Increase In Succinate Dehydrogenase Activity Research Articles

Effect of inoculation with arbuscular mycorrhizal fungi on the energy metabolism of selenite-rich amaranth.

A series of pot trials were undertaken to examine the impact of four arbuscular mycorrhizal fungi (AMF), namely Glomus mosseae (G.m), Glomus etunicatum (G.e), Corymbiglomus tortuosum (C.t), and the combined application of Glomus etunicatum and Corymbiglomus tortuosum (G.e + C.t), on the energy metabolism of amaranth plants grown in soil enriched with selenite at a concentration of 0.5 mg kg-1 . The inoculation of four AMFs resulted in an increase in both amaranth biomass and selenium (Se) content in leaves. The activities of phosphoglucose isomerase (PGI) and glucose-6-phosphate dehydrogenase + 6-phosphogluconate dehydrogenase were observed to decrease when AMFs were inoculated, as compared with the absence of AMF inoculation. The inoculation with G.m, C.t, and G.e + C.t resulted in an increase in succinate dehydrogenase activity; however, the inoculation with G.m, G.e, and G.e + C.t led to an increase in ascorbate oxidase activity. Furthermore, the inoculation of all four AMFs resulted in an increase in cytochrome c oxidase activity and the concentrations of oxidized coenzyme I (NAD) and reduced coenzyme I (NADH). The polyphenol oxidase activity of amaranth plants increased when inoculated with G.m and G.e, whereas it decreased when inoculated with C.t and G.e + C.t. Furthermore, the application of all four AMF treatments resulted in a reduction in adenosine triphosphate (ATP) levels and energy charge. It was worth mentioning that there was a clear inverse relationship between the energy charge and the biomass, Se concentration in the leaves. The findings presented in this research indicated that AMF may have an impact on energy metabolism and ultimately the biomass of amaranth by influencing the uptake of Se.

Coordination of the NF-κB signaling pathway and lymphocyte metabolism in children with autoimmune diseases

Metabolic aberrations underlie many chronic diseases, including autoimmune diseases (AUD). Immune metabolism is an area of immunological research that is actively developing and studying the processes of metabolic reprogramming in immune cells. The regulation of the nuclear factor kappa B (NF-κB) activity, which is involved in the coordination of innate and adaptive immunity, inflammatory reactions and other processes, is being actively studied. The studies on immune metabolism and regulation of NF-κB is a promising direction in searching for new therapeutic approaches in the AUD treatment. The aim of the present study was to evaluate the informative value of NF-κB and the activity of intracellular lymphocyte succinate dehydrogenase (SDH) and glycero-3-phosphate dehydrogenase (GPDH) determined in children with immune-dependent disorders. 350 children with autoimmune diseases were examined: 97 patients with IBD, 72 children with relapsing-remitting multiple sclerosis (MS), 83 pediatric patients with psoriasis vulgaris (PS), and 97 children with autoimmune hepatitis (AIH). The comparison group consisted of 100 conditionally healthy children. Activity of mitochondrial dehydrogenases, i.e., SDH and GPDH, was evaluated by immunocytochemical method. The levels of NF-κB translocation (per cent of cells with NF-κB translocation from cytoplasm to cell nucleus) was determined by flow cytometry, with visualization. Statistical evaluation and plotting were carried out using the Statistica 13.0 software. The highest activity of SDH and GPDH was detected in the population of cytotoxic T lymphocytes and T helper cells, and the lowest activity of the enzymes was registered in the population of B lymphocytes, both in children with AUD and in comparison group. In children with AUD, there was a significant decrease in SDH activity in T lymphocytes, cytotoxic T lymphocytes, B lymphocytes and NK cells against the comparison group (p 0.01). In children with PS, AIH and IBD, a decrease in SDH activity was revealed in Treg and Th17 cells. The most pronounced decrease in GPDH was characteristic of patients with AH (in T cells, cytotoxic T lymphocytes, B cells, NK cells and Tregs against the comparison group). In children with PS, the activity of GPDH was reduced only in Tregs (p 0.05). For children with multiple sclerosis, a decrease in GPDH was revealed in populations of T lymphocytes, B lymphocytes and activated T helpers (p 0.01). In the group of patients with IBD, there were no significant differences in the activity of GPDG relative to the comparison group. A significant increase in the level of NF-κB translocation in T helpers was revealed in all children with AUD relative to the comparison group. In children with AIH and PS, a significant increase in the level of NF-κB translocation was revealed in Treg, Thact and Th17 cells, in children with MS it was found in Treg cells, in patients with IBD, it was registered in Thact against the comparison group (p 0.05). An inverse correlation was found between the levels of NF-κB translocation in lymphocyte populations, and activity of mitochondrial dehydrogenases in the lymphocytes. The most significant dependencies are characteristic of NK cells and T cell populations, and these correlations are valid for all groups of AUD patientsh. In the course of in vitro experiments with a drug of metabolic action, a decreased number of cells with NF-κB translocation and an increased SDH activity was observed; the degree of SDH activation depended on the cell population type, the greatest changes were detectable in the population of T lymphocytes (by 61%), in B lymphocytes (by 30%), in NK cells (by 19%). The study of the metabolic activity of lymphocytes and the NF-κB signaling pathway allows us to assess the general mechanisms of immunopathological processes in children with autoimmune diseases of various etiologies. As based on the inverse correlation between the level of translocation of NF-κB and the activity of SDH in lymphocytes, one may consider the use of an available immunocytochemical method being an analogue for assessing activity of the NF-κB transcription factor. The studies of immune metabolic correction of immunocompetent cells are a promising direction in the AUD treatment.

