Molecular cloning and bacterial expression of cDNA encoding a plant cysteine synthase

Cysteine synthase (CSase) [O-acetyl-L-serine acetate-lyase (adding hydrogen sulfide), EC 4.2.99.8] catalyzes the formation of L-cysteine, the key step in sulfur assimilation in plants, from O-acetyl-L-serine and hydrogen sulfide. We report here the isolation and characterization of cDNA clones encoding cysteine synthase from spinach (Spinacia oleracea L.). Internal peptide sequences were obtained from V8 protease-digested fragments of purified CSase. A lambda gt10 cDNA library was constructed from poly(A)+ RNA of young green leaves of spinach. Screening with two synthetic mixed nucleotides encoding the partial peptide sequences revealed 19 positively hybridized clones among 2 x 10(5) clones. Nucleotide sequence analysis of two independent cDNA clones revealed a continuous open reading frame encoding a polypeptide of 325 amino acids with a calculated molecular mass of 34,185 Da. Sequence comparison of the deduced amino acids revealed 53% identity with CSases of Escherichia coli and Salmonella typhimurium. Sequence homology was also observed with other metabolic enzymes for amino acids in bacteria and yeast and with rat hemoprotein H-450. A bacterial expression vector was constructed and could genetically complement an E. coli auxotroph that lacks CSases. The accumulation of functionally active spinach CSase in E. coli was also demonstrated by immunoblotting and assaying enzymatic activity. Southern hybridization analysis showed the presence of two to three copies of the cDNA sequence in the genome of spinach. RNA blot hybridization suggested constitutive expression in leaves and roots of spinach.

Effect of oligomers of ethylene glycol on thermotropic phase transition of dipalmitoylphosphatidylcholine multilamellar vesicles

The effect of oligomers of ethylene glycol (EG) on thermotropic phase transitions of dipalmitoylglycerophosphatidylcholine multilamellar vesicles (DPPC-MLV) were investigated. Diethylene glycol (di-EG) had a biphasic effect on transition temperature, reducing pre-transition temperature (Tp) at low concentrations but increasing main transition temperature (Tm) and extinguishing pre-transition at high concentration. Results of the X-ray diffraction method and the excimer method indicated that di-EG induced interdigitated gel phase (L beta 1 phase) in the DPPC membranes at high concentration. Phase diagram of temperature-di-EG concentration for DPPC-MLV was determined by use of X-ray diffraction and differential scanning calorimetry, which was similar to that of temperature-EG concentration. The minimum concentration of di-EG where L beta 1 phase was induced was 42%(w/v), which was larger than that of EG (30%(w/v)). On the other hand, in the presence of triethylene glycol (tri-EG), Tm and Tp increased with an increased in tri-EG concentration, as well as poly(ethylene glycol). These differences, between the effects of di-EG and those of tri-EG, might be due to the differences of their sizes.

Analgesic components from bornean medicinal plants, Tabernaemontana pauciflora Blume and Tabernaemontana pandacaqui Poir

The analgesic components were isolated from a Bornean medicinal plant, Tabernaemontana pauciflora Blume (syn. Ervatamia blumeana Mark gr.), and the major components were identified as coronaridine and 3-(2-oxopropyl)coronaridine. Four minor components were estimated to be 5R- and 5S-(2-oxopropyl)coronaridine, 3-(2-oxopropyl)voacangine and 3,3'-(oxopropyl)dicoronaridine, which might be produced during the isolation process. Voacangine was also isolated as a major component of T. pandacaqui Poir. Coronaridine and voacangine exhibited significant analgesic and hypothermic effects in mice at a dose of 25 mg/kg, p.o., while 3-(2-oxopropyl)coronaridine was less effective. The former two compounds also revealed a surface anesthesia.

Prothrombin fragment F1 + 2 and thrombin-antithrombin III complex are useful markers of the hypercoagulable state in atrial fibrillation

It is well known that atrial fibrillation (AF) is one of the most important diseases that predispose patients to thrombosis. We have attempted to identify patients with AF in the hypercoagulable state by measuring molecular markers such as thrombin-antithrombin III complex (TAT) and prothrombin fragment 1 + 2 (PTF) and determining the effect of antithrombotic therapy on these markers; 83 patients with AF were studied. Increased levels of plasma TAT and PTF were more frequently observed in patients with AF and associated mitral stenosis than in patients with AF alone. In cases of AF without mitral stenosis, plasma levels of TAT and PTF were significantly lower in those patients receiving antithrombotic agents (aspirin or warfarin) than in those receiving no antithrombotic agents. Furthermore, plasma levels of PTF were significantly lower in patients given warfarin than in those receiving aspirin. These results suggest that (1) patients with AF and mitral stenosis who are not given warfarin are in an extremely hypercoagulable state and (2) some patients with AF without mitral stenosis who are not given antithrombotic agents are also moderately hypercoagulable. In vivo activation of blood coagulation was more effectively controlled in patients receiving warfarin than in those taking aspirin.

