Phosphoethanolamine in brain of the euritherm lake fish Perccottus glehni (Eleotridae, Perciformes, Dyb. 1877) as a phenomenon depending on temperature factor

The present work studied effect of a seasonal decrease of environmental temperature and cold shock on pools of free amino acids (FA) in brain of the euritherm lake fish P. glehni. For the first time, non-protein amino acid, phosphoethanolamine (PEA), revealed in the great amounts under conditions of near-zero temperatures was found in brain of ectothermic animals. An intensive rise of the PEA pool from 0.3% during the summer period to 33.6% at winter was shown to occur in the brain of P. glehni as a result of a seasonal temperature decrease. In contrast, the level of taurine showing the greatest pool in comparison with other FA (29.0% of the total pool) in summer decreases to 8.9% in the beginning of winter period. Similar negative correlation between the taurine and PEA content was found under effect of acute cold shock (1°C): the taurine level decreased for 4 days from 32.2 to 14.5% of the total pool, whereas the PEA level sharply increased (from 2.1 to 15.3%). Both types of the low-temperature actions have revealed, besides PEA, an intensive rise in the pool of serine and accumulation of phosphoserine. The role of PEA in biochemical evolution and adaptation of the brain to low temperatures is discussed. It is supposed that accumulation of PEA, phosphoserine, and serine is associated with changes in the status of membrane phospholipids at low temperatures.     

Biochemical strategy of survival of the freshwater mollusc <Emphasis Type="Italic">Lymnaea stagnalis</Emphasis> at near-zero temperatures

Effect of an autumn-winter decrease of the environmental temperature on changes of the content of free amino acids and reducing sugars was studied in tissues fluids of the freshwater mollusc L. stagnalis. At a decrease of the temperature to 4 and 0°C at the autumn period, concentration of free alanine rose several times; an increase of histidine, glutamate, glycine, and serine concentrations was less pronounced. Accumulation of methionine, leucine, isoleucine, tyrosine, and phenylalanine was revealed at 0°C. In the state of long hypobiosis (at 4°C), pools of all amino acids fell 4–8 times; essential amino acids, except for lysine, were not detected at all. Both at the summer and at the autumn periods, high concentrations of free fructose and glucose were revealed. In the process of hypobiosis the fructose pool decreased almost 35, while the glucose pool—12 times. Maltose that was absent in summer was found at 4 and 0°C as well as after 2.5 months of hypobiosis. The changes of the studied parameters in L. stagnalis in response to hypothermia are compared with the corresponding parameters of changes in cryoresistant animals in response to negative temperatures.     

Variation in the content of free amino acids in body fluids of freshwater mollusk Lymnaea stagnalis during seasonal adaptation to low positive temperatures

The effect of autumn and winter decrease in environmental temperature on the content of free amino acids in body fluids has been studied in freshwater snail Lymnaea stagnalis. In autumn, when temperature drops to 4 and 0°C, the highest increase in alanine concentration was observed and its pool was almost three times that in summer. A less pronounced accumulation of glutamate, glycine, histidine, and serine was observed in the same temperature range. Cysteine was detected at 0°C. The accumulation of essential amino acids methionine, leucine, isoleucine, tyrosine, and phenylalanine took place at 0°C, while only traces of these amino acids were detectable at 4°C. At the same time, free lysine undetectable in summer has been revealed in autumn at 4°C and its concentration increased as temperature decreased to 0°C. In winter, when the mollusks were hypermetabolic for 2.5 months, the pools of all amino acids decreased 4–8 times, while essential amino acids (except lysine) were undetectable. The involvement of alanine and, possibly, lysine in L. stagnalis adaptation to near-zero temperature is proposed.     

