Effects Of Cold Stress Research Articles

Effect of cold stress on heart rate and blood pressure in healthy offspring with and without parental history of type2 diabetes mellitus

Introduction: The cold pressor test which is considered to be a sympatho-excitatory maneuver is a simple, noninvasive and validated test of sympathetic activation. The heart rate and blood pressure responses to CPT could be used as indicators of global sympathetic activation, and thus of cardiac status and autonomic function. Autonomic nervous system dysfunction at the subclinical level seems to be the predisposing condition that occurs far earlier before developing an overt diabetic condition. Aims: To evaluate the cardiac autonomic status and its reactivity among healthy offspring with and without parental history of Type2 Diabetes Mellitus (T2DM). To Compare the autonomic reactivity by recording Heart Rate (HR) and Blood pressure during and after CPT between healthy offspring with and without parental history of T2DM. Materials and Methods: This study consists of 40 healthy male subjects with family history of T2DM (cases) and 40 healthy male subjects without family history of T2DM (controls) in the age group of 18-25 years. HR and BP during and after CPT were compared between cases and controls. Results: Student t test (two tailed, independent) has been used to find the significance of study parameters on continuous scale between two groups. HR response to post CPT showed significant differences between two groups across all the time points. Controls showed higher HR than cases at all the time points. However, the reduction of HR with time was more gradual in controls. The graphical representation of SBP changes after CPT, shows fluctuation among cases before it reaches the stable value, whereas, in controls the decrease was at constant level. Conclusion: The results suggest there was altered autonomic reactivity to physical stress among the offspring with parental history of T2DM when compared to their counterparts and hence this points towards the fact that they are at a risk of developing future autonomic dysfunction and cardiovascular complications. Keyword

Structural Diversity and Highly Specific Host-Pathogen Transcriptional Regulation of Defensin Genes Is Revealed in Tomato.

Defensins are small and rather ubiquitous cysteine-rich anti-microbial peptides. These proteins may act against pathogenic microorganisms either directly (by binding and disrupting membranes) or indirectly (as signaling molecules that participate in the organization of the cellular defense). Even though defensins are widespread across eukaryotes, still, extensive nucleotide and amino acid dissimilarities hamper the elucidation of their response to stimuli and mode of function. In the current study, we screened the Solanum lycopersicum genome for the identification of defensin genes, predicted the relating protein structures, and further studied their transcriptional responses to biotic (Verticillium dahliae, Meloidogyne javanica, Cucumber Mosaic Virus, and Potato Virus Y infections) and abiotic (cold stress) stimuli. Tomato defensin sequences were classified into two groups (C8 and C12). Our data indicate that the transcription of defensin coding genes primarily depends on the specific pathogen recognition patterns of V. dahliae and M. javanica. The immunodetection of plant defensin 1 protein was achieved only in the roots of plants inoculated with V. dahliae. In contrast, the almost null effects of viral infections and cold stress, and the failure to substantially induce the gene transcription suggest that these factors are probably not primarily targeted by the tomato defensin network.

Physiological and Molecular Studies on Thermotolerance of Bacillus cereus Isolated from Some Dairy Products and Fast Foods

