OBJECTIVETo explore the adaptive mechanism to hypoxia in skeletal muscle of tibetan antelope.

METHODSTibetan sheep which living at the same altitude (4 300 m) with tibetan antelope and low altitude (1 800 m) sheep as control, the content of myoglobin (Mb) and lactic acid (LA), the activity of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) in skeletal muscles among three animals were analyzed by spectrophotometer.

RESULTSThe content of myoglobin in skeletal muscle of tibetan antelope significantly higher than that of tibetan sheep and low altitude sheep (P < 0.05). And the content of LA in skeletal muscle of tibetan antelope significantly lower than that of tibetan sheep and low altitude sheep (P < 0.05), activity of LDH and MDH in skeletal muscle was significantly lower and higher respectively than that of tibetan sheep and low altitude sheep (P < 0.05). There was no significant difference between tibetan sheep and low altitude sheep.

CONCLUSIONTibetan antelope may improve their ability to get oxygen under hypoxia by increasing the content of myoglobin in skeletal muscle, and the proportion of aerobic metabolism is high in skeletal muscle, it may be relate that with high myoglobin content in skeletal muscle, we suppose that high myoglobin content in skeletal muscle of tibetan antelope might be one of the molecular basis to adapt hypoxia.

Altitude ; Animals ; Antelopes ; metabolism ; physiology ; Hypoxia ; metabolism ; L-Lactate Dehydrogenase ; metabolism ; Malate Dehydrogenase ; metabolism ; Muscle, Skeletal ; metabolism ; Myoglobin ; metabolism

The aim of the present study was to explore the changes and roles of dystrophin and membrane permeability in hypoxic training. Seventy-two 8-week-old Sprague Dawley (SD) rats were randomly divided into 4 groups, normoxic non-train (NC), normoxic train (NT), hypoxic non-train (HC), and hypoxic train (HT) groups. The rats of each group were randomly divided into three subgroups, non-exhaustive, low-speed exhaustive test and high-speed exhaustive test subgroups. Rats in hypoxia groups lived and were trained in a condition of 12.7% oxygen concentration (equal to the 4 300 m altitude). NT and HT groups received 4 weeks of training exercise. Then the rats in all non-exhaustive subgroups were sacrificed, and gastrocnemii were sampled for the measurements of lactate dehydrogenase (LDH), succinatedehydrogenase (SDH), malate dehydrogenase (MDH) activities. Moreover, serum LDH activity was analyzed. Low-speed exhaustive test and high-speed exhaustive test subgroups received exhaustive tests with 20 (71% VO2max) and 30 m/min speed (86% VO2max), respectively, and their exhaustive times were recorded. The results showed that, compared with normoxic groups, the weights in hypoxia groups exhibited slower increase. The level of dystrophin in HT group without exhaustion test didn't change significantly. The muscle MDH activities were markedly affected by the different oxygen concentration, training and their interaction (P < 0.05), whereas the muscle LDH activities were only affected by the different oxygen concentration (P < 0.05). Serum LDH activities were affected by the interaction of the different oxygen concentration and training (P < 0.05), showing decreased muscle LDH and increased blood LDH activities. The exhaustion time were markedly affected by the different test speed, training and their interaction (P < 0.05), and also affected by the interaction of the different oxygen concentration and training (P < 0.05), but didn't affected by oxygen concentration. The exhaustive time of HT high-speed exhaustive test subgroup was more than NT high-speed exhaustive test subgroup in 30 m/min exhaustion test. Compared with NT high-speed exhaustive test subgroup, HT high-speed exhaustive test subgroup had an earlier fatigue in the test, but had a rapid recovery. These results suggested that hypoxic training can effectively increase the rats' high-speed exhaustive time. The mechanism may be related to an increase in serum LDH caused by the increased membrane permeability after hypoxic training.
Altitude ; Animals ; Dystrophin ; metabolism ; Fatigue ; Hypoxia ; L-Lactate Dehydrogenase ; metabolism ; Malate Dehydrogenase ; metabolism ; Muscle, Skeletal ; enzymology ; Physical Conditioning, Animal ; Rats ; Rats, Sprague-Dawley ; Succinate Dehydrogenase ; metabolism

OBJECTIVETo explore the pathophysiological and biomechanical features of skeletal muscular injury for providing a rational basis for its treatment, prevention and rehabilitation.

