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PubMed1977

Metabolism of protein and RNA in liver of rats deprived of tryptophan.

Rat lost body weight after the second day of feeding a tryptophan free diet. After 15 days of tryptophan deprivation, they had lost 17% of body weight, whereas pair-fed controls had gained weight. Liver weights of deprived rats were significantly lower than those of controls. Water, protein, RNA, and DNA in the livers were not significantly changed after 15 days of tryptophan deprivation. Amounts of free typtophan and alanine in livers of derpived rats decreased to 40% of the controls after 15 days, whereas amounts of most other amino acids were nearly constant. Protein synthesis in livers of deprived rats for 15 days was impaired to about 55% of controls. Incorporation of orotic acid into different types of cytoplasmatic and nuclear RNA remained unaffected up to the tenth day. After 15 days of deprivation, more orotic acid had been incorporated into RNA fractions that correspond to the precursor ribosomal fractions.

Amino Acids↗
PubMed1981

[DNA methylation in wheat seedling and influence of phytohormones].

A labelled DNA is synthesized in the etiolated wheat seedlings 72 hrs after a single addition of [2-14C]orotic acid (1 mCi per 250 seedlings). This DNA does not differ in the methylation degree of cytosine residues and base composition (radioactivity ratios 100.m5C/(C+m5C) and T/(C++m5C) from total seeding DNA. Thus, the radioactivity ratio 100.m5C/(C+m5C) represents in fact the methylation degree of cytosine residues in labelled DNA, and [2-14C]orotic acid can be used for the study of DNA methylation in higher plants. The newly synthesized DNA (21 hr incubation of seedlings with radioactive precursor) is methylated about 2 times less in comparison with fully synthesized radioactive DNA and total seedling DNA. This supports the assumption on a step-wise character of replicative DNA methylation in plants. Phenylacetic acid (30 mg/l) and 6-benzylaminopurine (l mg/l) do not influence the post-replicative DNA methylation, but auxin (FAA) very strongly inhibits the replicative DNA methylation. The phytohormone-induced changes in replicative DNA methylation are considered as a possible mechanism for regulation of DNA replication and, probably, of cell differentiation in higher plants.

Adenine↗
PubMed1975

RNA synthesis in liver nuclei of young rats fed varying amounts of vitamin A.

Twenty five days old male rats were feed 5000, 20000 and 40000 I.U. of vitamin A for two days and its effects studied on RNA contents and its synthesis from orotic acid-6(-14)C in liver and its nuclear and mitochondrial fractions. RNA contents and its synthesis from orotic acid-6(-14)C in liver, its nuclear and mitochondrial fractions was not affected in rats 5000 I.U. of vitamin A, but these were reduced in rats fed 20000 and 40000 I.U. of vitamin A. The turnover rate of nuclear RNA was significantly greater in rats fed 5000 I.U. of vitamin A as compared to the controls.

Animals↗
PubMed1982

Carrier detection in ornithine transcarbamylase deficiency.

We have studied six known heterozygotes for ornithine transcarbamylase (McKusick 31125; OTC) deficiency. All had abnormal results when tested by measurement of urine orotic acid after protein loading. Duodenal mucosa OTC assay detected fewer of the known heterozygotes but was a useful supplementary test. Urine orotic acid excretion after protein loading is influenced by age and results from women being tested must be compared with those from controls of appropriate age.

Adolescent↗
PubMed2004

Alleviation of fatty liver by alpha-linolenic acid.