Several members of Bacillus cereus (B. cereus) have been recognized as a significant agent of food and health problems. Thermotoleranc of B. cereus after pre-exposure to temperature shifts or other stress may influence its ability to grow in minimally processed foods. This study was proposed to determine the recovery rate of B. cereus group from dairy products and fast foods. Moreover, the responses of a recovered isolate to different stresses were evaluated to stand upon its thermotolerance against lethal temperature. In total, 200 different samples from milk and milk products (164) and fast food (36) were examined for the presence of B. cereus group. The effects of heat, cold, acid and salt stresses on heat resistant B. cereus were physiologically and molecularly assessed through examining its viability and measuring the gene expression of its heat induced proteins (GroEL and DnaJ) by reverse transcription quantitative polymerase chain reaction (RT-qPCR), respectively. Overall, 35 (17.5%) samples were positive for B. cereus group isolates. The higher B. cereus count (> 104 CFU/mL or g) was found in 7% of milk and fast food samples. Three B. cereus group species (B. cereus, B. thuringiensis and B. pseudomycoides or B. mycoides) were identified. After time intervals of mild heat pre-exposure at 42 °C or exposure to other stresses, B. cereus developed an increased thermotolerance at 50 °C/20 min. This thermotolerance was pronounced after exposure of B. cereus cells to 42°C /1 h and 2.5 % salt / 30°C/ 40 min with a 3.9 CFU log increase compared to those exposed to lethal treatment only. Molecularly, RT-qPCR results revealed up-regulation of dnaJ gene expression in pretreated cells compared to the lethal treated cells only. Overall, these results confirmed the heat resistance occurs in B. cereus during food processing, which results in its survival in the food products.

Effects of Cold Stress and Ammonia Concentration on Productive Performance and Egg Quality Traits of Laying Hens

In a cold climate, ensuring indoor air quality and heat preservation simultaneously has always been a difficult problem in the poultry house. The current study was carried out in order to determine the effects of chronic low temperature and ammonia concentration on productive performance and egg quality of commercial laying hens. 576 18-week-old Hy-line Brown hens were used in this study. Birds were housed in cages and received for 20-week exposure to low temperature and ammonia in six artificial environmental chambers. Birds were randomly assigned into six treatments: treatment 1 (T1, 20 °C, ≤5 ppm, control group), treatment 2 (T2, 20 °C, 20 ppm), treatment 3 (T3, 20 °C, 45 ppm), treatment 4 (T4, 8 °C, ≤5 ppm), treatment 5 (T5, 8 °C, 20 ppm) and treatment 6 (T6, 8 °C, 45 ppm). Daily feed intake (DFI), feed efficiency (FE), egg production (EP) and body weight (BW) were recorded and calculated from 19 weeks of age. Egg samples were collected at 22, 26, 30, 34 and 38 weeks of age and egg weight (EW), shell breaking strength (SBS), albumen height (AH), yolk weight (YW), shell weight (SW), shell thickness (ST) and Haugh unit (HU) were measured. The results of the present study indicated that low temperature and excessive ammonia decreased the EP of hens compared with those of the T1 birds. Low temperature increased DFI of hens thereby FE showed significant differences among treatments. During the early period of the experiment, low temperature treatment increased the BW of laying hens, but this trend of increase was suppressed by the treatment of ammonia with the prolongation of the experimental period. Egg quality was also affected by low temperature and excessive ammonia. At different experimental periods, egg quality traits of hens exposed to the cold and ammonia stress presented significant differences compared to those of control birds. The present study indicated that the effect of ammonia was more pronounced on hens than that of low temperature at the early and peak laying period in terms of several main traits of productive performance and egg quality under long term hens breeding.

Effects of cold stress on metabolic regulation in the overwintering larvae of the Chinese white pine beetle, Dendroctonus armandi

AbstractThe Chinese white pine beetle, Dendroctonus armandi Tsai & Li (Coleoptera: Curculionidae, Scolytinae), is considered the most destructive forest pest in the Qinling and Bashan Mountains of China. In recent years, winter temperature has dropped in these regions, and extremely low temperatures are hard to survive for insects. Cold hardiness becomes a crucial strategy because temperature change often leads to fluctuations in insect abundance, and the metabolism rate is a key index of resistance to cold in overwintering insects. Therefore, we investigated the relationship between the change in respiratory rate and the activity of metabolism‐related mitochondrial enzymes in D. armandi larvae under cold conditions. We found that the respiratory rate decreased, and it was matched with the activity of glutamate dehydrogenase, aconitase, and lipase during overwintering. Among the various test times under cold conditions, the respiratory rate also decreased with decreasing temperature and increased under very low temperatures. At all cold stress periods, glutamate dehydrogenase and lipase showed increased activity at higher temperatures and decreased activity under lower temperatures, but the activity of NAD‐malic enzyme, NADP‐malic enzyme, mitochondrial isocitrate dehydrogenase, and aconitase were contrary. Under all low temperatures, the activity of enzymes – except for NADP‐malic enzyme, glutamate dehydrogenase, and lipase – increased in short‐term cold stress and decreased in long‐term cold stress at 4, 0, −4, −6, −8, and −10 °C. However, at −2 °C, the activity of enzymes showed a decreasing trend in short‐term treatments and an increasing trend in long‐term treatments, except for mitochondrial isocitrate dehydrogenase. The results not only improve our understanding of the metabolic mechanism of cold adaptation in D. armandi, but also provide an important experimental basis for further study and biological pest control.