Biochemical strategy of survival of the freshwater mollusc Lymnaea stagnalis at near-zero temperatures

Effect of an autumn-winter decrease of the environmental temperature on changes of the content of free amino acids and reducing sugars was studied in tissue fluids of the freshwater mollusc L. stagnalis. At a decrease of the temperature to 4 and 0 degrees C at the autumn period, concentration of free alanine rose several times; an increase of histidine, glutamate, glycine, and serine concentrations was less pronounced. Accumulation of methionine, leucine, isoleucine, tyrosine, and phenylalanine was revealed at 0 degree C. In the state of long hypobiosis (at 4 degrees C), pools of all amino acids fell 4-8 times; essential amino acids, except for lysine, were not detected at all. Both at the summer and at the autumn periods, high concentrations of free fructose and glucose were revealed. In the process of hypobiosis the fructose pool decreased almost 35, while the glucose pool--12 times. Maltose that was absent in summer was found at 4 and 0 degree C as well as after 2.5 months of hypobiosis. The changes of the studied parameters in L. stagnalis in response to hypothermia are compared with the corresponding parameters of changes in cryoresistant animals in response to negative temperatures.     

Free amino acids and reducing sugars in the freshwater shrimp <Emphasis Type="Italic">Gammarus lacustris</Emphasis> (Crustacea,Amphipoda) at the initial stage of preparation to winter season

A peculiarity of amino acid profile of the cold-resistant freshwater shrimp Gammarus lacustris in the beginning of autumn is a high level of ornithine, the second after alanine (17.0 ± 1.4 and 22.6 ± 1.4 μmol/ml of homogenate, respectively). The amount of alanine and ornithine accounts for 39.8% of the total pool of free amino acids and together with lysine and leucine—55%. Free glucose is the major reducing sugar (6.42 ± 0.78 μmol/ml).     

LEAF ONTOGENY AS A FACTOR IN SUSCEPTIBILITY TO OZONE: AMINO ACID AND CARBOHYDRATE CHANGES DURING EXPANSION

During development (expansion), the cotton leaf passes through a stage in which it is highly susceptible to ozone. This period of susceptibility occurs after the maximum expansion rate but before complete expansion occurs. The period of maximum susceptibility corresponds to a minimum concentration of soluble sugars and free pool amino acids. Specific amino acids such as aspartate, serine, threonine, glutamate, asparagine, alanine, glycine, valine, isoleucine, leucine, histidine, and tryptophan tended to reach a minimum concentration at about the same time leaves were susceptible to ozone. Ozone exposure during the susceptible period is manifested by visible leaf flecking of the upper surface and a dramatic (up to 2 fold) increase in total free pool amino acids. Most individual amino acids tended to increase except for phenylalanine, alanine, phosphoserine, phosphoethanolamine, and ethanolamine. Soluble protein is decreased but not to the same extent that the free pool amino acids increase. Because there is ample evidence that ozone enters the leaf during nonsusceptible periods as well as susceptible periods, it is postulated that ozone damage results because of the depletion of soluble reserves (carbohydrates and amino acids). Perhaps repair of damage cannot occur.     

DEVELOPMENTAL CHANGES IN MOUSE BRAIN: WEIGHT, WATER CONTENT AND FREE AMINO ACIDS

Abstract— —Glutamic acid, glutamine, GABA and aspartic acid exhibited postnatal increases in the developing mouse brain at the same time that the other amino acids, both essential and non-essential, of the pool decreased. The most significant decreases were observed in the concentrations of taurine, phosphoethanolamine, glycine and alanine. The period of rapid accumulation of the members of the glutamic acid family in the mouse brain was concurrent with dramatic increases and decreases in brain weight and water content, respectively.     

Seasonal dynamics of carbohydrate and nitrogenous components in the roots of perennial weeds

Abstract Chicory (Cichorium intybus L.) and dandelion (Taraxacum officinale L.) are persistent weeds, the aerial portions of which do not survive in winter. However, subterranean tissues remain viable and facilitate the rapid resumption of growth in early spring. The source of nutrients for growth prior to the establishment of foliage is the roots. Carbohydrate and N reserves are accrued during late summer and autumn, respectively. Hydrolysis of fructans during late autumn occurs coincidentally with increments in sucrose, the latter providing a readily accessible C pool. Nitrate, free amino acids and soluble protein all play substantial roles in nitrogen storage. Asparagine is the predominant amino acid in the free pool during winter, followed by glutamine, ornithine, serine, aspartic acid and glutamic acid. Storage reserves remain at peak levels throughout winter and deeline prior to the resumption of growth. The patterns observed here provide evidence that N is an important currency of storage metabolism and, thus, a framework has been provided for the examination of regulation of N storage in perennial weeds.     