Neuroglobin Facilitates Neuronal Oxygenation through Tropic Migration under Hypoxia or Anemia in Rat: How Does the Brain Breathe?

The discovery of neuroglobin (Ngb), a brain- or neuron-specific member of the hemoglobin family, has revolutionized our understanding of brain oxygen metabolism. Currently, how Ngb plays such a role remains far from clear. Here, we report a novel mechanism by which Ngb might facilitate neuronal oxygenation upon hypoxia or anemia. We found that Ngb was present in, co-localized to, and co-migrated with mitochondria in the cell body and neurites of neurons. Hypoxia induced a sudden and prominent migration of Ngb towards the cytoplasmic membrane (CM) or cell surface in living neurons, and this was accompanied by the mitochondria. In vivo, hypotonic and anemic hypoxia induced a reversible Ngb migration toward the CM in cerebral cortical neurons in rat brains but did not alter the expression level of Ngb or its cytoplasm/mitochondria ratio. Knock-down of Ngb by RNA interference significantly diminished respiratory succinate dehydrogenase (SDH) and ATPase activity in neuronal N2a cells. Over-expression of Ngb enhanced SDH activity in N2a cells upon hypoxia. Mutation of Ngb at its oxygen-binding site (His64) significantly increased SDH activity and reduced ATPase activity in N2a cells. Taken together, Ngb was physically and functionally linked to mitochondria. In response to an insufficient oxygen supply, Ngb migrated towards the source of oxygen to facilitate neuronal oxygenation. This novel mechanism of neuronal respiration provides new insights into the understanding and treatment of neurological diseases such as stroke and Alzheimer's disease and diseases that cause hypoxia in the brain such as anemia.

Effect of Salt Stress on the Activity, Expression, and Promoter Methylation of Succinate Dehydrogenase and Succinic Semialdehyde Dehydrogenase in Maize (Zea mays L.) Leaves

The effect of salt stress on the expression of genes, the methylation of their promoters, and the enzymatic activity of succinate dehydrogenase (SDH) and succinic semialdehyde dehydrogenase (SSADH) was investigated in maize (Zea mays L.). The incubation of maize seedlings in a 150 mM NaCl solution for 24 h led to a several-fold increase in the activity of SSADH that peaked at 6 h of NaCl treatment, which was preceded by an increase in the Ssadh1 gene expression and a decrease in its promoter methylation observed at 3 h of salt stress. The increase in SDH activity and succinate oxidation by mitochondria was slower, developing by 24 h of NaCl treatment, which corresponded to the increase in expression of the genes Sdh1-2 and Sdh2-3 encoding SDH catalytic subunits and of the gene Sdh3-1 encoding the anchoring SDH subunit. The increase in the Sdh2-3 expression was accompanied by the decrease in promoter methylation. It is concluded that salt stress results in the rapid increase in succinate production via SSADH operating in the GABA shunt, which leads to the activation of SDH, the process partially regulated via epigenetic mechanisms. The role of succinate metabolism under the conditions of salt stress is discussed.

