Effect of repetitive cortisol and thyroxine injections on chloride cell number and Na+/K+-ATPase activity in gills of freshwater acclimated rainbow trout,Salmo gairdneri

• 1.1. Freshwater nonanadromous rainbow trout, Salmo gairdneri, were injected three times a week with either saline, 10μg cortisol/g, 1.0μg thyroxine/g or 10μg cortisol/g + 1.0μg thyroxine/g during a period of 28 days (12 injections). A separate group was derived as a subgroup from the thyroxine group on day 14 and received Cortisol + thyroxine from day 14 until day 28 (six injections).
• 2.2. Gill chloride cell number and Na⁺/K⁺-ATPase activity increased by cortisol treatment, the changes being significant on days 7 and 14, respectively.
• 3.3. Thyroxine treatment did not affect gill Na⁺/K⁺-ATPase activity or chloride cell number directly. Neither did it modify the stimulatory effect of cortisol on these parameters.
• 4.4. Muscle water decreased in cortisol-treated fish and increased in thyroxine-treated fish, while no changes were observed in the combined hormone groups.
• 5.5. No changes were observed in plasma chloride in any group during the experiment.
• 6.6. The results demonstrate a putative role of cortisol in stimulating hypo-osmoregulatory mechanisms and suggest that thyroxine is without a direct or a supportive effect for cortisol action.

     

Miniature gel filtration: a simple and inexpensive method for the measurement of protein- and non-protein-bound cortisol: application to guinea pig plasma

• 1.1. A method is described for the accurate and rapid measurement of protein- and non-protein-bound cortisol by miniature gel filtration in small volumes of plasma, e.g. of rodents.
• 2.2. Binding of cortisol by guinea pig plasma proteins is strongly reduced at elevated temperature (4°C: 102 ± 12ng/ml; 40°C: 5 ± 2 ng/ml).
• 3.3. Incubation of guinea pig plasma with 1–5000 ng cortisol resulted in a dose-dependent increase in cortisol bound to proteins (specific binding by corticosteroid binding globulin: 230 ± 12 ng/ml).
• 4.4. Administration of 20 IU (1–24)ACTH induced a significant increase of total protein-bound and non-protein-bound cortisol.
• 5.5. Values reported in this study agree well with those of previous investigations, in which bound and non-bound glucocorticosteroids were separated by gel filtration on large Sephadex® columns.

     

A relationship between circulating natural glucocorticoids and the mechanical responses of the heart in atricial and precocial rodents

• 1.1. A comparison was made of the mechanical performance of heart muscle from mouse, an atricial mammal, with corticosterone as glucocorticoid and spiny mouse (Acomys cahirinus), a precocial mammal, with cortisol as glucocorticoid.
• 2.2. Force-frequency responses were negative in mouse and positive in spiny mouse.
• 3.3. During recovery, there was a gradual increase and an overshoot in the mouse, while in the spiny mouse there was an initial enhanced response, diminishing gradually with time.
• 4.4. High calcium concentration inhibited contractile tension in mouse heart, while it was positively inotropic in spiny mouse heart. Changes in the concentration of calcium did not change the patterns of force-frequency response.
• 5.5. Lowering the experimental temperature increased the time course and amplitude of the tension curve. However, various parameters exhibited different temperature sensitivity.
• 6.6. There was a significant difference in the levels of circulating cortisol between male and female spiny mice.
• 7.7. It is proposed that the differences in the mechanical responses of mouse and spiny mouse hearts may be explained in terms of the effects of the specific glucocorticoid hormone on the development of the sodium-calcium exchanger.