[A case of Machado-Joseph disease--cerebral blood flow and cerebral metabolic rate of oxygen]

A 51-year-old woman, with progressive gait disturbance and dysarthria, had been diagnosed as Menzel-type spinocerebellar degeneration. Later, she developed dystonic posture of upper limbs and bulging eyes. She was diagnosed as Machado-Joseph disease from neurological findings, which consisted of cerebellar signs, pyramidal tract signs and extrapyramidal tract signs and peripheral neuropathy. She died suddenly of unknown origin. Her illness lasted about 13 years. Neuropathological findings showed moderate neuronal loss with gliosis in the subthalamic nucleus, globus pallidus, substantia nigra, dentate nucleus, oculomotor and hypoglossal nucleus and anterior horn. Positron emission tomography (PET) using 15O steady state inhalation technique revealed reduction of cerebral blood flow and cerebral metabolic rate of oxygen in not only cerebellum but also cerebral cortex. These findings are different from typical PET findings of spinocerebellar degeneration.

Formation of multicellular spheroids composed of rat hepatocytes

A novel method for the preparation of spheroids containing two types of cells (hetero-spheroid) has been successfully developed by using a collagen-conjugated thermo-responsive polymer, poly-N-isopropyl acrylamide, as a cell substratum. The hetero-spheroid was prepared by detaching the confluent monolayer composed of parenchymal and non-parenchymal rat liver cells at a temperature below lower critical solution temperature and culturing it on the non-adhesive substratum. The hetero-spheroid had activity in albumin secretion and PNPA hydrolase activity over a period of 60 days in dishes. These findings suggest that this spheroid formation system is a useful model of an alternative to animal tests of hepatotoxicity.

Biopolymers from marine invertebrates. XII. A novel cytolytic factor from a hermit crab, Clibanarius longitarsus

Bioactive polymers were sought in marine arthropoda and a novel cytolytic factor was found in a hermit crab, Clibanarius longitarsus. The partially purified factor showed activity in fractions corresponding to a molecular weight of about 10 kilodaltons on a Sephadex G-75 column. This cytolytic factor was halfmaximally active for tumor cells at 0.13-0.66 micrograms/ml and for normal cells at 1.9-82 micrograms/ml. Tumor lysis by the factor was time dependent and was complete within 12 h. This bioactive polymer was labile on heating, at low and high pH.

Cloning and functional expression of a cDNA encoding the mouse beta 2 subunit of the kainate-selective glutamate receptor channel

The primary structure of the mouse glutamate receptor beta 2 subunit has been deduced by cloning and sequencing cDNA. The beta 2 subunit has structural characteristics common to the subunits of glutamate-gated ion channels. Expression of the cloned cDNA in Xenopus oocytes yields functional glutamate receptor channels selective for kainate.

Transgenic herbicide-resistant Atropa belladonna using an Ri binary vector and inheritance of the transgenic trait

Transgenic Atropa belladonna conferred with a herbicide-resistant trait was obtained by transformation with an Ri plasmid binary vector and plant regeneration from hairy roots. We made a chimeric construct, pARK5, containing the bar gene encoding phosphinothricin acetyltransferase flanked with the promoter for cauliflower mosaic virus 35S RNA and the 3' end of the nos gene. Leaf discs of A. belladonna were infected with Agrobacterium rhizogenes harboring an Ri plasmid, pRi15834, and pARK5. Transformed hairy roots resistant to bialaphos (5 mg/l) were selected and plantlets were regenerated. The integration of T-DNAs from pRi15834 and pARK5 were confirmed by DNA-blot hybridization. Expression of the bar gene in transformed R0 tissues and in backcrossed F1 progeny with a nontransformant and self-fertilized progeny was indicated by enzymatic activity of the acetyltransferase. The transgenic plants showed resistance towards bialaphos and phosphinothricin. Tropane alkaloids of normal amounts were produced in the transformed regenerants. These results present a successful application of transformation with an Ri plasmid binary vector for conferring an agronomically useful trait to medicinal plants.

