Arginase activity in different fish species and tissues

• 1.1. Arginase activity was measured in different tissues from eight species of fish.
• 2.2. Spur dogfish showed a very high arginase activity compared with the other species analysed.
• 3.3. The activity in teleosts was mainly found in tissues of high metabolic activity (liver, kidney and red muscle).

     

Some properties of the NADP-malic enzyme from mango fruit,Mangifera indica

• 1.1. Malic enzyme l-malate-NADP-oxidoreductase (oxaloacetate-decarboxylating) (EC 1.1.1.40) was located in the cytosolic fraction of ripening mango fruit.
• 2.2. The purified enzyme has an isoelectric point of 6.86 and an activation energy of 11.9kcal/mol.
• 3.3. The amino acid composition of the enzyme was determined and revealed a low cysteine and tryptophan content.
• 4.4. The enzyme has an ultraviolet absorption maximum at 266 nm with maxima for fluorescence excitation and emission at 285 and 328 nm.
• 5.5. The enzyme shows positive cooperativity between the malate binding sites and the effect of allosteric regulators and structural analogues on the activity were investigated.

     

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Heart rate and its cholinergic control in the sole (Solea vulgaris), acclimatized to different temperatures

• 1.1. The effects of thermal acclimatization at 10 and 24°C on heart rate were investigated on unrestrained soles (Solea vulgaris).
• 2.2. The sensitivity of heart rate to temperature changes induced by temperature acclimatization was higher in cold-acclimatized than in warm-acclimatized soles.
• 3.3. Heart rate of cold-acclimatized fish to temperature changes was not affected by blocking the vagal tone with atropine.
• 4.4. After atropine treatment the ability of heart rate to show thermal compensation decreased in warm-acclimatized soles.
• 5.5. It is suggested that the vagus nerve can function differently at different temperatures.

     

Evaporative water loss and uptake in juvenile and adult Salamandra salamandra (L.) (Amphibia: Urodela)

• 1.1. Both juveniles and adults of this rare salamander were studied.
• 2.2. The rate of evaporative water loss increased with temperature and at lower humidities.
• 3.3. At all four temperatures and three humidities studied, adults lost water at a lower rate than juveniles.
• 4.4. Aggregating juveniles reduced water loss especially at lower moisture.
• 5.5. The rate of water uptake was greater in juveniles than in adults.
• 6.6. Juveniles were capable of absorbing moisture from moist soil even at 40% saturated soil.

     

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Relationship between haematological parameters and progesterone blood concentration in different stages of estrous cycle in common vole,Microtus arvalis

• 1.1. Progesterone concentration and haematological parameters at different stages of estrous cycle of the common vole have been investigated.
• 2.2. During the estrous cycle progesterone concentration varied between 1.08 and 7.69 ng/ml of plasma; in the metaestrous period it was 7.69 ng/ml and 1.08 ng/ml in the proestrous period.
• 3.3. The highest haemoglobin level, hematocrit value and erythrocyte number have been found in the proestrous period, and the lowest, in the estrous and metaestrous periods.
• 4.4. The reverse changes were observed in the total and differential number of leukocytes.
• 5.5. Statistically significant changes in all these parameters have been found.

     

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Effect of lindane on phosphatidylinositol synthesis by cerebral cortex after acute and subchronic treatment

• 1.1. The incorporation of myo-[2-³H]inositol into phosphatidylinositols was unmodified in brain cortex miniprisms from convulsant rats.
• 2.2. However, the incorporation had increased by 300–400% in non convulsant rats which had received the same amount of lindane at a lower concentration.
• 3.3. This result suggests that phosphatidylinositols are implicated in the convulsion syndrome.
• 4.4. Experiments with lindane added in vitro were performed with both subchronically lindane intoxicated and untreated rats.
• 5.5. The results show an interesting lack of parallelism.
• 6.6. This might indicate the development of some resistance to the effects of lindane, possibly as the result of complex compensatory changes in inositol lipid biosynthesis.

     

Analysis of clotting defects in diseased lobsters—I. Alterations in blood parameters

• 1.1. In gaffkemic lobsters kept at 15°C. drastic declines in the hemocyte number and clotting ability occur.
• 2.2. In animals kept at 10°C, although some clotting defects rapidly occur, a high number of amoebocytes is found. Clotting ability reappears after 5 days.
• 3.3. The proportion of each type of hemocyte changes. Numerous hemocytes show morphologic altered features.
• 4.4. Dorsal hematopoietic tissue is as in control lobsters.
• 5.5. Total protein contents are similar in bacteremic or control lobster hemolymphs.