Free amino acid composition in blood and muscle of the gobi <Emphasis Type="Italic">Precottus glehni</Emphasis> at the period of preparation and completion of hibernation

The freshwater fish gobi Preccottus glehni survives after wintering in ponds frozen in winter till the very bottom. In adaptation of poikilothermal animals to wintering at near-zero temperatures, an essential role is played by free amino acids; accumulation of a large amount of some particular acid at the period of preparation to the state of hibernation can indicate the protective role of this acid in the low-temperature adaptation. In the present work it has been shown that as soon as by the end of August, in the gobi muscle, the taurine concentration increases three times as compared with that in July, the taurine pool after this reaching 50% of the total pool of free amino acids in the muscle tissue. During December and after the 3-month hibernation in ice, it exceeds the April and July levels 8 and 4 times, respectively, and amounts to 50% of the total free amino acid pool for muscle and to 40% for blood. Several days prior to the beginning of winter hibernation under natural conditions, both in blood and in muscle, there is revealed disappearance or a sharp fall of concentration of essential amino acids. An essential peculiarity of the change in the free amino acid composition after hibernation was a significant rise of alanine concentration in muscle—3.5 times as compared with July and 1.4–1.8 times as compared with changes in December. The total free amino acid pool in muscle in December as compared with that in July increased almost 1.5 times (34.76 ± 1.12 μmol/g wet weight), while after hibernation—2 times. Peculiarities of taurine accumulation long before the beginning of winter cold allow suggesting that role of taurine consists in providing a possibility of existence of eurythermal fish at near-zero temperature.     

Concentrations of Amino Acids in Extracellular Fluid After Opening of the Blood-Brain Barrier by Intracarotid Infusion of Protamine Sulfate

Abstract: This article evaluates the influence of an opening of the blood-brain barrier (BBB) on compounds in brain extracellular fluid. The concentrations of amino acids and some other primary amines were determined in dialysates sampled from the right parietal cortex of rats before and after an intracarotid infusion of protamine sulfate. Extravasated plasma proteins were visualized by Evans blue/albumin and immunohistochemistry. CSF albumin— an indicator of blood-CSF barrier opening—was quantified with immunoelectrophoresis. The brains were macroscopically edematous after 10 mg but not after 5 mg of protamine sulfate. The higher dose led to a 50% death rate. The concentrations of amino acids did not change 10 min after the BBB opening. No significant alterations in the amino acid concentrations were observed after the lower dose. The concentrations of glutamate, aspartate, GABA, glycine, taurine, and phosphoethanolamine increased significantly within 50–80 min after the infusion of 10 mg of protamine sulfate. CSF albumin levels were significantly increased 1 h after infusion. We conclude that a dysfunction of the BBB, of a degree known to induce brain edema (10 mg of protamine sulfate), significantly increases the extracellular concentration of excitatory amino acids, GABA, taurine, and phosphoethanolamine in the extracellular space.     

Synthesis of Ethanolamine and Its Regulation in Lemna paucicostata

The metabolism of ethanolamine and its derivatives in Lemna paucicostata has been investigated, with emphasis on the path-way for synthesis of phosphoethanolamine, a precursor of phosphatidylcholine in higher plants. In experiments involving labeling of intact plants with radioactive serine, ambiguities of interpretation due to entry of radioactivity into methyl groups of methylated ethanolamine derivatives were mitigated by pregrowth of plants with methionine. Difficulties due to labeling of diacylglyceryl moieties of phospholipids were avoided by acid hydrolysis of crucial samples and determination of radioactivity in isolated serine or ethanolamine moieties. The results obtained from such experiments are most readily reconciled with the biosynthetic sequence: serine → ethanolamine → phosphoethanolamine → phosphatidylethanolamine. A possible alternative is: serine → phosphatidylserine → phosphatidylethanolamine → ethanolamine → phosphoethanolamine. Cell-free extracts of L. paucicostata were shown to produce CO₂ from the carbon originating as C-1 of serine at a rate sufficient to satisfy the demand for ethanolamine moieties. A number of experiments produced no support for a hypothetical role for phosphoserine in phosphoethanolamine formation. Uptake of exogenous ethanolamine commensurately down-regulates the synthesis of ethanolamine moieties (considered as a whole, and regardless of their state of derivatization at the time of their formation). In agreement with previous observations, uptake of exogenous choline down-regulates the methylation of phosphoethanolamine, without being accompanied by secondary accumulation of a marked excess of ethanolamine derivatives.     