Establishment of an experimental rat model of high altitude cerebral edema by hypobaric hypoxia combined with temperature fluctuation

High altitude cerebral edema (HACE) is a kind of life threat disease encountered at high altitude, but the precise pathogenesis of it is far more understood. Hypobaic hypoxia (HH) and cold are conditions characteristic of high altitude environment. HH is always considered as the central causative factor for the development of HACE, but the effect of cold stress on HACE has been rarely investigated. The purpose of this study was to investigate the potential role of cold stress in the development of HACE and establish a stable experimental animal model. Male SPF Wistar rats were randomly divided into five groups for this experiment, control group (altitude, 1400 m, temperature, 25 ℃), NC + 2 ℃ group (altitude, 1400 m, temperature, 2 ℃), HH group (altitude, 6000 m, temperature, 25 ℃), HH+2 ℃ group (altitude, 6000 m, temperature, 2 ℃) and HH + 12/2 ℃ (altitude, 6000 m, temperature, 12 ℃/2 ℃ light/dark cycle). After exposure for 72 h, the blood and brain tissues were collected. Brain water content (BWC) and Evans Blue dye extravasation were used to assess the brain edema and blood-brain barrier (BBB) permeability, respectively. The levels of pro-inflammatory cytokines in serum were assessed via enzyme-linked immunosorbent assay. Oxidative stress markers and ATPase activity were determined using commercial kits. Western blotting was used to detect the expression of related proteins. Compared to control, HH+2 ℃ could significantly increase the BWC and BBB permeability, and these changes were further exacerbated by HH + 12/2 ℃. Furthermore, HH+2 ℃ and HH + 12/2 ℃ markedly increased the levels of H2O2 and MDA, restrained SOD and GSH levels and decreased Na+/K+-ATPase activitie compared with the control group. In addition, HH+2 ℃ and HH + 12/2 ℃ enhanced the levels of pro-inflammatory cytokines IL-1β, TNF-α and IL-6 in serum and significantly increased the expression of VEGF in brain compared with the control group, but only HH + 12/2 ℃ could increase the expression of AQP4. However, compared with control group, no significant differences in these parameters were observed in HH and NC+2 ℃groups. These results demonstrated that HH or cold stress alone did not successfully induce brain damage, while HH+2 ℃ could induce the onset of HACE via provoking injury caused by HH. HH + 12/2 ℃ was more obvious and efficient. Collectively, we firstly suggest that cold stress may promote the formation of HACE by aggravating the brain injury induced by HH exposure and supply an effective and reliable experimental rat model of HACE via HH combined with temperature fluctuation.

Plasma levels of corticosterone, tumor necrosis factor receptor 1 and interleukin 6 are influenced by age, sex and chronic inflammation in mice treated with acute temperature stress.

