exhibited declining trends in the sensitive genotype, while these photosynthetic pigments were stable in the tolerant genotype due to the superior performance of defensive processes under CS conditions. Overall, these results suggested the specific roles of putative PAs genes and PAs metabolism in development of effective CT responses in chickpea.

Effect of Cold Stress on the Content of Minerals and Water Soluble Vitamins in Spinach (Spinacia oleracea)

To assess the effect of cold stress on the levels of minerals (C, N, P, K, Ca, Mg, Mn, Zn, Cu and Fe) and water soluble vitamins (B1, B2, B3, B5, B6, B9 and C) in spinach, an experiment was set up under greenhouse conditions and compared to field results. Levels of macro and micronutrients, except iron in spinach were unaffected by growth conditions and cold stress. The abundance of water soluble vitamins were most pronounced in greenhouse grown plants exposed to 14 and 21 days of cold stress. Significant increases in vitamin C (from 22.73 to 34.47 mg 100 g-1 dry matter) accumulation in stressed plants were observed, thus highlighting its role in plant defense mechanisms. Results indicate that cultivation of leafy vegetables in a greenhouse with low temperature (4 to 7°C) exposure for a shorter period (14 to 21 days) before harvest can improve the nutritional quality. Water soluble vitamin (WSV) contents of field- and greenhouse-grown spinaches.

Effect of cold stress on oxidative damage and mitochondrial respiratory properties in chickpea

The present work aimed to characterize some of the mitochondrial and defense responses involved in tolerance to cold stress (CS) in tolerant (Sel96Th11439) and sensitive (ILC533) chickpea (Cicer arietinum L.) genotypes. During CS, the tolerant genotype prevented the H2O2 accumulation significantly; led to a decrease in electrolyte leakage index (ELI), which was a sign of relative acclimation of this genotype compared to sensitive one. A significant positive correlation between ELI and H2O2 (r0.01 = 0.86) content confirmed these results. Under cold, a significant increase in the alternative oxidase (AOX) activity was observed in tolerant genotype compared to sensitive one. In parallel, the high activity of superoxide dismutase (SOD) accompanied with catalase (CAT) and ascorbate peroxidase (APX) activities and also the extreme amounts of ascorbate and proline certified the active reactive oxygen species (ROS)-scavenging systems. There was a significant negative correlation between damage indices like H2O2 content and the activity of AOX (r0.01 = −0.79) as well as significant positive correlation between AOX activity with CAT (r0.05 = 0.61), SOD (r0.05 = 0.51) and APX activity (r0.05 = 0.52). The increasing succinate dehydrogenase (CaSDH), CaAOX and cytochrome c oxidase (CaCOX) gene expression showed an enhancing response of respiration under CS in tolerant plants compared to sensitive ones. The increasing trend of phosphoenol pyruvate carboxylase (PEPC) activity in tolerant genotype particularly in the sixth day of CS indicated the recovered performance of metabolism pathways. Therefore, the increase of AOX activity along with other defensive mechanisms could be coordinately related to cold tolerance mechanisms in order to alleviate cold-induced oxidative stress in chickpea.

Extrauterine placenta-perfusing fetal incubation of midgestational rabbits: a pilot study

We evaluated the effect of TiO2 nanoparticles (NPs) on cold tolerance (CT) development in two chickpea (Cicer arietinum L.) genotypes (Sel96Th11439, cold tolerant, and ILC533, cold susceptible) by using cDNA-amplified fragment length polymorphism (cDNA-AFLP) technique during the first and sixth days of cold stress (CS) at 4 °C. Selective amplification by primer combinations generated 4200 transcript-derived fragments (TDFs) while 100 of them (2.62%) were differentially expressed. During CS, 60 differentially expressed TDFs of TiO2 NPs-treated plants were cloned and 10 of them produced successfully readable sequences. These data represented different groups of genes involved in metabolism pathways, cellular defense, cell connections and signaling, transcriptional regulation and chromatin architecture. Two out of 10 TDFs were unknown genes with uncharacterized functions or sequences without homology to known ones. The network-based analysis showed a gene-gene relationship in response to CS. Quantitative reverse-transcriptase polymerase chain reaction (qPCR) confirmed differential expression of identified genes (six out of 10 TDFs) with potential functions in CT and showed similar patterns with cDNA-AFLP results. An increase in transcription level of these TDFs, particularly on the first day of CS, was crucial for developing CT through decreasing electrolyte leakage index (ELI) content in tolerant plants compared to susceptible ones, as well as in TiO2 NPs-treated plants compared to control ones. It could also indicate probable role of TiO2 NPs against CS-induced oxidative stress. Therefore, a new application of TiO2 NPs in CT development is suggested for preventing or controlling the damages in field conditions and increasing crop productivity.

