PubMed Health⌕ Search

Biomedical subjects

C Van Baalen

Publications and source records attributed to C Van Baalen.

At least 19 recordsLinked to original sources
PubMed1992

Metabolism of phenanthrene by the marine cyanobacterium Agmenellum quadruplicatum PR-6.

Under photoautotrophic growth conditions, the marine cyanobacterium Agmenellum quadruplicatum PR-6 metabolized phenanthrene to form trans-9,10-dihydroxy-9,10-dihydrophenanthrene (phenanthrene trans-9,10-dihydrodiol) and 1-methoxyphenanthrene as the major ethyl acetate-extractable metabolites. Small amounts of phenanthrols were also formed. The metabolites were purified by high-pressure liquid chromatography and identified from their UV, infrared, mass, and proton magnetic resonance spectral properties. A. quadruplicatum PR-6 formed phenanthrene trans-9,10-dihydrodiol with a 22% enantiomeric excess of the (-)-9S,10S-enantiomer. Incorporation experiments with 18O2 showed that one atom of oxygen from O2 was incorporated into the dihydrodiol. Toxicity studies, using an algal lawn bioassay, indicated that 9-phenanthrol and 9,10-phenanthrenequinone inhibit the growth of A. quadruplicatum PR-6.

Biodegradation, Environmental↗
PubMed1992

Evidence for an NIH shift in oxidation of naphthalene by the marine cyanobacterium Oscillatoria sp. strain JCM.

The marine cyanobacterium Oscillatoria sp. strain JCM oxidized naphthalene predominantly to 1-naphthol. Experiments with [1-2H]naphthalene and [2-2H]naphthalene indicated that 1-naphthol was formed with 68 and 74% retention of deuterium, respectively. No significant isotope effect was observed when the organism was incubated with a 1:1 mixture of naphthalene and [2H8]naphthalene. The results indicate that 1-naphthol is formed through a naphthalene 1,2-oxide intermediate, which rearranges spontaneously via an NIH shift mechanism.

Cyanobacteria↗
PubMed1990

Control of nitrogenase recovery from oxygen inactivation by ammonia in the cyanobacterium Anabaena sp. strain CA (ATCC 33047).

The control of nitrogenase recovery from inactivation by oxygen was studied in Anabaena sp. strain CA (ATCC 33047). Nitrogenase activity (acetylene reduction) in cultures grown in 1% CO2 in air was inhibited by exposure to 1% CO2-99% O2 and allowed to recover in the presence of high oxygen tensions. Cultures exposed to hyperbaric levels of oxygen in the presence of 10 mM NH4NO3 were incapable of regaining nitrogenase activity, whereas control cultures returned to 65 to 80% of their original activity within about 3 h after exposure to high oxygen tension. In contrast to the regulation of heterocyst differentiation and nitrogenase synthesis, recovery from oxygen inactivation in this organism was shown to be under the control of NH4+ rather than NO3-.

Ammonium Chloride↗
PubMed1987

Nitrogen starvation mediated by DL-7-azatryptophan in the cyanobacterium Anabaena sp. strain CA.

The addition of DL-7-azatryptophan (AZAT), a tryptophan analog, to continuous cultures of Anabaena sp. strain CA grown with 10 mM nitrate as the nitrogen source resulted in the differentiation of heterocysts. Analysis of the intracellular amino acid pools of Anabaena sp. strain CA after the addition of AZAT showed a marked decline in the intracellular glutamate pool and a slight increase in the levels of glutamine. The in vitro activity of glutamate synthase, the second enzyme involved in primary ammonia assimilation in Anabaena spp., was partially inhibited by the presence of AZAT at concentrations which are effective in triggering heterocyst formation (15% inhibition at 10 microM AZAT and up to 85% inhibition at 1.0 mM AZAT). Azaserine, a glutamine analog and potent glutamate synthase inhibitor, had no effect on the triggering of heterocyst development from undifferentiated batch and continuous cultures of Anabaena sp. strain CA. However, the presence of 1.0 microM azaserine significantly decreased the intracellular glutamate pool and increased the glutamine pool. The addition of AZAT also caused a decrease in the C-phycocyanin content of Anabaena sp. strain CA as a result of its proteolytic degradation. AZAT also had an inhibitory effect on the nitrogenase activity of Anabaena sp. strain CA. All these results suggest that AZAT causes a general nitrogen starvation of Anabaena sp. strain CA filaments, triggering heterocyst synthesis.

