Effects of temperature and food on the free amino acids in tissues of roach (Rutilus rutilus L.) and rudd (Scardinius erythrophthalmus L.)

• 1.1. In liver and muscle the concentrations of free amino acids (FAA) are highest in fish maintained at low temperature and fed mealworms. These effects are more pronounced in roach than in rudd.
• 2.2. In the liver alanine, glycine and glutamate are the dominant FAA but proline increases in mealworm-fed animals.
• 3.3. In muscle, histidine and glycine dominate, except that a mealworm diet leads to an increase in the concentration of proline and to a concomitant decrease in the concentration of glycine.
• 4.4. Starvation leads to a reduction of total FAA content but to relative increases of lysine and histidine. These two FAA can serve as indicators of the general state of nutrition of roach and rudd.
• 5.5. The molar ratio [gly]/[his] is strongly correlated with temperature, decreasing with an increase in the temperature to which the animals had been exposed prior to capture.
• 6.6. The patterns of free and bound amino acids diverge more widely in these species than in mammals which reflects the greater dependence of the FAA pools of fish on intrinsic and extrinsic factors.
• 7.7. The concentrations of histidine in the FAA pools of muscle and in food proteins are strongly correlated.

     

Anaerobic metabolism in sublittoral living Mytilus galloprovincialis in the mediterranean—IV. Role of amino acids in adaptation to low salinities during anaerobiosis and aerobiosis

• 1.1. When Mytilus galloprovincialis were transferred from 38 to 19%. sea water (S), the metabolism became anaerobic for at least 8 hr. After 24 hr the animals were entirely aerobic again.
• 2.2. Upon transfer to 19%. S, the total free amino acid concentration in haemolymph doubled within 4 hr, remaining nearly constant thereafter, up to 48 hr.
• 3.3. In the posterior adductor muscle a strong decrease of alanine and glycine occurred at 48 hr exposure to 19%. S, and a smaller decrease of glutamate; taurine remained relatively constant. When transferred again to 38%. S after 14 days, a strong overcompensation occurred in the concentrations of alanine and proline, and a smaller overcompensation in those of threonine and serine.
• 4.4. In the gill no distinct change in the amino acid pool occurred during 14 days of exposure, with the exception of a decrease in serine. When transferred again to 38%. S, a strong overcompensation occurred in alanine, proline, glycine and serine, and a smaller in glutamate and threonine.
• 5.5. No evidence for anaerobic metabolism in the decrease of the amino acid pool was found.
• 6.6. M. galloprovincialis is less able to adapt to low salinities than the more euryhaline M. edulis.

     

Effect of metabolic inhibitors on hyperosmotically induced free amino acid accumulation in the isolated foot muscle of the brackish-water bivalve Corbicula japonica

• 1.1. Accumulation of free amino acids (FAA) in the isolated foot muscle of the brackish-water bivalve Corbicula japonica during the initial stage of hyperosmotic stress was quantitatively and qualitatively similar to that in the foot of the intact animal.
• 2.2. Aminooxyacetate (AOA), a transaminase inhibitor, markedly inhibited alanine accumulation and promoted ornithine accumulation in the isolated foot. Iodoacetate (IAA), a glycolytic inhibitor, caused no significant alteration in the alanine level and the TLC pattern of FAA. Both the inhibitors scarcely influenced the pool size of total ninhydrin positive substances (NPS).
• 3.3. A major part of the carbon of accumulated FAA during the initial stage of hyperosmotic stess did not seem to arise from glycolysis.
• 4.4. Free d-alanine as well as l-alanine accumulated in isolated foot muscle exposed to hyperosmotic stress.

     

Changes in the free amino acid pool during environmental stress in the gill tissue of the oyster,Crassostrea virginica

• 1.1. Oysters were exposed for 2- and 5-day periods to increased salinity (26%.–38%.), anoxia, turbidity and drilling effluents.
• 2.2. After two days, the FAA pool in the gill tissue of oysters exposed to 38%. salinity had elevated glycine, alanine and β-alanine levels; oysters exposed to anoxia showed elevated glycine and alanine and decreased aspartic acid levels.
• 3.3. After 2 days, both oysters exposed to turbidity and to drilling effluents had increased cysteic acid levels. Glutamic acid and alanine levels were also elevated in oysters exposed to drilling effluents.
• 4.4. After 5 days, glycine, alanine and β-alanine remained above control levels in oysters exposed to increased salinity whereas in those exposed to anoxia, turbidity and drilling effluents, a significant decrease in most amino acids occurred with the total FAA pool decreasing by 50%.
• 5.5. The FAA pool's response was unique for each stress studied suggesting that the FAA pool may prove to be a useful diagnostic tool for determining a posteriori the causative agent responsible for a given stress response.

