Sudden Temperature Drop Research Articles

Effects of Melatonin on Ginseng Leaf Phenotypic and Photosynthetic Properties Following Chilling and Freezing Stress

Spring frost damage is a significant natural disaster, which can lead to large-scale ginseng (Panax ginseng C. A. Mey) yield reduction. To determine chilling and freezing stress damage to ginseng, we designed an experiment using three-year-old potted ginseng plants. We simulated chilling (0±0.3 ℃) and freezing (-2.5±0.3 ℃, -5±0.3 ℃) in an artificial room, with 16±2 ℃ of the room temperature at night as the control, to evaluate their physiological effects on ginseng leaf spectral reflectance, photosynthetic characteristics, and chlorophyll fluorescence parameters. We also investigated the mitigating effects of exogenous melatonin on ginseng leaves exposed to chilling and freezing stress. All ginseng leaves died under -5 ℃ freezing stress and the mortality rate reached 25∼57% under -2.5 ℃ freezing stress, while no plants died under 0 ℃ chilling stress. After -2.5 ℃ and 0 ℃ stress, leaf spectral reflectance in the 750∼1000 nm band was significantly lower than the control; transpiration rate, net photosynthetic rate, intercellular CO2 concentration, and stomatal conductance decreased significantly compared with the control, and there was no significant change in recovery time. The Fv/Fm ratio and qp decreased after low-temperature stress, while NPQ increased. After one week of melatonin application, leaf spectral reflectance in the 600∼650 and 750∼1000 nm bands reflected significant differences between the effects of melatonin application and no application on ginseng leaf chlorophyll content and structure under freezing stress. Ginseng leaf net photosynthetic rate increased by 23.79% and 4.48%, while intercellular CO2 concentration increased by 33.49 and 11.83% under stress at -2.5°C and 0°C. The ginseng leaf chlorophyll fluorescence parameter (Fv/Fm) recovered to 0.8 and above in one week after melatonin application, and qp decreased under -2.5°C and 0°C stress after melatonin application. Additionally, the NPQ values were 11.44% and 4.6% lower in -2.5+MT and 0+MT, respectively, compared to the treatment without MT applied. A sudden drop in temperature to 0 ℃ or even below caused ginseng plant growth inhibition, but melatonin application at a concentration of 100 nmol L−1 had certain mitigating effects on ginseng growth, which provides a theoretical basis and technical support for ginseng production.

Physiological and ecological responses of flue-cured tobacco to field chilling stress: insights from metabolomics and proteomics

IntroductionCurrently, research on tobacco's response to chilling stress is mostly limited to laboratory simulations, where temperature is controlled to study physiological and molecular responses. However, laboratory conditions cannot fully replicate the complex environment of field chilling stress, so conducting research under field conditions is crucial for understanding the multi-level adaptive mechanisms of tobacco to chilling stress in natural environments. MethodsThis study aims to use field trials, starting from physiological responses, combined with proteomics and untargeted metabolomics, to systematically reveal the physiological and biochemical characteristics and key molecular mechanisms of tobacco leaves under chilling stress. It provides new insights into tobacco's adaptation strategies under chilling stress. ResultsThe results showed that (1) chilling stress damages the appearance of tobacco leaves, reduces the chlorophyll content, increases H2O2 and malondialdehyde (MDA) levels in cold-injured tobacco leaves, and damages the plasma membrane system. Although catalase (CAT) activity increases to cope with the accumulation of reactive oxygen species (ROS), the activities of key antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD) significantly decrease, indicating that the antioxidant system of tobacco leaves fails in environments with sudden temperature drops. (2) Proteomics analysis indicated that 410 differentially expressed proteins were identified in cold-stressed tobacco leaves, with 176 upregulated and 234 downregulated. Tobacco leaves under chilling stress attempt to maintain energy supply and physiological stability by enhancing glycolysis, starch, and sucrose metabolism pathways. Concurrently, chilling stress triggers the expression of proteins related to cell wall reinforcement and antioxidant defense. However, due to impaired ribosomal function, protein synthesis is significantly inhibited, which aggravates damage to photosynthesis and cellular functions. (3) Metabolomics analysis revealed that the differential metabolites in cold-stressed tobacco leaves were mainly enriched in tyrosine metabolism, isoquinoline alkaloid biosynthesis, and fatty acid degradation pathways. This indicates that under chilling stress, tobacco leaves enhance adaptability by regulating energy metabolism, increasing antioxidant capacity, and stabilizing cell membrane structure. ConclusionsTherefore, under chilling stress, tobacco leaves exhibit complex physiological adaptability through multiple regulatory mechanisms involving proteins and metabolites. The research results provide important insights into the metabolic regulatory mechanisms of tobacco in response to extreme environments and also enhance the theoretical foundation for addressing low-temperature stress in practical production.

