Serum lipids,thyroxine and catecholamine levels in the reindeer with reference to the annual climatic cycle

• 1.1. Blood glucose and lactate, serum total lipid and triglyceride, thyroxine (T₄), epinephrine and norepinephrine concentrations and serum dopamine-β-hydroxylase activity were studied in 76 reindeer hinds and 127 calves with reference to the seasons.
• 2.2. Blood glucose level tended to be lowest in Autumn, and blood lactate highest in Summer.
• 3.3. Serum total lipids were smallest in Spring (2.8 g/l) and greatest in Autumn (5.3 g/l). Triglycerides were smallest in Winter (0.18 mmol/l) and highest in Autumn (0.32 mmol/l). In calves the total lipids increased during the neonatal period.
• 4.4. Serum epinephrine correlated with the weight, age, blood glucose and total lipids of the animals. In adult animals the lowest serum epinephrine level was found in Spring and the highest in Autumn (55 vs 190 ng/ml).
• 5.5. Serum norepinephrine concentration and dopamine-β-hydroxylase activity were highest in Spring and decreased towards Autumn. Parturition affected these parameters significantly.
• 6.6. The preponderance of high levels of some blood constituents in Autumn may be attributable to the replenishment of energy supplies for Winter time and also to the rutting season.
• 7.7. T₄ was smallest in Spring and highest in Summer. It was slightly greater in Winter than in Autumn. This suggests that the metabolic rate is tower in Winter than in Summer. Thus, the adaptation of the reindeer to a cold climate mainly utilizes insulation.

     

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.

     

Correlation of water translocation,cuticle dehydration and post-ecdysial sclerotization by the american cockroach

• 1.1. Haemolymph volume decreases during the initial 16 hr post-ecdysial period, increases after water ingestion and subsequently drops until the inter-ecdysial level is reached.
• 2.2. Total body water follows a similar pattern, but the changes are not as pronounced.
• 3.3. Tissue water is inversely proportional to the total body water.
• 4.4. Soluble cuticle protein declines throughout the initial 16 hr period while both β-glucosidase and alkaline phosphatase activity is lost within 6 hr after ecdysis.
• 5.5. Dehydration of the cuticle also occurs during the immediate 6 hr post-ecdysial period.
• 6.6. These data suggest that the formation of the protein-insoluble matrix is linked with water loss.
• 7.7. Water removal may decrease the distance between molecules allowing specific reactions to take place.

     

Hormonal regulation of human apolipoprotein E gene expression in HepG2 cells

• 1.1. Hormonal regulation of apolipoprotein E (apoE) gene expression by insulin and thyroid hormone was studied in a human hepatoma cell line, HepG2.
• 2.2. Changes at the mRNA level, mRNA translation, in vivo synthesis and secretion were monitored.
• 3.3. Both insulin and triiodothyronine were found to have no significant effect on apoE mRNA levels.
• 4.4. Insulin treatment caused an inhibition of: (a) the in vitro translation of endogenous apoE mRNA in a HepG2 cell-free system (25%), and (b) the incorporation of radioactivity into newly-synthesized apoE in an in vivo pulse-chase labeling experiment (32%).
• 5.5. Interestingly, apoE secretion rate was found to be significantly reduced with insulin (84%) suggesting that a major portion of newly-synthesized apoE may be shunted into a degradative pathway.
• 6.6. Using a similar experimental approach, triiodothyronine showed no significant effect on the rate of apoE synthesis or translation (6–15% decrease), however a slight reduction (20%) in secretion rate was shown.
• 7.7. Overall, apoE gene expression does not appear to be influenced by triiodothyronine significantly but is modulated by insulin at the translational and post-translational level.

     

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Effects of lysine administration on plasma arginine and on some nitrogenous catabolites in rainbow trout

• 1.1. Rainbow trout were fed either graded levels of lysine (0.8, 1.8 and 3%) at a constant level of arginine (1.4%) or excess arginine (2.4%) at a fixed level of lysine (1.8%).
• 2.2. Increasing the dietary lysine level affected plasma urea, plasma arginine and ammonia excretion.
• 3.3. Trout fed graded levels of lysine received an arginine challenge (U¹⁴C-l-arginine) and it was found that excess dietary lysine led to a decrease in arginine degradation.
• 4.4. Injection of l-lysine induced a decrease in urea excretion, while injection of l-arginine increased both urea and ammonia excretion in control well-fed trout.
• 5.5. These results are discussed in the light of current knowledge on the antagonism between lysine and arginine.