     

Olfactory responses to amino acids in marine teleosts

• 1.1. The olfactory responses to amino acids were recorded from the bulb of the red sea bream (Chrysophyrys major) and the conger eel (Conger myriaster).
• 2.2. The threshold concentration for l-glutamine was 10⁻⁷ M in the sea bream and below 10⁻⁸ and 10⁻⁹ M in the conger eel, and it was found that amino acids are good olfactory stimuli in both species.
• 3.3. A comparison of the olfactory spectrum of amino acids of the sea bream with that of each of three species of freshwater fishes revealed a high similarity of spectra.

     

Proteolysis post mortem in North Atlantic krill

• 1.1. The autoproteolytic processes in selected species of North Atlantic krill, Meganyctiphanes norvegica (M. Sars), Thysanoessa inermis (Krøyer) and T. raschii (M. Sars) have been examined at 0°C by following the release of peptides and free amino acids.
• 2.2. The krill contains high levels of peptide hydrolases, and autoproteolysis seems to be due mainly to digestive enzymes localized in the hepatopancreas and the intestinal tract of the animals.
• 3.3. During autoproteolysis the individual amino acids were generally released at rates corresponding to their proportion in the bulk protein of the krill. The major exceptions were alanine which accumulated in amounts larger than was to be expected from the composition of the krill protein, and glutamic acid/glutamine, aspartic acid/asparagine, arginine, and to some extent glycine, proline and serine, which accumulated to a lesser extent than was to be expected.
• 4.4. Storage of krill for 1 week resulted in only minor changes in the total content of amino acids as determined after acid hydrolysis, with the exception of alanine which increased in concentration.
• 5.5. The results suggest that the formation of free alanine is partly due to reactions other than proteolysis.
• 6.6. The release of free amino acids was accompanied by a considerable increase in the amount of small peptides, and glutamic acid/glutamine, aspartic acid/asparagine, glycine and proline tended to accumulate in these peptides.
• 7.7. The autoproteolytic activity of the Thysanoessa species showed seasonal variations, probably in response to food availability. In the case M. norvegica, the results suggest that there are smaller fluctuations in the level of proteolytic enzymes, probably indicating less pronounced variations in the food intake over the year.

     

The free amino acids of muscle in the cephalochordate Branchiostoma,the cyclostome Myxine and some fishes

• 1.1. Branchiostoma and Myxine have the highest concentrations of amino acids (207 and 234 mM) of the five species investigated.
• 2.2. The predominant amino acids are glycine, proline, alanine, taurine, serine and valine, which form 83–98% of the total, except in Latimeria (60%).
• 3.3. Total amino acids are considered from the point of view of osmotic concentration in relation to other nitrogenous compounds of muscle.

     

Changes in free amino acid composition in haemolymph of larvae of the wax moth,Galleria mellon ella L., during cold acclimation

• 1.1. Free amino acids were analysed in the haemolymph of Galleria mellonella larvae by HPLC chromatography with o-phthaldialdehyde (OPA)-l-thio-β-d-glucose as derivatization agent.
• 2.2. Fourteen primary amino acids were detected among which glutamine, alanine, γ-aminobutyric acid (GABA) and glycine predominated and constituted 67.7% of the amino acids found.
• 3.3. The concentration of GABA increased significantly with the age of larvae entering the wandering phase and reached a maximum during metamorphosis.
• 4.4. Analysis of cold-acclimated larvae revealed a net increase of free primary amino acids from 96 to 151.8 μmol/ml during consecutive acclimation to 0°C within 20 days and to 205.4μmol/ml during cold shock injury at 0°C (3 hr).
• 5.5. The bulk of this increase was accounted for by alanine, glycine, phenylalanine and lysine.

     

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.

     

A simple procedure for evaluating the protein degradation rate in mussel (Mytilus galloprovincialis Lam.) tissues and its application in a study of phenanthrene effects on protein catabolism

• 1.1. An improved, simple method for the evaluation of the protein catabolic rate in the tissues of the lamellibranch mollusc Mytilus galloprovincialis Lam. is presented.
• 2.2. This procedure, which utilizes the technique of the decay curve of a labeled amino acid (¹⁴C-leucine) in the tissues, exploits the capacity of these organisms to rapidly take up soluble compounds from sea-water.
• 3.3. When mussels are exposed to ¹⁴C-leucine in the sea-water, the labeled amino acid is rapidly accumulated into the cell proteins.
• 4.4. A further addition of unlabeled leucine to the sea-water drastically decreases the specific activity of soluble amino acids into the cells, so that the reincorporation of the labeled leucine into the proteins becomes negligible, allowing a correct estimation of the degradation rate of the proteins.
• 5.5. This procedure was utilized to evaluate the effect of phenanthrene on the rate of catabolism of cytosolic proteins in the digestive gland of mussels, and to study the relationship between the protein degradation rate and the activity of lysosomes, which play a well-established role in the catabolism of macromolecules.

