Acid Pool Research Articles

Effect of tavamin on the content of free amino acids in rat heart under alcohol withdrawal syndrome conditions

The effect of the new amino acid preparation tavamin on the free amino acid pool in heart has been studied under alcohol withdrawal syndrome (AWS) conditions in rats. The AWS in rats alcoholized according to Majchrowicz and Hunt leads to a pronounced dysbalance in the pool of free amino acids. It is established that tavamin is capable of normalizing the pool of free amino acids in rat heart against the AWS background.

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.

Caecal parameters of rats fed diets supplemented with inulin in exchange for sucrose

The effects of different modes of inulin supplementation on caecal fermentation were evaluated in rats. Groups S and IN were fed diets containing 5% of sucrose or inulin, respectively, for the whole experimental period of 40 days. Group IN/S was fed IN and S diets, whereas group S/IN was fed S and IN diets, in the first and the second 20-day period, respectively. Groups INup and INdown were fed diets in which the content of inulin increased from 1 – 5% and decreased from 5 – 1%, every 8 days, respectively. The common effects of inulin on caecal fermentation, i.e. enlargement of tissue, acidification of digesta, a decrease in activities of potentially harmful bacterial enzymes (β-glucuronidase and β-glucosidase), and an increase in the total volatile fatty acids concentration and pool, were especially observed in the IN, S/IN and INup groups. The results suggested that the intensity of caecal fermentation is increased when inulin is present at a relatively high dietary level and that these changes are easily reversible after inulin withdrawal from feed.

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.

Different effects of difructose anhydride III and inulin-type fructans on caecal microbiota in rats

The effects of different kinds of inulin-type fructans on caecal microbiota were evaluated in rats. Four groups of male Wistar rats were fed either a control diet, or diets containing 5% inulin, 5% fructooligosaccharides (FOS), or 5% difructose anhydride III (DFAIII) for two weeks. In the DFAIII group, caecal propionate, butyrate, counts of bifidobacteria, and total anaerobes were lower than in the inulin group, while caecal propionate, succinate, counts of bifidobacteria, and total anaerobes were lower than in the FOS group. Compared to controls, in the DFAIII group the counts of clostridia in caecum were increased by 3 log units. However, this change was statistically not significant. There were no differences between inulin and FOS groups for the pool of short chain fatty acids in caecum and bacterial counts. Results indicate that DFAIII has different effects on caecal microbiota compared to inulin and FOS and that these differences are most likely due to the α(3→2) bonds in DFAIII.

Microbial utilization of lipids in lake water

This report evaluates the importance of lipids as a source of substrates for metabolism of heterotrophic bacteria based on measurements of uptake of [3H]palmitic acid and lipase activity in lakes of differing degrees of eutrophication. The highest rates of utilization of lipids by bacteria (i.e. specific and actual rates of uptake of [3H]palmitic acid and specific lipase activity) were observed in pelagic water of mesotrophic lake where the highest concentration and the shortest turnover time of natural pool of palmitic acid was found. Lipids in highly eutrophicated lakes were less important for metabolism of aquatic bacterial communities. Lipid content in lake water depended on species composition of plankton in the studied lakes.

Cellular Regulation of Phospholipid Biosynthesis

How do cells homeostatically regulate the lipid composition of their membranes? Phospholipid metabolism in yeast is coordinately repressed by the transcription factor Opi1p, which in turn is activated by extracellular inositol. Loewen et al. now show that there is a pool of phosphatidic acid (PA) on the endoplasmic reticulum (ER) that is highly sensitive to growth conditions, in particular to the presence of exogenous inositol. This PA is directly sensed by the soluble transcriptional repressor Opi1p, which binds to PA in the ER and prevents it from entering the nucleus and altering transcription. When inositol is restored to cells, the Opi1p-associated PA is metabolized, which releases the Opi1p from the ER and allows its entry into the nucleus. C. J. Loewen, M. L. Gaspar, S. A. Jesch, C. Delon, N. T. Ktistakis, S. A. Henry, T. P. Levine, Phospholipid metabolism regulated by a transcription factor sensing phosphatidic acid. Science 304, 1644-1647 (2004). [Abstract] [Full Text]

Metabolic effects of mixture containing branched-chain amino acids and taurine during subchronic poisoning with barbiturates.

