Showing papers on "Catalase published in 2010"

Measurement of superoxide dismutase, catalase, and glutathione peroxidase in cultured cells and tissue

Abstract: Cells contain a large number of antioxidants to prevent or repair the damage caused by reactive oxygen species, as well as to regulate redox-sensitive signaling pathways. General protocols are described to measure the antioxidant enzyme activity of superoxide dismutase (SOD), catalase and glutathione peroxidase. The SODs convert superoxide radical into hydrogen peroxide and molecular oxygen, whereas the catalase and peroxidases convert hydrogen peroxide into water. In this way, two toxic species, superoxide radical and hydrogen peroxide, are converted to the harmless product water. Western blots, activity gels and activity assays are various methods used to determine protein and activity in both cells and tissue depending on the amount of protein required for each assay. Other techniques including immunohistochemistry and immunogold can further evaluate the levels of the various antioxidant enzymes in tissues and cells. In general, these assays require 24–48 h to complete.

Catalase function in plants: a focus on Arabidopsis mutants as stress-mimic models

Abstract: Hydrogen peroxide (H(2)O(2)) is an important signal molecule involved in plant development and environmental responses. Changes in H(2)O(2) availability can result from increased production or decreased metabolism. While plants contain several types of H(2)O(2)-metabolizing proteins, catalases are highly active enzymes that do not require cellular reductants as they primarily catalyse a dismutase reaction. This review provides an update on plant catalase genes, function, and subcellular localization, with a focus on recent information generated from studies on Arabidopsis. Original data are presented on Arabidopsis catalase single and double mutants, and the use of some of these lines as model systems to investigate the outcome of increases in intracellular H(2)O(2) are discussed. Particular attention is paid to interactions with cell thiol-disulphide status; the use of catalase-deficient plants to probe the apparent redundancy of reductive H(2)O(2)-metabolizing pathways; the importance of irradiance and growth daylength in determining the outcomes of catalase deficiency; and the induction of pathogenesis-related responses in catalase-deficient lines. Within the context of strategies aimed at understanding and engineering plant stress responses, the review also considers whether changes in catalase activities in wild-type plants are likely to be a significant part of plant responses to changes in environmental conditions or biotic challenge.

Caloric restriction or catalase inactivation extends yeast chronological lifespan by inducing H2O2 and superoxide dismutase activity

Abstract: The free radical theory of aging posits oxidative damage to macromolecules as a primary determinant of lifespan. Recent studies challenge this theory by demonstrating that in some cases, longevity is enhanced by inactivation of oxidative stress defenses or is correlated with increased, rather than decreased reactive oxygen species and oxidative damage. Here we show that, in Saccharomyces cerevisiae, caloric restriction or inactivation of catalases extends chronological lifespan by inducing elevated levels of the reactive oxygen species hydrogen peroxide, which activate superoxide dismutases that inhibit the accumulation of superoxide anions. Increased hydrogen peroxide in catalase-deficient cells extends chronological lifespan despite parallel increases in oxidative damage. These findings establish a role for hormesis effects of hydrogen peroxide in promoting longevity that have broad implications for understanding aging and age-related diseases.

Redox control of asthma: molecular mechanisms and therapeutic opportunities.

Abstract: An imbalance in reducing and oxidizing (redox) systems favoring a more oxidative environment is present in asthma and linked to the pathophysiology of the defining symptoms and signs including airflow limitation, hyper-reactivity, and airway remodeling. High levels of hydrogen peroxide, nitric oxide (•NO), and 15-F2t-isoprostane in exhaled breath, and excessive oxidative protein products in lung epithelial lining fluid, peripheral blood, and urine provide abundant evidence for pathologic oxidizing processes in asthma. Parallel studies document loss of reducing potential by nonenzymatic and enzymatic antioxidants. The essential first line antioxidant enzymes superoxide dismutases (SOD) and catalase are reduced in asthma as compared to healthy individuals, with lowest levels in those patients with the most severe asthma. Loss of SOD and catalase activity is related to oxidative modifications of the enzymes, while other antioxidant gene polymorphisms are linked to susceptibility to develop asthma. M...

Impact of excess zinc on growth parameters, cell division, nutrient accumulation, photosynthetic pigments and oxidative stress of sugarcane (Saccharum spp.)