Acetylene↗
PubMed1987

DL-7-azatryptophan and citrulline metabolism in the cyanobacterium Anabaena sp. strain 1F.

An alternative route for the primary assimilation of ammonia proceeds via glutamine synthetase-carbamyl phosphate synthetase and its inherent glutaminase activity in Anabaena sp. strain 1F, a marine filamentous, heterocystous cyanobacterium. Evidence for the presence of this possible alternative route to glutamate was provided by the use of amino acid analogs as specific enzyme inhibitors, enzymological studies, and radioistopic labeling experiments. The amino acid pool patterns of continuous cultures of Anabaena sp. strain 1F were markedly influenced by the nitrogen source. A relatively high concentration of glutamate was maintained in the amino acid pools of all cultures irrespective of the nitrogen source, reflecting the central role of glutamate in nitrogen metabolism. The addition of 1.0 microM azaserine increased the intracellular pools of glutamate and glutamine. All attempts to detect any enzymatic activity for glutamate synthase by measuring the formation of L-[14C]glutamate from 2-keto-[1-14C]glutarate and glutamine failed. The addition of 10 microM DL-7-azatryptophan caused a transient accumulation of intracellular citrulline and alanine which was not affected by the presence of chloramphenicol. The in vitro activity of carbamyl phosphate synthetase and glutaminase increased severalfold in the presence of azatryptophan. Results from radioisotopic labeling experiments with [14C]bicarbonate and L-[1-14C]ornithine also indicated that citrulline was formed via carbamyl phosphate synthetase and ornithine transcarbamylase. In addition to its effects on nitrogen metabolism, azatryptophan also affected carbon metabolism by inhibiting photosynthetic carbon assimilation and photosynthetic oxygen evolution.

Amino Acids↗
PubMed1987

Alteration of the Fe protein of nitrogenase by oxygen in the cyanobacterium Anabaena sp. strain CA.

Changes in protein composition were noted when heterocysts of Anabaena sp. strain CA were isolated from filaments grown in 1% CO2-99% N2 and subsequently exposed to oxygen. Immunospecific Western blot analysis showed that the Fe protein of nitrogenase is altered. In cells grown under microaerobic conditions, the Fe protein was found in a form with an apparent molecular weight of 30,000. Exposure to oxygen caused a shift in the migration of this polypeptide to a position corresponding to an apparent molecular weight of 31,500. This modification was reversible upon removal of oxygen from the culture. Chloramphenicol did not inhibit the alteration in either direction. Suppression by ammonium nitrate of the recovery of nitrogenase activity from the effects of oxygen did not prevent the alteration of the protein. Other inhibitors of nitrogenase activity, (metronidazole, carbonyl cyanide m-chlorophenylhydrazone, and phenazine methosulfate) were tested for their effect on Fe protein modification. Alteration of the Fe protein may relate to the protection of nitrogenase from the deleterious effects of oxygen.

Cyanobacteria↗
PubMed1985

Photosynthetic and respiratory rates of two psychrophilic diatoms.

The photosynthetic rates in two psychrophilic diatoms, Chaetoceros sp. strain K3-10 and Nitzschia sp. K3-3 for cells grown at 0 degrees C were 8 to 10 microliters O(2) evolved per milligram dry weight per hour, and 10-fold higher, about 80 for cells grown at 10 degrees C. The respiration rates followed the same pattern, with a value of around 1 microliter dark uptake per milligram dry weight per hour for both organisms grown at 0 degrees C, and 6 to 10 for cells grown at 10 degrees C. When cells grown at 0 degrees C were immediately shifted to 10 degrees C or cells grown at 10 degrees C were shifted to 0 degrees C, the respiratory rates quickly adapted to values characteristic of cells grown at the shift temperature. On the other hand, the light-saturated rate of O(2) evolution showed much less immediate adaptation, especially on the up shift, 0 degrees to 10 degrees C. The chlorophyll a content of 0 degrees C grown cells was about 0.5% of dry weight, in 10 degrees C grown cells 1.3% (strain K3-10) and 2.2% (strain K3-3). In addition to a diminished chlorophyll a content in 0 degrees C grown cells, there seemed proportionally (by absorbance and calculation) less c to a than in 10 degrees C grown cells. The relative fluorescence excitation spectra of 680-nm emission also showed a lower contribution by both chlorophyll c and fucoxanthin in 0 degrees C grown cells of Chaetoceros sp. strain K3-10 as compared to 10 degrees C grown cells. The data at hand suggest that in psychrophilic diatoms continuously growing at 0 degrees C there may be problems associated with synthesis of an effective accessory pigment system, and as a working hypothesis it is suggested this is related to restriction of synthesis of one or several accessory pigment proteins.