Effects of Melatonin on Anti-oxidative Systems and Photosystem II in Cold-Stressed Rice Seedlings.

Melatonin (N-acetyl-5-methoxytryptamine) plays important role in multiple plant developmental processes and stress responses. We investigated the possible mediatory role of melatonin in growth, photosynthesis, and the response to cold stress in rice by using three different experiments: soaking seed; immersing roots, and spraying to leaves with 0, 20, or 100 μM melatonin. After 6 days of cold stress, the growth of rice seedlings was significantly inhibited, but this inhibition was alleviated by exogenous melatonin. Furthermore, exogenous melatonin pretreatment alleviated the accumulation of reactive oxygen species, malondialdehyde and cell death induced by cold stress. Melatonin pretreatment also relieved the stress-induced inhibitions to photosynthesis and photosystem II activities. Further investigations showed that, antioxidant enzyme activities and non-enzymatic antioxidant levels were increased by melatonin pretreatments. The treatment methods of seed soaking and root immersion were more effective in improving cold stress resistance than the spraying method. The results also indicated the dose-dependent response of melatonin on rice physiological, biochemical, and photosynthetic parameters.

CDNA-AFLP analysis of transcripts induced in chickpea plants by TiO2 nanoparticles during cold stress

We evaluated the effect of TiO2 nanoparticles (NPs) on cold tolerance (CT) development in two chickpea (Cicer arietinum L.) genotypes (Sel96Th11439, cold tolerant, and ILC533, cold susceptible) by using cDNA-amplified fragment length polymorphism (cDNA-AFLP) technique during the first and sixth days of cold stress (CS) at 4 °C. Selective amplification by primer combinations generated 4200 transcript-derived fragments (TDFs) while 100 of them (2.62%) were differentially expressed. During CS, 60 differentially expressed TDFs of TiO2 NPs-treated plants were cloned and 10 of them produced successfully readable sequences. These data represented different groups of genes involved in metabolism pathways, cellular defense, cell connections and signaling, transcriptional regulation and chromatin architecture. Two out of 10 TDFs were unknown genes with uncharacterized functions or sequences without homology to known ones. The network-based analysis showed a gene-gene relationship in response to CS. Quantitative reverse-transcriptase polymerase chain reaction (qPCR) confirmed differential expression of identified genes (six out of 10 TDFs) with potential functions in CT and showed similar patterns with cDNA-AFLP results. An increase in transcription level of these TDFs, particularly on the first day of CS, was crucial for developing CT through decreasing electrolyte leakage index (ELI) content in tolerant plants compared to susceptible ones, as well as in TiO2 NPs-treated plants compared to control ones. It could also indicate probable role of TiO2 NPs against CS-induced oxidative stress. Therefore, a new application of TiO2 NPs in CT development is suggested for preventing or controlling the damages in field conditions and increasing crop productivity.

Effects of Cold Stress on Root Growth and Physiological Metabolisms in Seedlings of Different Sugarcane Varieties

This experiment aimed to study the effects of cold stress on root growth and related physiological characteristics in two sugarcane varieties with different cold resistance. The roots of sugarcane seedlings of cold-resistant variety GT28 and cold-susceptible variety ROC22 derived from water culture were used as the plant materials. Two treatments were performed at 25 °C as control and 4 °C as cold stress, respectively. Morphological growth characteristics and physiological characteristics, including root length, root volume, root microstructure, activities of root vigor, superoxide dismutase (SOD) and peroxidase (POD), contents of malondialdehyde (MDA), proline, soluble sugar, and soluble protein were measured. The results showed that as the root growth was inhibited under cold stress, the average root length and root volume were decreased in the cold treatment as compared to the control, and the decreases were less in GT28 than in ROC22. After 3 days of cold stress, the root microstructure was changed as getting swelling and deformed, and disorder of cellular structure was observed in both varieties; however, the root deformation was much significant in the cold-susceptible variety of ROC22 than in the cold-resistant variety of GT28. As the cold stress prolonged, the activities of root vigor were significantly decreased in both sugarcane varieties, but it decreased more obviously in ROC22 than in GT28. The contents of MDA, proline, soluble sugar, soluble protein, and the activities of POD and SOD were higher in cold treatments than in control. Compared to variety of ROC22, the contents of soluble sugar and proline and the activities of POD and SOD were higher in GT28. The results indicated that cold resistance/susceptibility is variety dependent in sugarcane.