We compared the efficacy of alpha-linolenic acid (alpha-LNA, n-3) and linoleic acid (LA, n-6) on orotic acid (OA)-induced fatty liver in Sprague-Dawley rats. Rats were fed semi-synthetic diets containing either LA or alpha-LNA with or without 1% OA for 2 wk. OA supplementation lowered serum lipids in LA+OA groups. In addition to the decline of serum lipids in alpha-LNA groups compared to LA groups, a further decrease was found in alpha-LNA+OA groups compared to LA+OA groups. OA-containing diets significantly increased the liver weights and triacylglycerol (TG) accumulations compared with the OA-free diets. These results were attributed to the significant increases in the activities of phosphatidate phosphohydrolase (PAP), a rate-limiting enzyme of TG synthesis, and glucose-6-phosphate dehydrogenase, a fatty acid synthesis-related enzyme. However, the increase of PAP activity was significantly less in the alpha-LNA+OA group as compared with the LA+OA group. These results suggest that dietary alpha-LNA alleviates OA-induced hepatic TG accumulation through the attenuation of hepatic TG synthesis in rats.

Animals↗
PubMed1985

Nutritional requirements of Plasmodium falciparum in culture. III. Further observations on essential nutrients and antimetabolites.

In a semi-defined minimal medium for cultivation of Plasmodium falciparum, ribose, mannose, fructose, galactose, and maltose could not replace glucose. Hypoxanthine was the preferred purine source for the parasite over adenine, guanine, inosine, adenosine and guanosine although all supported growth equally. Inhibitors of nucleoside uptake had low potency in killing the parasites but depressed incorporation of [3H]adenosine more than [3H]hypoxanthine. Glutamate could not be replaced by 5-oxoproline, indicating that the gamma-glutamyl transferase pathway for amino acid uptake is probably not found in this organism. Adenine, nicotinamide, and orotic acid could not supplement glutamine-deficient medium. The pyridoxine antagonists isoniazid and 4-deoxypyridoxine were reversed by amino acid supplementation, suggesting that transaminases may be targets of these drugs. Orotic acid, but not glutathione or its amino acid components, partially reversed the effects of 8-methylamino-8-desmethyl riboflavin. Thus, the flavin enzyme, dihydroorotic acid dehydrogenase, but not glutathione reductase, appears to be a target of this riboflavin antagonist. Five biotin antagonists had no significant activity. The choline antagonist 2-(tert-butylamino)ethanol and thiamin uptake inhibitors had nonspecific inhibitory effects, which were not reversed by the respective target vitamin. Buthionine sulfoximine and methionine sulfoximine, inhibitors of glutathione synthesis, had significant oxygen-dependent toxicity. Six sulfonamides showed marked variation in potency and efficacy. Sulfathiazole and sulfadoxine were reversed differentially by p-aminobenzoic acid, folic acid, and folinic acid. Folinic acid was more effective than folic acid at reversing the toxicity of the dihydrofolate reductase inhibitors aminopterin and pyrimethamine; p-amino-benzoic acid had no effect.

4-Aminobenzoic Acid↗
PubMed1984

Occurrence of cell death (apoptosis) in preneoplastic and neoplastic liver cells. A sequential study.

A sequential study was performed to investigate the occurrence of cell death in preneoplastic and neoplastic liver cells of F-344 rats. The animals were administered a single initiator dose of 1,2-dimethylhydrazine and were then subjected to a liver carcinogenesis promotion regimen, consisting of a diet containing 1% orotic acid. Cell death, morphologically similar to that described as apoptosis, was evident in foci of preneoplastic hepatocytes at 10 weeks after orotic acid feeding. An increased frequency of apoptotic bodies was observed in nodules, but not in the surrounding liver, 20 weeks after starting the dietary regimen, and in hepatocellular carcinomas that developed after 1 year of continuous promotion. Occurrence of this type of cell death was also observed in liver foci of rats subjected to two other promoting regimens, suggesting, thus, a possible relevance of apoptosis to the carcinogenic process in the liver.

Animals↗
PubMedDate not supplied

[Effect of hydrocortisone on the state of liver chromatin in rats of different age].

