Amino acid accumulation in kidney cortex of lambs and piglets as affected by insulin

• 1.1. Insulin stimulated intracellular accumulation of α-amino-isobutyric acid (AIB) in kidney cortex slices from young lambs and piglets.
• 2.2. The effect was similar in the absence or presence of glucose.
• 3.3. The induction of the stimulatory effect on renal AIB transport was blocked by cycloheximide. an inhibitor of protein synthesis.
• 4.4. The insulin stimulation of intracellular AIB accumulation is due to an increased influx and not to a reduced efflux of AIB.
• 5.5. Analysis of transport kinetics for AIB showed that insulin increased V_max but did not change K_m.
• 6.6. It is concluded that insulin stimulates uptake of certain neutral amino acids into kidney cortex cells in young animals.
• 7.7. The effect on renal amino acid transport appears to be mediated through increased synthesis of a membrane carrier.

     

Contrast in adenine uptake by chicken and rabbit erythrocytes in vitro

• 1.1. Relative to rabbit erythrocytes, chicken red blood cells exhibit a much greater capacity to utilize [³H]adenine for nucleotide synthesis in vitro, even at 5°C and in the absence of added inorganic phosphate.
• 2.2. This difference is largely due to a higher concentration of phosphoribosylpyrophosphate and greater activity of adenine phosphoribosyltransferase in the avian cells. lli]3. The capacity of avian erythrocytes for utilization of guanine and hypoxanthine is several fold less than that of adenine.
• 3.4. The data are consistent with lower activity for hypoxanthine/guanine phosphoribosyltransferase than for adenine phosphoribosyltransferase in intact chicken erythrocytes.
• 4.5. The results indicate that reutilization of adenine by chicken erythrocytes may be physiologically significant.

     

Seasonal variation in the metabolic rates and Q10-values of the fingernail clam,Sphaerium striatinum lamarck

• 1.1. Metabolic rates were highest during periods of maximum reproduction.
• 2.2. The exponent of the metabolic rate-weight equation varied seasonally, rates of metabolism of small animals exhibited greater annual fluctuations than those of large animals.
• 3.3. Absolute and weight-specific Q₁₀s (determined at 5–10°C above field temperatures) for smaller clams were greatest in the winter; absolute values of Q₁₀ were highest for larger individuals in the summer.
• 4.4. Small clams had Q₁₀ < 1.0 in the summer; Q₁₀-values for larger clams were near 1.0 at this time.
• 5.5. 38.9% of the total energy assimilated by the population annually was allocated to metabolism, which is near the low end of the range of values reported for freshwater molluscs, suggesting that this species can partition a large amount of energy to growth and reproduction.

     

Epidermal polyamine levels related to cell cycle events during the metamorphosis of Tenebrio molitor L. (insecta,coleoptera): Effect of juvenoid application

• 1.1. Three polyamines were separated by reverse-phase HPLC and detected by fluorescence in Tenebrio epidermis: putrescine, spermidine and spermine.
• 2.2. The levels of these compounds varied during metamorphosis: one peak was observed during the G₂-arrest preceding the pupal-adult mitotic crisis and a second occurred when cells were again G₂-arrested after the mitotic period.
• 3.3. A juvenile hormone analogue, which inhibits the G₂-M transition preparing cells to the adult mitoses, was unable to prevent the first polyamine increase suggesting that juvenile hormone does not act on further development via inhibition of polyamine synthesis.

     

The role of citrate derived from glucose in the acetylcholine synthesis in rat brain synaptosomes

• 1.1. Synaptosomes utilizing glucose or glucose plus malate produced citrate with rates of 2.4 and 7.8 nmol/hr/mg of protein, respectively.
• 2.2. (−)Hydroxycitrate increased citrate net synthesis 4 times and inhibited acetylcholine synthesis by 40%.
• 3.3. Oxygen and glucose consumption as well as lactate and CO₂ production were not changed by this inhibitor.
• 4.4. (−)Hydroxycitrate inhibited utilization of exogenous citrate in synaptosomes by 50%.