Cold stress causes rapid but differential changes in properties of plasma membrane H+-ATPase of camelina and rapeseed

Camelina (Camelina sativa) and rapeseed (Brassica napus) are well-established oil-seed crops with great promise also for biofuels. Both are cold-tolerant, and camelina is regarded to be especially appropriate for production on marginal lands. We examined physiological and biochemical alterations in both species during cold stress treatment for 3 days and subsequent recovery at the temperature of 25°C for 0, 0.25, 0.5, 1, 2, 6, and 24h, with particular emphasis on the post-translational regulation of the plasma membrane (PM) H+-ATPase (EC3.6.3.14). The activity and translation of the PM H+-ATPase, as well as 14-3-3 proteins, increased after 3 days of cold stress in both species but recovery under normal conditions proceeded differently. The increase in H+-ATPase activity was the most dramatic in camelina roots after recovery for 2h at 25°C, followed by decay to background levels within 24h. In rapeseed, the change in H+-ATPase activity during the recovery period was less pronounced. Furthermore, H+-pumping increased in both species after 15min recovery, but to twice the level in camelina roots compared to rapeseed. Protein gel blot analysis with phospho-threonine anti-bodies showed that an increase in phosphorylation levels paralleled the increase in H+-transport rate. Thus our results suggest that cold stress and recovery in camelina and rapeseed are associated with PM H+-fluxes that may be regulated by specific translational and post-translational modifications.

Acupuncture blocks cold stress-induced increases in the hypothalamus–pituitary–adrenal axis in the rat

Electroacupuncture (EA) is used to treat chronic stress; however, its mechanism(s) of action in allaying stress remains unclear. The interplay of stress hormones of the hypothalamus-pituitary-adrenal axis (HPA) and the sympathetic nervous system (SNS) is critical in the stress response. Our objective was to determine whether EA at acupoint, stomach 36 (EA St₃₆) is effective in preventing chronic cold stress-induced increased hormone levels in the rat by examining four groups of animals, three of which were exposed to cold and one of which was a non-treatment control group. Before exposure to the cold, two groups were treated with either EA St₃₆, or Sham-EA, before 10 days of cold stress. The EA St₃₆ animals demonstrated a significant decrease in peripheral HP hormones (ACTH and CORT) compared with stress animals (P<0.05). These effects were specific; rats receiving Sham-EA had elevation of these hormones, similar to the stress-only animals. These effects were mirrored centrally in the brain; CRH levels were significantly (P<0.05) reduced in EA St₃₆ animals compared with the other animals. Finally, EA effect on peripheral and adrenal SNS hormones (norepinephrine (NE) and neuropeptide Y (NPY) respectively) was examined, with no significant difference noted in adrenal tyrosine hydroxylase or circulating NE in any of the groups. However, EA St₃₆ was effective in preventing stress-induced elevation is adrenal Npy mRNA. These results indicate that EA St₃₆ blocks the chronic stress-induced elevations in the HPA and the sympathetic NPY pathway, which may be a mechanism for its specific stress-allaying effects.

Mapping of Quantitative Trait Loci Associated with Cold Tolerance at the Post-Germination Stage in Rice

ABSTRACTCold tolerance at the post-germination stage in rice was studied using gained shoot length (GSL) as a new parameter, which was measured as increased shoot length during cold stress at 4°C followed by a 4-day recovery period at 35°C. GSL decreased until 4th day in both japonica and indica cultivar, while a marked increase occurred in a japonica cultivar after 5 days of cold stress, indicating its higher ability of cold acclimation. Quantitative trait loci (QTLs) associated with cold tolerance were identified using recombinant inbred lines derived from these parents on a linkage map constructed with 102 simple sequence repeat (SSR) markers. By the interval analysis, one and five putative QTLs were identified after 5 and 11 days of cold stress, respectively. The single point analysis indicated that these QTLs explained 16% and 54% of the phenotypic variance after 5 and 11 days of cold stress, respectively. A cold tolerant japonica parent contributed all QTLs, among which one on the long arm of chromosome 7 was common for the two cold stress periods. Based on gained root length one QTL was identified on chromosome 12 explaining 11% of the variance.