We studied the effect of a mixture containing branched-chain amino acids and taurine on the pool of free amino acids and their derivatives during chronic phenobarbital poisoning. Subchronic barbiturate poisoning produced by daily intraperitoneal injection of phenobarbital caused imbalance in the content of some amino acids in blood plasma and liver of rats. Treatment with the mixture of branched-chain amino acids and taurine normalized the content of amino acids in the liver and blood plasma of animals with subchronic phenobarbital poisoning. The mixture of branched-chain amino acids and taurine corrects metabolic processes and normalized the peripheral pool of amino acids. Our findings extend the range for application of amino acids in clinical practice.

DNA-bound lipids: computer modeling of DNA interaction with stearic acid and unsaturated fatty acids

It was shown for the first time by computer experiments that fatty acids are strongly bound to DNA. This is consistent with the presence of free fatty acids in the specimens of DNA-bound lipids isolated from various cells. Binding of all fatty acids to the DNA minor groove is stronger than to the major groove, which is correlated with the presence of two pools of free fatty acids isolated from DNA specimens by biochemical methods. Since DNA polymerase is also bound to the DNA minor groove, fatty acids can play an important role in the regulation mechanism of DNA replication and signal transmission. The energy of interaction of fatty acids with DNA depends on both the number of double bonds and the geometric configuration of the fatty acid and the nucleotide composition of DNA. Dependence on the bond energy in the DNA—fatty acid complex on the nucleotide composition attests to the possibility of site-specific binding of lipids to DNA. On passing from a saturated fatty acid to unsaturated acids containing one, two, or three double trans-bonds, the bond energy of DNA with the fatty acid gradually decreases. The presence of one or three double cis-bonds results in weakening of the strength of the DNA—fatty acid complexes compared to those with the saturated acid. The strongest binding between DNA and fatty acid was found for the unsaturated acid with two double cis-bonds (linoleic). This can be explained by the fact that the bent (boomerang) shape of the molecule of this acid follows the curve of the DNA helix. The pattern of variation of the energy of DNA complexes with stearic, linoleic, oleic, and linolenic acids correlates with experimental data on the melting points of these complexes: the more stable the DNA—fatty acid complex, the lower the melting point of DNA.

Modulation of berberine bridge enzyme levels in transgenic root cultures of California poppy alters the accumulation of benzophenanthridine alkaloids.

California poppy (Eschscholzia californica Cham.) root cultures produce a variety of benzophenanthridine alkaloids, such as sanguinarine, chelirubine and macarpine, with potent biological activity. Sense and antisense constructs of genes encoding the berberine bridge enzyme (BBE) were introduced into California poppy root cultures. Transgenic roots expressing BBE from opium poppy (Papaver somniferum L.) displayed higher levels of BBE mRNA, protein and enzyme activity, and increased accumulation of benzophenanthridine alkaloids compared to control roots transformed with a beta-glucuronidase gene. In contrast, roots transformed with an antisense-BBE construct from California poppy had lower levels of BBE mRNA and enzyme activity, and reduced benzophenanthridine alkaloid accumulation, relative to controls. Pathway intermediates were not detected in any transgenic root lines. Suppression of benzophenanthridine alkaloid biosynthesis using antisense-BBE also reduced the growth rate of the root cultures. Two-dimensional 1H-NMR spectroscopy showed no difference in the abundance of carbohydrate metabolites in the various transgenic roots lines. However, transformed roots with low levels of benzophenanthridine alkaloids contained larger cellular pools of certain amino acids compared to controls. In contrast, cellular pools of several amino acids were reduced in transgenic roots with elevated benzophenanthridine alkaloid levels relative to controls. The relative abundance of tyrosine, from which benzophenanthridine alkaloids are derived, was only marginally altered in all transgenic root lines; thus, altering metabolic flux through benzophenanthridine alkaloid pathways can affect cellular pools of specific amino acids. Consideration of such interactions is important for the design of metabolic engineering strategies that target benzophenanthridine alkaloid biosynthesis.

Free and Bound Amino Acids during Germination of Maize Seed with Preincorporated Foreign Prolamines

Wheat prolamines were preincorporated into the endosperm of maize seed, and concentrations of free and bound amino acids were measured in the endosperm and seedlings during seed germination. Incorporation of foreign prolamines lowered the rate of decrease of free proline concentration in both the endosperm (sprouting and shoots) and the embryo (sprouting). The seedlings at the stage of shoots were characterized by higher concentrations of aspartic acid, glutamic acid, and tyrosine. At the stage of transition to autotrophic nutrition, the pool of amino acids that are physiologically important for plant growth was greater in maize seedlings with incorporated wheat prolamines.