Resiliency is the ability to respond to, adapt to and recover from stressors. Deterioration of resiliency in older adults has been hypothesized to be regulated by age-related changes in stress response systems, including the Hypothalamic Pituitary Adrenal (HPA) axis and the innate immune system response. Although age-related chronic inflammation is strongly related to lack of resiliency, the impact of chronic inflammation on acute stress response is unclear. Here we describe the impact of a five-hour exposure to cold temperature acute stressor, on immune and corticosterone response using older and younger IL-10tm/tm mice, a mouse model with chronic inflammatory pathway activation, and age and gender matched C57/Bl6 background control (WT) mice. Overall, mice exposed to 4°C for 5h had significantly higher plasma corticosterone levels compared to those that remained at room temperature (25°C), with the exception of the WT females. Cold stressed mice had lower plasma tumor necrosis factor receptor 1 (TNFR1) levels with varying significance, in all ages and phenotypes, with the exception of the old female WT mice. In contrast, the effects of cold stress on pro-inflammatory cytokine interleukin 6 (IL-6) levels were inconsistent and not significant, with the exception of the female IL-10tm/tm mice. In conclusion, these findings demonstrate that sex, age and chronic inflammatory pathway activation all influence corticosterone secretion and inflammatory processes in the face of acute cold stress.

Effects of exogenous \u03b1-oxoglutarate on proline accumulation, ammonium assimilation and photosynthesis of soybean seedling (Glycine max(L.) Merr.) exposed to cold stress

The objective of this study was to examine the effects of exogenous α-oxoglutarate on leaf proline accumulation, ammonium assimilation and photosynthesis of soybean when exposed to cold stress. To achieve this objective, exogenous α-oxoglutarate was sprayed to potted seedlings of Henong60 and Heinong48 at 0, 2.5, 5.0 and 7.5 mmol/L, identified as A0, A2.5, A5.0, and A7.5, respectively. Leaf samples were collected after cold stress of 24 h (S1 stage) and 48 h (S2 stage). The results indicated that exogenous α-oxoglutarate significantly enhanced leaf GS activity, NADP-GDH activity, glutamate content, proline content and photosynthesis of soybean seedling exposed to cold stress at S1 and S2 stages. The ammonium content in leaf was significantly decreased by exogenous α-oxoglutarate at both stages. 5.0 mmol/L of exogenous α-oxoglutarate is the optimum concentration in this study. Leaf proline content for Henong60 and Heinong48 at A5.0 was 37.53% and 17.96% higher than that at A0 at S1 stage, respectively. Proline content for Henong60 and Heinong48 increased by 28.82% and 12.41% at A5.0 and A0, respectively, at S2 stage. Those results suggested that exogenous α-oxoglutarate could alleviate the adverse effects of cold stress.

Phenotypic Responses, Reproduction Mode and Epigenetic Patterns under Temperature Treatments in the Alpine Plant Species Ranunculus kuepferi (Ranunculaceae).

Plant life in alpine habitats is shaped by harsh abiotic conditions and cold climates. Phenotypic variation of morphological characters and reproduction can be influenced by temperature stress. Nevertheless, little is known about the performance of different cytotypes under cold stress and how epigenetic patterns could relate to phenotypic variation. Ranunculus kuepferi, a perennial alpine plant, served as a model system for testing the effect of cold stress on phenotypic plasticity, reproduction mode, and epigenetic variation. Diploid and autotetraploid individuals were placed in climate growth cabinets under warm and cold conditions. Morphological traits (height, leaves and flowers) and the proportion of well-developed seeds were measured as fitness indicators, while flow cytometric seed screening (FCSS) was utilized to determine the reproduction mode. Subsequently, comparisons with patterns of methylation-sensitive amplified fragment-length polymorphisms (AFLPs) were conducted. Diploids grew better under warm conditions, while tetraploids performed better in cold treatments. Epigenetic patterns were correlated with the expressed morphological traits. Cold stress reduced the reproduction fitness but did not induce apomixis in diploids. Overall, our study underlines the potential of phenotypic plasticity for acclimation under environmental conditions and confirms the different niche preferences of cytotypes in natural populations. Results help to understand the pattern of geographical parthenogenesis in the species.