Abstract: The present study employed a sand culture experiment with three levels of zinc viz., 0.065 (control), 65.0 and 130 mg l−1 Zn (excess) as zinc sulfate, respectively, in sugarcane (Saccharum spp.), cultivar CoLk 8102. The results indicated growth depression, dark green leaves, decreased root number and length and sharp depression in mitotic activity of roots due to high doses of Zn (65 and 130 mg l−1); effects were significant at 130 mg l−1 Zn supply. The endogenous ion contents measurements revealed roots to be the major sink for excess Zn with lower amounts in leaves of sugarcane plants. High level of Zn decreased total phosphorus in leaves and increased it in roots. Fe and Cu content decreased, while, Mn increased in sugarcane plants due to high Zn in the growing medium. Plants experienced oxidative stress when exposed to higher levels of zinc. Biochemical investigations indicated high level of hydrogen peroxide, malondialdehyde contents with high chlorophyll a, b and carotenoids contents and activity of superoxide dismutase, catalase and peroxidase enzymes under high Zn conditions. These findings confirm suggest that excess Zn adversely affects root growth and mitotic efficiency, enhances chromosomal aberrations and increases growth and nutrient accumulation abnormalities, as well as oxidative stress.

Mercury-induced oxidative stress and impact on antioxidant enzymes in Chlamydomonas reinhardtii

Abstract: Investigation of mercury toxicology in green algae is of great importance from ecological point of view, because mercury has become a major contaminant in recent years. In higher plants, accumulation of mercury modifies many aspects of cellular functions. However, the process that mercury exerts detrimental effects on green algae is largely unknown. In this study, we performed an experiment focusing on the biological responses of Chlamydomonas reinhardtii, a unicellular model organism, to Hg(2+)-induced toxicity. C. reinhardtii was exposed to 0, 1, 2, 4, 6, and 8 μM Hg in media. Concentrations of Hg were negatively correlated with the cell growth. Treatment with Hg induced accumulation of reactive oxygen species and peroxidative products. Endogenous proline levels increased in Hg-exposed algae. Hg exposure activated superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). To get insights into the molecular response, a RT-PCR-based assay was performed to analyze the transcript abundance of Mn-SOD, CAT and APX. Our analysis revealed that expression of the genes was up-regulated by Hg exposure, with a pattern similar to the enzyme activities. Additional investigation was undertaken on the effect of Hg on the transcript amount of ∆(1)-pyrroline-5-carboxylate synthetase, a key enzyme of proline biosynthesis and on that of heme oxygenase-1 (HO-1), an enzyme regulating heavy metal tolerance. Expressions of both P5CS and HO-1 were up-regulated by Hg. These data indicate that Hg-induced oxidative stress was responsible for the disturbance of the growth and antioxidant defensive systems in C. reinhardtii.

Biochemical and enzymatic changes in rice plants as a mechanism of defense

Abstract: A laboratory study was undertaken to ascertain the impact and the extent of feeding by different pests on biochemical constituents and various enzyme levels in rice plants. The difference in these parameters due to the pest damage by three different modes of feeding was also studied and compared. The borer pest—yellow stem borer (YSB), Scirpophaga incertulas (W); surface feeder—-leaf roller (LR), Cnaphalocrosis medinalis (G) and a sucking pest—brown plant hopper (BPH), Nilaparvata lugens (S) fed rice plants were analyzed for the quantitative and qualitative changes in biochemical profile and enzymatic changes that occur as plant’s defensive responses were analyzed spectrophotometrically. The phenolic acids were analyzed using HPLC and quantitated with the standard samples. The quantity of biochemicals such as proteins, phenols and carbohydrates has been enhanced along with the enzyme activities of peroxidase (POD), catalase (CAT), chitinase (CHI). A decrease in superoxide dismutase (SOD), phenyl alanine ammonia lyase (PAL), β-1, 3-glucanase (GLU) enzyme activities were evident in pest infested plants. Phenolic acids like vanillic acid, syringic acid, cinnamic acid, and p-coumaric acids were mostly found in the infested plants. We demonstrate that the elevated levels of biochemicals, phenolic acids, and enzymes may play a major role in plant defense.