EFFECT OF NITROGEN STRESS ON GROWTH, SOLUBLE METABOLITES, AND GLUTAMINE SYNTHETASE ACTIVITY OF JACK PINE CALLUS CULTURES

Jack pine (Pinus banksiana Lamb.) callus cultures were grown in half-strength unmodified Litvay medium (control) and in media containing either no-nitrogen or nitrate. Almost no growth occurred in absence of nitrogen and in medium containing only nitrate. Glutamine synthetase (GS) activity was drastically reduced in comparison to callus grown in control medium. The pool of amino acids decreased by 66% in medium containing nitrate, and further by 50% in absence of nitrogen. Meanwhile total and reducing sugars sharply increased, and were 14 times higher in N-NO3 − and 22 times higher in nitrogen-free medium. Thirteen amino acids were identified in the control. Changes in the abundance and the relative content of amino acids confirmed that glutamine is the preferred nitrogen transport compound in Pinus. Jack pine cultures seemed to have a low capacity for nitrate uptake and assimilation as shown by the low GS activity and the decrease of glutamine content in nitrate-fed calli.

Dose dependence effects of ionizing radiation on bile acid metabolism in the rat

Purpose : To study radiation dose-related changes of individual or total bile acids in various physiological fluids in order to identify potential bio-indicators of radiation-induced gastrointestinal injuries. Materials and methods : Wistar rats were sham- or whole-body gamma irradiated (1-12Gy). Total and individual bile acids were quantified, 3 days after exposure, in bile collected after catheterization of the bile duct. Total bile acid concentrations were also measured in plasma and colonic contents 1, 2 and 3 days after irradiation. These concentrations were determined by an enzymatic method whereas individual bile acids were quantified by HPLC. Results : In bile, whereas total bile acid concentration remained unchanged after irradiation whatever the dose, the proportion of dihydroxy bile acids in the pool of total bile acids was gradually increased with the irradiation dose, especially from 8 Gy. In plasma samples, total bile acid concentrations fell for doses higher than 10 Gy. In colonic contents, bile acid concentrations increased progressively with time (from 1 to 3 days) and with irradiation dose (from 1 to 12Gy), reaching a plateau 3 days after exposure for doses higher than 10 Gy. Conclusions : These results show that changes in colonic bile acid concentrations which are reflected in faeces are perhaps a useful parameter to improve diagnosis and prognosis of radiationinduced gastrointestinal damage since it probably reflects directly intestinal bile acid malabsorption.

Metabolism of chylomicron cholesterol is delayed by estrogen. An in vivo study in the rat.

In order to test the effects of estrogen on the clearance of cholesterol of dietary origin from the blood and its elimination from the body via the bile in an in vivo animal model, the fate of radioactivity from intravenously injected [3H]cholesterol-labeled chylomicrons was investigated in the rat. The labeled lipoproteins were administered intrajugularly to male rats previously given 17alpha ethinyl estradiol or the vehicle only, and the removal of the radioactivity from the blood and its uptake by the liver and secretion into bile was determined. Experiments were carried out in animals with or without prior drainage (20 hr) of the pool of bile acids in the enterohepatic circulation, to take account of the different demands of the liver for cholesterol in the two conditions. In rats without biliary drainage, estrogen treatment decreased the rate of removal of radioactivity from the blood by about 30% and the recovery of cholesterol in the liver by about 50% in the first 30 min after injection of the labeled chylomicrons. After biliary drainage, however, the recovery of label in the liver after 90 min was similar in estrogen-treated and control animals, although its secretion into bile was markedly reduced in the estrogen-treated group (total biliary secretion in 90 min was 26% of the value found in control rats). In addition, the apolipoprotein E (aopE) content of the serum total lipoproteins was markedly reduced by estrogen. These results provide direct evidence indicating that estrogen retards the elimination of dietary cholesterol from the body via the bile in the rat, and this is likely to be mainly due to a reduced level of apoE in chylomicrons. In view of this, we suggest that the hypothesis that estrogen increases the hepatic uptake of chylomicron cholesterol, and its excretion in the bile during contraceptive and hormone replacement therapy should be re-examined.

Molecular cloning of a novel pathogen-inducible cDNA encoding a putative acyl-CoA synthetase from Capsicum annuum L.