Biopolymers from marine invertebrates. XIII. Characterization of an antibacterial protein, dolabellanin A, from the albumen gland of the sea hare, Dolabella auricularia

An antibacterial factor, dolabellanin A, was purified from the albumen gland of a sea hare, Dolabella auricularia. Purified dolabellanin A was a glycoprotein of 250 kilodaltons consisting of 4 subunits, and showed both antibacterial and antineoplastic activities. The two activities were lost in parallel on heating and at low and high pH. This factor was half-maximally active for gram-positive and -negative bacteria at 0.018-0.48 microgram/ml, and its action was not bactericidal but bacteriostatic. Dolabellanin A did not induce morphological elongation of bacteria or the release of adenosine triphosphate, but it completely inhibited the syntheses of deoxyribonucleic acid (DNA) and ribonucleic acid by E. coli within 6 min. These results suggest that dolabellanin A, which is found in a marine invertebrate, the sea hare, is a new antibacterial protein, and that it exerts its action by inhibiting nucleic acid synthesis, as does a DNA-inhibiting chemotherapeutic drug.

Properties of base-substituted and carboxyl-esterified analogues of griseolic acid, a potent cAMP phosphodiesterase inhibitor

Griseolic acid (GA) is a potent cyclic AMP (cAMP) phosphodiesterase (PDE) inhibitor that has an adenine base and two carboxyl groups in its molecule (Nakagawa F, Okazaki T, Naito A, Iijima Y and Yamazaki M, J Antibiot 38: 823-829, 1985). GA analogues were synthesized in which the adenine group was substituted with guanine (6-deamino-2-amino-6-hydroxygriseolic acid, G-GA) or hypoxanthine (6-deamino-6-hydroxygriseolic acid, H-GA). Their inhibitory activities to cyclic GMP (cGMP) PDE and cAMP PDE were compared with GA. For cGMP PDE from rod outer segments of bovine retina, the IC50 values of GA, G-GA and H-GA were 18, 0.040 and 0.12 microM, respectively, with 0.25 microM cGMP as substrate. For type IV PDE isozyme from mouse 3T3 fibroblast cells, the IC50 values of GA, G-GA and H-GA were 0.021, 15 and 11 microM, respectively, with 0.25 microM cAMP as substrate. Thus, GA and G-GA were found to be base-selective inhibitors of type IV PDE of 3T3 cells and type V PDE of bovine retinas, respectively. Esters of carboxylic acids of GA were synthesized in order to increase permeability into cells, and their efficacy was tested by measuring the accumulation of cAMP in 3T3 cells. The dipivaloyloxymethyl ester of GA was found to increase cAMP levels at 0.1 microM, while GA and 3-isobutyl-1-methylxanthine were active only above 100 microM, and the dimethyl ester of GA was inactive. The dipivaloyloxymethyl ester of GA seems to exert its activity after conversion to GA in the cell, since the pivaloyloxymethyl ester was easily hydrolysed by the enzyme action and the dipivaloyloxymethyl ester of GA itself was much less potent an inhibitor of PDE. The dipivaloyloxymethyl ester of GA inhibited thrombin-induced aggregation of platelets and stimulated lipolysis of adipocytes at low concentrations.

Gly145 to Arg substitution in HBs antigen of immune escape mutant of hepatitis B virus

A Japanese child born to an HBeAg-positive carrier mother received anti-HBs immunoglobulins and a plasma-derived HBs vaccine with a poor anti-HBs-antibody response. The child, who is now 3 years old, is presently suffering from chronic hepatitis with unusual serological findings that are positive for HBsAg, anti-HBs and HBeAg, since being infected with a measles virus at 12 months of age. The nucleotide sequences of the S region of HBV DNA obtained from the patient, the mother and an HBeAg-positive brother were completely identical except for one nucleotide at position 587 (mother and brother: guanosine, patient: adenosine), giving an amino acid change: Gly - greater than Arg at position 145 of the major HBs protein.