In Vivo Microdialysis Studies on the Effects of Decortication and Excitotoxic Lesions on Kainic Acid-Induced Calcium Fluxes, and Endogenous Amino Acid Release, in the Rat Striatum

The in vivo effects of kainate (1 mM) on fluxes of 45Ca2+, and endogenous amino acids, were examined in the rat striatum using the brain microdialysis technique. Kainate evoked a rapid decrease in dialysate 45Ca2+, and an increase in the concentration of amino acids in dialysates in Ca2+-free dialysates. Taurine was elevated six- to 10-fold, glutamate two- to threefold, and aspartate 1.5- to twofold. There was also a delayed increase in phosphoethanolamine, whereas nonneuroactive amino acids were increased only slightly. The kainic acid-evoked reduction in dialysate 45Ca2+ activity was attenuated in striata lesioned previously with kainate, suggesting the involvement of intrinsic striatal neurons in this response. The increase in taurine concentration induced by kainate was slightly smaller under these conditions. Decortication did not affect the kainate-evoked alterations in either dialysate 45Ca2+ or amino acids. These data suggest that kainate does not release acidic amino acids from their transmitter pools located in corticostriatal terminals.     

Anthelmintic efficacy of genistein, the active principle of Flemingia vestita (Fabaceae): alterations in the free amino acid pool and ammonia levels in the fluke, Fasciolopsis buski

The crude root-peel extract of Flemingia vestita, its active principle genistein and the reference flukicide oxyclozanide were tested against Fasciolopsis buski, the giant intestinal trematode. The amino acid composition of F. buski was demonstrated using HPLC and it was observed that the free amino acid (FAA) pool of the control worm consisted of aspartate, threonine, serine, glutamic acid, glutamine, proline, glycine, alanine, valine, methionine, isoleucine, leucine, tyrosine, lysine, histidine, arginine, phosphoserine, taurine, citrulline, ornithine, β-alanine, and γ-amino butyric acid (GABA). Of the amino acids detected valine was found to be the maximum in quantitative analysis. In qualitative analysis the FAA pool of the parasites under various treatments remained same as that of the control; however, quantitatively the level of various FAAs in the parasite was significantly affected. The treated parasites showed a marked decrease in the levels of arginine, ornithine, tyrosine, leucine, isoleucine, valine, alanine, glycine, proline, serine, threonine, and taurine following treatment with 20 mg/ml of crude peel extract, 0.5 mg/ml of genistein and 20 mg/ml of the reference drug, though an increase in the levels of glutamic acid, glutamine, phosphoserine, citrulline and GABA was noticeable. Enhanced levels of GABA and citrulline under the influence of genistein may be implicated in alterations of nitric oxide release and consequent neurological change (e.g. paralysis) in the parasite. Ammonia in the tissue homogenate as well as in the incubation medium showed a quantitative increase compared to the controls after treatment with the various test materials. The ammonia level increased by 40.7%, 66.4% and 18.16% in treatments with F. vestita, genistein and oxyclozanide, respectively, at the mentioned dosages. The changes in the levels of the amino acids and nitrogen components post treatment suggest that the amino acid metabolism in the parasite may have been altered under the influence of the test materials.     