METHODSIn 70 adult rabbits, the left tibialis anterior (TA) muscle was stretched to injury, while the right TA muscle served as control. Histological, enzymohistochemical and biomechanical changes were observed on days 0, 1, 2, 3, and 7 after injury. Cytochrome oxidase (CCO), acid phosphatase (ACP), ATPase, succinate dehydrogenase (SDH), malate dehydrogenase (MDH), NADH-diaphorase (NADHD), glutamatedehydrogenase (GDH), alpha-glycerophosphate dehydrogenase (alpha-GPD) and lactate dehydrogenase (LDH) were measured. The examined biomechanical parameters included maximal contractile force, ultimate load, length, energy absorption, tangent stiffness, and rupture site.

RESULTSPartial or complete rupture of TA muscle occurred near the muscle-tendon junction. There was an intense inflammatory reaction on day 1 and 2 after injury. Endomysium fibrosis and myotube formation were observed on day 3, and developed further on day 7. The activity of cell oxidases (CCO, ATPase, MDH, alpha-GPD, SDH, NADHD and GDH) showed a significant drop from day 0 to 2, and resumed with different levels on day 3. The increment of enzymatic activities continued on day 7 and the levels of NADHD and alpha-GPD reached to the levels of control muscle. Maximal contractile force was 70.17%+/-3.82% of controls immediately after injury, 54.82%+/-3.09% at 1 day, 66.41%+/-4.36% at 2 days, 78.39%+/-4.90% at 3 days and 93.64%+/-5.02% at 7 days. Ultimate load was 85.78%+/-7.54% of controls at the moment of injury, 61.44%+/-5.91% at 1 day, 49.17%+/-4.26% at 2 days, 64.43%+/-5.02% at 3 days, and 76.71%+/-6.46% at 7 days.

CONCLUSIONSEndomysium fibrosis and scar formation at the injured site are responsible for frequent recurrence of skeletal muscle injury. Recovery of tensile load slower than that of maximal contractile force may be another cause. Whether the injured muscle returns to normal exercise is mainly determined by the tensility on which the muscle-tendon can bear rather than the maximal contractile force.

Acid Phosphatase ; analysis ; Adenosine Triphosphatases ; analysis ; Animals ; Biomechanical Phenomena ; Dihydrolipoamide Dehydrogenase ; analysis ; Electron Transport Complex IV ; analysis ; Glutamate Dehydrogenase ; analysis ; Glycerolphosphate Dehydrogenase ; analysis ; L-Lactate Dehydrogenase ; analysis ; Malate Dehydrogenase ; analysis ; Muscle, Skeletal ; injuries ; pathology ; physiology ; Rabbits ; Succinate Dehydrogenase ; analysis