Morphofunctional changes in the rat's liver of different ages after L-methionine administration

Background: Literature data on the effect of methionine on functional activity and, especially, on morphological changes in the liver parenchyma in animals of different ages are sporadic, and research results are often ambiguous.
 Aim: The purpose of this work was to study and compare the morphofunctional changes in the liver of rats of different ages on prolonged administration of L-methionine.
 Material and Methods: The experiment was performed on 48 male Wistar rats of 3 and 15 months of age. Animals of the experimental group received L-methionine at a dose of 250 mg/kg body weight in addition to the standard diet, daily for 21 days. Histological preparations were prepared from liver tissue by a standard technique. Morphometry was performed on digital images using the computer program «Image J». Succinate dehydrogenase activity and protein concentration were determined in the suspension of hepatocyte mitochondria.
 Results: It was revealed that 21-day administration of L-methionine to rats led to hypertrophy of the hepatocyte nucleus, an increase in the nuclear-cytoplasmic ratio, the number of binuclear hepatocytes, and the nucleolus in the cell nucleus. The relative area of ​​the sinusoids network increased by 50% in 3-month-old animals. This indicated a better blood filling of the liver parenchyma. The increase in succinate dehydrogenase activity and protein concentration was revealed in the suspension of hepatocyte mitochondria of the experimental rats. This indicated an increase in the mitochondria energy potential and protein-synthetic activity.
 Conclusions: The administration of prophylactic doses of methionine to healthy rats leads to the appearance of pronounced morphological and functional signs of increased activity of hepatocytes. The severity of this effect has a distinct age-dependent character. In young rats, it is more pronounced than in mature rats. The results of the study are important for practical medicine when using methionine for therapeutic and prophylactic purposes.

Involvement of O2·− release in zearalenone-induced hormesis of intestinal porcine enterocytes: An electrochemical sensor-based analysis

Relationship between mycotoxin-induced hormesis and reactive oxygen species (ROS) has not been systematically investigated due to the lack of an effective analysis method. To monitor cellular release and intracellular level of O2·−, carboxymethyl cellulose-Mn3(PO4)2 nanocomposite was synthesized to fabricate an electrochemical biosensor, which selectively detects O2·− over the range of 57.50 nM ∼ 2.95 μM (R2 = 0.99) with the sensitivity of 78.67 μA μM−1 cm−2 and the detection limit of 8.47 nM. Transient exposure to zearalenone (ZEA) induces the enhancement on cell viability, immediate O2·− release from cells, and reduction of intracellular O2·− level. After post-treatment culture, intracellular O2·− initially increases to a high level and then decreases to the normal level. Concurrently, the ZEA-induced hormesis disappears. Based on the findings, we propose a mechanism, involving the ROS release, increase of succinate dehydrogenase activity and recovery of intracellular ROS, to explain the occurrence and disappearance of hormesis in intestinal porcine enterocytes.