Chemical and Thermal Changes in Mg3Si2O5 (OH)4 Polymorph Minerals and Importance as an Industrial Material

Serpentine (Mg3Si2O5(OH)4), like quartz, dolomite and magnesite minerals, is a versatile mineral group characterized by silica and magnesium silicate contents with multiple polymorphic phases. Among the phases composed of antigorite, lizardite, and chrysotile, lizardite and chrysotile are the most prevalent phases in the serpentinites studied here. The formation process of serpentinites, which arise from the hydrothermal alteration of peridotites, influences the ratio of light rare earth elements (LREE) to heavy rare earth elements (HREE). In serpentinites, the ratio of light rare earth elements (LREE)/heavy rare earth elements (HREE) provides insights into formation conditions, geochemical evolution, and magmatic processes. The depletion of REE compositions in serpentinites indicates high melting extraction for fore-arc/mantle wedge serpentinites. The studied serpentinites show a depletion in REE concentrations compared to chondrite values, with HREE exhibiting a lesser degree of depletion compared to LREE. The high ΣLREE/ΣHREE ratios of the samples are between 0.16 and 4 ppm. While Ce shows a strong negative anomaly (0.1–12), Eu shows a weak positive anomaly (0.1–0.3). This indicates that fluid interacts significantly with rock during serpentinization, and highly incompatible elements (HIEs) gradually become involved in the serpentinization process. While high REE concentrations indicate mantle wedge serpentinites, REE levels are lower in mid-ocean ridge serpentinites. The enrichment of LREE in the analyzed samples reflects melt/rock interaction with depleted mantle and is consistent with rock–water interaction during serpentinization. The gradual increase in highly incompatible elements (HIEs) suggests that they result from fluid integration into the system and a subduction process. The large differential thermal analysis (DTA) peak at 810–830 °C is an important sign of dehydration, transformation reactions and thermal decomposition, and is compatible with H2O phyllosilicates in the mineral structure losing water at this temperature. In SEM images, chrysotile, which has a fibrous structure, and lizardite, which has a flat appearance, transform into talc as a result of dehydration with increasing temperature. Therefore, the sudden temperature drop observed in DTA graphs is an indicator of crystal form transformation and CO2 loss. In this study, the mineralogical and structural properties and the formation of serpentinites were examined for the first time using thermo-gravimetric analysis methods. In addition, the mineralogical and physical properties of serpentinites can be recommended for industrial use as additives in polymers or in the adsorption of organic pollutants. As a result, the high refractory nature of examined serpentine suggests that it is well-suited for applications involving high temperatures. This includes industries such as metallurgy and steel production, glass manufacturing, ceramic production, and the chemical industry.

Multiple edge cracks in a coated semi-infinite medium due to non-Fourier thermal shock

In this wok, based on the non-Fourier C-V model, the problem for multiple edge cracks is investigated for a coating-substrate pair subjected to a sudden temperature drop at the surface of coating. The temperature and resulting thermal stresses without cracks are obtained by the method of Laplace transform. By numerically solving the singular integral equations, the thermal stress intensity factors (SIFs) are evaluated. The results from the Fourier model and C-V heat conduction model are presented for comparison. Two dimensionless quantities are proposed to account for the coupling effects of heat conduction parameters (i.e., thermal conductivity, thermal diffusivity, and thermal relaxation time). Numerical results are presented for the thermal SIF as a function of normalized quantities such as time, crack depth, material constants and crack spacing. The findings in this work are expected to provide references for maintaining the integrity of the coating-substrate pair in the extreme heat transfer applications.