The activity of pro- and antioxidant systems in the liver of freshwater fishes during different seasons

The content of lipid peroxidation products--diene conjugates, lipid hydroperoxides, thiobarbituric acid reactive substances (TBARS), vitamins A, E and carotenoids and the activity of antioxidant enzymes--superoxide dismutase, glutathione peroxidase and catalase in the liver of freshwater fishes of different species (silver carp, grass carp and common carp) in different seasons have been studied. It was established the activity of antioxidant defence system in the liver of fish depends significantly on the season and fish species. In particular, the content of lipid peroxidation products in the liver of freshwater fishes at the beginning of winter and spring was significantly higher compared to their content at the beginning of summer and autumn. The superoxide dismutase and glutathione peroxidase activities in the liver of these fish species at the beginning of winter and spring were significantly lower than at the beginning of summer and autumn while the seasonal changes of catalase activity in the liver of fish are expressed insignificantly. The content of vitamins E, A1, A2 and carotenoids in the liver of fishes of different species at the beginning of winter and spring was significantly lower than at the beginning of summer and autumn. The content of lipid peroxidation products and vitamins E, A1 and A2 in the liver of common carp is significantly lower than in the liver of silver carp and grass carp and species differences in antioxidant enzymes activity are insignificant.     

Saving for the future: Pre‐winter uptake of algal lipids supports copepod egg production in spring

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Seasonal changes in nitrogen fractions of Pachysandra terminalis, a forest evergreen chamaephyte

Seasonal changes in several forms of nitrogen were investigated in the evergreen chamaephyte Pachysandra terminalis Sieb. et Zucc. growing in temperate evergreen coniferous forest. After plants sprouted new shoots, nitrogen accumulated largely as proteins in the leaves from summer to late autumn and, additionally, during a short spring period in the following year. Proteins accumulated in the overwintered leaves decreased markedly in summer, indicating that they were used for new shoot growth. A similar change was found in Fraction 1 protein. This is consistent with the seasonal changes in photosynthetic capacity and carboxylation efficiency observed in previous studies. The allocation of nitrogen to Fraction 1 protein increased in the spring, presumably to utilize better the relatively high light intensity at the forest floor before leaf expansion of the understory deciduous plants. In contrast to protein nitrogen, soluble nitrogen was present largely in stems and rhizomes. Aspargine was the major component of the amino acid pool in all organs throughout the year, especially in stems in summer. Since asparagine has the highest N:C ratio (2N:4C), an amino acid pool dominated by asparagine is economic in the use of carbon and advantageous for the carbon-limited environment of the forest understory.     

The establishment of essential and metabolically derived amino acid profiles in developing chick embryo organs

The accumulation of certain essential and metabolically derived amino acids in the free amino acid pools of three excitable tissues has been studied in the chick embryo. Valine together with leucine are at the onset present in the yolk at higher concentrations than any of the other essential amino acids. By 15 days all the amino acids studied have accumulated in the embryonic pools at a higher rate than valine, although certain amino acids, such as phenylalanine or methionine, always remain at lower relative concentrations than valine. This reflects their low supply in the yolk, rather than a more rapid rate of disappearance (utilization). During early embryogenesis (E₂–E₄), tissues preferentially concentrate glutamic acid, besides taurine and phosphoethanolamine (6). The next distinct stage of development (E₄–E₇) is marked in the brain by a gradual rise in glutamic acid, glutamine and aspartic acid; the same three amino, acids do not demonstrate a further increase in the pool of the heart, while in the whole eye the amino acid profile begins to resemble the blood. Leucine in all three tissues declines rapidly, to reach isoleucine levels by day 7 of development; tyrosine increases slowly in apparent reciprocity to an equally gradual phenylalanine decrease. Into the second week of embryo growth (E₇–E₁₅), GABA appears in the mesencephalon (E₇) and the eye (E₉–E₁₀). In the mesencephalon, the free amino acid pool composition exhibits a rather sudden increase of most metabolically derived amino acids. Glutamic acid and glutamine in the brain increase in parallel; the rate of GABA and aspartic acid accumulation is slower, and for GABA stabilizes on day 14, as does glutamine. In the eye, by day 15, GABA levels are more closely aligned with the aspartic acid content. Finally, throughout embryogenesis serine fluctuations in blood and tissues are in parallel with those of threonine, and different from glycine or alanine which also change in tandem.     