As a process to study the mechanism of steroid hormones at the molecular level,the activities of lactic dehydrogenase (L.D.) and malic dehydrogenase (M.D.),NAD-linked transhydrogenases, were measured in the testis and the prostate. Ahundred male rabbits were divided into ten group as follows: Group 1: Control Group 2: Estrogen (6,000 units) injected Group 3: Androgen (1,200 unite)injected Group 4: Progesterone (1,200 units) injected Group 5: Hydrocortisone(30 mg) injected Group 6: DOCA (6 mg) injected Group 7: Castration control Group8: Castration and estrogen (6, OOO units) injected Group 9: Castration and androgen (1,200 units) injected Group 10: Castration and progesterone (1,200units) injected Changes in the activities of lactic dehydrogenase and malic dehydrogenase in theorganic tissues by exogenous steroid hormones were carefullyobserved. The lactic dehydrogenase activities were measured by the method of Wroblewski and La Due, and malic dehydrogenase activities by the Bodansky's modification of Porter's method. The results are as follows: 1) The control valueof L.D. activities in the testicular tissue of normal rabbits proved to be 89,400units per ram. The L.D. activities showed an increase up to 110.4 per cent in theestrogen injected group, 179.3 per cent in the androgen injected group and 147.0 per cent in the progesterone injected group, while the administration of hydrocortisone and DOCA decreased the value down to 85.2 per cent and 81.5 per cent, respectively. 2) The control value of M.D. activities in the testicular tissue of the normal rabbits was 23,600 units per gram. The M.D. activities showed an increase upto 111.4 per cent in the estrogen injected group. 191.1 per cent in the androgen injected group, and 156.8 per cent in the progesterone injected group, while the administration of hydrocortisone and DOCA decreased the value down to 85.2 per cent and 81.5 per cent, respectively. 3) In the prostate tissues of non-castrated rabbits, the L.D. activities were estimated normally to be 48,100 units per gram. The administration of sex hormone resulted in raising the activities upto 101.8 per cent in the estrogen injected group, 196.9 per cent in the androgen injected group and 153.9 per cent in the progesterone injected group. But the administration of hydrocortisone and DOCA decreased the value down to 92.5 per cent and 97.1 per cent, respectively. 4) In the prostate tissue of non-castrated rabbits, the control value of M.D. activities proved to be 14,600 unite per gram. The M.D. activities showed an increase upto 117.8 per cent in the estrogen injected group, 206.8 per cent in the androgen injected group and, 176.7 per cent in the progesterone injected group, while the administration of hydrocortisone and DOCA decreased the value down to 81.9 per cent and 95.2 per cent, respectively. 5) The prostatic L.D. activities were decreased to half the normal two weeks after castration. The administration of sex hormones (i.e., estrogen, androgen and progesterone) acted inclusively upon elevating the level f activities. Androgen, in general, was the most effective to restore the activity to the level of pre-castrated state. 6) The prostatic M.D. activities were also decreased to half the normal two weeks after castration. The administration of sex hormones acted inclusively upon elevating the level ofthe activities. Androgen had a remarkable effect in elevating the M.D. activities, which showed twice the precastration level. In this study, it is concluded that L.D. and M.D. activities are present in the testis and the prostate. They are induced and activated by the administration of sex hormones, of which androgen has the most remarkable effect, and estrogen and progesteronehave less effect, while hydrocortisone and DOCA are ineffective in some cases orinhibitory in others.
Castration* ; Desoxycorticosterone Acetate ; Estrogens ; Gonadal Steroid Hormones ; Humans ; Hydrocortisone ; Malate Dehydrogenase* ; Male* ; Oxidoreductases ; Progesterone ; Prostate* ; Rabbits* ; Testis*

Escherichia coli NZN111 is a double mutant with lactate dehydrogenase (ldhA) and pyruvate formate-lyase (pflB) inactivated. Under anaerobic conditions, disequilibrium of coenzyme NADH and NAD+ causes Escherichia coli NZN111 losing the glucose utilizing capability. In this study, we constructed a recombinant strain E. coli NZN111/pTrc99a-mdh and overexpressed the mdh gene with 0.3 mmol/L of IPTG under anaerobic fermentation condition in sealed bottles. The specific malate dehydrogenase (MDH) activity in the recombinant strain was 14.8-fold higher than that in E. coli NZN111. The NADH/ NAD+ ratio decreased from 0.64 to 0.26 and the concentration of NAD+ and NADH increased 1.5-fold and 0.2-fold respectively. Under anaerobic conditions, the recombinant strain possessed the capability of growth and glucose absorption. We took dual-phase fermentation for succinate production. After the dry cell weight (DCW) reached 6.4 g/L under aerobic conditions, the cell culture was changed to anaerobic conditions. After 15 h, 14.75 g/L glucose was consumed and succinic acid reached 15.18 g/L. The yield of succinic acid was 1.03 g/g Glu and the productivity of succinic acid was 1.012 g/(L x h).
Acetyltransferases ; genetics ; Anaerobiosis ; Escherichia coli ; genetics ; metabolism ; Fermentation ; Gene Knockout Techniques ; Glucose ; metabolism ; L-Lactate Dehydrogenase ; genetics ; Malate Dehydrogenase ; genetics ; metabolism ; Mutation ; Recombinant Proteins ; biosynthesis ; genetics ; Recombination, Genetic ; Succinic Acid ; metabolism