Regulating the interaction between protein and starch in noodles through heat loss: Used to improve the edible quality of noodles

The impact of heat loss during water-cooling process on the edible quality of cooked noodles currently remains unclear. This study aimed to explore the effects of different water-cooling times (0, 20, 40, 60, 80, 100, and 120 s) on changes in gluten and starch structures and their impact on the sensory evaluation and texture of noodles. Results showed that the control group had a higher core temperature, while the core temperature of the noodles equilibrated with the water temperature after water-cooling for 100 s. Within the range of 20–100 s of water-cooling time, a sudden drop in the core temperature of the cooked noodles caused the gluten conformation to transition toward more compact β-sheets. Surface hydrophobicity decreased, while S-S and hydrogen bonds increased. The microstructure of the noodles became more compact, reducing gaps between protein and starch molecules. Small-angle X-ray scattering and atomic force microscopy analyses demonstrated that gluten chains aggregated after water-cooling, resulting in increased chain width and height. The wheat gluten protein structure transitioned from a disordered state to a random coil. Ultimately, the hardness, springiness, and chewiness of the noodles gradually increased. Water distribution results revealed that the free water content of the noodles increased after 120 s of water-cooling, enhancing the hydration between protein and water molecules but decreasing the noodle texture. According to X-ray diffraction and differential scanning calorimeter analyses, heat loss did not alter the gelatinized starch crystal structure of noodles. Therefore, changes in core temperature were the primary cause of gluten structural changes prior to 100 s of water-cooling. After 120 s of water-cooling, increased hydration between noodle surface gluten and water negatively affected the edible quality of noodles. This study provides theoretical data on noodle edible quality and is of significant practical importance.

Time-resolved analysis of Ar metastable and electron populations in low-pressure misty plasma processes using optical emission spectroscopy

Misty plasmas have recently emerged as a promising tool for nanocomposite thin films deposition. However, aerosol-plasma interactions remain poorly documented, especially at low working pressure. In this work, optical emission spectroscopy is used to probe the temporal evolution of three fundamental plasma parameters during pulsed liquid injection in an inductively coupled argon plasma at low-pressure. Time-resolved values of metastable argon density, electron temperature, and electron density are determined from radiation trapping analysis and particle balance equations of selected argon 1s and 2p levels. Pulsed liquid injection is found to induce a sudden drop in metastable density and electron temperature, and an increase in electron density. These results are attributed to the lower ionization thresholds of the injected molecular species compared to the one of argon. In addition, upstream liquid temperature is found to affect the transitory kinetics for non-volatile solvents more than volatile ones, in accordance with a previously reported flash boiling atomization mechanism.

Aircraft observations of aerosol and BC during the East Asian dust storm event: Vertical profiles, size distribution and mixing state

The vertical structure of meteorological elements, black carbon (BC), and aerosols were in situ characterized by the King Air 350 aircraft measurements over the northeast of China during an East Asian dust storm event from April 10 to 13, 2023. The main causes of this dust storm event were the strong winds generated by the Mongolian cyclone, the cold front on the ground provided dynamic conditions, and the unstable atmospheric state provided thermal conditions and less precipitation in the dust source areas led to exposed the ground surface. The number concentrations of BC and aerosol had significant vertical distribution. The number concentration of aerosol in the dust storm (DS) layer increased rapidly with height, while the number and mass concentrations of BC were higher and varied slightly with height. The BC core mass median diameters (MMD) first increased with height, reaching a maximum value of 0.24 μm at 3000 m; and it rapidly decreased to 0.18 μm at 3200 m and then varied slightly with height above 3200 m. BC's bulk relative coating thickness (coated diameter divided by uncoated core diameter Dp/Dc) first decreased with height, reaching a minimum value of 1.16 at 3000 m, then increased with height, reaching a maximum of 1.38 (4250 m). A wind shear layer (7.9 m s−1 at 1850 m) with a sudden drop in temperature (the cooling rate can reach 7.4 °C·(100 m)−1) at 1900 m hinders the transportation of dust particles to the ground, allowing the dust particles to be transported at long-term distances. There were two stratifications in the dust storm layer: DS1 (1700–3000 m, the vertical wind speed was downward, the horizontal wind speed was small) and DS2 (3000–4500 m, the vertical wind speed was upward, the horizontal wind speed was large). The distinct atmospheric flow field conditions between DS1 and DS2 led to different BC and aerosol pollution characteristics. In DS2, the number concentrations of BC and aerosol were higher, the aging ratio of BC particles was higher, and the size of the core particle of BC was smaller. The concentrations of BC, aerosol, Dp/Dc, and MMD in DS2 were 1.1, 59.0, 1.02, and 0.84 times higher than those in DS1, respectively. Dust particles transported over long distances were primarily small. The number concentrations of aerosols at 0.1–0.12 μm and 0.1–0.24 μm were higher in DS1 and DS2, respectively. Still, the number concentration of aerosol at 0.12–0.28 μm in DS1 was lower than in the planetary boundary layer (PBL) and residual layer (RL).

