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.

     

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 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.

     

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.

     

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.

     

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.

     

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.

     

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.

     

Chemical feeding stimulants for the herbivorous fish,Tilapia zillii

• 1.1. Chemical feeding stimulants for an herbivorous fish, Tilapia zillii have been determined by fractionation and bioassay of substances derived from a model food plant.
• 2.2. Stimulation was produced by amino acids; glutamic acid, aspartic acid, serine, lysine and alanine produced the bulk of stimulatory activity.
• 3.3. These amino acids are among the most abundant in the test plant, and are markedly different from the amino acids found to stimulate feeding in carnivorous fish.
• 4.4. On the basis of these results, a chemically-mediated mechanism of feeding niche separation is postulated.

     

Fructose-bisphosphate aldolase from Helix pomatia—II. Chemical and physical properties

• 1.1. Fructose-bisphosphate aldolase from Helix pomatia is a tetramer of 40,000 mol. wt. sub-units like mammalian aldolases.
• 2.2. The snail enzyme differs slightly in amino acid composition from mammalian aldolases and has glycine as its amino terminus rather than proline.
• 3.3. Spectroscopic measurements (u.v., fluorescence, ORD, CD) show small yet definite differences in secondary structure between the snail and mammalian aldolases but indicate thaT no major structural changes have occurred during evolution.

     

Changes in composition and proteolytic enzyme activities of artemia during early development

• 1.1. The proximate composition, total and free amino acids, and proteases of Artemia nauplii were determined during early development.
• 2.2. Moisture increased from 71.0% to 80.8%, crude protein decreased from 13.2% to 8.8%, crude fat and ash varied slightly.
• 3.3. The total amino acids decreased. Free amino acids changed in three patterns.
• 4.4. Trypsin, chymotrypsin, carboxypeptidase A, B and cathepsin B and C increased in activity. The activity of trypsin was lower, while cathepsin B and C were the highest.
• 5.5. The protease activities were maximal at pH 7.5 and 8.0, and at 45°C on casein.
• 6.6. The optimal pH for carboxypeptidase A was 4.0, for carboxypeptidase B was 4.5, for trypsin and chymotrypsin were 7.0–7.5. The protease(s) active at pH 9.0–9.5 were to be determined.

     

Changes in chemical composition of muscle in young hybrids between russian sturgeon Acipenser guldenstadti brandt × beluga Huso huso l. (Pisces; acipenseriformes) under different levels of salinity

• 1.1. The salinity tolerance in young RS × B hybrids increases as the fingerlings grow. The specimens weighing about 7 g are able to tolerate the direct transfer to the water salinity 18%..
• 2.2. Under hypo- and iso-osmotic water ion concentration in the hybrid muscle free amino acids, the exchange of taurine for β-alanine and glycine takes place.
• 3.3. Under hyperosmotic conditions within the first 2 days in the hybrid muscle the water quantity declines, the protein quantity also slightly decreases, the urea and free amino acids concentration (mostly alanine, aspartic and glutamic acids, leucine), and a portion of reserved lipids increase.
• 4.4. During the next 4 days the muscle moisture, protein quantity, and the concentration of urea and free amino acids return to control values, but the portion of reserved lipids declines below the original level.

     

The effect of changes in external salinity on the free amino acids and two aminotransferases of white muscle from fasted Salmo gairdneri Richardson

• 1.1. Aspartic acid. glutamic acid and serine concentrations in the white muscle of starved rainbow trout kept in diluted sea water (600 mOsm/l) for 8 days were significantly higher than in control animals kept in fresh water.
• 2.2. After 24 days the levels of all amino acids investigated (aspartic acid, glutamic acid, serine, glycine. alanine, threonine and lysine) in the white muscle of starved rainbow trout kept in diluted sea water were higher than in the white muscle of animals kept in fresh water without food.
• 3.3. Alanine aminotransferase activity in starved rainbow trout kept in diluted sea water for 24 days was higher than in the control animals kept in fresh water.
• 4.4. There is a significant correlation between alanine concentration and alanine aminotransferase activity in the white muscle of rainbow trout.