Effects of cold stress and starvation on the liver of yellow drum Nibea albiflora: histological alterations and transcriptomic analysis

The yellow drum Nibea albiflora is a marine fish of great economic value in China. Despite efforts to improve yields, aquaculture of this species has been hindered by increases in winter-related mortalities associated with cold temperatures and associated natural fasting periods. To better understand the molecular mechanisms that regulate stress responses in yellow drum during periods of cold and starvation, the effect of these stresses on the liver was investigated by performing comparative analyses among fish subjected to different temperatures and feeding strategies. The experiment lasted for 22 d and involved 4 groups: one fed group (control) and one fasted group at 16°C, and one fed group and one fasted group at 8°C. Our results showed that all stress-treated groups exhibited body weight loss during the experiment, demonstrating that both cold stress and fasting caused growth inhibition, but only the fish in the fasted group at 16°C showed a loss in the liver/body ratio, suggesting that starvation can cause mass loss in the liver while cold stress can result in mass loss in both liver and other tissues. Histological alterations were observed in the liver cells from stress-treated groups, also indicating mass loss in the liver during cold stress and starvation. Transcriptomic analysis showed that genes related to the metabolism of carbohydrates, lipids and amino acids were the most enriched differentially expressed genes during the challenge conditions. These findings can help reveal molecular mechanisms regulating the stress responses of yellow drum exposed to cold and starvation.

Cryostabilization of the Cell Membrane of a Psychrotolerant Bacteria via Homeoviscous Adaptation.

Homeoviscous adaptation (maintenance of a critical balance between the saturated and unsaturated lipids) of the cell membrane of psychrotolerant bacteria is essential to protect them against freeze-thaw cycle. But how does the homeoviscous adaptation protect the cell membrane during cold stress? In this Letter, we answer this question using a coarse-grained molecular dynamics simulation technique. On the basis of the reported fatty acid profiles of psychrotolerant bacteria at different temperatures, multiple lipid membranes are simulated at a wide range of temperatures between 250 and 300 K. We explicate how the homeoviscous adaptation minimizes the effect of cold stress on the structure and fluidity of the membrane. Partial freezing of the saturated lipid domain occurs with the self-aggregation of saturated and unsaturated lipids near the melting temperature of the unadapted lipid membrane. The gel-like phase provides necessary local packing density that can be sensed by sensor proteins responsible for the homeoviscous adaptation.

Mercury (Hg2+) interferes with physiological adaptations to freezing in the arctic earthworm Enchytraeus albidus

Freezing temperatures is an important stressor in the arctic regions and has a significant influence on the population dynamics and geographic distribution of terrestrial invertebrates. Toxic metals in the environment can interfere with protective cold-acclimation responses of organisms. It is therefore important to evaluate the combined effects of cold stress and environmental contaminants. Here, we aimed to investigate the effects of Hg (HgCl2) on various physiological aspects of freeze-tolerance in the earthworm (Enchytraeus albidus). We measured the levels of the cryoprotectant glucose, the glycogen content (source of glucose molecules for cryoprotection and fuel for metabolism), and changes in the composition of membrane phospholipid fatty acids (PLFA) as an indicator of lipid peroxidation.Freezing at −6 °C had no effect on survival in uncontaminated soil, however, survival of freezing in Hg contaminated soil was clearly reduced, especially at extended exposure times. Thus, the LC50 value in frozen soil decreased from 8.3 mg Hg kg−1 (when exposed for 17 days) to only 4.2 mg Hg kg−1 after 36 days’ exposure indicating that combined effects of Hg and freezing became larger at prolonged exposure times. Hg caused a depletion of glycogen reserves (almost 50% at 12 mg kg−1 dry soil), but despite this effect worms were able to maintain a constant cryoprotectant level (about 0.12 mg glucose mg−1 dry weight) at all Hg concentrations. Hg had clear negative effects on the proportion of unsaturated PLFAs, which could be an indication of lipid peroxidation. Since a high proportion of unsaturated fatty acids in the membrane is important for invertebrate freeze-tolerance, our results suggest that the negative effect of Hg on freeze-tolerance in E. albidus is related to degraded membrane functionality at low temperature.