The Brucella mdh gene was successfully cloned and expressed in E. coli. The purified recombinant malate dehydrogenase protein (rMDH) was reactive to Brucella-positive bovine serum in the early stage, but not reactive in the middle or late stage, and was reactive to Brucella-positive mouse serum in the late stage, but not in the early or middle stage of infection. In addition, rMDH did not react with Brucella-negative bovine or mouse sera. These results suggest that rMDH has the potential for use as a specific antigen in serological diagnosis for early detection of bovine brucellosis.
Animals ; Antigens, Bacterial/*immunology ; Brucella abortus/*enzymology/immunology ; Brucellosis/diagnosis/*veterinary ; Cattle ; Cattle Diseases/*diagnosis ; Cloning, Molecular ; Enzyme-Linked Immunosorbent Assay ; Escherichia coli/genetics ; Malate Dehydrogenase/*genetics/*immunology/isolation & purification ; Mice ; Recombinant Proteins/genetics/*immunology

Protozoan viruses may influence the function and pathogenicity of the protozoa. Trichomonas vaginalis is a parasitic protozoan that could contain a double stranded RNA (dsRNA) virus, T. vaginalis virus (TVV). However, there are few reports on the properties of the virus. To further determine variations in protein expression of T. vaginalis, we detected 2 strains of T. vaginalis; the virus-infected (V⁺) and uninfected (V⁻) isolates to examine differentially expressed proteins upon TVV infection. Using a stable isotope N-terminal labeling strategy (iTRAQ) on soluble fractions to analyze proteomes, we identified 293 proteins, of which 50 were altered in V⁺ compared with V⁻ isolates. The results showed that the expression of 29 proteins was increased, and 21 proteins decreased in V⁺ isolates. These differentially expressed proteins can be classified into 4 categories: ribosomal proteins, metabolic enzymes, heat shock proteins, and putative uncharacterized proteins. Quantitative PCR was used to detect 4 metabolic processes proteins: glycogen phosphorylase, malate dehydrogenase, triosephosphate isomerase, and glucose-6-phosphate isomerase, which were differentially expressed in V⁺ and V⁻ isolates. Our findings suggest that mRNA levels of these genes were consistent with protein expression levels. This study was the first which analyzed protein expression variations upon TVV infection. These observations will provide a basis for future studies concerning the possible roles of these proteins in host-parasite interactions.
Glucose-6-Phosphate Isomerase ; Glycogen Phosphorylase ; Heat-Shock Proteins ; Host-Parasite Interactions ; Malate Dehydrogenase ; Metabolism ; Polymerase Chain Reaction ; Proteome ; Reticuloendotheliosis virus ; Ribosomal Proteins ; RNA, Double-Stranded ; RNA, Messenger ; Trichomonas vaginalis* ; Trichomonas* ; Triose-Phosphate Isomerase ; Virulence

BACKGROUND/OBJECTIVES: The study was conducted to evaluate the effects of dietary leucine supplementation on mitochondrial biogenesis and energy metabolism in the liver of normal birth weight (NBW) and intrauterine growth-retarded (IUGR) weanling piglets. MATERIALS/METHODS: A total of sixteen pairs of NBW and IUGR piglets from sixteen sows were selected according to their birth weight. At postnatal day 14, all piglets were weaned and fed either a control diet or a leucine-supplemented diet for 21 d. Thereafter, a 2 × 2 factorial experimental design was used. Each treatment consisted of eight replications with one piglet per replication. RESULTS: Compared with NBW piglets, IUGR piglets had a decreased (P < 0.05) hepatic adenosine triphosphate (ATP) content. Also, IUGR piglets exhibited reductions (P < 0.05) in the activities of hepatic mitochondrial pyruvate dehydrogenase (PDH), citrate synthase (CS), α-ketoglutarate dehydrogenase (α-KGDH), malate dehydrogenase (MDH), and complexes I and V, along with decreases (P < 0.05) in the concentration of mitochondrial DNA (mtDNA) and the protein expression of hepatic peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α). Dietary leucine supplementation increased (P < 0.05) the content of ATP, and the activities of CS, α-KGDH, MDH, and complex V in the liver of piglets. Furthermore, compared to those fed a control diet, piglets given a leucine-supplemented diet exhibited increases (P < 0.05) in the mtDNA content and in the mRNA expressions of sirtuin 1, PGC-1α, nuclear respiratory factor 1, mitochondrial transcription factor A, and ATP synthase, H+ transporting, mitochondrial F1 complex, β polypeptide in liver. CONCLUSIONS: Dietary leucine supplementation may exert beneficial effects on mitochondrial biogenesis and energy metabolism in NBW and IUGR weanling piglets.
Adenosine Triphosphate ; Birth Weight* ; Citrate (si)-Synthase ; Diet ; DNA, Mitochondrial ; Energy Metabolism* ; Fetal Growth Retardation ; Leucine* ; Liver ; Malate Dehydrogenase ; Nuclear Respiratory Factor 1 ; Organelle Biogenesis* ; Oxidoreductases ; Parturition* ; Peroxisomes ; Pyruvic Acid ; Research Design ; RNA, Messenger ; Sirtuin 1 ; Transcription Factors