By means of differential display, a pool of salicylic acid (SA)-induced mRNAs were identified and subsequently their cDNAs were isolated from a cDNA library prepared from SA-induced leaf tissues of hot pepper. One of these cDNA clones, designated CaSIG4, was 1900 bp and contained an open reading frame encoding 523 amino acids with a calculated molecular mass of 56.3 kDa. The predicted amino acid sequence of CaSIG4 showed high sequence similarity to the AMP-binding protein family of both prokaryotic and eukaryotic acyl-CoA synthetases. CaSIG4 transcripts accumulated rapidly after SA treatment and in response to both incompatible and compatible interactions with Xanthomonas campestris pv. vesicatoria race 1. To investigate the cis-acting elements mediating CaSIG4 expression, the CaSIG4 5'-flanking region was isolated by inverse PCR. Database searches indicated that a potential cis-regulatory element is almost identical to the consensus core sequences ACC(A/T)ACC(A/C) which are conserved among promoters of other phenylpropanoid biosynthetic genes. The subcellular localization of the CaSIG4 protein was studied by using a soluble modified GFP gene fusion delivered into epidermal cells of onion by biolistic bombardment. The CaSIG4-smGFP fusion protein was localized to the plasma membrane. Taken together, CaSIG4 encoding a putative acyl-CoA synthetase could function as a plasma membrane-bound protein with a role in signaling in plant defense.

Chemical changes in fed and starved larval trout cod, Maccullochella macquarensis during early development

The changes in proximate composition, amino acid (total and free) and fatty acid content of artificially propagated trout cod, Maccullochella macquariensis larvae from five mothers hatched, weaned and reared separately, each in two groups, one fed with Artemia naupli and the other starved, for 15 days (after yolk resorption), are presented. There was no significant change in the proximate composition of fed larvae with devlopment, but in starved larvae the protein (linearly) and lipid (curvi-linearly) content decreased significantly as starvation progressed. The essential amino acids (EAA) and non- essential amino acids (NEAA) found in highest amounts in trout cod larvae were lysine, leucine, threonine and arginine, and alanine, serine and glutamic acid, respectively. In fed larvae the total amino acid (TAA), TEAA and TNEAA content did not vary significantly as development progressed. In starved larvae the TAA, EAA and NEAA content, as well as all the individual amino acids decreased significantly (P<0.05) from the levels in day of hatch and/or yolk-sac resorbed larvae. The greatest decrease occurred in the TEAA content (7.38±0.76 at day of hatch to 1.96±0.09 15 day starved in μmoles larva−1; approximately a 74% decrease), whereas the decrease in TNEAA was about 38%. Unlike in the case of TAA distinct changes in the free amino acid (FAA) pool were discernible, from day of hatch and onwards, in both fed and starved trout cod larvae. In both groups of larvae the most noticeable being the decrease of % FEAA in TFAA, but not the % FAA in TAA. Four fatty acids together, accounted for more than 50% of the total in each of the major fatty acid categories in all larvae sampled; 16: 0, 18:1n-9, 22: 6n-3 and 20: 4n-6, amongst saturates, monoenes, n-3 PUFA and n-6 PUFA, respectively. Twelve fatty acids either decreased (14: 0, 16: 1n-7, 20: 1n-9, 20: 4n-6, 20: 5n-3, 22: 5n-3 and 22: 6n-3) or increased (18: 2n-6, 18: 3n-3, 18: 3n-6, 18: 4n-3 and 20: 3n-3) in quantity, after 15 days of feeding, from the base level in day of hatch and/ or yolk- sac resorbed larvae. The greatest increase occurred in 18: 3n-3 from 6.4±0.1 to 106.2±13.1 μg mg lipid−1 larva−1, and the greatest decrease occurred in 22: 6n-3 (181.2±12.4 to 81.4±6.2 μg mg lipid−1 larva−1). In starved larvae, at the end of 15 days, all the fatty acids, except 18: 0, 20: 3n-3 and 20: 4n-6, decreased significantly (P<0.05) from the levels in day of hatch and/or yolk- sac resorbed larvae.

Keeping Cholesterol in Check

Controlling the absorption of dietary cholesterol from the digestive tract is an integral part of maintaining whole-body cholesterol homeostasis. Repa et al . (see the news story by Ferber) report that certain nuclear steroid receptors regulate this process. One nuclear receptor heterodimer stimulates the expression of a transmembrane protein of the ABC-binding cassette family and facilitates cholesterol efflux from intestinal cells. Another receptor heterodimer decreases the pool of bile acids in the liver, molecules that are needed to absorb free cholesterol. These activities serve to reverse cholesterol transport and to decrease absorption of cholesterol and further expand the roles of nuclear steroid receptors in maintaining cholesterol homeostasis. Repa, J.J., Turley, S.D., Lobaccaro, J.-M. A., Median, J., Li, L., Lustig, K., Shan, B., Heyman, R.A., Dietschy, J.M., and Mangelsdorf, D.J. (2000) Regulation of absorption and ABC1-mediated efflux of cholesterol by RXR heterodimers. Science 289 : 1524-1529. [Abstract] [Full Text] Ferber, D. (2000) Possible new way to lower cholesterol. Science 289 : 1446-1447. [Full Text]