Functional PCA and deep neural networks-based Bayesian inverse uncertainty quantification with transient experimental data

This work focuses on developing an inverse uncertainty quantification (IUQ) process for time-dependent responses, using dimensionality reduction by functional principal component analysis (PCA) and deep neural network (DNN)-based surrogate models. The demonstration is based on the IUQ of TRACE physical model parameters using the FEBA benchmark transient experimental data on peak cladding temperatures during reflooding. The quantity-of-interest (QoI) is time-dependent peak cladding temperature (PCT) profiles. Conventional PCA can hardly represent the data precisely due to the sudden temperature drop at the time of quenching. As a result, a functional alignment method is used to separate the phase and amplitude information in the PCT profiles before conventional PCA is applied for dimensionality reduction. The resulting PC scores are then used to build DNN-based surrogate models to significantly reduce the computational cost in Markov Chain Monte Carlo sampling, while the code/interpolation uncertainty is accounted for using Bayesian neural networks. We compared four IUQ processes with different dimensionality reduction methods and surrogate models. The proposed approach has demonstrated the best performance in reducing the dimensionality of the transient PCT profiles. This approach also produces the posterior distributions of the physical model parameters with which the model predictions have the best agreement with the experimental data.

Manchas de Wischnewsky em casos de hipotermia fatal em bovinos

ABSTRACT: Wischnewsky spots (WS) are hemorrhagic, non-erosive, and non-ulcerative lesions that affect the gastric mucosa. They are considered common in the stomachs of humans who have died from hypothermia and are rarely described in other animal species. This study describes the occurrence of WS in cattle that had died of hypothermia in two cities in the state of Mato Grosso do Sul. Two properties were visited, and three cattle were necropsied by the team from the Pathological Anatomy Laboratory of the Federal University of Mato Grosso do Sul (LAP-UFMS). The epidemiological conditions and clinical signs of the cattle examined on both properties were similar. The deaths occurred on days when there was a sudden drop in environmental temperature, with continuous rain for more than 24 hours. During the visits, the most affected live cattle were found in sternal decubitus, with their heads resting on their flanks, or laterally in a comatose state, with nystagmus and a rectal temperature below 32°C. Macroscopically, there were multifocal to coalescent red and black areas on the mucosal surface of the abomasums of the three cattle necropsied, mainly at the apex of the folds, oval or punctate in shape, measuring 0.1 to 1.0cm in diameter. Microscopically, these dark areas corresponded to areas of rarefaction of the mucosal epithelial cells associated with hemorrhage and the frequent deposition of golden-brown pigment (hematin) in the extracellular medium. The diagnosis of hypothermia in cattle was based on epidemiology, clinical-pathological examination, and the exclusion of differential diagnoses. The lesions found in the abomasum of cattle that had died from hypothermia were compatible with WS, highlighting the importance of recognizing them in cases of cattle deaths in which this condition is suspected.