Nitrogen storage forms in nine boreal understorey plant species

Storage forms of N were studied in below-ground structures of nine boreal forest understorey plants. The ericaceous shrubs Vacciniumvitis-idaea and V.myrtillus, the fern Gymnocarpium dryopteris, the grass Deschampsia flexuosa, and the herbs Epilobium angustifolium, Maianthemum bifolium, Solidago virgaurea, Geranium sylvaticum and Trientalis europaea were sampled in early summer and late autumn from plots fertilised with a complete mixture of nutrients and from non-fertilised control plots. Concentrations of total nitrogen, insoluble and soluble proteins, free amino acids and nitrate were measured, and changes in absolute and relative concentrations of these N fractions between early summer and late autumn were used to identify the forms in which the plants store N. In all species studied, the concentration of free amino acids increased both between summer and autumn and in response to fertilisation, while the concentration of protein N increased only in response to fertilisation. Thus, free amino acids appear to have a central role in N storage. In all of the species except G. dryopteris, D. flexuosa and S. virgaurea, arginine dominated the pool of free amino acids and thus arginine was the major form of stored N in most species. In D. flexuosa and S. virgurea, however, asparagine and arginine together were the major forms of stored N, while glutamine was the major free amino acid, and N storage form, in G. dryopteris. Received: 10 March 1996 / Accepted: 22 December 1996     

Seasonal changes in the gamma-aminobutyric acid system of the mouse brain

Dynamics of gamma-aminobutyric acid (GABA) content, the level of glutamate and total content of dicarboxylic amino acids and their amides as well as glutamate decarboxylase and GABA-alpha-ketoglutarate aminotransferase activities in the brain of F1CBAXC57BL/6 hybrid mice were determined during a year. The content of GABA and adicarboxylic acids in the brain in autumn-winter is higher than in summer. An analogous regularity is observed in the activity of basic enzymes of the GABA metabolism. Against a background of the common regularity (higher values of these indices in winter and autumn and comparatively low in summer) a particularly pronounced significant increase (as compared with the minimum level) is found in March for the activity of GABA-shunt enzymes, the content of GABA and dicarboxylic amino acids. The data obtained testify to the fact that in autumn-winter the brain tissue is characterized by a comparatively high content of dicarboxylic amino acids, their amides and GABA as well as by a more intensive functioning of the GABA-shunt, which is confirmed by the activation of the enzymes of GABA production and utilization in the corresponding seasons.     

Seasonal changes of freshwater ammonia-oxidizing archaeal assemblages and nitrogen species in oligotrophic alpine lakes

The annual changes in the composition and abundance of ammonia-oxidizing archaea (AOA) were analyzed monthly in surface waters of three high mountain lakes within the Limnological Observatory of the Pyrenees (LOOP; northeast Spain) using both 16S rRNA and functional (ammonia monooxygenase gene, amoA) gene sequencing as well as quantitative PCR amplification. The set of biological data was related to changes in nitrogen species and to other relevant environmental variables. The whole archaeal assemblage was dominated by phylotypes closely related to the crenarchaeal 1.1a group (58% ± 18% of total 16S rRNA gene sequences), and consistent structural changes were detected during the study. Water temperature was the environmental variable that better explained spring, summer, and winter (ice-covered lakes) archaeal assemblage structure. The amoA gene was detected year round, and seasonal changes in amoA gene composition were well correlated with changes in the archaeal 16S rRNA gene pool. In addition, copy numbers of both the specific 1.1a group 16 rRNA and archaeal amoA genes were well correlated, suggesting that most freshwater 1.1a Crenarchaeota had the potential to carry out ammonia oxidation. Seasonal changes in the diversity and abundance of AOA (i.e., amoA) were better explained by temporal changes in ammonium, the substrate for nitrification, and mostly nitrite, the product of ammonia oxidation. Lacustrine amoA gene sequences grouped in coherent freshwater phylogenetic clusters, suggesting that freshwater habitats harbor typical amoA-containing ecotypes, which is different from soils and seas. We observed within the freshwater amoA gene sequence pool a high genetic divergence (translating to up to 32% amino acid divergence) between the spring and the remaining AOA assemblages. This suggests that different AOA ecotypes are adapted to different temporal ecological niches in these lakes.