Physiological and gene expression analysis of the Manila clam Ruditapes philippinarum in response to cold acclimation

Overwinter mortality of the Manila clam (Ruditapes philippinarum) is a major impediment to the aquaculture industry in China. Cold tolerance ability has a tremendous impact on the survivability of R. philippinarum during the overwintering season. In this study, we evaluated the effects of acute and chronic cold stress on the expression of Cold Shock Domain-containing E1 (CSDE1) and Antifreeze protein type II (AFPII) genes and the activities of lysozyme (LZM), catalase (CAT), and superoxide dismutase (SOD) in three cultivated strains (zebra, white, and white zebra) and two wild populations (northern and southern) of R. philippinarum. Under acute and chronic cold stress, the expression levels of CSDE1 and AFPII mRNA in the gills and hepatopancreas were significantly increased in all populations, but the increase varied among different strains and populations. Under acute cold stress, SOD activity significantly decreased in the two wild populations and the white zebra strain. LZM activity significantly decreased but CAT activity significantly increased in selected strains and populations after acute low temperature stress (P < 0.05). Under chronic cold stress, SOD activity significantly increased in the northern population and white zebra strain, while CAT activity significantly increased in the southern population and the white and zebra strains. These results provide useful information about the Manila clam response to cold stress that may be applied to improve the low temperature resistance of Manila clams in aquaculture environments.

Temperature Stress Affects Survival and Antibiotic Susceptibility of Pathogenic and Indicator Bacteria in Drinking Water Dispensing System

Point-of-use water treatment and dispensing systems are becoming common features in middle-to-upper class homes and public spaces. However, their effectiveness at providing potable water is yet to be substantiated. In this study, the effect of temperature stress (cold ≈ 10oC and hot ≈ 78oC) on survival of three pathogenic (Salmonella typhi, Shigella dysenteriae, Vibrio cholerae), a nuisance (Proteus vulgaris) and the indicator (Escherichia coli) bacteria was evaluated in water dispensers. Individual test organism was spiked into pre-sterilized distilled water in a 25-L dispenser bottle. The bottle was fitted and the machine set on to allow the organisms acclimatized for 30 mins before samples were collected. The holding temperatures apparently had an immediate significant inhibitory effect (p&lt;0.05) on the pathogens, being greater in dispensed hot water. Effect of cold temperature stress was least on Escherichia coli. While Shigella dysenteriae and Vibrio cholerae were completely inactivated in dispensed hot water, there were some levels of resuscitation in the other organisms that were initially stressed by either the hot or cold temperature after just 1 h of cooling to room temperature. The re-inactivation was significant (p&lt;0.05) in the dispensed cold water for Salmonella typhi and Vibrio cholerae. With exception of Shigella dysenteriae, other organisms exhibited varied susceptibility (5–11 mm) to six of eight antibiotics; this appeared to increase following the temperature stress. However, increased resistance to augmentin, nitrofurantoin and tetracycline was observed in some temperature-stressed strains, particularly Salmonella typhi and Vibrio cholerae as well as Escherichia coli. The findings indicate that, while hot or cold temperature may have an immediate inhibitory effect on microbial loads and antibiotic susceptibility, the unwholesome practice of drinking dispensed water several hours after should be discouraged.