Analyzing structure loss in Czochralski silicon growth: Root causes investigation through surface examination

A considerable proportion of the grown Czochralski Si ingots are remelted due to the generation of dislocations or the so-called structure loss. The assessment of the failed ingots is a crucial step toward achieving higher yield. Nonetheless, characterizing Si ingots poses a challenge attributed to their inherent high brittleness and the elevated concentration of dislocations, further complicating the cutting process. In this work, we utilize a non-destructive method to categorize the failed ingots and reveal the root causes of this failure. This study is performed on roughly 80 industrial monocrystalline silicon ingots that are grown for solar cell applications. Most of these ingots have experienced structure loss during the body growth. Analyzing the surface features reveals major categories of the structure loss ingots. Approximately, 66% of the examined ingots seem to be linked with temperature fluctuations, specifically a sudden drop in the melt temperature, and contamination by foreign particles. It is found that the primary causes can be categorized into four major groups: melt contamination, thermal fluctuations, melt vibration, and variations in growth rate. The primary root causes are identified within a fishbone diagram.

An efficient approach to detect and track winter flush growth of litchi tree based on UAV remote sensing and semantic segmentation

The immature winter flush affects the flower bud differentiation, flowering and fruit of litchi, and then seriously reduces the yield of litchi. However, at present, the area estimation and growth process monitoring of winter flush still rely on manual judgment and operation, so it is impossible to accurately and effectively control flush. An efficient approach is proposed in this paper to detect the litchi flush from the unmanned aerial vehicle (UAV) remoting images of litchi crown and track winter flush growth of litchi tree. The proposed model is constructed based on U-Net network, of which the encoder is replaced by MobeilNetV3 backbone network to reduce model parameters and computation. Moreover, Convolutional Block Attention Module (CBAM) is integrated and convolutional layer is added to enhance feature extraction ability, and transfer learning is adopted to solve the problem of small data volume. As a result, the Mean Pixel Accuracy (MPA) and Mean Intersection over Union (MIoU) on the flush dataset are increased from 90.95% and 83.3% to 93.4% and 85%, respectively. Moreover, the size of the proposed model is reduced by 15% from the original model. In addition, the segmentation model is applied to the tracking of winter flushes on the canopy of litchi trees and investigating the two growth processes of litchi flushes (late-autumn shoots growing into flushes and flushes growing into mature leaves). It is revealed that the growth processes of flushes in a particular branch region can be quantitatively analysed based on the UAV images and the proposed semantic segmentation model. The results also demonstrate that a sudden drop in temperature can promote the rapid transformation of late-autumn shoots into flushes. The method proposed in this paper provide a new technique for accurate management of litchi flush and a possibility for the area estimation and growth process monitoring of winter flush, which can assist in the control operation and yield prediction of litchi orchards.

Late Triassic–Jurassic bivalve biochronology, palaeogeography and palaeoenvironment of the Junggar Basin, NW China

Abstract The middle Mesozoic of the southern Junggar Basin is a source of abundant Late Triassic–Jurassic non-marine and Early Jurassic marine–littoral bivalves. The bivalve chronology provides a framework for dating the strata and documents Early Jurassic transgressions and the end-Triassic mass extinction in the Junggar Basin. The first occurrences (FOs) and last occurrences (LOs) of Utschamiella cf. tungussica and Utschamiella cf. obrutschevi lie in the basal upper Rhaetian. The FOs of Ferganoconcha sibirica , Ferganoconcha subcentralis , Unio manasensis , Unio mirabilis and Waagenoperna are at, and the FOs of Margaritifera isfarensis , Tutuella rotunda and Tutuella chachlovi adjoin, the base of the middle Sinemurian. The LOs of Yananoconcha hengshanensis and Waagenoperna are at the Lower–Middle Jurassic boundary. The LOs of Psilunio , Cuneopsis and F . subcentralis are near the Middle–Upper Jurassic boundary. Non-marine bivalves disappeared in the late Rhaetian, due to a sudden Norian–Rhaetian temperature drop. New forms did not return until the Sinemurian, when the climate warmed. The transgressions created low-relief terrestrial environments, in which organisms including bivalves thrived, leading to the formation of large quantities of coal, oil and gas. The Junggar Basin shifted from Arctic to subtropical latitudes in the Northern Hemisphere between the Early and Middle Jurassic.