     

Myo-inositol transport in the small intestine of the domestic fowl

• 1.1. Myo-inositol is transported in chicken small intestine by a mediated route with an apparent K_m of 0.1 mM and by a diffusion mechanism.
• 2.2. The mediated route is susceptible to inhibition by sugars, though sugars are not transported by this process, nor is myo-inositol transported by the sugar transport system.
• 3.3. Myo-inositol influx is inhibitable by phlorizin, sulfhydryl reagents, removal of Na⁺ from the incubation medium, and preloaded sugar; it can be stimulated by theophylline.
• 4.4. The ability to absorb this nutrient varies greatly between individual animals.

     

Effect of starvation and experimental feeding on the proximate composition and caloric content of an antarctic teleost,Notothenia coriiceps neglecta

• 1.1. Starving Notothenia coriiceps nn/lecta at 1°C for 20 days resulted in a loss of 4.22 gcal/kcal per day.
• 2.2. During starvation energy was obtained from lipid and carbohydrate stores of the liver and red muscle.
• 3.3. Feeding N. coriiceps neglecta low lipid, high protein shrimp meat at 18.9 gcal/kcal per day at 1°C for 20 days resulted in a gain of 8.5 gcal/kcal per day.
• 4.4. The level of carbohydrate in the liver and red muscle increased five times.
• 5.5. Gross growth efficiency (K₁) equalled 0.52.
• 6.6. Net growth efficiency (K₂) equalled 0.67.

     

Effects of recombinant salmon growth hormone on hypophysectomized male Fundulus heteroclitus

• 1.1. Recombinant salmon growth hormone at doses of 0.8 and 2.1 μg/g significantly enhanced linear growth in hypophysectomized male killifish, Fundulus heteroclitus, over that of controls and a significant regression was found between growth and the logarithm of dose.
• 2.2. Bovine growth hormone elicited significant growth enhancement at all three dosages tested (1,4 and 10 μg/g) and a significant log/dose relationship was also observed.
• 3.3. Observations on the relative weight of the gonads indicate that whole salmon pituitary extract (25 μg/g) possesses strong gonadotropic activity and that both bGH and rsGH had smaller but significant effects on the gonads.
• 4.4. It is suggested that growth hormone may play a subsidiary synergistic role to other pituitary hormones in gonadal development.

     

Temperature dependency of protein synthesis in toadfish liver in vivo

• 1.1. Elongation of polypeptide chains in toadfish liver in vivo shows two temperature dependencies: Q₁₀ = 2.5 (E_a = 16 kcal/mol) in 17–30°C range; Q₁₀ = 5 (E_a = 26 kcal/mol) in the 7–17dgC range.
• 2.2. Total protein synthesis measured by fractional leucine incorporation is proportional to elongation rate from 7 to 30°C. Synthesis is inhibited below 7°C.
• 3.3. The results suggest a relationship between protein turnover and overall metabolic rate in poikilotherms and provide a framework for evaluation of mechanisms of temperature acclimation and adaptation.

     

Content and synthesis of several abundant glycolytic enzymes in skeletal muscles of normal and dystrophic mice

• 1.1. In both 2- and 3-month-old 129 ReJ mice, the catalytic activity levels of three enzymes involved in glycogen breakdown (phosphorylase, enolase, and aldolase) were found to be 35–50% lower in hind limb muscles of dystrophic mice as compared with normal mice.
• 2.2. The reduced activities of these enzymes in the diseased tissue was directly due to corresponcling reductions in the number of enzyme molecules rather than being due to inactivation of the enzymes in the dystrophic muscle.
• 3.3. Results of short term double isotope incorporation experiments conducted with muscle expiants in vitro suggested that the rates of synthesis of these enzymes, and of most other abundant cytosolic proteins, relative to each other, were similar in hind limb muscles of normal and dystrophic mice.
• 4.4. The present work on murine muscular dystrophy is discussed in terms of our previous studies into the influence of avian muscular dystrophy on the content and synthesis of abundant glycolytic enzymes in chicken skeletal muscles.