Alleviation of cold stress in vegetable crops

Low temperature is a major environmental factor that limits crop productivity of plants. Cold stress is a serious threat to the sustainability of crop yields. Low temperature has a huge impact on the survival and geographical distribution of plants. It negatively affects cellular components and metabolism, and temperature extremes impose stresses of variable severity that depend on the intensity and duration of the stress. Low temperature (less than minimum) leads to chlorosis, necrosis, membrane damage, changes in cytoplasm viscosity, and changes in enzyme activities leading to death of plant. Cold stress disrupts the integrity of intracellular organelles, leading to the loss of compartmentalization. It also causes reduction and impairing of photosynthesis, protein assembly and general metabolic processes. Moreover, cold stress during anthesis induces flower dropping, sterility of pollen, pollen tube distortion, ovule abortion and reduced fruit set, which leads to declined growth and lower yield. A number of approaches are being used to mitigate the deleterious effects of cold stress which threatens the successful vegetable crop production, application of plant growth regulators (salicylic acid, abscisic acid, jasmonic acid, Gibberellin and brassinosteroids) and unitization of genetics tools and plant breeding is one of the strategies to alleviate the low temperature stress in vegetable crops. Plant growth regulators play a greater role in improving the cold stress tolerance. In this paper, the effects of cold stress on vegetable growth, productivity and physiological activities were discussed, and some effective techniques for the mitigation of cold stress that help sustainable vegetable production under fluctuating climate is presented.

Effects of Different Stress Treatments on the Total Terpene Trilactone Content and Expression Levels of Key Genes in Ginkgo biloba Leaves

As unique secondary metabolites of Ginkgo biloba L. and relics of Ginkgoaceae, terpene trilactones (TTLs) possess great medicinal value. In this study, we investigated the effects of ultraviolet (UV) irradiation, cold stress (4 °C), and exogenous hormone treatment on TTLs and key genes expression in ginkgo leaves in annual potted ginkgo seedlings subjected to different stress treatments. The processing conditions were as follows: UV treatment (1500 μJ/m2) for 0, 8, 16, 24, and 48 h; cold stress at 4 °C, 400 µmol photons m−2 s−1; 100 μM abscisic acid (ABA); 100 μM methyl jasmonate (MeJA); 10 mM salicylic acid (SA); and 10 mM ethephon (ETH) treatments for 0, 2, 4, 6, and 8 days. Results of evaporative light-scattering detector–high-performance liquid chromatography showed that UV, cold stress, ABA, SA, MeJA, and ETH treatments increased the TTL content at various levels and up to 21.9%. The relationships among the expression levels of the key enzyme genes GbDXS, GbGGPPS, GbLPS, and GbMVD in the TTL biosynthesis pathway were also analyzed. Changes in the TTL content and expression levels of the key genes were significantly and positively correlated with TTL content. UV, cold stress, ABA, SA, MeJA, and ETH were found to increase the TTL content by upregulating the expression of the key genes. This study aimed to reveal the molecular mechanism through which TTLs are synthesized. The results can also provide theoretical guidance for the application of treatment methods to increase TTL content.

Variation of antibiotic resistance in Salmonella Enteritidis, Escherichia coliO157:H7, and Listeria monocytogenes after exposure to acid, salt, and cold stress

AbstractBacteria with antibiotic‐resistant could seriously threaten to human health, increasing the treatment cost for infections and negatively affecting treatment outcomes. Stress adaptation is one possible mechanism for the acquisition or enhancement of antibiotic resistance in bacteria as a result of cross‐protection. In this study, the effects of acid, salt, and cold stress on the antibiotic resistance of Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli O157:H7 were investigated using the disc diffusion method. For S. Enteritidis, acidic growth conditions increased resistance to ciprofloxacin and erythromycin (p &lt; .05), and addition of 4% NaCl to growth media decreased resistance to chloramphenicol (p &lt; .05). Irrespective of pH and the NaCl concentration of the growth medium, refrigerated E. coli O157:H7 showed increased resistance to amoxycillin, ciprofloxacin, gentamicin, streptomycin, and erythromycin (p &lt; .05). Acid‐adapted L. monocytogenes showed decreased the resistance to amoxycillin, ampicillin, chloramphenicol, ciprofloxacin, erythromycin, gentamicin, streptomycin, and tetracycline (p &lt; .05). In conclusion, prolonged exposure of foodborne pathogens to acid, salt, and cold stress alters their antibiotic resistance. However, the effect of acid, salt, and cold stress on bacterial antibiotic resistance depend on both the bacterial species and the specific antibiotic. Therefore, multiple factors need to be considered for a foodborne antimicrobial resistant risk assessment.