Activity of antioxidant enzymes and physiological responses in ark shell, Scapharca broughtonii, exposed to thermal and osmotic stress: Effects on hemolymph and biochemical parameters

Abstract: Changes in water temperature and salinity are responsible for a variety of physiological stress responses in aquatic organisms. Stress induced by these factors was recently associated with enhanced reactive oxygen species (ROS) generation, which caused oxidative damage. In the present study, we investigated the time-related effects of changes in water temperature and salinity on mRNA expression and the activities of antioxidant enzymes (SOD and CAT) and lipid peroxidation (LPO) in the gills and digestive glands of the ark shell, Scapharca broughtonii. To investigate physiological responses, hydrogen peroxide (H(2)O(2)), lysozyme activity, aspartate aminotransferase (AspAT), and alanine aminotransferase (AlaAT) were measured in the hemolymph. Water temperature and salinity changes significantly increased antioxidant enzyme mRNA expression and activity in the digestive glands and gills in a time-dependent manner. H(2)O(2) concentrations increased significantly in the high-temperature and hyposalinity treatments. LPO, AspAT and AlaAT levels also increased significantly in a time-dependent manner, while lysozyme activity decreased. These results suggest that antioxidant enzymes play important roles in reducing oxidative stress in ark shells exposed to changes in water temperature and salinity.

Role of oxidative stress in various stages of psoriasis.

Abstract: Psoriasis is a chronic inflammatory, proliferative skin disease characterized by pathological skin lesions due to various exogenous and endogenous factors. It is associated with a number of biochemical and immunological disturbances. Recently, it has been suggested that increased reactive oxygen species (ROS) production and compromised function of antioxidant system may be involved in the pathogenesis of this disease. In the present study, 90 psoriasis patients were selected. Disease severity was assessed by psoriasis area severity index score and grouped as mild, moderate and severe (each group consists of 30 subjects) and compared with 30 healthy controls. Serum levels of malondialdehyde, nitric oxide end products and the activities of antioxidant enzymes such as erythrocyte-superoxide dismutase, catalase and total antioxidant status were investigated in these groups/subjects. As compared to controls, we found severitywise significantly increased serum malondialdehyde, nitric oxide end products with decrease in erythrocyte-superoxide dismutase activity, catalase activity and total antioxidant status in patients with psoriasis suggesting worsening of the disease. It seems to be linked with the enhancement of Reactive Oxygen Species production and decreased antioxidant potential in psoriasis.

Spectrophotometric assays for antioxidant enzymes in plants.

Abstract: Reactive oxygen species (ROS) are formed in biological systems as part of normal metabolism. Adverse environmental factors like drought stress result in increased levels of ROS that are detrimental to the plant (1, 2). To avoid damage caused by these excess ROS, plants have developed elaborate mechanisms to manage them at sustainable levels. Enzymes play an important role in lowering the ROS levels and helping avoid oxidative stress. Superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase play a vital role in combating oxidative stress. Measuring these enzyme activities spectrophotometrically provides researchers an easy and precise way to study and understand an important part of the defense against oxidative stress. In this chapter we provide details of the assays we used to determine the enzyme activities spectrophotometrically. Antioxidant enzyme responses to moderate water-deficit stress were studied. All enzyme assays were conducted using wheat leaf tissue.

Role of metabolically generated reactive oxygen species for lipotoxicity in pancreatic β‐cells

Abstract: Chronically elevated concentrations of non-esterified fatty acids (NEFAs) in type 2 diabetes may be involved in β-cell dysfunction and apoptosis It has been shown that long-chain saturated NEFAs exhibit a strong cytotoxic effect upon insulin-producing cells, while short-chain as well as unsaturated NEFAs are well tolerated Moreover, long-chain unsaturated NEFAs counteract the toxicity of palmitic acid Reactive oxygen species (ROS) formation and gene expression analyses together with viability assays in different β-cell lines showed that the G-protein-coupled receptors 40 and 120 do not mediate lipotoxicity This is independent from the role, which these receptors, specifically GPR40, play in the potentiation of glucose-induced insulin secretion by saturated and unsaturated long-chain NEFAs Long-chain NEFAs are not only metabolized in the mitochondria but also in peroxisomes In contrast to mitochondrial β-oxidation, the acyl-coenzyme A (CoA) oxidases in the peroxisomes form hydrogen peroxide and not reducing equivalents As β-cells almost completely lack catalase, they are exceptionally vulnerable to hydrogen peroxide generated in peroxisomes ROS generation in the respiratory chain is less important because overexpression of catalase and superoxide dismutase in the mitochondria do not provide protection Thus, peroxisomally generated hydrogen peroxide is the likely ROS that causes pancreatic β-cell dysfunction and ultimately β-cell death