     

Lipoxygenase of the thermophilic bacteria thermoactinomyces vulgaris—properties and study on the active site

• 1.1. A lipoxygenase activity was purified from Thermoactinomyces vulgaris and some of its properties were characterized.
• 2.2. The enzyme showed a temperature activity range of 40–55°C with still significant activity over 60°C.
• 3.3. The pH of activity on linoleic acid had a broad range with an optimum at pH 6.0 and a weaker one at pH 11.0.
• 4.4. On arachidonic acid the pattern was narrow bell-shaped with an optimum at pH 6.5.
• 5.5. The purified lipoxygenase from Th. vulgaris showed an apparent K_m of 1 mM and V_max of 0.84 μmol diene/min/mg protein.
• 6.6. It was inhibited by the oxidation products, 9-HPOD and 13-HPOD.
• 7.7. A 160,000 Da molecular weight of the enzyme was determined by molecular filtration. Methionine, tyrosine, tryptophan and cysteine are apparently involved in its activity.

     

The effects of extracellular-and intracellular-pH on transmitter mobilization and fractional release in Helix pomatia

• 1.1. Transmitter mobilization and fractional release were studied in Helix pomatia. The right palliai nerve was stimulated and a synaptic potential was recorded in cell F76 in the right parietal ganglion.
• 2.2. The extra- and intra-cellular pH were changed with Tris-maleate, CO₂ or (NH₄)₂SO₄.
• 3.3. The time constant for the monoexponential part of mobilization decreased with reduced intracellular pH. Only a fraction of this effect could be related to an increase in the intracellular Ca-activity.
• 4.4. Fractional release was reduced in low external pH, but was increased in low intracellular pH. Fractional release is affected more by changes in internal pH than external pH.

     

Isotopic labeling of taurine; implications for its synthesis in selected tissues of Homarus americanus

• 1.1. The abdominal muscle and ventral nerve chord of Homarus americanus were incubated with radioactive precursors.
• 2.2. ³⁵SO₄ and ¹⁴C-CO₂ were not incorporated into amino acids in the abdominal muscle.
• 3.3. ¹⁴C-glucose was incorporated into serine, cysteine, cysteine-sulfinic acid and taurine in the abdominal muscle.
• 4.4. ¹⁴C-CO₂ appeared to be slightly incorporated into taurine in the ventral nerve chord.
• 5.5. ¹⁴C-glucose incubation with the ventral nerve chord resulted in labeling of the same amino acids as in the abdominal muscle.
• 6.6. The results are discussed in view of the catabolism of carbohydrates and the synthesis of taurine.

     

Vitellogenin synthesis in female larvae of the gypsy moth,Lymantria dispar (L.): suppression by juvenile hormone

• 1.1. Fat body from feeding-phase, last instar gypsy moth females incorporates l-[³⁵S]methionine in vitro into two vitellogenins with the same molecular masses (165 and 180 kDa) as the apo-vitellogenins found in teh hemolymph and the apo-vitellins in teh eggs.
• 2.2. Both apo-vitellogenins are observed in the medium of fat body cultures, but only the 180 kDa apo-vitellogenin is observed in extracts of cultured tissue.
• 3.3. Synthesis and accumulation of the apo-vitellogenins are suppressed in a dose-dependent manner by topical treatment with the juvenile hormone analog, methoprene, prior to day 4.
• 4.4. This suppression suggests that a declining juvenile hormone titre is involved in the initiation of vitellogenin synthesis.

     

Strontium-calcium concentration ratios in fish otoliths as environmental indicators

• 1.1. External and internal examinations of otoliths in fishes for macrostructure and microstructure has demonstated yearly, daily and population rhythmic patterns.
• 2.2. Chemical analyses (atomic absorption) of otolith carbonate from reared Fundulus heteroclitus for strontium-calcium concentration ratios demonstrated changes in chemistry related to temperature.
• 3.3. Microprobe analyses made it feasible to interpret almost daily changes in temperature to provide the temperature history of an individual fish.
• 4.4. A combination of microprobe analyses and daily increment analyses of otoliths can provide a life history profile for individual fish and can provide information on the environmental history of each fish.
• 5.5. Such information is vital to our understanding of the processes underlying recruitment and growth rates, and would make it possible to link growth and mortality rates to environmental occurrences.

