Lactate dehydrogenase of goldfish red and white muscle in relation to thermal accumulation

• 1.1. Activities of the red and white muscle LDH from 8°C-acclimated goldfish were about three times higher than those acclimated to 28°C.
• 2.2. Isozyme composition and some kinetic properties of the red muscle LDH differed from those of the white muscle enzyme.
• 3.3. The amount of red muscle as well as LDH activity tended to increase during cold acclimation.

     

On the variation in enzyme activities during the growth of burkitts lymphoma cells in suspension culture

• 1.1. The growth characteristics of Burkitt's lymphoma cells in suspension culture have been studied, and a mean population doubling time of 20–21 hr established for this cell line under a range of nutritional and physical conditions; data which have provided a basis for the assessment of the reproducibility of the culture techniques and conditions which were employed in the subsequent studies.
• 2.2. Activities of lactate dehydrogenase (LDH), aldolase and esterase, as well as the cellular content of total soluble protein, and the isoenzyme pattern of LDH, were monitored in randomly growing Raji cells for the duration of a complete growth cycle.
• 3.3. In this period, the temporal pattern of variation in the levels of total soluble protein were seen to reflect alterations in LDH activity during a single growth cycle.
• 4.4. The fluctuations observed in LDH activity were greater than those observed for either aldolase or esterase activity, and, from the data considered, the maximum degree of variation appeared to be confined to the initial stages of growth.
• 5.5. Extracellular levels of LDH activity remained relatively constant throughout the growth cycle. so that the large fluctuations in intracellular LDH activity could not be attributed to either secretion or leakage of the enzyme into the culture medium.
• 6.6. No gross changes in the pattern of LDH isoenzymes in these Raji cells were detected during the course of a single growth cycle.

     

Variations in the lactate dehydrogenase activity during the development of the shrimp Palaemon serratus

• 1.1. The lactate dehydrogenase (LDH) from Palaemon serratus muscle has been studied throughout the development of the animal.
• 2.2. Enzymatic activities have been traced by polyacrylamide gel electrophoresis and kinetic studies.
• 3.3. The existence of two enzymes (L₁ and L₂) has been demonstrated.
• 4.4. During the larval development, both L₁ and L₂ remain at a low level.
• 5.5. After the larvae hatch L₁ and L₂ gradually rise although L₁ is predominant.
• 6.6. Measurement of kinetic parameters shows that the general behaviour of the enzymes of the embryo resembles that of the adult enzymes.
• 7.7. However, one can observe during the development a constant increase in the affinity of the enzyme towards its substrate, lactate.

     

LDH isozymes in amazon fish—III. Distribution patterns and functional properties in Serrasalmidae (Teleostei: Ostariophysi)

• 1.1. The patterns of distribution of LDH isozymes in five tissues from 12 Serrasalmidae species have been studied through two-fold serial dilution (Klebe's test) as well as the pyruvate inhibition of LDH enzyme in skeletal and heart muscles (low/high ratios).
• 2.2. The species' electrophoretic patterns differ by orthologous A₄ isozyme mobilities since the orthologous B₄ isozymes present similar electrophoretic migration. These differences between Ldh-A and Ldh-B products reflect three-, four-, and five-banded patterns. Thus, different LDH isozyme numbers formed from A and B subunits should not be used as an evolutionary or phylogenetic characteristic from different taxonomic groups.
• 3.3. Out of 66 pairs of species only five pairs showed significant differences in the distribution patterns in all five analyzed tissues, while no pair of species showed the same distribution in these tissues. This variation was explained as differential regulation of structural genes among tissues and/or species.
• 4.4. Functional properties showed significant between the LDHs from heart and skeletal muscles, and are consistent with a preference for aerobic metabolism. We suppose that by selecting B-like subunits these fishes are able to maintain good control of aerobic/anaerobic transitions, maintaining predominantly oxidative metabolism even in hypoxic waters, with which they have to cope.

     

Adaptative features of amazon fishes: Hemoglobins,hematology, intraerythrocytic phosphates and whole blood Bohr effect of Pterygoplichthys multiradiatus (Siluriformes)

• 1.1. Hemoglobin, hematological parameters, intraerythrocytic phosphates and whole blood Bohr effect of Pterygoplichthys multiradiatus, from the Amazon river, were studied in three different conditions: in their natural environment, acclimated to normoxia and acclimated hypoxia conditions.
• 2.2. Nine anodal hemoglobin fractions were detected on starch gel electrophoresis. No qualitative differences in the Hb electrophoretic patterns were detected in the three studied groups.
• 3.3. Hematocrit, hemoglobin concentration, MCV, MCHC and MCH were different among studied conditions.
• 4.4. GTP was almost absent in the blood of animals in natural conditions and acclimated to hypoxia, but was present at a concentration similar to ATP in normoxic acclimated animals.
• 5.5. There is a tendency for higher Hb-O₂ affinity for hypoxic acclimated/acclimatized animals.

