Effects of high dietary methionine on activities of selected enzymes in the liver of kittens (felis domesticus)

• 1.1. Growing male kittens were fed an 18% casein diet supplemented with 2, 3, or 4% l-methionine (MET) for 6 weeks.
• 2.2. Free MET concentration in liver increased 30-fold and cystathionine two- to three-fold; the activity of adenosyl-MET transferase and cystathionase also increased but remained lower than previously found in rats.
• 3.3. Taurine concentration in liver decreased in cats fed excess MET and appeared to depend on taurine intake.
• 4.4. Alanine aminotransferase activity was high in all groups while serine dehydratase activity was very low.
• 5.5. Pyruvate kinase and malic enzyme activities which are normally low in cat liver increased after excess MET. Also, glucose 6-phosphate and 6-phosphogluconate dehydrogenases increased.
• 6.6. Cat liver metabolism showed limited adaptation to an excess dietary intake of methionine compared to that found in rats.

     

Activity and electrophoretic profiles of brain aldehyde dehydrogenases in mice genetically selected for their ethanol preference

The activities and electrophoretic profiles of NAD⁺-aldehyde dehydrogenases (EC 1.2.1.3, ALDHs) in the different brain regions from the mice of inbred C57BL 6J strain (alcohol preferring) and DBA/2 sirain (alcohol avoicling) were studied.

• 1.1. Kinetic studies on ALDH of the different brain regions revealed the existence of at least two ALDHs in both strains.
• 2.2. The ALDH activity in the cerebellum, which was measured spectrophotometrically with 0.1 and 5mM acetaldehyde as the substrates, was the highest of the three regions and it was about 2-fold higher than that in the cortex in both strains.
• 3.3. The ALDH activities of mice of DBA/2 strain were higher than those ol mice of C57BL/6J strain in all the regions. Only in the cortex the F₁ hybrids (intermediate alcohol preferring) between C57BL/6J and DBA/2 strains had intermediate ALDH activity between their parental strains.
• 4.4. Electrophoretic analysis of cortex ALDH revealed that strain differences were observed in the isozyme pattern between pH 7.2 and 7.8 with cither acetaldehyde or propionaldehyde as substrate. These findings suggest that the ALDH activity in the cerebral cortex could be related to alcohol preference.

     

Gender-related differences of mouse liver d-aspartate oxidase in the activity and response to administration of d-aspartate and peroxisome proliferators

• 1.1. The hepatic d-aspartate oxidase activity was found to be higher in female ddY and ICR mice than in their male counterparts. On the contrary, the free d-aspartate content in the liver was lower in female mice than in male mice, suggesting that d-aspartate is actually metabolized by d-aspartate oxidase in vivo.
• 2.2. Oral administration of d-aspartate to the animals increased the hepatic d-aspartate oxidase activity 2–3 fold in both genders without any significant difference in the rate of the increase between the genders.
• 3.3. Several peroxisomal enzyme activities other than d-aspartate oxidase examined were not affected by this treatment.
• 4.4. Experiments in vitro suggested that the increase in the d-aspartate activity might be explained in part by stabilization of the enzyme by d-aspartate.
• 5.5. The administration of clofibrate, a peroxisome proliferator, to male mice, increased the hepatic d-aspartate oxidase activity with a significant simultaneous decrease of d-aspartate content in the liver, in agreement with a possible role of the enzyme n vivo.
• 6.6. On the other hand, the administration of clofibrate or dehydroepiandrosterone to female mice decreased the d-aspartate oxidase activity.
• 7.7. The peroxisome proliferators were suggested to act to eliminate the gender difference of hepatic d-aspartate oxidase activity in mice.

     

Plasma lipid transport in the horse (Equus caballus)

• 1.1. Equine plasma contains lipoproteins corresponding to very low density (VLDL), low density (LDL) and high density lipoproteins (HDL).
• 2.2. HDL accounts for approximately 60% of plasma lipoprotein mass and consists of a single population of particles.
• 3.3. LDL is heterogeneous comprising three discrete subfractions.
• 4.4. Two proteins are found in the region of apolipoprotein (apo) B-100 in VLDL and LDL and a third similar to apo B-48 is in VLDL.
• 5.5. Lecithin:cholesterol acyl transferase is active in plasma and hepatic lipase and lipoprotein lipase are evident in post-heparin plasma.
• 6.6. There is no significant cholesteryl ester transfer protein activity.