     

Ventilatory rate in the butterfish (Pholis gunnellus) as a consequence of temperature and previous emersion

• 1.1. Observation of ventilation in immersed Pholis gunnellus showed a linear relationship between ventilatory rate and temperature between 8 and 20°C.
• 2.2. At 13°C and after 30 min emersion, ventilatory rate was initially lower than prior to emersion, providing evidence of adequate uptake of O₂ for standard metabolism during the emersion period.
• 3.3. This species has a laterally elongate body form with reduced scales and extensive mucus secretion.
• 4.4. During emersion, gaping behaviour probably exposes the gills and extensively vascularised oesophageal regions to air.
• 5.5. These are considered to be morphological and behavioural adaptations by P. gunnellus, to aerial respiration in the intertidal habitats occupied by this species.

     

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.

     

Comparative studies of sodium transport and its relation to hydrostatic pressure in deep and shallow water gammarid crustaceans from Lake Baikal

• 1.1. Freshwater gammarids from 900–1400 m depths lose Na at 1 atm, 4°C, while related shallow water gammarids are near neutral Na balance.
• 2.2. Na⁺ influx rates are similar at 1 atm, 4°C, for abyssal and shallow water gammarids of similar weight.
• 3.3. Na⁺ efflux is faster for abyssal gammarids than for comparable shallow water gammarids.
• 4.4. Compressing abyssal gammarids to 90–140 atm increases Na⁺ influx rates enough to restore neutral Na balance, while in shallow water crustaceans, compression decreases Na⁺ influx.
• 5.5. Na⁺ influx rates in Baikalian gammarids vary with the 0.55 power of weight.
• 6.6. The equation F_{ma × t} = 1.3 × W^0.55 μEq/hr/animal applies to freshwater crustaceans over the weight range from 0.03 to 35 g.

     

Oxidation of methionine residues in equine growth hormone by chloramine-T

• 1.1. Reactivity of methionine residues towards Chloramine-T was studied in the equine growth hormone.
• 2.2. With a 20.0-fold molar excess of reagent over methionine, full oxidation of the four residues of the protein is achieved.
• 3.3. Methionine 4 is the most reactive group, followed by methionines 72 and 178—methionine 123 being the less reactive residue.
• 4.4. As judged by circular dichroism spectra and binding assays, protein conformation and binding capacity to specific receptors remains unchanged even after full oxidation of all four methionine residues.
• 5.5. Results agree with data previously obtained with bovine growth hormone.

     

Growth rates and body condition factors of Alligator mississippiensis in coastal Louisiana wetlands: A comparison of wild and farm-released juveniles

• 1.1. Growth rates and body condition factors for native wild and captive-raised juvenile alligators (Alligator mississippiensis) that had been released to the wild were studied using tag-recapture methods for 274 alligators over a 4-year period. Alligators were grouped by sex, size class, source (farm-released vs native wild) and as to whether they had overwintered or not.
• 2.2. In most groups, the farm-released alligators grew significantly better than wild alligators matched for sex and size; in the remaining groups the post-release alligators grew as well as their counterparts, though not better.
• 3.3. Overwintering tended to slow growth rates in both groups, but farm-released alligators still demonstrated superior growth over native wild alligators even after overwintering.
• 4.4. Males tended to grow faster than females, though this trend was not always significantly greater. In no matched group did females grow faster than males.
• 5.5. Growth rates diminished with increasing size in native wild alligators (smaller alligators grew faster), but growth rates of farm-released alligators remained accelerated even at the larger size classes.
• 6.6. Growth curves were constructed using known recapture data with three growth models (von Bertlanffy, Gompertz and logistic); the calculated maximum attainable length and growth parameters were significantly larger (P < 0.01) for farm-released alligators than wild using all three models.
• 7.7. Body condition factors were not different in captive-raised post-released alligators than native wild alligators.