     

Carbonic anhydrase III content in various equine muscles

• 1.1. In this study, carbonic anhydrase III (CA-III) content in 18 equine muscles was determined by enzyme immunoassay.
• 2.2. It was found to differ in several muscles.
• 3.3. That in external intercostal muscle, rectus abdominis muscle and splenius muscle from four horses was very high.
• 4.4. Although the masseter muscle had only type I fibers, CA-III content was similar to that in mixed-fiber type muscles such as the biceps femoris muscle.
• 5.5. It thus appear that equine type I fibers can be further subgrouped.

     

Polymorphism and tissue specificity of scallop tropomyosin

• 1.1. Molecular polymorphism of tropomyosin from various muscle sources of the scallop, Patinopecten yessoensis, was investigated by electrophoretic and immunochemical methods.
• 2.2. Treatment of the muscle sources with trichloroacetic acid (TCA) prior to tropomyosin preparation was found useful to prevent proteolytic degradation of this protein.
• 3.3. Electrophoretic and immunochemical analysis revealed that at least six kinds of tropomyosin isoforms may exist in scallop muscle tissues.
• 4.4. The tropomyosin isoforms showed tissue-specific distribution in amounts and molecular species among the various muscle sources.

     

The effect of hypoxia on carbohydrate metabolism in flounder (Platichthys flesus L.)—II. High energy phosphate compounds and the role of glycolytic and gluconeogenetic enzymes

• 1.1. ATP, ADP, AMP, energy charge potential and total adenylates in heart, kidney and muscle are relatively unaffected by environmental hypoxia. In the liver, hypoxia causes a 90% drop in ATP, a rise in ADP and AMP, and a drop in energy charge potential and total adenylates. In the muscle tissue ATP concentration is stabilized by a large creatine phosphate pool.
• 2.2. Hexokinase activity in the heart is 20 times higher than in the swimming muscle, and thus the heart has a high potential for utilizing exogenous glucose as an anaerobic substrate.
• 3.3. The role of creatine phosphate in regulating muscle glycolysis is discussed on background of the strong inhibition of muscle phosphofructokinase by physiological concentrations of creatine phosphate.
• 4.4. Flounder heart has a dominating M-type lactate dehydrogenase which is identical to the muscle enzyme by electrophoretic and kinetic criteria. This improves the anaerobic capabilities of the flounder heart compared to other fish hearts.
• 5.5. Both liver and kidney have high activities of the gluconeogenetic enzymes glucose-6-phosphatase, fructose-1,6-diphosphatase, and phosphoenolpyruvate carboxykinase and both are capable of synthesizing glucose from [¹⁴C]lactate. Because of more favorable energy conditions in the kidney this organ may substitute the liver as a gluconeogenetic organ during hypoxia.

     

The influence of ehrlich ascites tumour growth on the turnover of lactate dehydrogenase in tissues of the mouse

• 1.1. The influence of Ehrlich ascites tumour growth on the turnover of total soluble protein and lactate dehydrogenase (LDH) in mouse tissues has been studied.
• 2.2. Turnover parameters were determined by means of double-labelling technique, with the enzyme (LDH) being isolated by affinity chromatography.
• 3.3. Tumour growth was accompanied by a decreased rate of synthesis of total protein in all tissues.
• 4.4. Lactate dehydrogenase by contrast snowed an increased rate of synthesis in all tissues but kidney.
• 5.5. These directions of change, in combination with the lesser response of degradation constants, resulted in a consequent conservation of enzyme activity in all tissues except kidney.
• 6.6. A generalized shift in the LDH isozyme pattern of these tissues was also observed during tumour growth with an increased contribution of A-type subunit.
• 7.7. These results have been discussed in relation to the redirection of protein synthesis and degradation, the occurrence of foetal isozymes, and possible mechanisms involved in the redistribution of protein resources in the animal during tumour development.

     

Characterization of procollagen type iv and of its heterogenous accumulation products in the extracellular matrix of bovine lens cells in culture

• 1.1. Bovine lens epithelial cells synthesized in culture medium type IV procollagen which can be labelled both with [³H]mannose and [¹⁴C]glucosamine.
• 2.2. This procollagen eluted on Agarose column ahead the component of collagen type I. After reduction and alkylation it has an apparent molecular weight of 180,000.
• 3.3. The behaviour of the pepsin extractible collagen from both culture medium and cell layer submitted to salf fractionation and thermal gelation was similar to that of type IV collagen isolated from lens capsule.
• 4.4. Ion exchange chromatography and CNBr peptides profiles of these collagen molecules are similar to that obtained with lens capsule collagen. However, some heterogeneity is detected in the CMC Chromatographic profile obtained with the collagen isolated from the cell layer.
• 5.5. Analysis on SDS PAGE of the collagen isolated from the cell layer gives an heterogenous profile similar to that of lens capsule collagen and contrasts with homogenous electrophoretic pattern of collagen extracted from culture medium.