Hydrocortisone (5 mg/100 g) injected intraperitoneally induced redistribution of hepatic chromatin fractions in pubertal (aged 6--8 months) and old (aged 24--26 months) rats. Changes in the content of these chromatin fractions begin earlier and end later in old animals. Hydrocortisone stimulated 14C-orotic acid incorporation into RNA of active and inactive hepatic chromatin in rats of both age groups. The maximal incorporation of 14C-orotic acid into RNA of inactive chromatin in pubertal rats occurred 7 hours after the hormone administration, and in old rats after 4 hours; in case of active chromatin these figures were 17 and 6 hours, respectively.

Aging↗
PubMed1988

Intestinal very-low-density lipoprotein secretion in the genetically obese Zucker rat.

The objectives of this study were to measure intestinal very-low-density lipoprotein (VLDL) production in obese Zucker rats and to assess an eventual effect of a high-fat diet. VLDL secretion was specifically inhibited by orotic acid, and intestinal VLDL output was measured following the Triton WR-1339 method. After a control diet, total VLDL secretion (without orotic acid) was 4.8 +/- 0.3 and 1.4 +/- 0.1 mg triacylglycerol/ml in obese and lean rats, respectively, decreasing by 30% in obese rats after fat-feeding. Intestinal VLDL production was similar in obese and lean rats fed the control diet (0.32 +/- 0.05 and 0.27 +/- 0.05 mg triacylglycerol/ml, respectively), increasing 2.5-fold after fat-feeding in both genotypes. Thus, intestine contributed 21 and 60% of total VLDL in lean but only 7 and 24% in obese rats with the control and high-fat diets, respectively. These results show that the intestine of obese Zucker rats does not contribute to their hypertriglyceridemia, suggesting that it originates solely from liver. Moreover, their intestinal VLDL production was stimulated by fat-feeding to the same extent as in lean animals.

Animals↗
PubMed1975

Determination of urinary carbamylaspartate and dihydro-orotate in normal subjects and in patients with hereditary orotic aciduria.

An isotope dilution assay for urinary dihydro-orotic acid and carbamylaspartic acid (CAA) has been developed which has been shown to yield accurate measurements for these pyrimidine precurosrs. Dihydro-orotic acid could not be detected in 24-hour urine specimens from 10 normal adults and 7 normal children, or in specimens from 2 children with hereditary orotic aciduria Type I. Small amounts (approximately 10 mumole per 24 hours) of carbamylaspartic acid are excreted in normal urine, and there was a modest elevation in CAA excretion in the 2 patients with hereditary orotic aciduria.

Adult↗
PubMed1999

Large-scale production of N-acetyllactosamine through bacterial coupling.

A large-scale production system of N-acetyllactosamine, a core structure of various oligosaccharides, was established by a whole-cell reaction through the combination of recombinant Escherichia coli strains and Corynebacterium ammoniagenes. Two recombinant E. coli strains over-expressed the UDP-Gal biosynthetic genes and the beta-(1-->4)-galactosyltransferase gene of Neisseria gonorrhoeae, respectively. C. ammoniagenes contributed the production of UTP from orotic acid. N-Acetyllactosamine was accumulated at 279 mM (107 g L-1) after a 38 h reaction (2.5 L in volume) starting from orotic acid, D-galactose, and 2-acetamido-2-deoxy-D-glucose.

Acetylglucosamine↗
PubMed1981

Codon-specific serine transfer ribonucleic acid degradation in avian liver during vitellogenin induction.