     

Amino acid activating enzymes in Sarcophaga bullata

• 1.1. The fat-body soluble fraction from two-day Sarcophaga bullata larvae contain amino acid activating enzymes for nineteen amino acids.
• 2.2. The level of activity varies with the amino acid substrate.
• 3.3. The total ³²PP-ATP exchange activity of the pupae decreased with age for the first 6 days, then increased to a maximum one or two days prior to emergence of the adults.
• 4.4. The free amino acid concentration in the pupae decreased during the period when the amino acid activating activity increased.

     

Chemical composition of North Atlantic krill

• 1.1. The main chemical components of Meganyctiphanes norvegica (M. Sars), Thysanoessa inermis (Krøyer) and T. raschii (M. Sars) have been examined.
• 2.2. Protein accounted for 42–47% of the dry weight of M. norvegica and 32–50% of the dry weight of the Thysanoessa species. On a wet weight basis, the protein content was relatively constant and independent of season.
• 3.3. The dominating amino acids in the bulk protein of the krill were glutamic acid/glutamine, aspartic acid/asparagine, glycine, alanine, lysine and leucine.
• 4.4. Lipids were present in amounts of 13–29% of the dry weight in M. norvegica, 15–50% in T. inermis and 12–44% in T. raschii, and the lipid content varied with season.
• 5.5. The main nitrogen extractives in krill, expressed on a dry weight basis, were free amino acids (5–10%), trimethylamine oxide (about 4%), peptides (about 1%) and nucleotides (0.4–1.3%). Trimethylamine and ammonia were present in very low concentrations in living krill.
• 6.6. The amino acids taurine, glycine, proline, arginine, sarcosine and alanine made up 89–93 mol% of the free amino acid pool.
• 7.7. The ash content of krill was in the order of 10–13% of the dry weight, and fluoride represented 1040 and 3200 ppm in the Thysanoessa species and M. norvegioca, respectively.

     

Transintegumentary absorption of acidic amino acids in the oligochaete annelid Enchytraeus albidus

• 1.1. Transintegumentary absorption of acidic amino acids in Enchytraeus albidus amounts to only a few per cent of neutral amino acid uptake.
• 2.2. Influx of acidic amino acids is composed of a mediated route with high affinity and an apparent diffusional entry.
• 3.3. Glutamic acid influx is susceptible to metabolic inhibition, reduced salinity and Na⁺-levels and the presence of additional acidic amino acids.
• 4.4. Inhibition experiments suggest the presence of a distinct integumentary uptake system for acidic amino acids.

     

Characterization of NaK ATPase from the gills of the freshwater prawn Macrobrachium rosenbergii (de Man)

• 1.1. The specific activity of Na-K ATPase was determined from the microsomal preparation of gills dissected from adult Macrobrachium rosenbergii.
• 2.2. Maximal ATPase activity was achieved at a substrate concentration of 0.5 mM ATP.
• 3.3. Optimal enzyme activity was obtained at pH of 7.5.
• 4.4. The Arrhenius plot of Na-K ATPase activity revealed a marked discontinuity at 30°C. “Mg” ATPase activity did not exhibit a marked discontinuity.
• 5.5. The E_a for Na-K ATPase and “Mg” ATPase was 14.6 kCal/mole and 9.31 kCal/mole respectively. Q₁₀ values for Na-K ATPase was 2.34 and for “Mg” ATPase 1.65.
• 6.6. ATPase activity and gill homogenate protein concentration exhibited a linear relationship up to 130 μg protein/ml.
• 7.7. Na-K ATPase activity was inhibited by 10⁻³ M ouabain. It was equally inhibited by the removal of K⁺ from the reaction medium.