The effects of cold stress on Mytilus species in the natural environment

Environmental stressors induce changes in marine mussels from molecular (e.g., neurotransmitter and chaperone concentration, and expression of immune- and heat-shock protein-related genes) to physiological (e.g., filtration and heart rates, the number of circulating hemocytes) levels. Temperature directly affects the biogeographic distribution of mussels. Chaperones might form an essential part of endogenous protective mechanisms for the adaptation of these animals to low temperatures in nature. Here, we review the available studies dealing with cold stress responses of Mytilidae family members in their natural environment.

Effect of cold stress on ovarian & uterine microcirculation in rats and the role of endothelin system

BackgroundCold, an environmental factor, induces many reproductive diseases. It is known that endothelin (ET) is a potent vasoconstrictor, and cold stress can increase the expression of ET and its receptors. The cold stress rat model was developed to examine two parameters: (1) the effects of cold stress on ovarian and uterine morphology, function, and microvascular circulation and (2) possible mechanisms of ET and its receptors involved in cold stress-induced menstruation disorders.MethodsThe rat cold stress model was prepared with an ice water bath. The estrous cycle was observed by methylene blue and hematoxylin and eosin (H&E) staining. Serum estradiol 2 (E2), testosterone (T), progesterone (P) were detected by radioimmunoassay. Hemorheology indices were measured. The real-time blood flow of auricle and uterine surfaces was measured. Expressions of CD34 and α-SMA in ovarian and uterine tissues were detected by immunohistochemistry. ET-1 contents in serum were tested, and expressions of ET-receptor types A and B (ET-AR and ET-BR) in ovarian tissues were detected via Western blotting.ResultsCold stress extended the estrous cycle, thereby causing reproductive hormone disorder, imbalance of local endothelin/nitric oxide expression, and microcirculation disturbance. Cold-stress led to up-regulation of ET-AR expression and protein and down-regulation of ET-BR expression in rats.ConclusionsThis study suggests that the reason for cold stress-induced dysfunction in reproductive organs may be closely related to the imbalance of ET-1 and its receptor expressions, leading to microvascular circulation disorders in local tissues.

Impact of cold stress on birth and weaning weight in a composite beef cattle breed

Beef cattle are often exposed to extreme environmental conditions with varying temperatures, humidity, wind speed, and solar radiation. The objective of this study was to investigate the impact of cold stress on growth-related traits and to assess its variation between sire families in a composite beef cattle breed in eastern Montana. Weather data were collected from an airport close to the research station. Comprehensive climate index (CCI), a measure of cold load, was used to classify cold stress into mild (CCI < -5), moderate (CCI < -15), and severe (CCI < -25). The phenotypic data consisted of 4,221 and 4,217 records for birth weight (BWT) and weaning weight (WWT), respectively. For both traits, the statistical model included an overall mean, contemporary groups, and a regression on cold stress load. For WWT, the model included additional regressions on birth weight and age at weaning. The results showed that mild and moderate cold stress increased BWT by 5.88 and 0.71 kg, respectively. However, severe cold stress slightly decreased BWT (-0.010 kg). Cold stress resulted in a significant decrease in WWT for mild (27.90 kg) and moderate (17.42 kg) cold stress, while the decrease in WWT for severe (2.07 kg) cold stress was insignificant. Using only data from three different sire families with the largest paternal half-sib families, estimates of within family regression coefficients on cold stress were statistically different (based on Welch's t-test) for BWT and WWT. These results seem to indicate that cold stress has a limited negative (often positive) effect on BWT which could be due to some nutritional prioritization of nutritional resources toward the fetus. Furthermore, comparing cold stress effects across different sire families indicated the existence of potential genetic variation in cold stress response.