Endurance training-induced increase in muscle oxidative capacity without loss of muscle mass in younger and older resistance-trained men

While concurrent training is regularly used in older populations, the inverse relationship between fibre size and oxidative capacity suggests that endurance training in resistance-trained individuals may result in some loss of resistance training-induced gains in muscle mass, which may be more pronounced in older people. We investigated the impact of superimposed endurance training in younger (28.5 ± 4.8 years; n = 8) and older (67.5 ± 5.5 years; n = 7) highly resistance-trained men. Participants underwent a 10-week endurance cycling training programme consisting of five 6-min intervals at 75% max heart rate (HRmax) separated by 4-min intervals at 90% HRmax. The anatomical cross-sectional area (ACSA) of the thigh muscles, as determined with MRI, was 24% smaller in older compared to younger participants (p < 0.001). Although maximal oxygen consumption (VO2max) was also lower in the older group (p < 0.001), VO2max per kg body mass did not differ significantly between younger and older participants. Histological analyses of biopsies of the m. vastus lateralis showed that endurance training induced an increase in succinate dehydrogenase activity in both younger and older participants (p ≤ 0.043), and an increase in the number of capillaries around type I fibres (p = 0.017). The superimposed endurance training did not induce a significant decrease in thigh ACSA, fibre cross-sectional area, or knee extensor maximum voluntary isometric force. These observations indicate that adding endurance training to resistance training can lead to positive endurance-related adaptations without negative consequences for muscle size and strength in older and younger resistance-trained people.

Two adjacent mutations in the conserved domain of SdhB confer various resistance phenotypes to fluopyram in Corynespora cassiicola.

For Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei, a necrotrophic pathogen with a broad host range and a worldwide distribution, resistance to fluopyram has been attributed to mutations in SdhB/C/D subunit of the succinate dehydrogenase (SDH) complex. In our previous study, two point mutations in SdhB from isoleucine to valine at position 280 (I280V) and histidine to tyrosine at position 278 (H278Y) showed different resistance phenotypes to fluopyram and boscalid. This research was conducted to explore the correlation between the mutation of SdhB-I280V or SdhB-H278Y and resistance to fluopyram or boscalid and its effect on the fitness characteristics of C. cassiicola. The sdhB gene in a succinate dehydrogenase inhibitor (SDHI)-sensitive C. cassiicola strain (wild type) was successfully replaced with the mutant sdhB gene (GTT at position 280, SdhB-I280V) or with the mutant sdhB gene (TAC at position 278, SdhB-H278Y,). Compared with the wild-type strain, the replacement mutants exhibited significantly different resistance phenotypes, with SdhB-V280 demonstrating moderate resistance to fluopyram and low resistance to boscalid, while SdhB-Y278 was supersensitive to fluopyram and very highly resistant to boscalid. Both of the mutants exhibited decreased sensitivity to salt stress and increased SDH activity. These two mutations had no effect on the mycelial growth rate, sporulation ability, pathogenicity in vivo, sensitivity to osmotic stress and oxidative stress, cell wall damaging agents, or SHAM. Two adjacent mutations in the SdhB gene conferred different resistance phenotypes to SDHIs in C. cassiicola, which is important for the development of alternative antifungal fungicides and fluopyram resistance management. © 2021 Society of Chemical Industry.

Вплив метіоніну на морфофункціональний стан паренхіми печінки щурів

We studied morphofunctional changes in the liver parenchyma of young male Wistar rats after methionine administration. The experiments were performed on 24 male 3 months old Wistar rats. Animals of the experimental group, in addition to the standard diet, daily for 21 days received methionine at a dose of 250 mg/kg body weight. Histological preparations were prepared from liver tissue by a standard technique. Morphometry was performed on digital images using the computer program «Image J». Succinate dehydrogenase activity and protein concentration were determined in the suspension of hepatocyte mitochondria. It was revealed that 21-day administration of methionine led to hypertrophy of the hepatocyte nucleus, an increase in the nuclear cytoplasmic ratio (by 13 %), the number of binuclear hepatocytes (by 94 %), the nucleolus in the cell nucleus (by 17 %) and the relative area of the sinusoid network (by 50 %). The increase in succinate dehydrogenase activity and protein concentration was revealed in the suspension of hepatocyte mitochondria of the experimental rats. This indicated an increase in the mitochondria energy potential and protein-synthetic activity. The administration of methionine to young rats was accompanied by the appearance of morphological and functional signs of the liver parenchyma synthetic and regenerative processes activation.