     

Anaerobic threshold in rats

• 1.1. The aim of this study was to find out whether the anaerobic threshold (AT) can be estimated in rats running at increasing speed and if so what is the reproducibility of the measurements.
• 2.2. Lactate (LA) concentrations in blood taken from 11 rats were determined during a discontinued, multistage treadmill exercise test repeated four times in each animal.
• 3.3. It was found that blood LA changes vs speed have an exponential pattern with a distinct, rapid rise at the speed above 25 m/min which corresponds to blood LA of approx. 4 mmol/1.
• 4.4. The variation coefficient of the speed at which AT occurred in individual animals ranged between 10 and 20%.
• 5.5. These results offer a potential application of AT determination in the animal studies concerning mechanisms controlling exercise metabolism.

     

Skin blood flow in the Wistar-Kyoto rat and the spontaneously hypertensive rat

• 1.1. Using laser Doppler techniques in man, we have previously demonstrated differences in skin blood flow properties at sites with primarily nutritive (NUTR) perfusion, such as the elbow or knee, as compared to sites such as the finger pulp, with predominantly arteriovenous anastomotic (AVA) perfusion.
• 2.2. Basal and heat stimulated flow is greater at AVA sites. In man, blood pressure changes are reflected primarily by changes at AVA rather than NUTR sites.
• 3.3. These blood pressure induced changes affect the red blood cell velocity (VEL) component at AVA sites more than microvascular volume (VOL).
• 4.4. Given these findings in man, we decided to compare skin blood flow properties in a suitable animal model.
• 5.5. We chose the Wistar-Kyoto (WKY) and Spontaneously Hypertensive Rat (SHR) strains, in view of the marked difference in systemic blood pressure in these two related strains.
• 6.6. Skin blood flow varied considerably at different skin sites in the rats. Skin sites with hair covering, on the back and at the base of the tail, showed low basal and heat stimulated blood flow.
• 7.7. In contrast, the plantar surface of the paw behaved similarly to the finger or toe pulps in man, with 3–4-fold higher basal flow than the hair covered areas and a 7–8-fold rise with local heating to 44°C.
• 8.8. Furthermore, there was a 25% greater blood flow at the plantar paw surface in the SHR rats as compared to the WKY rats, corresponding to the 25% higher systemic blood pressure in these animals.
• 9.9. The heat induced increase in flow at the plantar surface of the paw was primarily a result of a marked increase in VEL rather than VOL.
• 10.10. The higher flow at this site in SHR as compared to WKY rats was likewise ascribable to an increase in VEL, VOL being equivalent in the two strains.

     

Effect of methyl methacrylate on mitochondrial function and structure

• 1.1. Treatment of isolated rat liver mitochondria with methyl methacrylate (MM) produced membrane disruption as evidenced by the release of citrate synthase, and changes in the ultrastructure of mitochondria.
• 2.2. At concentration 0.1%, MM uncoupled oxidative phosphorylation as evidenced by stimulation of state 4 respiration supported either by pyruvate plus malate or succinate (+rotenone) and ATP-ase activity in intact mitochondria.
• 3.3. At concentration 1% MM stimulated ATP-ase activity in intact mitochondria and succinate (+rotenone) oxidation at state 4 and was without effect on this substrate oxidation at state 3.
• 4.4. MM inhibited pyruvate plus malate oxidation either at state 3 or in the presence of uncoupling agents.
• 5.5. MM inhibited the NADH oxidase of electron transport particles at a concentration which failed to inhibit either succinic oxidase or the NADH-ferricyanide reductase activity.
• 6.6. The data presented suggest that in the isolated mitochondria MM inhibits NADH oxidation in the vicinity of the rotenone sensitive site of complex I.
• 7.7. The general conclusion is that MM may block an electron transport and to uncouple oxidative phosphorylation in rat liver mitochondria. The overall in vitro effect would be to prevent ATP synthesis which could result in cell death under in vivo conditions.

     

Cloning and characterization of rabbit pancreatic colipase

• 1.1. Among the digestive enzymes synthesized by pancreas, lipase is the principle lipolytic enzyme which hydrolyses dietary glycerides.
• 2.2. For its action it requires a coenzyme, colipase.
• 3.3. The molecular mechanisms of the interaction of these two are not fully understood.
• 4.4. Further, molecular events that regulate and influence lipid absorption are ill denned.
• 5.5. The rabbit is the conventional animal model for the study of lipid absorption. We have undertaken the molecular cloning, and characterization of rabbit pancreatic colipase, the coenzyme for pancreatic lipase.
• 6.6. Colipase has been cloned from a gt 11 library of an adult rabbit pancreatic cDNA by probing with an oligonucleotide derived from human colipase sequence.
• 7.7. The total reading frame consists of 321 nucleotides coding for 90 amino acids of the functional protein and 17 nucleotides of the leader peptide.
• 8.8. Northern blot analysis revealed a distinct band around 0.5kb. Comparison with other species revealed an over all homology of 75% at the nucleotide level.
• 9.9. At the amino acid level highest conservation is observed at the lipase-binding region (AA 53–73).
• 10.10. Rabbit enzyme also retained the N-terminal pentapeptide of it preform.
• 11.11. The regions of homology and conservation may aid to define the sites of interaction of colipase with lipase.