Journal Article↗
PubMed1985

H2, N2, and O2 metabolism by isolated heterocysts from Anabaena sp. strain CA.

Metabolically active heterocysts isolated from wild-type Anabaena sp. strain CA showed high rates of light-dependent acetylene reduction and hydrogen evolution. These rates were similar to those previously reported in heterocysts isolated from the mutant Anabaena sp. strain CA-V possessing fragile vegetative cell walls. Hydrogen production was observed with isolated heterocysts. The ratio of C2H4 to H2 produced ranged from 0.9 to 1.2, and H2 production exhibited unique biphasic kinetics consisting of a 1 to 2-min burst of hydrogen evolution followed by a lower, steady-state rate of hydrogen production. This burst was found to be dependent upon the length of the dark period immediately preceding illumination and may be related to dark-to-light ATP transients. The presence of 100 nM NiCl2 in the growth medium exerted an effect on both acetylene reduction and hydrogen evolution in the isolated heterocysts from strain CA. H2-stimulated acetylene reduction was increased from 2.0 to 3.2 mumol of C2H4 per mg (dry weight) per h, and net hydrogen production was abolished. A phenotypic Hup- mutant (N9AR) of Anabaena sp. strain CA was isolated which did not respond to nickel. In isolated heterocysts from N9AR, ethylene production rates were the same under both 10% C2H2-90% Ar and 10% C2H2-90% H2 with or without added nickel, and net hydrogen evolution was not affected by the presence of 100 nM Ni2+. Isolated heterocysts from strain CA were shown to have a persistent oxygen uptake of 0.7 mumol of O2 per mg (dry weight) per h, 35% of the rate of whole filaments, at air saturating O2 levels, indicating that O2 impermeability is not a requirement for active heterocysts.

Acetylene↗
PubMed1983

High endogenous nitrogenase activity in isolated heterocysts of Anabaena sp. strain CA after nitrogen starvation.

Metabolically active heterocysts were isolated from a mutant of Anabaena sp. strain CA with fragile vegetative cells. Heterocysts isolated from cultures grown in 1% CO2 in air reduced C2H2 at 57 and 10 nmol of C2H2 per mg (dry weight) per min under H2 and Ar, respectively. However, if whole filaments were sparged with 1% CO2 in 99% Ar for 12 h before heterocyst isolation, these heterocysts showed C2H2 reduction rates of 83 nmol of C2H4 per mg (dry weight) per min under either H2 or Ar, or 40% the activity of whole filaments grown in 1% CO2 in air. Heterocysts isolated from cultures sparged with 100% Ar or 1% CO2 in 99% N2 had the same C2H2 reduction pattern as heterocysts from cultures grown in 1% CO2 in air, i.e., low activity under Ar and high activity under H2. Labeling of whole filaments incubated with NaH14CO3 for 12 h under 1% CO2 in air or 1% CO2 in 99% Ar resulted in a twofold higher accumulation of 14C-labeled compounds in vegetative cells and heterocysts of Ar-incubated cells. Our results suggest that during incubation under 1% CO2 in 99% Ar, presumably a nitrogen starvation condition, continuing photosynthetic fixation of CO2 leads to accumulation of material(s) in the heterocysts that supports a high, persistent endogenous rate of C2H2 reduction. This material appears to be, in part, glycogen.

Acetylene↗
PubMed1983

Aerobic hydrogen production by the heterocystous cyanobacteria Anabaena spp. strains CA and 1F.