     

Heart rates of adult red-spotted newts,Notophthalmus viridescens in air and submerged in normoxic and hypoxic water at different temperatures

• 1.1. Heart rates of adult aquatic red-spotted newts can be conveniently recorded using an impedance pneumograph.
• 2.2. Heart rates decrease linearly with decreasing temperature.
• 3.3. Submergence in normoxic and hypoxic water at 10°, 15°, and 20°C results in bradycardia which is more pronounced in hypoxic water.
• 4.4. At 5°C one newt exhibited the above pattern, but bradycardia was not exhibited by the other newt during normoxic submergence.
• 5.5. Diminishing heart rates are probably due to oxygen deficiency, not immersion alone.
• 6.6. Recovery from bradycardia in air is rapid and not linked with resumption of aerial breathing.

     

Kinetic mechanism of guinea-pig skeletal muscle lactate dehydrogenase (M4) with oxaloacetate-NADH and pyruvate-NADH as substrates

• 1.1. Guinea-pig skeletal muscle lactate dehydrogenase M₄ isoenzyme, with pyruvate and NADH as substrates, is adapted to an ordered bi-bi ternary complex mechanism at pH 7.0.
• 2.2. In the same conditions, the kinetic mechanism of the reaction, with oxaloacetate and NADH as substrates, is of the rapid equilibrium ordered bi-bi ternary complex type; NADH is the first substrate in the reaction sequence.

     

Kinetic analysis of the michaelis-menten mechanism in which the substrate and the product are unstable

• 1.1. A kinetic analysis of the Michaelis-Menten mechanism for the case in which both the substrate and the product are unstable, either spontaneously or as the result of the addition of a reagent, has been made.
• 2.2. The explicit time course equations of the immediate product and the species into which it subsequently is transformed have been derived under the conditions of rapid equilibrium and limiting substrate concentration.
• 3.3. The validity of these equations has been checked using numerical simulations.
• 4.4. The kinetic data analysis which we suggest is based on the time progress curves of the product or, in the case in which the product accumulation cannot be monitored experimentally, on the time progress curve of the species into which the immediate product is transformed.
• 5.5. This analysis allows the determination of the rate and the equilibrium constants if adequate experimental results are available.
• 6.6. We have chosen a numerical example, with which we illustrate the procedure of the kinetic data analysis by simulating some curves with assumed experimental errors.

     

Lactate dehydrogenase (LDH) in 27 species of amazon fish: Adaptive and evolutive aspects

• 1.1. Among the 27 species of Amazon fish belonging to the orders Rajiformes, Clupeiformes, Osteoglossiformes, Characiformes, Siluriformes and Perciformes here analyzed, 56% showed an electrophoretic pattern of five, 7% of four, 30% of three, and 7% of two LDH isozymes, suggesting the presence of both LDH-A¹ and LDH-B¹ loci. In addition to these loci, the third gene LDH-C¹ was detected only in the Osteoglossiform species O. bicirrhosum and in the perciform species P. squamosissimus, with a generalized expression in the first and a restricted in the second.
• 2.2. Only P. squamosissimus (Perciformes) showed a LDH reversed pattern, in which the A₄ is more anodic than the B₄.
• 3.3. Like other vertebrates, in most (93%) of the species here analyzed, a direct correlation between electrophoretic mobility and thermostability was observed. The inactivation temperatures varied from 55°C in the Rajiformes species of 70°C in the Perciformes species.
• 4.4. Polymorphism in at least one of the LDH loci was detected in 22% of the species studied here: P. castelnaena (Clupeiformes) and B.cf. cephalus (Characiformes) at the LDH-A¹ locus, R. myersi and H. unitaeniatus (both Characiformes) at the LDH-B¹ and L. agassizi (Characiformes) at both loci.
• 5.5. No modifications of the classic LDH pattern found by other authors in organisms routinely subjected to hypoxic stress were observed in these Amazon species. In 93% of the species screened here, subjected to considerable hypoxic stress, large daily oscillations in temperature, O₂ and CO₂ levels, pH, low ionic content, and seasonal drought, a bidirectional pattern of expression of the LDH loci was observed.

     

The influences of individual variations in metabolic rate and tidal conditions on the response to hypoxia in Carcinus maenas (L.)