Exogenous Hydrogen Peroxide Changes Antioxidant Enzyme Activity and Protects Ultrastructure in Leaves of Two Cucumber Ecotypes Under Osmotic Stress

Abstract: Cucumber (Cucumis sativus L.) varieties cv. Jinchun no. 4 (a North China ecotype) and cv. Lvfeng no. 6 (a South China ecotype) were cultivated to explore the effects of osmotic stress on the ultrastructure of chloroplasts and mitochondria, as well as to assess the possible protective effect of exogenous hydrogen peroxide (H2O2). Under osmotic stress induced by 10% polyethylene glycol 6000, 84.3% of the chloroplasts in Jinchun no. 4 were abnormal, whereas 88.6% were abnormal in Lvfeng no. 6. Abnormal mitochondria occurred in these two strains at rates of 78.5 and 87.1%, respectively. The stress condition disintegrated the membranes of most chloroplasts and mitochondria in the leaf cells of both cucumber ecotypes, and it also increased the malondialdehyde (MDA) content. We subjected the two cultivars to a combined treatment with H2O2 and osmotic stress and made the following observations: (1) Abnormal chloroplasts occurred at rates of 25.7 and 28.6%, and abnormal mitochondria were observed at rates of 22.9 and 32.8%, respectively. (2) Most of the investigated membranes were well organized in leaves of Jinchun no. 4 and Lvfeng no. 6, and the levels of endogenous H2O2, superoxide anion, and MDA were lower. Osmotic stress and exogenous H2O2 both increased the activities of antioxidative enzymes such as manganese superoxide dismutase, glutathione peroxidase, catalase, guaiacol peroxidase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, dehydroascorbate reductase, and the antioxidants ascorbate and reduced glutathione. The combined effect of osmotic stress and exogenous H2O2 resulted in the highest antioxidant activities in both cucumber ecotypes. We propose that exogenous H2O2 increases antioxidant activity in cucumber leaves and thereby decreases lipid peroxidation to some extent, thus protecting the ultrastructure of most chloroplasts and mitochondria under osmotic stress.

A different role for hydrogen peroxide and the antioxidative system under short and long salt stress in Brassica oleracea roots

Abstract: Salinity affects normal growth and development of plants depending on their capacity to overcome the induced stress. The present study was focused on the response and regulation of the antioxidant defence system in Brassica oleracea roots under short and long salt treatments. The function and the implications of hydrogen peroxide as a stressor or as a signalling molecule were also studied. Two different zones were analysed—the elongation and differentiation zone and the fully differentiated root zone—in order to broaden the knowledge of the different effects of salt stress in root. In general, an accumulation of hydrogen peroxide was observed in both zones at the highest (80 mM NaCl) concentration. A higher accumulation of hydrogen peroxide was observed in the stele of salt-treated roots. At the subcellular level, mitochondria accumulated hydrogen peroxide in salt-treated roots. The results confirm a drastic decrease in the antioxidant enzymes catalase, ascorbate peroxidase, and peroxidases under short salt treatments. However, catalase and peroxidase activities were recovered under long salt stress treatments. The two antioxidant molecules analysed, ascorbate and glutathione, showed a different trend during salt treatments. Ascorbate was progressively accumulated and its redox state maintained, but glutathione was highly accumulated at 24 h of salt treatment, but then its concentration and redox state progressively decreased. Concomitantly, the antioxidant enzymes involved in ascorbate and glutathione regeneration were modified under salt stress treatments. In conclusion, the increase in ascorbate levels and the maintenance of the redox state seem to be critical for root growth and development under salt stress.

Chromium-induced biochemical, genotoxic and histopathologic effects in liver and kidney of goldfish, carassius auratus.