     

Temperature acclimation in respiratory and cytochrome c oxidase activity in common carp (Cyprinus carpio)

• 1.1. Common carp (Cyprinus carpio) exposed to experimental temperatures of 12, 18, 24, 30 or 36°C for a 4-week period were used to investigate the effect of temperature acclimation on the frequency of opercular movement (FOM), growth and cytochrome c oxidase (CCO) activity in heart, liver and muscle.
• 2.2. An exponential relationship between FOM and temperature after the first week (10₁₀ =1.76) disappeared after the second week.
• 3.3. The initially high FOM at temperatures of 30 or 36°C and the low FOM at 18 or 12°C changed over 4 weeks to approach the FOM of fish at 24°C.
• 4.4. This change in the relationship of FOM to temperature from highly dependent to independent appeared to be thermal compensation.
• 5.5. Heart and liver CCO activities were significantly affected by temperature, with the lowest activity at the approximate optimum temperature for growth, 24°C.
• 6.6. Highest CCO activities for heart and liver occurred at both the highest and lowest temperatures.
• 7.7. Among the three tissues, heart CCO activity was generally the highest and most affected by acclimation temperature.
• 8.8. Muscle tissue had the lowest CCO activity and was unaffected by temperature.
• 9.9. The high CCO activity at a cold acclimation of temperature 12°C was probably due to thermal compensation and the high activity at 36°C may have been a result of thermal stress.

     

Xenobiotic metabolizing enzymes in rainbow trout exposed to river water

• 1.1. Juvenile rainbow trout were exposed to river water in a flow-through system. After 15 days of exposure, hepatic biotransformation activities and related parameters were measured and compared to those of the control group organisms that were maintained in tap water under identical experimental conditions.
• 2.2. Liver somatic index (LSI), microsomal protein and cytochrome P-450 contents, benzo[a]pyrene hydroxylase (AHH), ethoxyresorufin-O-deethylase (EROD) and UDP glucuronyl transferase activities were not significantly affected.
• 3.3. Aminopyrine-N-demethylase (APD) activity showed a slight yet significant increase in exposed trout.

     

A comparison of aspartate transcarbamylase activity in juvenile pacific oysters (Crassostrea gigas) when fed various diets

• 1.1. The optimum pH for measurement of aspartate transcarbamylase activity in oyster tissue was determined to be 9.35 while the optimum temperature was 39.5°C.
• 2.2. Aspartate transcarbamylase activity varied significantly over short periods of time (hr) possibly due to fluctuations in the amount of food digested.
• 3.3. The composition of the oyster's diet also affected the levels of aspartate transcarbamylase activity in oyster tissues.
• 4.4. Those oysters fed an egg yolk-starch diet contained significantly lower aspartate transcarbamylase activity than oysters fed an egg yolk-starch-salmon oil diet or a casein-starch-salmon oil diet.
• 5.5. The aspartate transcarbamylase activities in oysters fed Phacedactylum tricornutum or a starch diet were not significantly different from the activities in oysters fed the egg yolk-starch diet.

     

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.

     

Mixed function oxidase activity in the harbour seal (Phoca vitulina) from sable is., N.S.

• 1.1. One adult male, eight pups (including two full term foetuses) and nine adult female harbour seals (Phoca vitulina) were analysed for indices of mixed function oxidase (MFO) activity.
• 2.2. MFO activity was present in liver samples, but was at or below detection limits in samples of kidney, lung and pancreas.
• 3.3. Hepatic ethoxyresorufin O-de-ethylase and benzo[a]pyrene hydroxylase activities were similar to those reported in other seals and in other mammals.
• 4.4. Cytochromes P-450 and b₅ concentrations were slightly lower than those observed in other mammals.
• 5.5. MFO activities in newborn pups and foetuses were significantly lower than those in adult females.
• 6.6. No qualitative differences in cytochrome P-450 isozyme distribution between foetal and adult samples could be discerned by electrophoresis.