     

Free amino acids in fluids and tissues of Mytilus galloprovincialis in relation to the environment. Their behaviour as an index of normality of metabolism

• 1.1. A population of Mytilus galloprovincialis has been sampled at 6 different stations of the Bay of Naples (Italy) to analyse the behaviour of free amino acids (FAA) of proteic or non-proteic nature, and the relative parameters of environment.
• 2.2. Thirty FAA of proteic and non-proteic nature have been determined in deproteinized tissue and fluids of M. galloprovincialis.
• 3.3. The most frequent FAA were taurine, as representative of the non-proteic amino acid, cystine, alanine and glutamic acid for non-essential proteic amino acids; valine for the essential proteic amino acids; and other ninhydrin-positive constituents.
• 4.4. There were differences in the environment of the colonies of M. galloprovincialis among the several stations and substantial differences in the macromorphological aspect of the animal were found in relation to their source.
• 5.5. The authors conclude that the FAA content is connected essentially to the regulation of the osmotic pressure and that their concentration represents an index of normality of the metabolism (INM): at FAA concentration total values higher than 550 μmole/g of dry tissue corresponds a negative INM with habitat of osmotic stress, while to concentration values between 0 and 550 μmole/g of dry tissue INM is positive or normal with vital habitat for M. galloprovincialis.
• 6.6. The shape of the concentration curves of the single free amino acids was analysed station by station.

     

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.

     

Isolation,characterization, and comparison of hemolytic peptides in nematocyst venoms of two species of jellyfish (Chrysaora quinquecirrha and Cyanea capillata)

• 1.1. Hemolysins of the sea nettle, Chrysaora quinquecirrha, and the lions' mane jellyfish, Cyanea capillata, collected in the Delaware Bay were partially purified by sequential gel-filtration and high performance liquid chromatography.
• 2.2. The nematocyst contents of both jellyfish had hemolytically active fractions containing large quantities of glycine and serine along with an unknown amino acid residue.
• 3.3. The Chrysaora hemolysin appeared to have a mol. wt greater than 6000 but less than 10,000 daltons.
• 4.4. Glycophorins were the most effective inhibitors to the hemolysins at the lowest concentration.

     

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.

     

Amino acid synthesis during hyperosmotic stress in penaeus aztecus postlarvae

• 1.1. Glycine, proline, and taurine are the quantitatively most important amino acid osmolytes in Penaeus aztecus postlarvae.
• 2.2. Taurine dominates the amino acid pool in low salinity, while proline dominates the amino acid pool at higher salinities.
• 3.3. Although not major contributors to the pool, glutamate and alanine are constitutively synthesized from [¹⁴C]glucose and [¹⁴C]glutamate under constant salinity and under hyperosmotic stress treatments.
• 4.4. Proline synthesis from [¹⁴C]-precursors is apparent under constant high (but not low) salinity and is significantly induced by hyperosmotic stress.
• 5.5. No appreciable glycine synthesis was observed from [¹⁴C]glucose or [¹⁴C]glutamate under any experimental conditions.

     

Role of arginase transferred from the vesicula seminalis during mating and changes in amino acid pools of the spermatophore after ejaculation in the silkworm,Bombyx mori

.

• 1.1. Ejaculation of seminal fluid into the spermatophore formed inside the female bursa copulatrix terminates 20 min after the beginning of copulation of Bombyx mori. The amounts of amino acids transferred are small, but the amounts of amino acids in the spermatophore continue to increase after this time due to protein degradation and amino acid interconversions.
• 2.2. Arginase, which has high activity in the vesicula seminalis, is transferred to the spermatophore without loss of activity during ejaculation. During mating, ornithine and much urea are formed in the spermatophore, indicating activity of the transferred arginase.
• 3.3. In the spermatophore, marked increase of alanine with low concentrations of ornithine and glutamate suggests the presence of a pathway for the active formation of 2-oxoglutarate with pyruvate via glutamate from arginine. During mating, proline and glutamine also increase, but at low rates.
• 4.4. Of the exocrine glands in the male reproductive system, the vesicula seminalis secretes the highest concentration of glutamate (30% of the total amino acids); serine is the amino acid present at highest concentration in secretions of other glands (20–30%). No urea was found in the secretions of any of the glands.

     

Effects of protein synthesis inhibitors on A- and L-site amino acid incorporation by bullfrog tadpole liver and tail fin cells

• 1.1. Cycloheximide and puromycin inhibited leucine transport and incorporation into isolated bullfrog tadpole tail and hepatic cells.
• 2.2. However, high concentrations of these 2 inhibitors did not affect alanine incorporation appreciably in either tissue.
• 3.3. NEM and DNP inhibited leucine and alanine incorporation in both cell types, but at different concentrations.
• 4.4. NEM stimulated leucine transport only in hepatocytes; alanine transport was inhibited by NEM in tail fin cells.
• 5.5. The results suggest different mechanisms of transport and protein synthesis for the 2 types of amino acids by tadpole liver and tail fin cells.