     

Effects of niacin deficiency on the relative turnover rates of proteins in various tissues of Japanese quail

• 1.1. The effects of niacin deficiency on the relative turnover rates of proteins in various tissues of Japanese quail were investigated.
• 2.2. The level of liver NAD was not affected by niacin deficiency whereas the level of pectoral muscle NAD was markedly reduced.
• 3.3. In all dietary treatments the liver had the highest turnover rates of proteins, heart and brain had intermediate rates, and pectoral muscle had the lowest rates.
• 4.4. Relative turnover rates of proteins in all tissues (particularly pectoral muscle) of the niacin deficient group were significantly higher than those of pair-fed control group, although there were no significant differences in turnover rate between pair-fed control and control groups.
• 5.5. The high turnover rate of proteins in niacin deficiency was primarily attributed to enhanced degradation rate of proteins rather than enhanced synthesis rate of proteins.
• 6.6. Optical density scanning (or densitometric) of water-soluble pectoral muscle proteins separated by isoelectric focusing revealed several additional minor protein bands between major protein bands in the niacin deficient group which were more pronounced in the acidic region of the gel.
• 7.7. These results suggest that proteins with a low pI value in pectoral muscle of the niacin deficient animal are highly sensitive to protein degradation.

     

Changes in serum immunoglobulin M (IgM) concentrations during early development of chum salmon (Oncorhynchus keta) as determined by sensitive elisa technique

• 1.1. A specific and sensitive sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the measurement of low levels of serum immunoglobulin M (IgM) of chum salmon Oncorhynchus keta.
• 2.2. In this assay, 5 μl serum was enough to measure the concentration of IgM and the minimum detectable concentration of serum IgM was about 5 ng/ml.
• 3.3. Coefficients of variation within and between assays ranged from 2.90 to 9.61%.
• 4.4. IgM concentrations remained at low level (< 300 ng/ml) until 40 days after hatching and then increased rapidly at the period of emergence (48 days after hatching).

     

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.

     

Seasonal variation of LH and testosterone in the smallest deer,the pudu (Pudu puda molina) and its relationship to the antler cycle

• 1.1. In order to obtain a seasonal profile of LH, three adult male pudu (Pudu puda, Molina) were sampled monthly from the saphenous vein for a period of one year.
• 2.2. A significant circannual variation of plasma LH levels was detected with an average peak value (1.77 ng/ml) recorded in February and nadir concentrations (0.19 ng/ml) observed in November.
• 3.3. The peak level of testosterone (1.54 ng/ml) was detected in March, the time of the rut.

     

Rates of heat exchange in the ornate box turtle,Terrapene ornata

• 1.1. Eight ornate box turtles, Terrapene ornata, were heated and cooled in water at 35 and 15°C respectively.
• 2.2. Thermal time constants were calculated and no significant differences were found (t-test; 0.05 level) between warming and cooling rates.
• 3.3. Heart-rate data indicated slightly higher, but non-significant, mean values during warming.
• 4.4. It was concluded that T. ornata is not able to physiologically alter rates of heat exchange in water significantly and must rely on behavioral mechanisms to maintain body temperature.

     

Changes in the activities of lysosomal enzymes in the fat body and midgut of two lepidopteran insects (Mamestra brassicae and Pieris brassicae) during metamorphosis

• 1.1. The activities of three lysosomal enzymes (acid phosphatase, β-galactosidase, catepsin D) was observed during metamorphosis in the fat body and midgut cells of two insects (Mamestra brassicae and Pieris brassicae).
• 2.2. The activities increased slightly during the feeding period and showed a sharp rise at the beginning of the wandering period.
• 3.3. Subsequently, a decrease was observed during the pre-pupal stage and pupation.
• 4.4. The activities increased again 2 days after the larval-pupal moult.
• 5.5. We suggest that an inhibitory mechanism works in the studied cells before pupation to protect the stored proteins from the degradation until the beginning of differentiation of imaginai cells in the pupal stage.

     

Kinetics and stoichiometry of cysteinyldopa formation in the first steps of melanogenesis

• 1.1. Spectra of products obtained during dopa oxidation by mushroom tyrosinase in presence of cysteine or glutathione were recorded for the first minutes of the enzymatic reaction.
• 2.2. Two isosbestic points were defined, indicating the existence of a constant ratio between the disappearance of dopa and the formation of cysteinyl- or glutathione-dopa.
• 3.3. Matrix analysis of these spectra verified that there were two kinetically related absorbing species in solution, these being dopa and either cysteinyldopa or glutathione-dopa.
• 4.4. This stoichiometry (1:1) was confirmed by measuring the lag period in dopachrome accumulation, arising from the presence of thiol.
• 5.5. A kinetic approach has been proposed for the first steps, considered common, in the eumelanin and phaeomelanin biosynthesis pathway, thereby allowing us to establish a quantitative relation between the lag period and thiol concentration.
• 6.6. This relation can be used as a simple kinetic method for thiol evaluation.