• 1.1. The oxygen consumption of crabs in normoxic and hypoxic (50% O₂) seawater was measured directly after collection.
• 2.2. The influences of size and lunar cycles were removed by scaling the data.
• 3.3. Strong negative correlations between low individual levels of O₂ consumption and the ability to compensate for hypoxia were apparent in Wicklow (subtidal) crabs.
• 4.4. Compensation for hypoxia was much greater on the flood tide than on the ebb.
• 5.5. Crabs from Roscoff (intertidal) had lower levels of compensation than those from Wicklow.
• 6.6. Size, sex and condition had no apparent effect upon these relationships.
• 7.7. Crabs acclimated to laboratory conditions have not shown this tidal variation in compensation for hypoxia.

     

Distribution of opine dehydrogenases and lactate dehydrogenase activities in marine animals

• 1.1. Opine dehydrogenases (OpDHs) and lactate dehydrogenase (LDH) activities were determined in various marine animals. OpDHs were detected in six marine invertebrate phyla; Porifera, Coelenterata, Annelida, Mollusca, Arthropoda and Echinodermata in phylogenic sequence.
• 2.2. Among several OpDHs, tauropine dehydrogenase (TaDH) occurred widely in marine invertebrates, from Porifera to Echinodermata.
• 3.3. With a few exceptions, total OpDHs activities exceeded that of LDH activity in the marine invertebrates investigated.
• 4.4. With respect to anaerobic glycolysis, OpDHs are indicated to play an important role in phylogenically lower invertebrates, whereas LDH is more important in higher animals.

     

Adenosine effect on lactate and pyruvate production in the hypoxic guineapig heart

• 1.1. It has been shown that adenosine stimulates glycolysis in some cells and this ability of adenosine was tested in the hypoxic guineapig heart.
• 2.2. Adenosine (10 μM) activated lactate production in the isolated perfused guineapig heart under conditions of normoxia but did not under hypoxia.
• 3.3. Despite this, the nucleoside favorably influenced the energy metabolism of the hypoxic heart as revealed by the better posthypoxic functional recovery (98%) compared to the control without adenosine (78%).
• 4.4. Our findings suggest a role for the glycolytic pathway in this effect of the nucleoside as long as other cardiac energy-yielding pathways are strictly aerobic.

     

Sex differences in vascular reactivity to adrenergic agents in the rat

• 1.1.The study was designed to determine if there are sex-dependent differences in vascular reactivity to adrenergic agents.
• 2.2.Vascular reactivity of both aortic and tail artery smooth muscle from male and female rats to various vasoactive agents was assessed. 3.li]The vascular response of aortic smooth muscle to both phenylephrine and isoproterenol were significantly greater in male rats as compared to females.
• 3.4.There were apparent sex differences in responsiveness to the KCl-induced, non-receptor mediated contraction of aortic smooth muscle in that the sensitivity to KCl was enhanced in male rats.
• 4.5.No sex differences were observed in tail artery preparations.
• 5.6.Phentolamine reduced the maximal tension induced by KCl in the tail artery but not aortic artery preparations. This effect was not sex dependent.
• 6.7.No differences in the vascular smooth muscle responsiveness to acetylcholine or sodium nitrate was observed between groups or within different vascular beds.
• 7.8.The increased sensitivity of males to adrenergic challenge could explain in part some of the existing sex differences in cardiovascular disease and hypertension.

     

Differential weighting of electrophoretic data in crayfish and fiddler crabs (decapoda: astacidae and ocypopidae)

• 1.1. Muscle proteins from the chelae of six crayfish species and ten species of Uca were compared through disc electrophoresis (split gel technique).
• 2.2. No intraspecies variation of the electrophoretic pattern was found.
• 3.3. In interspecies comparisons all components (bands) were weighted individually and specified as ancestral or derived characters.
• 4.4. In the crayfishes the phylogenetic trees constructed from electrophoretic and classical data were found to be congruent. In Uca some branches of either tree remained undefined. Each tree, however, helped complete the other one.

     

Allozyme variation in a dimeric esterase of the oriental fruit fly,Dacus dorsalis (insecta: tephritidae), from peninsular malaysia

• 1.1. Seven natural populations of Dacus dorsalis were analyzed for a dimeric esterase by means of horizontal starch-gel electrophoresis.
• 2.2. The electrophoretic phenotypes were governed by nine codominant Est-D alleles.
• 3.3. The commonest allele in all seven population samples was Est-D¹⁰⁰ which encoded an electrophoretic band with intermediate mobility.
• 4.4. The distribution of EST-D phenotypes were in accordance with Hardy-Weinberg expectations.
• 5.5. There was no geographic variation in the distribution of Est-D alleles.