Decay Characteristics of Mechanical Properties of Asphalt Mixtures under Sizeable Wet Temperature Cycle

Asphalt mixtures will inevitably be affected by rainwater and the effect of the wet temperature cycle during a pavement’s life span. Especially in coastal areas such as Guangdong and Hainan in China, asphalt pavement is particularly susceptible to the sizeable wet temperature cycle formed by the high temperature and sudden temperature drop of rainstorms in summer. For this study, we used a homemade sizeable wet temperature cycle environment simulation device to analyze the decay characteristics and the mechanical properties of asphalt pavements in this environment; modified bending and tensile strength and shear strength tests were used to study the decay patterns of shear strength, bending, and tensile strength, and the stiffness modulus of asphalt mixtures with different air voids and different pavement depths under the action of a sizeable wet temperature cycle. In addition, the Grey correlation method was used to analyze the significance of each influencing factor on the decay of mechanical properties, and mathematical fitting was used to establish the prediction equation of the mechanical properties of asphalt mixtures. The results show that with the increase in the number of sizeable wet temperature cycles, the asphalt mixture’s shear strength, flexural tensile strength, and flexural tensile modulus decrease, the degree of decay increases, and the rate of decay gradually slows down. In the case of the same number of sizeable wet temperature cycles, the degree of decay of the asphalt mixtures gradually decreases with increasing depth or decreasing void ratio. After 100 sizeable wet temperature cycles, the maximum values of the decay of shear strength, modulus of strength, and flexural tensile strength were 22.30%, 23.29%, and 32.01%. The importance of the influence of each factor on the decay of the mechanical properties is as follows: the number of sizeable wet temperature cycles > void rate > depth. The prediction equations of the established mechanical properties have a good prediction effect, and the correlation between predicted values and actual values can be up to 0.925. The prediction equations can effectively predict the mechanical properties of asphalt mixtures with different air voids and depths under the action of sizeable wet temperature cycles.

Heat load-carrying capacity of surface water source and its heating load matching characteristics

Meteorological parameter changes not only affect the heat load-carrying capacity of the surface water, but also affect the heat load demand of the building, thus changing the heat load matching between the water source heat pump system and the users. In order to study the climatic adaptation of the heat load-carrying capacity, this paper establishes an analytical model of the water body's heat load-carrying capacity and the building's heat load with the solar radiation intensity, the change of the water body and the heat extraction time as variables. Experimental and simulation studies on the heat load-carrying capacity of lake water were carried out under the winter climate conditions in hot summer and cold winter areas. The results show that increasing the depth or area of the lake can improve the heat load-carrying capacity. Solar radiation is an important factor affecting the temperature of surface water body, the stronger the solar radiation the greater the temperature rise of the water body. Changes in outdoor air temperature have a significant impact on water temperature, and a sudden drop in outdoor air temperature will result in a sharp drop in water temperature. When the water body area was 3000 m2 and 50000 m2, the maximum integrated temperature drop of the water body was 15.0℃ and 9.7℃, which was 2.02 and 4.85 times of the temperature drop of heat extraction, respectively. Reduced heat load-carrying capacity of the surface water body or decreased COP of the heat pump is an important reason why the surface water source heat pump heat supply fails to meet the user's heat demand in winter.

Failure Analysis of Casing in Shale Oil Wells under Multistage Fracturing Conditions

During the multistage fracturing in shale oil and gas wells with tieback and liner, one of the major challenges is the wellbore temperature variation due to the high-rate fracturing. In such a case, the axial shrinkage trend of the casing string could be caused due to the sudden drop in temperature, but the actual axial length of the casing string would not change due to the cement constraints. Therefore, this could lead to cementation damage between the casing and cement due to excessive load from the casing string. A wellbore seal that is out of control often leads to irreversible consequences, even well abandonment. In order to study the mechanism of casing deformation in shale oil and gas wells with tieback and liner quantitatively, in this paper, take LS1 well (a typical shale oil and gas well with tieback and liner, and casing deformation is caused) for example, the transient changes of temperature and pressure in the whole wellbore during multistage fracturing are studied. Moreover, the cementing strength test of the interface between casing and cement is also tested. Then, the testing results are carried out and extended to model the finite element (FE) model with the whole vertical section casing string with tieback and liner. The model is used to simulate the internal force changes under fracturing conditions with different stages of fracturing. Meanwhile, the casing deformation mechanism in LS1 well is analyzed and studied in detail. Our simulation results indicated the failure process and mechanism of cementation between casing and cement in shale oil and gas wells with tieback and liner. Our work can provide a detailed theoretical reference and a basis for field application.