The relative rates of degradation of two major tRNASer species in rooster liver were simultaneously assessed during induction by estradiol-17 beta benzoate of the synthesis of a serine-rich phosphoprotein, vitellogenin. The relative rate of degradation was determined by an in vivo pulse-chase labeling method, which included a 24-h labeling period with [5-3H]orotic acid prior to and a 6-day chase period with nonradioactive orotic acid after the administration of estrogen. tRNA Ser(AGU,C) and tRNASer (UCU,C,A) were extensively purified by chromatography on benzoylated DEAE-cellulose in the presence and absence of Mg2+ and their radioactivities determined. In three separate labeling experiments, the difference in radioactivity of pulse-labeled and chased tRNASer (AGU,C) vs. that of tRNASer(UCU,C,A) was approximately 2-fold, suggesting a slower rate of degradation of tRNASer(AGU,C) during vitellogenin induction. Calculation of the approximate half-lives of the two tRNASer species indicates that the half-life of tRNASer (AGU,C) was increased from 3.1 days to 6.2 days during vitellogenin induction, while that of tRNASer (UCU,C,A) was essentially unchanged (2.6 days). Regulation of tRNA degradation which is possibly connected with the frequency of its use in ribosomal protein synthesis may help to explain why, in many differentiated cells, the tRNA population is adapted to the amino acid composition of the synthesized proteins.

Animals↗
PubMedDate not supplied

[Biosynthesis of pyrimidine nucleotides in normal and regenerating bone tissue].

RNA from bone tissue of healthy animals exhibited low specific radioactivity, when labelled orotic acid was used as precursor. These data suggest that the ability of sceletogenic cells to carry of formation of pyrimidine nucleotides was low. Labelled orotic acid and uridine were incorporated rapidly into regenerating bone tissue during the last days of the first week after the beginning of the regeneration process, gradually decreasing in course of maturation of the regenerated tissue.

Animals↗
PubMed1967

A direct effect of growth hormone on the incorporation of precursors into proteins and nucleic acids of perfused rat liver.

1. The livers of rats were perfused in situ. When the amino acid concentration in the perfusing medium was that present in rat plasma, the addition of growth hormone to the medium stimulated the incorporation of labelled amino acids into liver protein only marginally and not to a statistically significant extent. When, however, the amino acid concentration was raised to three times that present in rat plasma, growth hormone significantly and substantially stimulated amino acid incorporation into protein within 30min. of perfusion of normal rat liver. 2. A significant effect of growth hormone on labelling of normal rat-liver protein was seen with concentrations not much greater than those reported to be present in rat plasma. 3. The labelling of nucleic acids of normal and hypophysectomized rat liver by [(3)H]orotic acid was enhanced by addition of growth hormone to the perfusing medium when normal concentrations of amino acids were used. 4. At elevated concentrations of amino acids, growth hormone stimulated labelling of nucleic acids of hypophysectomized rat liver at 30 and 60min. of perfusion. Under these conditions, nucleic acids of normal rats were labelled to about the same extent in control and hormone-treated livers at 30min. and, because of a fall in the radioactivity of the control livers, there was more labelled nucleic acids in growth-hormone-treated livers at 60min. than in the control livers. 5. Growth hormone, unlike insulin, had no inhibitory effect on the release of glucose by the perfused liver. 6. It is concluded that growth hormone can stimulate the incorporation of precursor into proteins and nucleic acids of liver directly and without the mediation of other organs or of insulin.

Animals↗
PubMed1986

Growth of Lactobacillus bulgaricus in milk. 2. Characteristics of purine nucleotides, pyrimidine nucleotides, and nucleic acid synthesis.

Lactobacillus bulgaricus incorporated exogenous guanine only into guanine nucleotides and not into adenine nucleotides. Lactobacillus bulgaricus lacks the ability to interconvert adenine nucleotides and guanine nucleotides. Biosynthesis of pyrimidine nucleotides from orotic acid was depressed by addition of guanosine monophosphate or adenosine monophosphate. Some step in pyrimidine biosynthesis from orotic acid may be negatively regulated by the intracellular amount of purine nucleotides. Lactobacillus bulgaricus could not grow in milk from which orotate was removed. This indicates that the activity of de novo pyrimidine synthesis is very low in this organism. When the intracellular amount of purine or pyrimidine base was limited, ribonucleic acid synthesis was markedly depressed, resulting in cell elongation, whereas deoxyribonucleic acid synthesis was not so much affected.