Aerobic photoproduction of H2 was demonstrated in Anabaena spp. strains CA and 1F when cells were growing under nitrogen-fixing conditions. The rates of production, measured either by the hydrogen electrode or in a flow system by gas chromatography, were 10 to 15% of the rate of photosynthetic O2 evolution or 50 to 80% of the rates of acetylene reduction. Strains CA and 1F differed in several respects. In strain CA, H2 production was immediately partially sensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea, whereas strain 1F was not immediately affected. Strain CA also showed a consistently higher rate of H2 production than did strain 1F. H2 production in strain CA was also markedly influenced by the light intensity used for growth, although the growth rates indicated that the light intensities used were essentially saturating.

Acetylene↗
PubMed1981

Biotransformation and toxicity of aniline and aniline derivatives of cyanobacteria.

Agmenellum quadruplicatum strain PR-6 and Oscillatoria sp. strain JCM grown photoautotrophically in the presence of aniline metabolized the aromatic amine to formanilide, acetanilide and p-aminophenol. The metabolites were isolated by either thin-layer, gas-liquid or high pressure liquid chromatography and identified by comparison of their chromatographic, ultraviolet absorbance and mass spectral properties with those of authentic compounds. The toxicity of aniline derivatives towards Agmenellum quadruplicatum strain PR-6 indicated that the cyanobacterium was extremely sensitive to o-, m- and p-aminophenols, and phenylhydroxylamine.

Aniline Compounds↗
PubMed1980

Oxidation of biphenyl by the cyanobacterium, Oscillatoria sp., strain JCM.

The oxidation of biphenyl by Cyanobacterium, Oscillatoria sp., strain JCM was studied. The organism grown photoautotrophically in the presence of biphenyl oxidized biphenyl to form 4-hydroxybiphenyl. The structure of the metabolite was elucidated by ultraviolet and mass spectra and shown to be identical to authentic 4-hydroxybiphenyl. In addition this metabolite had properties identical to 4-hydroxybiphenyl when analyzed by thin-layer and high-pressure liquid chromatography. Experiments with [14C]-biphenyl showed that over a 24 h period the organism oxidized 2.9% of the added biphenyl to ethyl acetate-soluble products.

Biphenyl Compounds↗
PubMed1980

Novel mutant of Anabaena sp. strain CA which growns on N2 but not on combined nitrogen.

A mutant has been isolated from Anabaena sp. strain CA by treatment with N-methyl-N'-nitro-N-nitrosoguanidine, which has the unusual phenotypic characteristic of growth only under N2-fixing conditions. Growth of the mutant was completely inhibited by NO3- or NH4+ at concentrations routinely used for growth of the wild type, and sensitivity to NH4+ was especially pronounced. The inhibitory effect of NH4+ could not be overcome by glutamine, glutamate, or casein hydrolysate. Ammonia had no immediate inhibitory effect on protein synthesis, CO2 fixation, or O2 evolution, and the gradual inhibition of C2H2 reduction activity by NH4+ resembled a repression phenomenon. The glutamine synthetase activity of N2-fixing cultures appeared normal, yet the mutant was incapable of utilizing exogenous NH4+ for growth. Preliminary evidence suggests a possible alteration of glutamine synthetase, which could result in sensitivity to exogenous NH4+ by progressive inactivation of the enzyme or repression of its synthesis.

Amino Acids↗
PubMed1979

Control of heterocyst and nitrogenase synthesis in cyanobacteria.

The development of the heterocyst by filamentous nitrogen-fixing cyanobacteria provides an attractive model system for studying cellular differentiation. Heterocyst synthesis is repressed by the presence of exogenous combined nitrogen. In this report, it is shown that the tryptophan analog, D,L-7-azatryptophan (Aza-T), is capable of relieving the repressive effect of exogenous NH4NO3 on heterocyst and nitrogenase synthesis. In nitrogen-fixing cultures, the presence of 20 micron Aza-T increases the heterocyst frequency twofold. The glutamate analog, L-methionine-D,L-sulfoximine (MSX), has also been shown to cause a derepression in the synthesis of heterocysts and nitrogenase. However, unlike MSX, Aza-T does not appear to exert its effects by inhibiting the activity of glutamine synthetase. Therefore, glutamine synthetase may not be the sole key to the derepression of heterocyst and nitrogenase development in the cyanobacteria. It is hoped that a study of Aza-T action may lead to the elucidation of a novel control mechanism.

Cyanobacteria↗