Effect of Duration of Cold Stress on Plasma Adrenal and Thyroid Hormone Levels and Immune Responses in Chicken Lines Divergently Selected for Antibody Responses

There is increasing evidence that stress affects various immune processes. Some of these changes are due to hormonal changes involving corticosterone (CORT), triiodothyronine (T3), and thyroxine (T4). Effects of stress depend on the nature of specific stressors (e.g., thermal extremes, diet, pollutants), and stress-modifiers (e.g., genetic make-up, duration and severity of the stressors). We studied the effects of a specific stress (cold stress) with stress-modifiers (duration of stress and genotype of the bird) on immune responses and plasma adrenal and thyroid hormone levels in 3 layer-type chicken lines. Two lines were divergently selected for high (H line) or low (L line) antibody responses to SRBC, and the third line was a randombred control (C) line. Growing chicks (3- to 4-wk-old) of the 3 lines were feed-restricted at 80% of ad libitum consumption, and subjected to cold stress (CS) at 10°C continuously for 7, 5, 3, 1, or 0 d before immunization with keyhole limpet hemocyanin (KLH). Specific antibody titers to KLH, and in vitro lymphocyte proliferation (LP) upon mitogen stimulation were measured. In addition, adrenal and thyroid hormone levels were measured in the plasma samples collected at the end of CS. No significant effect of duration of CS on specific antibody titers was found in the 3 lines. A significant enhancing effect of CS was found on LP. A significant dose-dependent suppressive effect of CS was found on plasma CORT levels. One day of CS had a significant enhancing effect on T3 levels. There was no significant effect of duration of CS on T4 levels. We conclude that CS does not affect specific antibody responses, but may have a modulating effect on cellular immunity and plasma CORT levels, depending on the duration of the stress. The present study suggests an inverse relationship between LP and CORT. This is the first study that reveals an absence of significant differences in adrenal and thyroid hormone levels in the described selection lines.

The effects of delta sleep-inducing peptide on the intensity of lipid peroxidation and xanthine oxidase activity in rat tissues during cold stress.

Exogenous delta sleep-inducing peptide given i.p. to intact rats at a dose of 12 microg/100 g decreased the levels of diene conjugates and Schiff bases in liver and brain tissues and had no effect on xanthine oxidase activity in these tissues. Cold stress was accompanied by increases in xanthine oxidase activity in rat liver and brain, with a consequent accumulation of diene conjugates and Schiff bases, as compared with intact animals. Preliminary administration of delta sleep-inducing peptide before three days of cold stress led to decreases in xanthine oxidase activity and lipid peroxidation products in the liver and brain, as compared with values in stressed rats. The protective effect of delta sleep-inducing peptide in stress is discussed.

Effects of Prenatal Ethanol Exposure on Hypothalamic‐Pituitary‐Adrenal Responses to Chronic Cold Stress in Rats

Animals prenatally exposed to ethanol typically exhibit hypothalamic-pituitary-adrenal (HPA) hyperresponsiveness to stressors. In contrast to previous studies that have investigated effects of prenatal ethanol exposure on HPA responses to acute or intermittent stressors, our study investigated HPA responses to a chronic continuous stressor, cold stress (4 degrees C for 0, 1, or 3 days). We tested the hypothesis that prenatal ethanol exposure would result in increased plasma corticosterone (CORT) and adrenocorticotropin (ACTH) responses and increased peptide [corticotropin-releasing factor and vasopressin] mRNA levels in the paraventricular nucleus (PVN) of the hypothalamus compared to that in control animals. In addition, CORT and ACTH responses were measured after exposure to an acute stressor (i.p. isotonic saline injection), superimposed during chronic cold exposure, to examine possible sensitization of the HPA response to the acute stress. Thus, blood samples were collected at the end of each of the three periods of cold exposure, either before (0 min) or 15 min after acute stress. The subjects were adult male and female Sprague-Dawley rat offspring from prenatal ethanol (E), pair-fed (PF), and ad libitum-fed control (C) treatment groups. Exposure to cold stress resulted in significant body weight loss in E males at 1 day and in both males and females of all prenatal treatment groups by 3 days of cold stress. Males in all prenatal groups also exhibited significant increases in adrenal weight:body weight ratios. Cold stress alone (0 min condition) increased CORT levels in E males and overall ACTH levels in E males and females compared to controls. ACTH levels were also higher overall in E compared to control males after acute stress (15 min condition). Sensitization of the CORT response to acute stress was observed in males but not females across all prenatal treatment groups. Corticotropin-releasing factor and vasopressin mRNA levels in the PVN were not significantly affected by prenatal treatment or chronic cold stress in either males or females. In contrast, both males and females displayed increases in PVN thyrotropin-releasing hormone (TRH) mRNA levels after cold stress. These data support and extend previous work demonstrating differential effects of prenatal ethanol exposure on HPA responsiveness of male and female offspring, and suggest that E males may be more vulnerable to the effects of chronic cold stress than E females.