     

Physiological responses to exercise and hypoglycaemia stress in pigs of differing adrenal responsiveness

• 1.1. Twelve Large White × Landrace male pigs, six with high adrenocortical response to ACTH, and six with low response, were subjected to mild and moderate exercise, and then to insulin-induced hypoglycaemia.
• 2.2. Plasma ACTH, cortisol, catecholamines and some haematological and plasma biochemical parameters were determined in response to exercise, and glucose and cortisol in response to insulin challenge.
• 3.3. High responders had significantly greater increases than low responders in ACTH, cortisol and catecholamines following exercise, and in cortisol following insulin challenge.
• 4.4. The results suggest that differences in adrenocortical response to exogenous ACTH are an accurate reflection of the animal's response to stressful stimuli.

     

Adrenocorticol responsiveness to immobilization stress in spotted hyenas (Crocuta crocuta)

• 1.1. The adrenocortical responsiveness to an induced Stressor was monitored in free-living spotted hyenas belonging to a number of social and reproductive categories.
• 2.2. No significant differences between sexes, or changes in mean cortisol concentrations during serial sampling within the sexes, could be demonstrated.
• 3.3. The extreme individual variance in temporal cortisol profiles recorded in this study is inexplicable, as it was not related to differences in immobilization procedure, sex, age, reproductive or social category.
• 4.4. Females, which are the dominant sex in this species, generally showed larger percentage increases in cortisol concentrations during serial sampling.
• 5.5. Significant correlations between initial cortisol concentrations, as well as cortisol responsiveness and androgen concentrations, in a number of social and reproductive categories, suggest that these categories do not provide sufficient resolution for the identification of specific dominance-related trends.

     

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.

     

l-Leucine intestinal transport at different ages in chicken: Effect of anticoccidial drugs

• 1.1. l-Leucine transport by everted slices of duodenum, jejunum ileum and cecum of 1-, 2- and 3-week-old chickens has been determined.
• 2.2. The effects of the administration with the diet of three anticoccidial drugs: monensin, maduromicin ammonium and nicarbazine have been studied.
• 3.3. In the control animals, there is a reduction on intestinal transport with age, except in the duodenum which is not age-dependent.
• 4.4. Momensine induces an increase on leucine transport in the duodenum and cecum at all ages studied and only in the 3-week-old animals in the jejunum and ileum.
• 5.5. Nicarbazine reduces jejunal absorption of leucine and does not affect the function of the other segments.
• 6.6. Maduromicin ammonium has almost no effect on the absorptive process.

     

Electrolyte changes,cell volume regulation and hormonal influences during acclimation of rainbow trout (Salmo gairdnerii) to salt water

• 1.1. Rainbow trout were acclimated to salt water (1.5, 2.0 or 3.0%, which means 40, 60 or 85% concentrated sea-water) and the electrolyte, glucose and cortisol concentrations of the plasma as well as the extra- and intracellular muscle space, the muscle electrolyte concentrations and the ATPase activity were analysed.
• 2.2. Plasma osmolality, Na⁺, Ca²⁺ and Mg²⁺ concentrations of the plasma had a maximum at 24 hr after the start of acclimation when acclimated to 3.0% salt water. Plasma osmolality, Na⁺ and Mg²⁺ concentrations were significantly higher during the whole acclimation time when exposed to 3.0% salt water.
• 3.3. Variations and regulations of ECS and ICS were clearly demonstrated. The intracellular electrolyte concentrations were also maximal at 24 hr.
• 4.4. The plasma glucose level was just slightly elevated, but the cortisol level clearly indicated a stress response at 24 hr.
• 5.5. The activity of gill Na-K-ATPase increased during the acclimation time.
• 6.6. The regulatory processes in trout during acclimation to salt water are compared with those occurring in tilapia and carp.