Abstract: Fish constitute an excellent model to understand the mechanistic aspects of metal toxicity vis-a-vis oxidative stress in aquatic ecosystems. Hexavalent chromium (Cr (VI)), due to its redox potential can induce oxidative stress (OS) in fish and impair their health. In the present investigation, we hypothesize that OS plays a key role in chromium induced toxicity in goldfish; leading to the production of reactive oxygen species (ROS) such as O(.)(2), H(2)O(2), OH(.), and subsequent modulation of the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), metallothioneins (MT), glutathione proxidase (GPx), genotoxicity and histopathology. To test this hypothesis, antioxidant enzymes, DNA damage and histopathology assays were performed in liver and kidney tissues of goldfish exposed to different concentrations of Cr (VI) (LC(12.5), LC(25) and LC(50)) following 96h static renewal bioassay. The results of this study clearly show that the fish experienced OS as characterized by significant modulation of enzyme activities, induction of DNA damage and microscopic morphological changes in the liver and kidney. In both tissues, CAT activity was decreased whereas SOD activity and hydroperoxide levels were increased. In addition, GPx activity also increased significantly in higher test concentrations, especially in the kidney. MT induction and DNA damage were observed in both tissues in a concentration dependent manner. Microscopic examination of organ morphology indicated degeneration of liver tissue and necrosis of central vein. Necrosis of kidney tubular epithelial cells and tubules was observed at higher Cr (VI) concentrations. Taking together the findings of this study are helpful in organ-specific risk assessment of Cr (VI)-induced oxidative stress, genotoxicity and histopathology in fish.

Photosynthesis, photoprotection and antioxidant activity of purging nut under drought deficit and recovery

Abstract: Biodiesel is an alternative to petroleum diesel fuel. It is a renewable, a biodegradable, and also a non-toxic fuel. The general interest to produce biodiesel from Jatropha (Jatropha curcas L.) seeds oil has increased but its ability to grow on drought-prone areas has barely been investigated. The objective of this work was to identify some physiological processes that allow the Jatropha to produce in severe arid conditions by studying its leaf gas exchange and antioxidant systems under drought stress and recovering. It measured the activity of antioxidant enzymes involved in the scavenge of reactive oxygen species (ROS), as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutamine synthetase (GS), as well as malondialdehyde (MDA) content. It was also analyzed the chlorophyll (CHL), carotenoids, amino acids and soluble proteins contents. Net photosynthesis (A) and stomata conductance (g(s)) decreased associate with drought stress and dropped to zero in soil water beneath 5%. Drought induced decrease in stomatal and non-stomatal photosynthetic activity. The activities of SOD, CAT, APX and GS and MDA content in leaves were significantly higher in the water-stressed plants compared to well-watered plants and decreased when the plants were rewatered. These observations suggest that oxidative stress resulting from drought deficit in Jatropha could result in the production of antioxidative enzymes to counteract the oxidative damage, and the enzymes may contribute to its ability to survive in the adverse arid environment. (C) 2010 Elsevier Ltd. All rights reserved.

SHORT COMMUNICATION The ameliorative effect of silicon on soybean seedlings grown in potassium-deficient medium

Abstract: †Background and Aims Crop yield and nutritional quality are significantly reduced when potassium (K) in soil is deficient. As a beneficial element for plants, silicon (Si) is effective in alleviating the toxic effects of mineral nutrients. However, the roles played by Si in mediating deficiency in essential mineral nutrients in general and K in particular have not been investigated. †Methods To evaluate the role of Si in K deficiency-induced inhibition of growth of soybean (Glycine max) seedlings, the effects of K deficiency on shoot and root growth, hydrogen peroxide accumulation, K contents, lipid peroxidation and activities of antioxidant enzymes in the absence and presence of 2 mM sodium silicate (Na2SiO3) were investigated. †Key Results Both shoot and root biomass of soybean seedlings were markedly reduced when grown in Kdeficient medium (1 mM K) compared with those grown in K-sufficient medium (5 mM). Addition of Na2SiO3 significantly ameliorated the K deficiency-induced reductions in shoot and root growth. Sodium silicate enhanced K concentrations in leaf, stem and root of K-deficient seedlings by 105.4, 83.4 and 58.8 %, respectively. Hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents in soybean seedlings were increased by 25 and 97 %, respectively, when exposed to K-deficient medium. These increases in accumulation of H2O2 and MDA were removed by addition of Na2SiO3. Addition of Na2SiO3 reduced the K deficiency-induced increases in activities of superoxide dismutase, catalase and peroxidase. †Conclusions Application of Si to soybean seedlings grown in K-deficient medium markedly enhanced K use efficiency. Therefore, Si not only increases tolerance to nutrient toxicity, but also ameliorates symptoms associated with deficiency in essential nutrients in plants.