Transcriptome Analysis Reveals Brassinolide Signaling Pathway Control of Foxtail Millet Seedling Starch and Sucrose Metabolism under Freezing Stress, with Implications for Growth and Development.

Low-temperature stress limits the growth and development of foxtail millet. Freezing stress caused by sudden temperature drops, such as late-spring coldness, often occurs in the seedling stage of foxtail millet. However, the ability and coping strategies of foxtail millet to cope with such stress are not clear. In the present study, we analyzed the self-regulatory mechanisms of freezing stress in foxtail millet. We conducted a physiological study on foxtail millet leaves at -4 °C for seven different durations (0, 2, 4, 6, 8, 10, and 12 h). Longer freezing time increased cell-membrane damage, relative conductance, and malondialdehyde content. This led to osmotic stress in the leaves, which triggered an increase in free proline, soluble sugar, and soluble protein contents. The increases in these substances helped to reduce the damage caused by stress. The activities of superoxide dismutase, peroxidase, and catalase increased reactive oxygen species (ROS) content. The optimal time point for the response to freezing stress was 8 h after exposure. The transcriptome analysis of samples held for 8 h at -4 °C revealed 6862 differentially expressed genes (DEGs), among which the majority are implicated in various pathways, including the starch and sucrose metabolic pathways, antioxidant enzyme pathways, brassinolide (BR) signaling pathway, and transcription factors, according to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. We investigated possible crosstalk between BR signals and other pathways and found that BR signaling molecules were induced in response to freezing stress. The beta-amylase (BAM) starch hydrolase signal was enhanced by the BR signal, resulting in the accelerated degradation of starch and the formation of sugars, which served as emerging ROS scavengers and osmoregulators to resist freezing stress. In conclusion, crosstalk between BR signal transduction, and both starch and sucrose metabolism under freezing stress provides a new perspective for improving freezing resistance in foxtail millet.

Transcriptome analysis reveals reduced immunity and metabolic level under cold stress in Mauremys mutica

The yellow pond turtle (Mauremys mutica) is widely cultured for food, medicine and for keeping as pets in China. The high risk of disease outbreaks and mortality caused by sudden sharp temperature drop events has significant negative effects on the aquaculture industry of M. mutica. However, the mechanism underlying the damage caused by cold stress is still unclear. To fill this gap, we performed transcriptome sequencing of M. mutica samples collected at three sampling time points (3h, 24h and 48h) during cold treatment, and at a recovery time point (96 h after the end of cold stress). The results showed that immunity and metabolism-related pathways (neuroactive ligand-receptor interactions, cytokine-cytokine receptor interactions and NOD-like receptor signaling pathways) were significantly enriched at both 24h and 48h. The expression of immunity and metabolism-related genes (BS2A1, PIWIL2 and Fads1) significantly decreased at all-time points compared to the control group. These results suggested that impaired immunity and depressed metabolism under cold stress may be the main cause of the massive cold-stress mortality of M. mutica. This study provides novel insights into the molecular mechanisms underlying mass disease and mortality caused by sudden sharp temperature drop events in M. mutica.