     

Relationship between brain trehalase activity and trehalosema during direct and diapausing development in Pieris brassicae

• 1.1. Brain trehalase specific activity and trehalosemia were measured during the end of the developmental life cycle in non-diapausing and diapausing insects.
• 2.2. During non-diapausing development, trehalosemia reached maximum values at the beginning of pupal life. Then a constant decrease was observed up to the end of adult life.
• 3.3. The specific activity of brain trehalase was maximum when the insects were in active feeding periods, minimum activity appearing during moulting phases.
• 4.4. During diapausing development, trehalosemia was very high at the beginning of pupal life, particularly when insects were exposed to wintering conditions.
• 5.5. When diapause was broken, trehalosemia fell, announcing adult emergence.
• 6.6. Brain trehalase activity showed the same qualitative variations as in non-diapausing larvae, but with rather lower values.
• 7.7. During pupal life, brain trehalase activity decreased markedly during the long period necessary to obtain diapause breakdown.
• 8.8. Wintering conditions allow a progressive increase of brain trehalase activity, which preceded the fall of trehalosemia.

     

Regulation of spermidine transport in l1210 cells

• 1.1. 1 mM 2-amino isobutyric add (AIB), glutamine or asparagine when preincubated for 3 hr with L1210 cells promoted a marked increase in the rate of spermidine uptake.
• 2.2. Cycloheximide also increased the transport rate and completely prevented the increase due to AIB.
• 3.3. Trifluoperazine and iso-H7 inhibited the uptake of spermidine, much less the uptake of AIB.
• 4.4. Adenosine promoted an increase in the uptake of AIB, a decrease in that of spermidine.
• 5.5. Hypotonic stress also increased the rate of spermidine transport. This modification was only partially prevented by cycloheximide.
• 6.6. Okadaic arid had no effect on this increase, whereas it prevented the increase of ODC activity.

     

Role of the visceral nerve in heart rate variations during different behavioral patterns in Megalobulimus sanctipauli (mollusca,gastropoda, pulmonata)

• 1.1. The role of the visceral nerve in mediating the changes in heart rate associated with different behavioral patterns was investigated in Megalobulimus sanctipauli.
• 2.2. The results of acute and chronic denervation experiments indicate that the visceral nerve has no excitatory or inhibitory tonic action on the heart of snails retracted into the shell, nor does it account for the increase in heart rate associated with the locomotion and feeding behaviors.
• 3.3. These changes in heart rate are, probably, indirect effects of increased activity such as an increase in venous return.
• 4.4. The visceral nerve is responsible for approximately 3/4 of the increase in heart rate associated with the first minute of extrusion.
• 5.5. The small increase in heart rate observed in denervated animals is probably caused by an increase in venous return generated by muscle activity that forces the head and food out of the shell.

     

Potassium balance in freshwater-adapted xtrout Oncorhynchus mykiss

• 1.1. Potassium loss occurs through the gills of trout.
• 2.2. This loss is compensated by intestinal absorption.
• 3.3. During a fasting period, branchial regulation appears after 2–3 days.
• 4.4. The maintenance of potassium balance is discussed as a function of experimental conditions.

     

Purification and some particular kinetic properties of rat spleen cytosolic deoxynucleotidase

• 1.1. Rat spleen cytosolic deoxynucleotidase was purified 40,000-fold to almost homogeneity and had a specific activity of 3000 μmol/min per mg.
• 2.2. Molecular mass of the native enzyme was 45 kDa. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis indicated that the native enzyme comprises two identical 27-kDa subunits.
• 3.3. Specific enzyme activity increases with increasing concentration of enzyme protein and approaches a plateau at high enzyme concentrations.
• 4.4. Enzyme activity increases gradually and nonlinearly with increasing concentration of enzyme in the low concentration range. Above a certain concentration the increase attains a maximal and constant slope.
• 5.5. The kinetic properties can be explained by assuming dissociation of the enzyme into subunits with low or no activity.