Functional characterization of a heteromeric NMDA receptor channel expressed from cloned cDNAs

The glutamate receptor (GluR) channel plays a key part in brain function. Among GluR channel subtypes, the NMDA (N-methyl-D-aspartate) receptor channel which is highly permeable to Ca2+ is essential for the synaptic plasticity underlying memory, learning and development. Furthermore, abnormal activation of the NMDA receptor channel may trigger the neuronal cell death observed in various brain disorders. A complementary DNA encoding a subunit of the rodent NMDA receptor channel (NMDAR1 or zeta 1) has been cloned and its functional properties investigated. Here we report the identification and primary structure of a novel mouse NMDA receptor channel subunit, designated as epsilon 1, after cloning and sequencing the cDNA. The epsilon 1 subunit shows 11-18% amino-acid sequence identity with rodent GluR channel subunits that have been characterized so far and has structural features common to neurotransmitter-gated ion channels. Expression from cloned cDNAs of the epsilon 1 subunit together with the zeta 1 subunit in Xenopus oocytes yields functional GluR channels with high activity and characteristics of the NMDA receptor channel. Furthermore, the heteromeric NMDA receptor channel can be activated by glycine alone.

Phase transitions of phospholipid vesicles under osmotic stress and in the presence of ethylene glycol

The effects of poly(ethylene glycol) (PEG) on the phase transition of phospholipid multilamellar vesicles (MLVs) were investigated by using differential scanning calorimetry (DSC). Main transition temperature (Tm) and the pre-transition temperature (Tp) of neutral phospholipid-, DMPC-1, DPPC- and DSPC-MLVs increased with an increase in PEG concentration. The subtransition temperature of DPPC-MLV also increased with an increase in PEG concentration. These results could be qualitatively explained by enhancement of the lateral packing on the basis of the osmoelastic coupling theory. The pretransition temperature increased faster than the main transition temperature did with an increase in PEG concentration. The increment of Tm depended on the hydrocarbon chain length, the shorter the hydrocarbon chain length was, the larger the increment was. The transition width in the DSC peak was broadened with an increase in PEG concentration. These three above-mentioned effects are the main differences between the effects of the osmotic stress on the phase transition of MLVs and those of hydrostatic pressure. On the other hand, ethylene glycol (EG), which is the monomer of PEG, had a biphasic effect on transition temperature of DPPC-, DSPC-, and DMPC-MLV, reducing Tm and Tp at low concentrations, but increasing Tm and extinguishing pretransition at high concentrations. This is explained by the induction of an interdigitated gel phase at high concentrations of EG, which indicates that EG can easily penetrate into the head group region of the lipid, in contrast with PEG 6K, because EG is small. Temperature-EG concentration phase diagrams for the various PC-MLVs were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Ferric(III) ions inhibits copper(II)/hydrogen peroxide-catalyzing lipid peroxidation in human erythrocyte membranes

1. Effect of ferric ions (Fe3+) on the lipid peroxidation catalyzed by copper ions (Cu2+) and hydrogen peroxide (H2O2) was studied in human erythrocyte membranes. 2. The formation of thiobarbituric acid-reactive products elicited by CuCl2/H2O2 was inhibited by FeCl3 in a concentration-dependent manner; 0.25 mM FeCl3 were enough to cause 50% inhibition of the formation of peroxides. 3. The inhibitory effect of FeCl3 is not due to competition against Cu2+. 4. FeCl3 inhibited the initiation, but did not inhibit the propagation of Cu2+/H2O2-catalyzing lipid peroxidation. 5. In the heat- or trypsin-treated erythrocyte membranes, FeCl3 had no inhibitory effect on Cu2+/H2O2-catalyzing lipid peroxidation. 6. Sodium azide, an inhibitor of catalase, had no effect on the inhibitory effect of FeCl3. 7. These results suggest that a protein factor(s), which is not catalase, is involved in the inhibition of Cu2+/H2O2-catalyzing lipid peroxidation by Fe3+.

Studies of alcohol-induced interdigitated gel phase in phosphatidylcholine multilamellar vesicles by the excimer method

We have developed a new spectroscopic method (excimer method) for detecting the interdigitated gel phase (L beta I) in phospholipid vesicles. This method is based on the disappearance of an excimer fluorescence peak of pyrenephosphatidylcholine (pyrene-PC) in the L beta I phase. Using this method we have studied the phase transition from gel phase (L beta') to L beta I phase of dipalmitoylphosphatidylcholine multilamellar vesicles in the presence of ethanol or ethylene glycol (EG). In both the cases of ethanol and EG, a sharp decrease in the ratio of excimer to monomer fluorescence intensity (E/M) of pyrene PC appeared at the same concentration of the transition from L beta' to L beta I as determined by the X-ray diffraction method or the scanning density method. After the transition to the L beta I phase, E/M values became very low. This excimer method enables us to detect the L beta I phase in unilamellar vesicles of phospholipids, which can hardly be studied by other methods such as X-ray diffraction.