EFFECT OF DOSED NORMOBARIC HYPOXIA ON MORPHO-FUNCTIONAL CHANGES IN HEPATOCYTES OF NORMOTENSIVE AND HYPERTENSIVE RATS

Problem. Study of the effect of dosed hypoxia on the hepatocytes activity and morphometric parameters of rats of different lines.The aim of the work was to investigate and compare the morphological and functional changes in hepatocytes of normotensive and spontaneously hypertensive rats after exposure to dosed normobaric hypoxia.Materials and methods. The study was conducted in the autumn on 48 male rats of the Wistar and SHR line. Experimental animals were given daily hypoxic gas mixture (12 % oxygen in nitrogen) in intermittent mode: 15 minutes deoxygenation / 15 minutes reoxygenation for 2 hours. The duration of the experiment was 28 days. Histological preparations were made from liver tissue using a standard technique. Morphometry was performed using the computer program "Image J". The activity of succinate dehydrogenase and protein concentration in a hepatocytes mitochondrial suspension was determined.Results. It was revealed that morphological changes in the liver parenchyma and biochemical parameters of hepatocyte mitochondria activity in spontaneously hypertensive rats, breathing in a hypoxic gas mixture, were manifested to a greater extent than in animals of the Wistar line. Experimental animals showed an increase in the number of binuclear cells (SHR line) and nucleolus in the nucleus hepatocyte, an increase in nuclear-cytoplasmic and nucleolus-nuclear ratio, as well as an increase in succinate dehydrogenase activity and protein concentration (SHR line) in a suspension of hepatocyte mitochondria. These data may indicate an increase in the functional activity of hepatocytes and activation of physiological cell regeneration at the intracellular level.Conclusions. The effects of dosed normobaric hypoxia have morphofunctional signs of increased physiological regeneration and activity of the liver parenchyma in spontaneously hypertensive rats to a greater extent than in animals of the Wistar line.Key words: liver; intermittent hypoxia; arterial hypertension.

Parkin the progression of sarcopenia.

Parkin the progression of sarcopenia.

Detoxification potential and rehabilitation of activated sludge after shock loading of Sofia's wastewater treatment plant ‘Kubratovo’ with mazut

The shock loading of wastewater treatment plants (WWTPs) with toxic pollutants remains a critical problem with crucial significance for the technologies. On 5 November 2014, 30 tons of mazut were emitted in Sofia's WWTP 'Kubratovo', passing through equipment and damaging the functioning of the technological modules. The rehabilitation of activated sludge (AS) after shock loading as well as the development of detoxification activity were investigated. The hydrocarbon index of petroleum products, filamentous index (FI), sludge biotic index, sludge volume index (SVI), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), oxygenases and succinate dehydrogenase activities were analyzed for a period of two weeks. The results show that independently from prolonged rehabilitation period, AS remained with filamentous bulking (SVI over 200 ml/g and FI over 1.107 μm/mg). At the same time, the detoxification potential of the AS was developed. Although the morphological and functional structure was still not fully recovered, the AS developed two adaptive mechanisms. First, activation of shorter, more effective ways for benzene ring cleavage, operated by catechol 2,3-dioxygenase; second, strong increase of succinate dehydrogenase activity, which is consistent with the activation of the degradation of trivial substrates for energy generating to overcome the intoxication and synthesis of oxygenases.

Repetitive TLR3 activation in the lung induces skeletal muscle adaptations and cachexia