Malic acid is widely used in food, and chemical industries. Through overexpressing pyruvate carboxylase and malate dehydrogenase in pdc1-deficient Saccharomyces cerevisiae, malic acid was successfully produced through the reductive TCA pathway. No malic acid was detected in wild type Saccharomyces cerevisiae, however, 45 mmol/L malic acid was produced in engineered strain, and the concentration of byproduct ethanol also reduced by 18%. The production of malic acid enhanced 6% by increasing the concentration of Ca2+. In addition, the final concentration reached 52.5 mmol/L malic acid by addition of biotin. The increasing is almost 16% higher than that of the original strain.
Citric Acid Cycle ; Fermentation ; Industrial Microbiology ; methods ; Malate Dehydrogenase ; genetics ; metabolism ; Malates ; metabolism ; Metabolic Engineering ; methods ; Metabolic Networks and Pathways ; Oxidation-Reduction ; Pyruvate Carboxylase ; genetics ; metabolism ; Saccharomyces cerevisiae ; genetics ; metabolism ; Signal Transduction

A large amount of nicotinamide adenine dinucleotide phosphate (NADPH) is required for fatty acid synthesis and maintenance of the redox state in cancer cells. Malic enzyme 1(ME1)-dependent NADPH production is one of the three pathways that contribute to the formation of the cytosolic NADPH pool. ME1 is generally considered to be overexpressed in cancer cells to meet the high demand for increased de novo fatty acid synthesis. In the present study, we found that glucose induced higher ME1 activity and that repressing ME1 had a profound impact on glucose metabolism of nasopharyngeal carcinoma(NPC) cells. High incorporation of glucose and an enhancement of the pentose phosphate pathway were observed in ME1-repressed cells. However, there were no obvious changes in the other two pathways for glucose metabolism: glycolysis and oxidative phosphorylation. Interestingly, NADPH was decreased under low-glucose condition in ME1-repressed cells relative to wild-type cells, whereas no significant difference was observed under high-glucose condition. ME1-repressed cells had significantly decreased tolerance to low-glucose condition. Moreover, NADPH produced by ME1 was not only important for fatty acid synthesis but also essential for maintenance of the intracellular redox state and the protection of cells from oxidative stress. Furthermore, diminished migration and invasion were observed in ME1-repressed cells due to a reduced level of Snail protein. Collectively, these results suggest an essential role for ME1 in the production of cytosolic NADPH and maintenance of migratory and invasive abilities of NPC cells.
Carcinoma ; Cell Line, Tumor ; Cell Movement ; Cell Survival ; Glucose ; metabolism ; Glycolysis ; Humans ; Malate Dehydrogenase ; metabolism ; NADP ; metabolism ; Nasopharyngeal Neoplasms ; metabolism ; pathology ; Neoplasm Invasiveness ; Oxidation-Reduction ; Oxidative Phosphorylation ; Pentose Phosphate Pathway ; Proto-Oncogene Proteins c-akt ; metabolism