     

Specific dynamic action (SDA) in the supralittoral isopod,Ligia pallasii: Identification of components of apparent SDA and effects of dietary amino acid quality and content on SDA

• 1.1. Specific Dynamic Action (SDA) effects of diet were investigated in the supralittoral isopod, Ligia pallasii, using defined chemical diets.
• 2.2. “Apparent SDA”, or the total rise in metabolic rate following a meal, was resolved in animals eating a nutritionally complete chemical diet into three components: 8% mechanical costs of moving food through the gut, 40% “excitement costs” due to investigator disturbance and presence of food, and 52% SDA.
• 3.3. Excitement costs in animals exposed to food but which chose not to eat showed non-significant variation between diets containing different levels of chemical nutrients, but were significantly less on a diet containing only cellulose and agar.
• 4.4. SDA increased with increasing concentration of amino acids in the diet.
• 5.5. Substitution of whole-protein casein for free amino acids in the diet had no significant SDA effect, while substitution of free amino acids in the ratio found in casein more than doubled the SDA effect.
• 6.6. Deletion of alanine from the diet caused no significant effect on SDA, while deletion of phenylalanine caused a highly significant elevation in SDA.

     

Specific dynamic action (SDA) in the supralittoral isopod,Ligia pallasii: Effect of ration and body size on SDA

• 1.1. Ration and body size effects on specific dynamic action (SDA) were investigated in the supralittoral isopod Ligia pallasii using seaweed and chemical diets.
• 2.2. SDA increased asymptotically with ingested meal size for all diets.
• 3.3. Body weight had a significant positive effect on SDA for only one of the six diets tested, but weak tendencies were present in the data for the other diets.
• 4.4. SDA appeared to increase geometrically with increasing concentration of amino acids at high ration levels.

     

Aerobic glucose disposal in the oyster: An in vivo kinetic analysis

• 1.1. Aerobic glucose disposal in starved oysters exposed to 1 mM external glucose was 2.29 μg C/g wet wt/min.
• 2.2. It was hypothesized that the maximum disposal rate is limited by the maximum rate of transepithelial glucose transport.
• 3.3. The major recipients of glucose-carbon were glycogen and amino acids. 4. The rate of glucose-carbon disposal to these two pools was 0.80 and 0.42 μg C/g/min, respectively.
• 4.5. The internal energy state determines the pathways of glucose disposal.
• 5.6. Disposal of glucose-carbon in “glucose-primed” oysters is primarily into glycogen.
• 6.7. In fasted bivalves the disposal is primarily into amino acids and carboxylic acids.
• 7.8. The uptake of dissolved glucose has the potential of contributing significantly to growth under conditions where the external glucose concentration is kept artificially high.

     

Biosynthesis of membrane and a membrane glycoprotein in Tetrahymena pyriformis

• 1.1. A membrane glycoprotein was isolated from Tetrahymena surface membrane with properties similar to mammalian erythrocyte glycoprotein.
• 2.2. This membrane glycoprotein had a specific acitivity less than whole membrane at various time intervals up to 40 hr.
• 3.3. In double labelling experiments, glucosamine contributed a greater degree of the labelling of this glycoprotein than did amino acids.
• 4.4. Greater incremental increases in the glucosamine radioactivity over amino acids at the longer time intervals suggests that the carbohydrate and protein moieties may have independent metabolic pathways.
• 5.5. When Tetrahymena was grown in proteose peptone-tryptone in the presence of labelled amino acid, the specific activity of the surface membrane was less than one-tenth of the specific activity obtained in defined growth media. Under these same conditions, there were only slight changes in the specific activities of glucosamine in the membrane.
• 6.6. Data is presented suggesting independent synthesis of the protein and oligosaccharide from different pools.

     

Purification and some properties of isocitrate dehydrogenase of a blowfly Aldrichina grahami

• 1.1. NADH-dependent isocitrate dehydrogenase has been purified 110-fold from the crude extract of the flight muscle mitochondria of Aldrichina grahami.
• 2.2. The purification procedure involved Triton X-100 treatment of isolated mitochondria, column chromatography on DEAE-cellulose, Affi-gel blue, and P-cellulose.
• 3.3. The purified enzyme was homogeneous by criteria of the polyacrylamide gel electrophoresis.
• 4.4. The enzyme of the blowfly contains more acidic amino acids and less hydrophobic amino acids than that of pig heart.
• 5.5. The molecular weight was determined to be 330,000 daltons. The subunit construction differs from ghat of mammalian isocitrate dehydrogenase.

     

Osmotic changes in an estuarine bivalve,Modiolus fluviatilis

• 1.1.Responses to different salinities monitored by opening and closing of the shell valves were observed in Modiolus fluviatilis.
• 2.2.The osmotic pressure, sodium and chloride ion concentrations were measured in the haemocoelic fluid of Modiolus fluviatilis under similar conditions.
• 3.3.Free amino acids (measured as ninhydrin-positive substances) were determined in the muscle tissue of Modiolus.
• 4.4.It appears that these free amino acids are involved in the ability of the estuarine bivalve Modiolus fluviatilis to osmoregulate in a wide range of salinities.