Due to immunosenescence, older adults are particularly susceptible to lung-based viral infections, with increased severity of symptoms in those with underlying chronic lung disease. Repeated respiratory viral infections produce lung maladaptations, accelerating pulmonary dysfunction. Toll like 3 receptor (TLR3) is a membrane protein that senses exogenous double-stranded RNA to activate the innate immune response to a viral infection. Polyinosinic-polycytidylic acid [poly(I:C)] mimics double stranded RNA and has been shown to activate TLR3. Utilizing an established mouse viral exacerbation model produced by repetitive intranasal poly(I:C) administration, we sought to determine whether repetitive poly(I:C) treatment induced negative muscle adaptations (i.e. atrophy, weakness, and loss of function). We determined skeletal muscle morphological properties (e.g. fiber-type, fiber cross-sectional area, muscle wet mass, etc.) from a treated group ((poly(I:C), n = 9) and a sham-treated control group (PBS, n = 9); age approximately 5 months. In a subset (n = 4 for both groups), we determined in vivo physical function (using grip test for strength, rotarod for overall motor function, and treadmill for endurance) and muscle contractile properties with in vitro physiology (in the EDL, soleus and diaphragm). Our findings demonstrate that poly(I:C)-treated mice exhibit both muscle morphological and functional deficits. Changes of note when comparing poly(I:C)-treated mice to PBS-treated controls include reductions in fiber cross-sectional area (−27% gastrocnemius, −25% soleus, −16% diaphragm), contractile dysfunction (soleus peak tetanic force, −26%), muscle mass (gastrocnemius −19%, soleus −23%), physical function (grip test −34%), body mass (−20%), and altered oxidative capacity (140% increase in succinate dehydrogenase activity in the diaphragm, but 66% lower in the gastrocnemius). Our data is supportive of a new model of cachexia/sarcopenia that has potential for future research into the mechanisms underlying muscle wasting.

Salicylic Acid-Dependent Plant Stress Signaling via Mitochondrial Succinate Dehydrogenase.

Mitochondria are known for their role in ATP production and generation of reactive oxygen species, but little is known about the mechanism of their early involvement in plant stress signaling. The role of mitochondrial succinate dehydrogenase (SDH) in salicylic acid (SA) signaling was analyzed using two mutants: disrupted in stress response1 (dsr1), which is a point mutation in SDH1 identified in a loss of SA signaling screen, and a knockdown mutant (sdhaf2) for SDH assembly factor 2 that is required for FAD insertion into SDH1. Both mutants showed strongly decreased SA-inducible stress promoter responses and low SDH maximum capacity compared to wild type, while dsr1 also showed low succinate affinity, low catalytic efficiency, and increased resistance to SDH competitive inhibitors. The SA-induced promoter responses could be partially rescued in sdhaf2, but not in dsr1, by supplementing the plant growth media with succinate. Kinetic characterization showed that low concentrations of either SA or ubiquinone binding site inhibitors increased SDH activity and induced mitochondrial H2O2 production. Both dsr1 and sdhaf2 showed lower rates of SA-dependent H2O2 production in vitro in line with their low SA-dependent stress signaling responses in vivo. This provides quantitative and kinetic evidence that SA acts at or near the ubiquinone binding site of SDH to stimulate activity and contributes to plant stress signaling by increased rates of mitochondrial H2O2 production, leading to part of the SA-dependent transcriptional response in plant cells.

Two transgenic mouse models for β-subunit components of succinate-CoA ligase yielding pleiotropic metabolic alterations.

Succinate-CoA ligase (SUCL) is a heterodimer enzyme composed of Suclg1 α-subunit and a substrate-specific Sucla2 or Suclg2 β-subunit yielding ATP or GTP, respectively. In humans, the deficiency of this enzyme leads to encephalomyopathy with or without methylmalonyl aciduria, in addition to resulting in mitochondrial DNA depletion. We generated mice lacking either one Sucla2 or Suclg2 allele. Sucla2 heterozygote mice exhibited tissue- and age-dependent decreases in Sucla2 expression associated with decreases in ATP-forming activity, but rebound increases in cardiac Suclg2 expression and GTP-forming activity. Bioenergetic parameters including substrate-level phosphorylation (SLP) were not different between wild-type and Sucla2 heterozygote mice unless a submaximal pharmacological inhibition of SUCL was concomitantly present. mtDNA contents were moderately decreased, but blood carnitine esters were significantly elevated. Suclg2 heterozygote mice exhibited decreases in Suclg2 expression but no rebound increases in Sucla2 expression or changes in bioenergetic parameters. Surprisingly, deletion of one Suclg2 allele in Sucla2 heterozygote mice still led to a rebound but protracted increase in Suclg2 expression, yielding double heterozygote mice with no alterations in GTP-forming activity or SLP, but more pronounced changes in mtDNA content and blood carnitine esters, and an increase in succinate dehydrogenase activity. We conclude that a partial reduction in Sucla2 elicits rebound increases in Suclg2 expression, which is sufficiently dominant to overcome even a concomitant deletion of one Suclg2 allele, pleiotropically affecting metabolic pathways associated with SUCL. These results as well as the availability of the transgenic mouse colonies will be of value in understanding SUCL deficiency.