Aspects of the distribution and movement of aluminium in the surface of the Te Kopia geothermal field, Taupo Volcanic Zone, New Zealand

The principal Al-bearing components of two surface quadrats in the central Te Kopia geothermal field are the atmosphere, substrate (∼10 wt% Al in ignimbrite, clay and protosoils, 0.3–0.6 Al wt% in sinter), vegetation (4–5 g Al/m 2) and waters (1–4 μg/g Al in semi-permanent acid surface waters, 6–9 μg/g in acid pools, 10–14 μg/g in post-rain, ephemeral streams and pools). About 0.7 g/ha/a of Al is received from the atmosphere. Water transports Al in and out of each quadrat and distributes it between the different components. During initial alteration of the parent ignimbrite by alkali chloride water in the deep reservoir, Al either remained within the quadrat boundaries or transfers out were balanced by contemporaneous gains. Subsequently, alteration by acid sulfate fluids redistributes elements into new mineral assemblages but again with no net movement of Al in or out of either quadrat. The latest, surface alteration event involves interaction of all the previously and variously altered rocks by steam, gases and steam condensate. A primary product of this process is transient, hydrated, Al-rich, water-soluble sulfate efflorescences whose persistence indicates a steady flux of Al at the surface. The magnitude of this flux depends on available moisture and the activities of H +, SiO 4− 4, SO 2− 4 and K + such that variations in the rate of discharge of Al alone may be used to detect changes in surface conditions as may result from exploitation of a geothermal field.

Effects of inhibitors of arachidonic acid turnover on the production of prostaglandins by the guinea-pig uterus.

The supply of free arachidonic acid from phospholipids is generally regarded as the rate-limiting step for prostaglandin (PG) synthesis by tissues. Two enzymes involved in arachidonic acid uptake into, and release from, phospholipids are acyl-CoA:lysophospholipid acyltransferase (ACLAT) and phospholipase A2 (PLA2), respectively. PGF2 alpha produced by the endometrium induces luteolysis in several species including guinea-pigs. Thimerosal, an inhibitor of ACLAT, and aristolochic acid, an inhibitor of PLA2, both reduced, in a concentration-dependent manner, the output of PGF2 alpha from guinea-pig endometrium cultured for 24 h on days 7 and 15 of the oestrous cycle. This study showed that the continual production of PGF 2 alpha by guinea-pig endometrium is not only dependent upon the activity of PLA2 for releasing free arachidonic acid for PGF2 alpha synthesis, but also on the incorporation of arachidonic acid into the phospholipid pool by the activity of ACLAT. The inhibitory effects of thimerosal and aristolochic acid on the outputs of PGE2 and 6-keto-PGF1 alpha were less marked, particularly on day 7 when the low output of PGE2 was unaffected and the output of 6-keto-PGF1 alpha was increased at the lower concentrations of thimerosal. This finding indicates that there are different pools of arachidonic acid bound as phospholipid for the syntheses of PGF2 alpha and 6-keto-PGF1 alpha by guinea-pig endometrium.

Monocarboxylic, dicarboxylic and hydroxy acids released by sequential treatments of suspended particles and sediments of the Black Sea

Highly variable mixtures of free and bound monocarboxylic, dicarboxylic and hydroxy acids are present in particulate matter from oxic and anoxic zones of the water column and underlying sediments of the Black Sea. Three pools of acids were obtained by sequential treatment: (1) an organic solvent-extractable free fraction, (2) an OH −-labile fraction released by alkaline hydrolysis of the solvent-extracted material, and (3) a H +-fraction obtained by acid hydrolysis of extracted and base-hydrolysed material. Monocarboxylic acids quantitatively dominated acid distributions in particles and sediments, but hydroxy [α-, β-, ω- and (ω-1)] acids were relatively enriched in particles from the anoxic zone and in sediments, reaching nearly 30% of total acids. β-Hydroxy acids were the most abundant hydroxy acids, being present in all particulate and sediment samples. α-, ω- and (ω-1)-Hydroxy acids were found only in sediments and then at low relative abundances. Distributions of carboxylic and hydroxy acids varied considerably between the three treatments and between oxic-zone particles, anoxic-zone particles, and sediment. Results are discussed in terms of biogeochemical mechanisms of differential production, degradation and preservation.