     

Influence of temperature,rate of feeding and body weight on nitrogen metabolism of bream,Abramis brama L

• 1.1. Measurements of the rate of nitrogen consumption, total nitrogen and ammonia excretion and nitrogen absorption of bream, Abramis brama L. (body weight range 0.4–519 g wet wt) were made at 10, 15 and 20 C.
• 2.2. Fish were fed once daily on live zooplankton collected in Lake Balaton and cultured Tubifex sp. at 5–15% of their body weight.
• 3.3. Fish size and temperature had a combined effect on the rate of total nitrogen excretion. Total nitrogen excretion did not increase proportionally with an increase in consumption.
• 4.4. On average, 52–80% of the nitrogen consumed with food was excreted by bream.
• 5.5. The greatest part of total nitrogen excretion was ammonia and its proportion in the total ranged between 53 and 75%.
• 6.6. Temperature did not have any significant effect on the proportion of excreted ammonia and the rate of excreted total nitrogen was the only factor determining its proportion in the total.
• 7.7. The rate of nitrogen absorption of bream was surprisingly very high.

     

In brief

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• US Government

     

Agaricus bisporus tyrosinase—II. Characterization of hydroxylase and dehydrogenase activities

• 1.1. Preparative Isoelectric focusing (PIEF) was used to isolate hydroxylasic and dehydrogenasic activities, at different pI.
• 2.2. The fraction at pI 4.7 and 4.9 displays a pure dehydrogenase activity (substrate l-DOPA).
• 3.3. This fraction did not react with tyrosine, either in the spot-test or in absorption spectra (200–620 nm), and did not exhibit any oxygen consumption.
• 4.4. The fraction at pI 4.1 and 4.3 reacted with both l-DOPA and tyrosine as substrate, showing dehydrogenase and hydroxylase activity.
• 5.5. The latter activity was confirmed by the oxygen consumption test, showing that molecular oxygen is used to ortho-hydroxylate tyrosine.

     

Plasma lipoprotein profiles and arylesterase activities in two inbred strains of rabbits with high or low response of plasma cholesterol to dietary cholesterol

• 1.1. Cholesterol feeding for 4 weeks of female and male rabbits of two inbred strains increased plasma cholesterol concentrations by about 11 and 48 mmole/I in the hypo- and hyperresponsive strain, respectively.
• 2.2. On the low-cholesterol pre-experimental diet, the hyporesponsive animals had significantly higher plasma HDL (high density protein) cholesterol levels than hyperresponders.
• 3.3. In both strains, cholesterol feeding caused elevations of cholesterol in all lipoprotein classes, the difference between the hypo- and hyperresponsive strains in essence only being observed in the VLDL (very low density lipoprotein) fraction.
• 4.4. Basal plasma total arylesterase activity was significantly higher in the hypo- than in the hyperresponsive rabbits.
• 5.5. Dietary cholesterol caused an increase in plasma esterase activity in both strains.
• 6.6. We suggest that in rabbits a low plasma arylesterase activity and a low concentration of HDL cholesterol are associated with an increased sensitivity to dietary cholesterol.

     

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.

     

In vivo effect of Berenil on rat liver polyamine metabolism

• 1.1. Berenil, administered to rats in vivo, promoted a decrease in liver SAMDC activity, but an increase in ODC and SAT activity.
• 2.2. Its effect on ODC was completely prevented by cycloheximide, that on SAT only partially.
• 3.3. Berenil had no effect on ODC activity in adrenalectomized rats. Adrenergic antagonists counteracted the effect of Berenil on ODC activity.
• 4.4. Polyamine content was increased. The maximum modification was observed for putrescine and N¹-acetylspermidine.

     

Glucosyl and galactosyl transferase activities of diabetic (db/db) and obese (ob/ob) mice kidneys

• 1.1. Glucosyl and galactosyl activities were determined in kidney cortex tissue prepared from two strains of mice, genetically diabetic and obese mice.
• 2.2. These activities were measured as a function of ageing between 6 weeks and 13 months.
• 3.3. For both strains glucosyl transferase activity was shown to increase with respect to ageing whereas galactosyl transferase activity decreased at the same time.
• 4.4. These changes of enzymatic activities would suggest that a smaller increase of hydroxylysine-linked glycans than expected was observed under these pathological conditions.