Resveratrol protects human lens epithelial cells against H2O2-induced oxidative stress by increasing catalase, SOD-1, and HO-1 expression

Abstract: Purpose Oxidative damage induced by H2O2 treatment can irreversibly damage the lens epithelium, resulting in cell death and cataract. Whether the effects of oxidative stress could be attenuated in cultured human lens epithelial cells by incubation with resveratrol (RES) is still unknown. In the present study, we examined the function of resveratrol in protecting human lens epithelial B-3 (HLEB-3) cells against H2O2 induced cell death and cell apoptosis, its role in reducing H2O2 induced intracellular reactive oxygen species (ROS) accumulation, and investigated the mechanism by which resveratrol underlies the effect.

Hydrogen sulfide protects soybean seedlings against drought-induced oxidative stress

Abstract: Increasing evidence indicates that hydrogen sulfide (H2S) is the third “gas signal molecule” after NO and CO in animal In the present study, we found that soybean (Glycine max L) seedlings sprayed with exogenous H2S donor NaHS prolonged the longer survival time of life, and enlarged higher biomass of both leaf and root than in non-sprayed controls under continuous drought stress With the continuous drought stress, the content of chlorophyll in the leaves of both Xu-1 and Xu-6 cultivar of soybean decreased dramatically The drought-induced decrease in chlorophyll could be alleviated by spraying H2S donor It was also shown that spraying with H2S donor dramatically retained higher activities of superoxide dismutase (SOD, EC 11511), catalase (CAT, EC11116) and lower activity of lipoxygenases (LOX, EC 1131112), delayed excessive accumulation of malondialdehyde, hydrogen peroxide, and superoxide anion (O 2 ·− ) compared with the control These results suggest that H2S can increase drought tolerance in soybean seedlings by acting as an antioxidant signal molecule for the response

Fluroxypyr triggers oxidative damage by producing superoxide and hydrogen peroxide in rice (Oryza sativa

Abstract: The present study has evaluated effect of fluroxypyr concentrations 0–0.8 mg l−1 (a widely-used herbicide for controlling annual or perennial weeds growth) on selected metabolic and stress-related parameters in Oryza sativa plants after 6 days of exposure. Increasing concentrations decreased shoot growth and accumulation of chlorophylls but had no effect on root biomass. Increasing doses led also to increase in superoxide radical, hydrogen peroxide and proline accumulation, while malondialdehyde, an indicator of lipid peroxidation, was constitutively elevated. Histochemical staining with nitroblue tetrazolium and 3, 3-diaminobenzidine were positively correlated with the generation of superoxide radical and H2O2. The fluroxypyr-induced oxidative stress triggered significant changes in activities of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase (POD). Activities of the antioxidant enzymes show a general increase at low fluroxypyr concentrations and a decrease at high fluroxypyr levels (except for POD). Analysis of naturing polyacrylamide gel electrophoresis confirmed these results. These data support the observation that fluroxypyr-triggered oxidative stress was responsible for the disturbance of the growth in the rice plants.

Gilthead sea bream liver proteome altered at low temperatures by oxidative stress

Abstract: Gilthead sea bream exposed to the cold show multiple physiological alterations, particularly in liver. A typical cold-stress response was reproduced in gilthead sea bream acclimated to 20 degrees C (Warm group) when the water temperature was lowered to 8 degrees C (Cold group). After 10 days, thiobarbituric acid reactive substances in the liver had increased by 50%, and nitric oxide had increased twofold. This indicates that lipid peroxidation and oxidative stress had occurred. Protein profiles of liver from fish in warm and cold environments were obtained by 2-DE. Quantification of differential expression by matching spots showed that a total of 57 proteins were altered significantly. Many proteins were downregulated following cold exposure, including actin, the most abundant protein in the proteome; enzymes of amino acid metabolism; and enzymes with antioxidant capacity, such as betaine-homocysteine-methyl transferase, glutathione-S-transferase and catalase. Some proteins associated with protective action were upregulated at low temperatures, including peroxiredoxin, thioredoxin and lysozyme; as well as enzymes such as aldehyde dehydrogenase and adenosin-methionine synthetase. However, the upregulation of proteases, proteasome activator protein and trypsinogen-like protein indicated an increase in proteolysis. Increases in elongation factor-1alpha, the GAPDH oxidative form, tubulin and Raf-kinase inhibitor protein indicated oxidative stress and the induction of apoptosis. These data indicate that cold exposure induced oxidative damage in hepatocytes.