Molecular cloning of a cDNA encoding a novel member of the mouse glutamate receptor channel family

The primary structure of a novel putative subunit of the mouse glutamate receptor channel, designated as delta 1, has been deduced by cloning and sequencing the cDNA. The delta 1 subunit shows 21-25% amino acid sequence identity with previously characterized rodent glutamate receptor channel subunits and thus may represent a new subfamily of the glutamate receptor channel.

Changes in rat striatum catecholamine during hypoxia with reference to protective effects of flunarizine

We investigated the changes in dopamine, homovanillic acid, 3,4-dihydroxyphenylacetic acid, and norepinephrine content in striatum of rats ventilated with 5% oxygen in nitrogen gas. We also examined the effects of flunarizine, a calcium channel blocker, on these catecholamine levels. During 10-20 min. of hypoxia, the dopamine content gradually increased and the 3,4-dihydroxyphenylacetic acid and norepinephrine levels decreased, while the concentration of homovanillic acid remained unchanged. The concentrations of these substances subsequently returned to control values after 4 hr of room air breathing. In animals pretreated with intravenous flunarizine injection, there was a slight increase in dopamine, with no appreciable change in homovanillic acid or 3,4-dihydroxyphenylacetic acid content during 10-20 min. of hypoxia. The decrease in norepinephrine which occurred during 10-20 min. of hypoxia was identical between non-treated and flunarizine-treated animals. Catecholamine levels subsequently returned to control values after 4 hr of room air breathing. These results suggest that flunarizine minimizes the alterations in striatal catecholamine contents during hypoxic ventilation.

Isolation, identification and pharmacological studies on three toxic metabolites from a mushroom, Hebeloma spoliatum

Three metabolites, tentatively named HS-A, -B and -C, were isolated from a mushroom, Hebeloma spoliatum, as the fatal toxic principles to mice. HS-A was identified as 3-acetyl-2-(3'-hydroxy-3'-methyl)glutarylcrustulinol, which has been isolated from Hebeloma crustuliniforme and H. sinapizans as a cytotoxic principle. HS-B and -C were deduced to be 3,21-diacetyl-2-(3'-hydroxy-3'-methyl)glutarylcrustulinol and 3-acetyl-2-(3'-hydroxy-3'-methyl)glutarylanhydrocrustulinol, respectively, from their chemical and spectral data. Intraperitoneal administration of HS-A, -B and -C at a dose of 100 mg/kg caused death after paralysis of the limbs in mice. The compounds caused relaxation of mouse small intestine contracted by acetylcholine chloride or barium chloride treatment in vitro. They appear to exhibit a papaverine-like relaxation effect.

Significance of binding to Na,K-ATPase in the tissue distribution of ouabain in guinea pigs

Ouabain binds specifically to Na,K-ATPase on the plasma membrane and therefore serves to measure the tissue concentration of Na,K-ATPase. We examined the role of ouabain binding to Na,K-ATPase in its overall tissue distribution. The tissue-to-plasma concentration ratio (Kp,vivo) was defined in each tissue after intravenous administration of 3H-ouabain in guinea pigs, and specific binding of ouabain to Na,K-ATPase was measured in tissue homogenate to obtain the dissociation constant and binding capacity in each tissue. A predicted tissue-to-plasma concentration ratio (Kp,vitro) was calculated using the obtained binding parameters and the volume of extracellular space in each tissue. The absolute values of Kp,vitro were comparable to those of Kp,vivo, except in brain. Regression analysis showed that the specific binding capacity of Na,K-ATPase in each tissue is the main factor in the tissue variation of Kp,vivo. Therefore, the binding of ouabain to Na,K-ATPase plays a significant role in the tissue distribution of ouabain.

Cloning, expression and modulation of a mouse NMDA receptor subunit

The primary structure and presence of two forms of the mouse N-methyl-D-aspartate (NMDA) receptor channel subunit zeta 1 have been disclosed by cloning and sequencing the cDNAs. The zeta 1 subunit shows approximately 20% amino acid sequence identities with the rodent alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)- or kainate-selective GluR subunits and has structural features common to neurotransmitter-gated ion channels. Functional homomeric zeta 1 channels expressed in Xenopus oocytes by injection of the subunit-specific mRNA exhibit current responses characteristic for the NMDA receptor channel such as activation by glycine, Ca2+ permeability, blocking by Mg2+ and activation by polyamine. It has been found that the zeta 1 channel activity is positively modulated by treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA).