     

Purification and characterization of hatching enzyme of the pike (Esox lucius)

• 1.1. A choriolytic enzyme was isolated from the hatching medium of the pike, Esox lucius.
• 2.2. The enzyme is defined as hatching enzyme.
• 3.3. The molecular weight of the enzyme is 24,000.
• 4.4. The enzyme is a glycoprotein containing 2% carbohydrate.
• 5.5. Its isoelectric point is 6.5.
• 6.6. The pH optimum is around pH 8.
• 7.7. The enzyme molecule contains two disulfide bonds but no free cysteine.
• 8.8. Inhibitor studies and metal analysis show that the enzyme is a zinc-metalloprotease.

     

Changes in plasma glucose and lipid concentrations during treadmill exercise in domestic fowl

• 1.1. Plasma glucose, non-esterified fatty acid, triglyceride, cholesterol and lactate concentrations were measured during 90 min treadmill exercise at a work intensity of 55–60% maximum.
• 2.2. After 90 min exercise plasma glucose fell by 35% whilst the non-esterified fatty acid concentration rose to as much as 3–4 times resting.
• 3.3. Exercise had no significant effect on plasma cholesterol, triglyceride or lactate concentrations.
• 4.4. The findings indicate a progressive increase in fat utilization during prolonged exercise. Possible hormonal mechanisms underlying exercise-induced changes in lipid and carbohydrate metabolism are discussed.

     

The influence of seasonal changes on energy metabolism in Mytilus edulise (L.).—III. Anaerobic energy metabolism

• 1.1. Seasonal changes in the accumulation of end products after 48 hr of exposure to air and in the composition of the free amino acid pool were studied in Mytilus edulis.
• 2.2. The accumulation levels of succinate and acetate showed only weak seasonal changes.
• 3.3. Conversion of succinate to propionate was high in summer and virtually zero in winter
• 4.4. Alanine and most other free amino acids were present in relatively high concentrations in summer and early autumn and reached minimal values in winter and early spring.
• 5.5. Exceptions were glutamate, aspartate and taurine, which showed hardly an season related changes and glycine, which changed inversely to the majority of the free amino acids.
• 6.6. The anaerobic formation of alanine was inversely proportional to the endogenous concentration.
• 7.7. The only other free amino acids affected by anaerobiosis were glutamate and aspartate, which respectively increased and decreased under these conditions.

     

Temperature and salinity tolerance of the mole crab,Emerita talpoida (Say) (Crustacea,Anomura)

• 1.1. Adult Emerita talpoida were subjected to 25 temperature-salinity combinations within the range of 5–35°C and 15–65‰.
• 2.2. E. talpoida tolerated 15–65‰ salinity at 20°C and below.
• 3.3. Optimum salinity for survival at stressful temperatures was 40‰.
• 4.4. Crabs transferred directly from one salinity to another experienced changes in osmoconcentration toward that of the new salinity.
• 5.5. Temperature modified the rate of change toward the experimental salinity. Q values averaged 1.2.

     

Changes in high-energy phosphate metabolism in the water scorpion,Ranatra chinensis,under cold water-warm water stress

• 1.1. To evaluate changes in high-energy phosphate metabolism in the water scorpion (Ranatra chinensis) under restraint and cold water-warm water stresses, in vivo [³¹P]NMR spectra were obtained.
• 2.2. Under restraint stress, arginine phosphate (Arg-P) decreased by 10% after 1 hr and remained at that level thereafter, while β-ATP showed negligible changes over 6 hr.
• 3.3. As the water temperature gradually increased or decreased, the relative concentration of Arg-P decreased due to enzyme regulation.
• 4.4. Repeated cold water-warm water stress, which consisted of repeated 15 min exposures to cold water (5°C) followed by 15 min exposures to warm water (30°C) caused distinct decreases in Arg-P and β-ATP concentration. These decreases were dependent on the frequency of exposure.
• 5.5. Phosphomonoesters (PME) increased not only with restraint stress but also with cold water-warm water stress.
• 6.6. The effect of cold water-warm water stress on high-energy phosphate metabolism was greater than that of restraint stress.