Adenine↗
PubMed1993

Argininosuccinic aciduria: clinical and biochemical findings in three children with the late onset form, with special emphasis on cerebrospinal fluid findings of amino acids and pyrimidines.

Three children with the late onset form of argininosuccinic aciduria are presented. The first two are sisters. The clinical features are characterized by mild retardation and ataxia, complicated by episodes of hyperammonemia. All patients showed elevated concentrations of argininosuccinic acid and its anhydrides in all body fluids, most pronounced in cerebrospinal fluid (CSF). Moreover, in Cases 1 and 2, we found elevated concentrations of pseudouridine and uridine limited to CSF, which was not reported before. In Case 3, with some residual activity of argininosuccinate lyase (ASL), we found normal values of these compounds. In urine we found elevated concentrations of uracil in Cases 1 and 2, and orotic acid in Case 2. Plasma showed an elevated concentration of orotic acid in all three patients, uracil was elevated in Case 2, cytidine was elevated in Cases 2 and 3. The results are being discussed and indicate that CSF values of pyrimidines reveal new biochemical abnormalities of brain tissue in urea cycle disorders.

Argininosuccinate Lyase↗
PubMed1970

The effect of whole-body x-irradiation of guinea pigs on liver ribonucleic acid synthesis.

1. Liver RNA synthesis was studied within 24h after whole-body X-irradiation of guinea pigs that had been starved for 22-24h. 2. Microsomal RNA was labelled in vivo for 3h with [(14)C]orotic acid and the isolated labelled RNA was fractionated by sucrose-density-gradient centrifugation. Incorporation was 50-100% higher between 3 and 12h after 2000rd X-irradiation and at 22h was not elevated any further. Whole nuclear RNA was labelled with [(14)C]orotic acid for 15min. At 5h after irradiation the incorporation showed a 50-100% increase. Incorporation increased in all types of RNA studied. 3. The RNA phosphorus/DNA phosphorus ratio of whole liver gradually increased after X-irradiation. Maximal increase was found between 24 and 36h, which corresponds to a value about 40% above that of the starved control. The RNA phosphorus content of isolated ribonucleoproteins obtained from various cell fractions of the liver was similarly increased after X-irradiation. 4. Liver microsomes were obtained from X-irradiated and control animals. Microsomes were incubated in vitro with [(14)C]phenylalanine in the presence and absence of polyuridylic acid. After the incubation the microsomes were fractionated by sucrose-density-gradient centrifugation. The polyuridylic acid enhancement was twice as great in the microsomes of the control preparation as in the irradiated one. The experiment demonstrated a higher saturation of microsomes by endogenous messenger after X-irradiation. 5. RNA polymerase activity of the purified nuclear preparation was assayed. The activity of the Mg(2+)-dependent RNA polymerase activity was 50 and 200% respectively above the control values at 6 and 9h after X-irradiation. 6. Animals were treated with actinomycin D shortly before X-irradiation. This treatment abolished the radiation-induced enrichment of polyribosomes and the increase of protein-synthesizing activity. The effect of X-irradiation on the transcription of the genetic code of the liver is discussed.

Animals↗
PubMed1981

Urinary pyrimidine excretion in arginase deficiency.

A high-performance liquid-chromatographic method was used to separate and identify uracil, uridine, pseudouridine and orotic acid after preliminary extraction in two patients (McKusick 20780). Urinary uracil excretion was 10-35 times normal in both patients with arginase deficiency. Uridine and orotic acid, not normally detected, were excreted in large amounts and were directly influenced by protein intake. Their excretions were correlated with urinary arginine excretion. Urinary uracil levels remained consistently high and showed minimal variations with increased protein intake or urinary arginine levels. The measurement of urinary pyrimidines appears to be useful for the detection, differential diagnosis and dietary monitoring of patients with urea cycle disorders. The data presented extends this observation to include patients with arginase deficiency.

Adolescent↗