Genome-wide transcriptional profiling provides clues to molecular mechanisms underlying cold tolerance in chickpea

Chickpea is an important food legume cultivated in several countries. A sudden drop in autumn temperature, freezing winter temperature, and late spring cold events result in significant losses in chickpea production. The current study used RNA sequencing of two cold tolerant (Saral) and sensitive (ILC533) Kabuli chickpea genotypes to identify cold tolerance-associated genes/pathways. A total of 200.85 million raw reads were acquired from the leaf samples by Illumina sequencing, and around 86% of the clean reads (199 million) were mapped to the chickpea reference genome. The results indicated that 3710 (1980 up- and 1730 down-regulated) and 3473 (1972 up- and 1501 down-regulated) genes were expressed differentially under cold stress in the tolerant and sensitive genotypes, respectively. According to the GO enrichment analysis of uniquely down-regulated genes under cold stress in ILC533, photosynthetic membrane, photosystem II, chloroplast part, and photosystem processes were enriched, revealing that the photosynthesis is severely sensitive to cold stress in this sensitive genotype. Many remarkable transcription factors (CaDREB1E, CaMYB4, CaNAC47, CaTCP4, and CaWRKY33), signaling/regulatory genes (CaCDPK4, CaPP2C6, CaMKK2, and CaHSFA3), and protective genes (CaCOR47, CaLEA3, and CaGST) were identified among the cold-responsive genes of the tolerant genotype. These findings would help improve cold tolerance across chickpea genotypes by molecular breeding or genetic engineering.

Effects of cold-season climate hazards on livestock health and mortality in Mongolia

Recent global climatic changes have caused frequent cold-season climate hazards and associated damage to societies in Mongolia. Here, we investigated the interannual variability of cold-season hazard indicators and their relationships to livestock health (mortality, health, and weight). A principal component analysis was applied to indicators (snow depth in January, SD1; air temperature for October–March, AT10-3) to extract significant modes. Then, we performed correlation and regression analyses to identify the contribution of each indicator to mortality and weight. Prior to analysis, we classified the cold season into two periods: early winter (EW) and late winter (LW). To our knowledge, this is the first study involving a detailed analysis of monthly indicators for livestock that reveals the dynamics of how weather affects health over time.The results showed that the higher SD1 and lower AT10-3 coefficients of the first modes coincided with severe winters (SW) and, conversely, mild winters (MW). Compositing SW and MW, mortality increased seven times per winter, and weight decreased twice as fast per month during SW. Focusing on EW and LW, the accumulated temperature of cold outbreak events was most significantly correlated with mortality during EW. This indicates that when temperatures are moderate, a sudden drop in temperature may have deleterious effects on livestock, leading to rapid weight loss and death because they have not had sufficient time to acclimatize. These seasonally changing dynamics connecting weather events and health will provide vital information for disaster risk management, including timely weather forecasts and proactive countermeasures to avoid a mass loss of livestock.

Rapid cold hardening response of the phytoseiid mite Neoseiulus striatus: increased cold tolerance but not reduced predation

The predatory mite Neoseiulus striatus (Wu) (Acari: Phytoseiidae), which has been found on maize plants in Inner Mongolia, is regarded as a promising biological control agent of small sucking pests, especially Tetranychid mites. Temperature is an important abiotic factor, and a sudden drop in temperature may affect its performance when released in areas with big circadian temperature differences. Rapid cold hardening is a type of phenotypic plasticity that allows ectotherms to quickly enhance their cold tolerance in response to a brief chilling exposure. However, it is not clear whether N. striatus possesses such plasticity. To understand how this species of phytoseiid mite copes with short-term low-temperature stress, its rapid cold hardening response was studied in the laboratory by first exploring its critical temperature. Then, the effects of exposure to a series of temperatures (0, 5, 10, 15, and 20°C) for different durations on the survival of N. striatus were investigated to determine the optimal temperature and duration for cold hardening. Moreover, the effect of cold hardening on the consumption of Tetranychus urticae by N. striatus was also investigated, as was the response of immature stages. The critical temperature for N. striatus was - 15°C, at which its survival dropped below 10%. An exposure to 5°C for 2h was optimal for rapid cold hardening, efficiently increasing survival in N. striatus. Rapid cold hardening was found in all developmental stages of N. striatus, and there was no significant effect of exposure on the consumption of spider mites. Our study shows that exposure to low temperatures during a limited period can enhance the cold hardiness but not reduce predation by N. striatus, which will be advantageous to its field applications during a period of large diurnal temperature fluctuations.