     

Differential vitamin and choline requirements of symbiotic and aposymbiotic s. oryzae (coleoptera: curculionidae)

• 1.1. Development times, fertilities and weights of symbiotic and aposymbiotic strains of the rice weevil Sitophilus oryzae in response to single omissions of seven vitamins and choline were studied.
• 2.2. No strict requirement for choline could be demonstrated: development times and weights were comparable to diets with or without choline, but the presence of choline increased fertility of the symbiotic strain on vitamin-deficient diets.
• 3.3. The 0.02% concentration used in these experiments may be too high since it resulted in a lower fertility of the aposymbiotic strain.
• 4.4. The results indicated that niacin could be synthesized by the weevils.
• 5.5. Thiamine, folic acid and pyridoxine were found to be required in the diet of both strains but the latter two may be supplied in part by symbiotes since a first symbiotic generation was obtained.
• 6.6. Pantothenic acid, biotin and riboflavin were only required by aposymbiotic weevils: their omission from the diet did not modify the development of symbiotic insects.
• 7.7. It is therefore suggested that these three vitamins are supplied by symbiotes.

     

The haemocytes and the activities of leucine aminopeptidase and alkaline phosphatase during development of Ceratitis capitata: Specific secretion of a leucine aminopeptidase isozyme

• 1.1. The types of haemocytes during larval development were studied.
• 2.2. The developmental profile of leucine aminopeptidase and alkaline phosphatase was studied. The maximum LAP activity was found to be in early larval development, while the maximum alkaline phosphatase during the white pupal stage.
• 3.3. These activities were compared with those determined in cell-free haemolymph.
• 4.4. Both hydrolytic enzymes have been found histochemically in the prohaemocytes and in the plasmatocytes.
• 5.5. In cultured haemocytes experiments it was found that 64% of the total LAP activity was secreted into the incubation medium, while electrophoretic analysis of released LAP activity demonstrated that only LAP A isozyme was secreted.
• 6.6. Based on the above results we suggest that both hydrolytic enzymes are functionally important throughout larval development.

     

Ontogeny of type I and type III deiodinase activities in embryonic and posthatch chicks: Relationship with changes in plasma triiodothyronine and growth hormone levels

• 1.1. The ontogeny of type I and type III deiodinase activities was studied in embryonic and posthatch chicks.
• 2.2. Hepatic type I activity showed a 3-fold increase up to the period of pipping and hatching and decreased slowly thereafter.
• 3.3. Hepatic type III activity increased by 3-fold from E14 to E17 and decreased more than 10-fold from E17 to CO. Posthatch levels were very low.
• 4.4. Type I activity in the kidney decreased slowly after hatching while type III activity was very low over the whole period studied.
• 5.5. Developmental changes during the late embryonic period suggest a causal relationship between the increase in plasma GH and T₃ levels and the decrease in hepatic type III activity.

     

Na+-K+ ATPase and carbonic anhydrase activities in larvae,postlarvae and adults of the shrimp Penaeus japonicus (Decapoda,Penaeidea)

• 1.1. Activities of Na⁺-K⁺ ATPase and carbonic anhydrase were measured through the early post-embryonic development of Penaeusjaponicus. In adults, only the Na⁺-K⁺ ATPase activity was measured.
• 2.2. ATPase activity was variable in the successive development stages. From zero in nauplii, the activity slightly increased in zoeae, and rose sharply in mysis stages 2 and 3.
• 3.3. A further significant increase in activity was noted at the transition from late mysis to early postlarvae, concomitant with a change from the larval osmoconforming pattern of osmoregulation to the postlarval and adult hyper-hyporegulating pattern.
• 4.4. The activity of Na⁺-K⁺ ATPase, measured in isolated cephalothorax, increased from PL3 to PL4 to its maximum value in PL5; at this stage, osmoregulatory capacity was fully efficient.
• 5.5. In young stages of P. japonicus, the variations in Na⁺-K⁺ ATPase activity appear correlated with the development of osmoregulatory ultrastructures, and with osmoregulation and salinity tolerance.
• 6.6. These results are discussed with regard to their ecological and physiological implications.
• 7.7. In adults, the activity of Na⁺-K⁺ ATPase was high in gills and epipodites and no activity was detected in branchiostegites. These results are related to the ultrastructure of these organs.
• 8.8. The activity of carbonic anhydrase did not change significantly in larval and postlarval stages.
• 9.9. From these results, it is proposed that the effector sites of osmoregulation are located in branchiostegites, pleurae and epipodites in postlarvae, and in epipodites and mainly in gills in adults.