Dehydroepiandrosterone inhibits cell proliferation and improves viability by regulating S phase and mitochondrial permeability in primary rat Leydig cells.

Dehydroepiandrosterone (DHEA) is widely used as a nutritional supplement and exhibits putative anti-aging properties. However, the molecular basis of the actions of DHEA, particularly on the biological characteristics of target cells, remain unclear. The aim of the current study was to investigate the effects of DHEA on cell viability, cell proliferation, cell cycle and mitochondrial function in primary rat Leydig cells. Adult Leydig cells were purified by Percoll gradient centrifugation, and cell proliferation was detected using a Click-iT® EdU Assay kit and cell cycle assessment performed using flow cytometry. Mitochondrial membrane potential was detected using JC-1 staining assay. The results of the current study demonstrate that DHEA decreased cell proliferation in a dose-dependent manner, whereas it improved cell viability in a time-dependent and dose-dependent manner. Flow cytometry analysis demonstrated that DHEA treatment increased the S phase cell population and decreased the G2/M cell population. Cyclin A and CDK2 mRNA levels were decreased in primary rat Leydig cells following DHEA treatment. DHEA treatment decreased the transmembrane electrical gradient in primary Leydig cells, whereas treatment significantly increased succinate dehydrogenase activity. These results indicated that DHEA inhibits primary rat Leydig cell proliferation by decreasing cyclin mRNA level, whereas it improves cells viability by modulating the permeability of the mitochondrial membrane and succinate dehydrogenase activity. These findings may demonstrate an important molecular mechanism by which DHEA activity is mediated.

The effect of cell-phone radiation on rabbits: Lymphocyte enzyme-activity data

The effect of a GSM 900/1800 mobile phone, which is a widespread source of electromagnetic radiation of the microwave frequency in the environment, on rabbits was studied at power densities of 5–7 μW/cm2. The biological effect was recorded by a sensitive method for the detection of the physiological regulation of enzyme activity inside lymphocytes in blood smears. Succinate dehydrogenase, which is the most powerful energy-supply enzyme in mitochondria, and lactate dehydrogenase, which is an enzyme of glycolysis, were measured. The lactate dehydrogenase to succinate dehydrogenase activity ratio was also calculated as an analog of the Warburg effect, which demonstrates the relationship between glycolysis and respiration. After 60 min of mobile-phone exposure each day for 11 days at a moderate dose, the emitted radiation induced a threefold increase in succinate dehydrogenase activity and a twofold decrease in lactate dehydrogenase activity. As a result, the lactate dehydrogenase/succinate dehydrogenase activity ratio falls from 15 to 5, thus indicating that respiration is predominant over glycolysis. The changes develop already after the first exposure and reach a maximum in 4 days. The predominance of respiration is usually considered as a beneficial state of an organism. However, continuous activation of respiration by mobile phone exposure may cause damage to the normal restorative processes that are supported by glycolysis during periods of rest.

Pre-treatment of seeds with salicylic acid attenuates cadmium chloride-induced oxidative damages in the seedlings of mungbean (Vigna radiata L. Wilczek)