     

Selective modification of tryptophan-150 in ovine placental lactogen

• 1.1. Ovine placental lactogen was modified by reaction with o-nitrophenylsulfenyl chloride. Fluorescence measurements indicated that one of the two tryptophan residues of the molecule had reacted. Besides, there was some reagent not covalently bound.
• 2.2. The reagent was covalently bound to Trp-150. No evidence of modification of Trp-90 was found.
• 3.3. Binding capacity to lactogenic as well as somatogenic receptors was diminished but not abolished upon modification, indicating that absolute molecular integrity of Trp-150 is not required for binding.
• 4.4. This behavior is similar to that of the tryptophan residues of ovine prolactin.

     

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.

     

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Long-term starvation in Xenopus laevis daudin—III. Effects on enzymes in several tissues

• 1.1. Adult, female Xenopus laevis were subjected to 12 months of starvation.
• 2.2. Starvation resulted in a continuous reduction in the activity of both hepatic and renal glucose-6-phosphate dehydroganse.
• 3.3. Fructose-1,6-diphosphatase was significantly reduced at months 10 and 12 in the liver, and at months 4, 10, and 12 in the kidney.
• 4.4. Pyruvate kinase activity of muscle and liver decreased during the experimental period whereas the renal enzyme remained essentially unchanged.
• 5.5. Both hepatic and renal glutamate-pyruvate transaminase (GPT) and hepatic glutamate-oxaloacetate transaminase (GOT) showed a reduction of activity after 2 and 4 months of starvation followed by an increase in GPT but not in GOT.

     

The effects of artificial solar radiation on wind-stressed tufted titmice (Parus bicolor) and Carolina chickadees (Parus carolinensis) at low temperatures

• 1.1. Changes in metabolic rates and behavior were observed in tufted titmice (Parus bicolor) and Carolina chickadees (Parus carolinensis) exposed to varying conditions of artificial solar radiation, wind, and temperature in a wind tunnel experiment.
• 2.2. During the wind-on condition, both species showed a significant decrease in mean metabolic rates in the high radiation treatments when compared to the low radiation treatments (P < 0.05).
• 3.3. Titmouse orientation, posture and level of activity were significantly affected by radiation and wind conditions.
• 4.4. Metabolic rates observed in the wind tunnel treatments without wind and at low radiation did not significantly differ from similar standard metabolic (black box) treatments (P > 0.05).
• 5.5. Activity levels did not appear to directly affect metabolic rates observed in the wind tunnel treatments.

     

Relative bioavailability and DNA adduct formation of benzo[a]pyrene and metabolites in the diet of the winter flounder

• 1.1. Radiolabeled metabolites of the carcinogenic polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP) were shown to be absorbed through the diet of the winter flounder, Pseudo pleuronectes americanus.
• 2.2. Oral bioavailability of a mixture of naturally produced metabolites was significantly less than that of the parent BaP.
• 3.3. Oral bioavailability of a pure metabolite, BaP-7,8-dihydrodiol (7,8-D) was found to be similar to that of BaP.
• 4.4. Both metabolites and BaP formed DNA adducts in liver.

     

Increased muscle glucose uptake in response to chronic glyburide treatment is not related to changes in glucose transporter (GLUT4) protein

• 1.1. The mechanism of action of glyburide (a sulfonylurea) on muscle has been investigated by measuring glucose uptake and glucose transporter (GLUT4) protein levels after chronic glyburide treatment.
• 2.2. A dietary induced insulin resistant rat model (4 wk of high-fat, high-sucrose feeding) was given glyburide (2mg/kg/day) for 10 days and glucose uptake was measured in a perfused hindquarter preparation.
• 3.3. Protein levels of the GLUT4 glucose transporter were determined by Western analysis.
• 4.4. After 7 days of treatment, rats fed glyburide had lower blood glucose concentrations 2 hr (72 ± 5 vs 103 ± 12 mg/dl) and 24 hr (97 ± 7 vs 123 ± 7 mg/dl) after glyburide administration with no difference in serum insulin levels compared to vehicle treated animals.
• 5.5. Glucose uptake was approx doubled in basal state (0 insulin) in response to glyburide (2.8 + 0.4 vs 1.7 ± 0.2μ mol/g per hr).
• 6.6. Maximal insulin (100 nM) stimulated glucose uptake tended to be higher in the glyburide treated group, but did not reach statistical significance (8.0 ± 0.7 vs 7.0 ± 0.6 μmol/g per hr).
• 7.7. Western analysis revealed no significant effect of glyburide on the GLUT4 protein level in skeletal muscle.
• 8.8. These results suggest that glyburide alters glucose uptake through some mechanism other than alterations in the level of the GLUT4 glucose transporter protein.