     

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.

     

Distribution of serine esterase activity in the lymphoid system of C57bl/6 mice,effect of aging on the enzymatic activity

• 1.1. The activity of serine esterase (SE) was investigated in the lymphoid system of C57BL/6 mice. SE activity increased in the lymphoid tissues with their content of mature T-lymphocytes, except that high levels were also observed in various populations of bone marrow cells.
• 2.2. The maturation of T-lymphocytes in the thymus was accompanied by an increase in their SE activity.
• 3.3. Experiments on the influence of age on SE activity showed that while thymocytes were not affected, a three-fold increase in activity occurs in spleen lymphocytes between the ages of 26 and 78 wk.

     

Main serum protein of rainbow trout (Salmo gairdnerii): its biological properties and significance

• 1.1. Main serum α₁-protein (α₁P) of rainbow trout was purified and its biochemical and physico-pathological properties were studied.
• 2.2. α₁P was suggested to be a primitive protein having both properties of albumin and AFP in serum proteins of mammals according to the following results.
• 3.3. Molecular weight (75,000), two kinds of molecules (pI 4.55 and 5.05) and amino acid composition.
• 4.4. Dye- or ConA binding activity.
• 5.5. Estrogen binding activity and inhibitory effect on lymphoblastoid-forming activity.
• 6.6. Possible osmotic regulator.
• 7.7. Significant elevation of blood α₁P level in the course of hepatoma induction.

     

Correlation of acid phosphatase but not alkaline phosphatase activity with myelination in the developing mouse brain

• 1.1. Neonatal mice received subcutaneous injections of buffer, thiourea (TU) or propylthiouracil (PTU).
• 2.2. The PTU-treated mice were sacrificed on postnatal day 14 (P14) and the TU-treated mice on P28.
• 3.3. Brain weights of the TU- and PTU-treated mice were not significantly different from the controls.
• 4.4. Acid but not alkaline phosphatase activity in the braistem decreased after TU and PTU treatment.
• 5.5. Myelination as indicated by intensity of luxol fast blue staining was weaker in drug-treated animals.
• 6.6. The level of myelin marker enzyme, 2′,3′-cyclic nucleotide 3′-phosphohydrolase, was lower in the brainstem of PTU-treated animals.
• 7.7. The results suggest a correlation between acid phosphatase but not alkaline phosphatase activity with myelination in the developing mouse brain.

     

Protein tyrosine kinase activity in cultured vascular smooth muscle cells (VSMC) from rat aorta

• 1.1. Protein tyrosine kinase (PTK) activities were detected in both cytosolic and particulate fractions of cultured vascular smooth muscle cells by using poly (Glu: Tyr; 4:1) as an exogenous substrate.
• 2.2. The percent distribution of the enzyme activity between these two fractions was 70 and 30 respectively.
• 3.3. The particulate and not the cytosolic enzyme activity was stimulated by about 4-fold in the presence of non-ionic detergent, Triton X-100 (0.5% v/v).
• 4.4. The PTK activity in both the fractions was absolutely dependent on the presence of divalent cations such as Mg²⁺ and Mn²⁺ which were equipotent in the activation of the enzyme.These data indicate that PTK activity is expressed in cultured VSMC and provide a basis for further studies to examine a possible role of PTKs in growth and proliferation of VSMC.

     

Improved isolation and further characterization of beta-trichosanthin,a ribosome-inactivating and abortifacient protein from tubers of trichosanthes cucumeroides (cucurbitaceae)

• 1.1. Beta-trichosanthin was isolated from root tubers of Trichosanthes cucumeroides with a procedure involving acetone fractionation, ion exchange chromatography on CM-Sepharose and DEAE-Sepharose and gel filtration on Sephadex G-50.
• 2.2. The protein was homogeneous by SDS-polyacrylamide gel electrophoresis, polyacrylamide gel electrophoresis, immunodiffusion and immunoelectrophoresis. It possessed a molecular weight of 28,000 and was a strongly basic glycoprotein.
• 3.3. It was immunochemically identical to trichosanthin but different from alpha- and beta-momorcharins.
• 4.4. It possessed potent abortifacient and ribosome-inactivating activities. In the latter type of activity it was more potent than trichosanthin.