Salicylic acid (SA) is known to be responsive to major abiotic stress factors like drought, cold, heavy metal toxicity, and such other forms of osmotic stress. However, molecular regulation of SA signaling, including the mechanism of action in heavy metal stress tolerance, is not well understood, so that currently there is an increasing trend in studies in this area. The present study was focused to assess the possible regulatory role of SA in mitigating oxidative damages under cadmium (Cd) toxicity, taking mungbean (Vigna radiata) seedlings as the experimental model. Pre-soaking of seeds in SA, prior to Cd exposure of germinated seedlings, alleviated the overall detrimental effects of Cd toxicity. The SA-promoted seedling growth under stress was correlated with improved germination percentage due to enhanced α-amylase activity, thereby stimulating tissue growth, biomass, and relative water content. The seedlings showed considerably less chlorophyll degradation or reduced chlorophyllase activity, lesser malondialdehyde and total peroxide content, and increased reducing power. The loss in free amino acid and cysteine pool, and protease activity with Cd stress was overcome by SA-pre-treatment. The restoration to almost the normal level of osmolytes like total sugar and Pro, antioxidants like ascorbic acid, total phenolics and polyphenol oxidase activity, and antioxidative enzymes like catechol peroxidase, ascorbate peroxidase, catalase and superoxide dismutase, in seedlings grown from SA-pre-treated seeds also pointed towards partial Cd stress recovery. Isozyme profiling revealed induction of isoform(s) of guaiacol peroxidase and superoxide dismutase, in particular, in stressed seedlings, grown from SA-pre-treated seeds. Pre-treatment could also overcome the Cd-induced loss in nitrate reductase activity, leading to better nitrogen assimilation. While the decline in pyruvate dehydrogenase and malate dehydrogenase with Cd stress was recovered by SA, the increased succinate dehydrogenase activity with stress was lowered by SA, since lesser malic acid was required for osmotolerance in presence of SA. On the basis of the above observations, it can be concluded that priming with SA before seed sowing can attenuate Cd-induced oxidative stress in mungbean seedlings through induced antioxidative defense mechanism and improving the overall growth performances.

The state of the mitochondrial energy-supplying system of blood leukocytes in the dynamics of Guerin's carcinoma growth under the low-level irradiation conditions

Mitochondrial NADH-dehydrogenase, succinate dehydrogenase and cytochrome oxidase activities of peripheral blood leukocytes of rats with the grafted Guerin's carcinoma were studied in the dynamics of oncogenesis under the conditions of the preliminary low-level irradiation. Tumor growth was accompanied by a decrease in NADH-dehydrogenase activity, an increase of succinate dehydrogenase activity. Cytochrome oxidase activity of leucocytes remained at the control level up to the terminal stages of tumor growth. Preliminary low-level irradiation of the tumor bearing animals caused a tendency to the decrease of enzymatic activities studied. This tendency was observed from the initial stages of oncogenesis.

パーキンソン症候群と多発ニューロパチーを呈し，&lt;i&gt;POLG1&lt;/i&gt;遺伝子変異をみとめた家族性進行性外眼筋麻痺の1家系

Multiple mitochondrial DNA (mtDNA) deletions usually occur secondarily to a mutation in one of the enzymes involved in mtDNA maintenance, such as polymerase γ, which is encoded by the nuclear polymerase γ1 gene (POLG1) and POLG2. Patients with multiple mtDNA deletion disorders show clinical heterogeneity of symptoms, in addition to usually seen progressive external ophthalmoplegia (PEO). We conducted clinical, histological and genetic analyses of two affected sisters in a family with the autosomal dominant inheritance pattern of PEO. A 73-year-old woman (patient 1) with congenital hypogonadism and PEO developed L-dopa responsive parkinsonism about the age of 60. Neurological examination revealed mild proximal muscle weakness and polyneuropathy too. Her 69-year-old sister (patient 2) also showed PEO, parkinsonism and polyneuropathy. Histopathological studies of biopsied muscle specimens from patient 1 revealed numerous ragged red fibers as well as fibers with increased succinate dehydrogenase activity and decreased cytochrome c oxidase activity. Multiple mtDNA deletions were detected, both by Southern blot and long-range PCR assays of total DNA from the biopsied muscle specimens. A systemic mutational analysis in both sisters revealed a heterozygous p.Y955C (c.2864A>G) mutation in POLG1. This is the first Japanese family identified with this mutation. We reviewed cases with this mutation highlighting a wide phenotypic spectrum of this disorder.