Morphological and immuno-cytochemical characterization of a hetero-spheroid composed of fibroblasts and hepatocytes

A novel method for the preparation of spheroids containing two types of cells (hetero-spheroid) has been successfully developed by utilizing a collagen-conjugated thermo-responsive polymer, poly-N-isopropyl acrylamide (PNIPAAm), as a cell substratum. PNIPAAm solidifies above its lower critical solution temperature (LCST, about 30 degrees C), and instantly dissolves into the culture medium below its LCST. We firstly seeded and cultured human dermal fibroblasts on the substratum up to a confluent state and then seeded rat primary hepatocytes onto the fibroblast monolayer. The heterospheroid was prepared by detaching the hepatocyte-attached fibroblast monolayer at a temperature below LCST and culturing it on the non-adhesive substratum. The surface area of the substratum and the seeding population ratio of each cell precisely and reproducibly regulated the size and the cell composition of the resulting hetero-spheroid, respectively. Histological and immuno-cytochemical observations of spheroids revealed characteristic organizations of fibroblasts and hepatocytes within a spheroid because the latter cells expressed albumin for up to at least 3 weeks. TEM study of the hetero-spheroid showed the presence of structures morphologically similar to the Disse's space and the bile canaliculus, which are features characteristic of liver. These findings suggest that the method described above is useful for making a hetero-spheroid that morphologically and functionally resembles tissues or organs in vivo, i.e. an organoid.

Increased levels of plasma thrombomodulin in chronic myelogenous leukemia

Circulating blood plasma contains proteinase-degraded forms of thrombomodulin that are soluble. We quantitatively assayed the plasma levels of thrombomodulin in 15 patients with chronic myelogenous leukemia (CML) in chronic phase by method of an enzyme-linked immunosorbent assay using a monoclonal antibody to protease-degraded products of thrombomodulin. Plasma levels of thrombomodulin in patients with CML at diagnosis were significantly increased (19.5 +/- 6.2 ng/ml: means +/- SD) compared with the levels in normal controls (8.0 +/- 1.9 ng/ml, n = 20) (P less than 0.001). Fibrin degradation products (D-dimer), thrombin-antithrombin III complex, and plasmin alpha 2-antiplasmin complex were almost normal, suggesting that intravascular coagulation or plasmin-mediated fibrinolysis little occurred in these patients. On the other hand, the plasma levels of elastase-alpha 1-proteinase inhibitor (E-alpha 1PI) complex, which was the indicator of released leukocyte elastase, were significantly increased in CML (P less than 0.0001). The plasma levels of thrombomodulin and E-alpha 1PI complex were decreased in parallel with decline of leukocyte counts in 10 patients with CML following anti-leukemic therapy. Furthermore, a statistically significant correlation was observed between the plasma levels of thrombomodulin and E-alpha 1PI complex obtained at 39 time points in 15 patients with CML (r = 0.81, P less than 0.001). These results suggest that the increased plasma levels of thrombomodulin in CML may be partly caused by leukocyte elastase, which may split the surface thrombomodulin and release protease-degraded fragments of it into the circulation.

Biosynthesis of griseolic acids: incorporation of 13C-labeled compounds into griseolic acid A

Biosynthesis of griseolic acids, competitive inhibitors of cyclic nucleotide phosphodiesterase, was investigated with the culture of a producing strain of Streptomyces griseoaurantiacus. 13C-Labeled and 15N-labeled compounds were added into the culture, and 13C-enriched and 15N-enriched griseolic acid A was isolated from the culture medium and analyzed by 13C NMR and 15N NMR spectroscopy. The compounds added to growth medium were [2-13C]acetate, [1,2-13C]acetate, [1,4-13C]succinate, [1-13C]glucose, [6-13C]glucose, [2-13C]ribose, and [1-13C, 15N]glycine. The results suggest that adenosine, which is formed from amino acids and sugars contributes the adenine and ribose moieties to griseolic acid A. The data also suggest that a dicarboxylic acid from the Krebs tricarboxylic acid cycle contributes to the dicarboxylic part of the compound.