Induction of Hypercoagulability Condition by Chronic Localized Cold Stress in Rabbits

To evaluate the effect of cold-induced stress on renal and hepatic blood flow and coagulation parameters, rabbits' soles were exposed to ice pad (0 degrees C). Renal and hepatic blood flow was measured after 1 h and 15 days of cold stress. Coagulation parameters (0, 8th and 15th days of stress) and histological studies were performed. Renal and hepatic blood flow was significantly reduced after cold-stress. Decreased platelet count, antithrombin III (AT III) activity, increased fibrinogen (Fbg) level, shortened activated partial thromboplastin time (aPTT) and prothrombin time (PT) was found after 8 and 15 days of cold-stress. Histology showed enlarged glomeruli with fibrin deposition in kidney, ischemic changes and fibrin deposition in liver and hemorrhagic necrosis in adrenal cortex. We conclude that undesirable localized cold induced sympathetic stimulation in daily life may be a predisposing factor for coagulopathy.

The Effect of Cold Stress on Lymphocyte Proliferation in Fetal Ethanol‐Exposed Rats

Prenatal ethanol exposure and stress have each been shown to have significant effects on the immune system. This study examined the possible interactive effects of prenatal ethanol exposure and exposure to stress later in life on the immune system. Differential vulnerability to these challenges in female and male offspring was assessed. At 5 to 6 months of age, female and male offspring from prenatal ethanol-exposed (E), pair-red (PF), and ad libitum-fed control (C) conditions were exposed to 0, 1 or 3 days of cold (4 degrees C). At the end of the cold period, the proliferative response of splenic lymphocytes to the mitogens concanavalin A (Con A) and pokeweed mitogen (PWM) was assessed. The data demonstrate a significant interactive effect between prenatal ethanol exposure and cold stress in female offspring. After 1 day of cold stress, E females had significantly increased PWM-induced lymphocyte proliferation compared with PF and C females, and significantly increased Con A-induced lymphocyte proliferation compared with PF females. There were no differences in PWM or Con A-induced lymphocyte proliferation among E, PF, and C females after 0 or 3 days of cold stress, nor among E, PF, and C males on any test day. Regardless of prenatal treatment, females exposed to 1 or 3 days of cold had significantly greater basal plasma corticosterone levels than females not exposed to cold. In contrast, only E males exposed to 1 or 3 days of cold had significantly increased basal plasma corticosterone levels, compared with E males not exposed to cold; PF and C males showed no significant change in basal corticosterone after cold stress. These data demonstrate that, in response to the challenge of cold stress, changes in lymphocyte proliferation to PWM and Con A may occur selectively in E females. Moreover, the interactive effects of prenatal ethanol and cold stress may result in enhanced rather than suppressed immune responsiveness.

Cold‐induced changes in the polysome pattern and protein synthesis in winter rye (Secale cereale) leaves

Cold‐induced changes in the polysome pattern and protein synthesis were analyzed in winter rye, Secale cereale L. cv. Voima, during one week's cold stress treatment, which was performed by transferring the 7‐day‐old plants from the greenhouse (25°C, long‐day conditions) to 3°C and a photoperiod of 10. 5 h. Freezing resistance determined by electrolyte leakage increased significantly upon cold stress starting from LT50 value –5°C. and reaching –9°C on the day 7 of cold exposure. After 4 weeks at low temperature, plants reached an LT50 of –12°C. The polysome content increased markedly during cold stress compared to the control plants. After 2 weeks of cold treatment the polysome content decreased to the same level as that in control plants. The size‐class distribution of polysomes showed a high proportion of large protein synthesizing polysomes in cold‐stressed plants. After 2 weeks the values were comparable to those in control plants. Cold‐induced proteins were detected using 35S‐labelled methionine for in vitro translations. At least 2 new polypeptides, Mr 30000 and 18000, were induced on the first day of cold stress and continued to be expressed at low temperatures 4 weeks later.

The effects of cold-stress. Hibernation, and prolonged inactivity on bone dynamics in the golden hamster, Mesocricetus auratus.

The effects of cold-stress and hibernation on bone dynamics in the femurs of hamsters were investigated using histometric analyses. Control animals were maintained at 27 degrees C for 90 days; experimental animals were kept at 5 degrees C and hibernated for 7, 15, 21, 50, or 90 days. Histometric analyses of cross sections indicated that bone diameter and cortical thickness at the femoral midshaft increased after 83 days of extreme cold and 7 days of hibernation but decreased significantly after 69 days of cold stress and 21 days of hibernation. Osteoporosis was evident although the number of osteons per unit area of bone increased during hibernation. An initial decrease in the number of non-Haversian longitudinal vessels per unit area of bone was seen in experimental animals which was apparently related to a corresponding reduction in cortical thickness. Lacunar area increased in these animals, suggesting that osteocytic osteolysis may be a significant mechanism for calcium regulation during hibernation.