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Estudo da redução do cobalto(II) em meio aquoso de azoteto de sódio por polarografia de pulso; Study of reduction of cobalt(II) in sodium azide aqueous medium by pulse polarography

Motta, Claudia Giovedi
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 16/03/1994 PT
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56.6%
A solução de cobalto(lI) em meio de perclorato de sódio apresenta uma onda polarográfica de redução próxima a -1,4 V em relação ao ECS a 25°C. A adição do ligante azoteto, N3-, causa a antecipação desta onda catódica para a região mais positiva de potencial. A máxima antecipação - de 320 mV - é atingida pela adição de 0,600 M do ligante. A antecipação da onda por ocasião da adição de azoteto, é explicada pela capacidade deste Iigante se adsorver sobre a superfície do mercúrio, formando uma ponte entre o eletrodo e o cátion metálico, facilitando a transferência de elétrons. A diminuição de sobretensão verificada com a adição do ligante reflete a queda da energia de ativação necessária para que ocorra a transferência de elétrons e como o azoteto é o responsável por este fenômeno, ele pode ser chamado de ligante catalítico. Critérios de caracterização para processos de eletrodo mostraram que a adição do ligante diminui o grau de irreversibilidade do processo de redução do cobalto(lI) - na técnica de pulso - em relação ao meio de perclorato. Em concentrações de azoteto inferiores a 0,600 M ocorre a antecipação gradativa da onda de redução do cobalto(lI) com um desdobramento em duas ondas com potenciais de meia-onda próximos a -1...

In vitro antioxidant capacity of tea of Echinodorus grandiforus, “leather hat,” in Wistar rat liver

LUNARDI,RAFAELA F.; WOHLENBERG,MARIANE; MEDEIROS,NIARA; AGOSTINI,FABIANE; FUNCHAL,CLÁUDIA; DANI,CAROLINE
Fonte: Academia Brasileira de Ciências Publicador: Academia Brasileira de Ciências
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2014 EN
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46.61%
Oxidative stress has been considered as one of the factors responsible for hepatic diseases, which sometimes require new ways of treatment. The present study aimed to evaluate the in vitro antioxidant capacity of the tea of Echinodorus grandiforus (“leather hat” plant) in rat liver. Different preparations of tea were evaluated for phenolic composition, antioxidant activity by DPPH assay and ability to inhibit lipid peroxidation induced by copper sulfate. The antioxidant activity was assessed in liver tissue treated with sodium azide in the presence or absence of tea by assays for lipid peroxidation (TBARS), protein oxidation (carbonyl) and the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). The results show that different preparations of tea are important sources of polyphenols and contain theobromine, catechin and vitexin. Furthermore, the results indicate that this tea exhibits an antioxidant activity by its ability to scavenge DPPH radical. Different preparations of tea prevented damage to lipids and proteins induced by sodium azide, as well as assisting in restoring CAT and SOD activities. Thus, it can be seen that E. grandiforus tea had antioxidant activity in serum and liver being able to prevent oxidative damages generated by sodium azide.

Efficient synthesis of functionalized 1,2,3-triazoles by catalyst-free 1,3-dipolar cycloaddition of nitroalkenes with sodium azide

Wang,Ting; Hu,Xiao-Chun; Huang,Xu-Jiao; Li,Xin-Sheng; Xie,Jian-Wu
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 EN
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66.49%
A simple and efficient protocol has been developed for the synthesis of 1,2,3-triazole derivatives by catalyst-free 1,3-dipolar cycloaddition of nitroalkenes with sodium azide under mild conditions.

Synergy between chronic corticosterone and sodium azide treatments in producing a spatial learning deficit and inhibiting cytochrome oxidase activity.

Bennett, M C; Mlady, G W; Fleshner, M; Rose, G M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 06/02/1996 EN
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46.69%
Previously, we developed a rat model of persistent mitochondrial dysfunction based upon the chronic partial inhibition of the mitochondrial enzyme cytochrome oxidase (EC 1.9.3.1). Continuous systemic infusion of sodium azide at approximately 1 mg/kg per hr inhibited cytochrome oxidase activity and produced a spatial learning deficit. In other laboratories, glucocorticoids have been reported to exacerbate neuronal damage from various acute metabolic insults. Therefore, we tested the hypothesis that corticosterone, the primary glucocorticoid in the rat, would potentiate the sodium azide-induced learning deficit. To this end, we first identified nonimpairing doses of sodium azide (approximately 0.75 mg/kg per hr) and corticosterone (100-mg pellet, 3-week sustained-release). We now report that chronic co-administration of these individually nonimpairing treatments produced a severe learning deficit. Moreover, the low dose of corticosterone, which did not elevate serum corticosterone, acted synergistically with sodium azide to inhibit cytochrome oxidase activity. The latter result represents a previously unidentified effect of glucocorticoids that provides a candidate mechanism for glucocorticoid potentiation of neurotoxicity induced by metabolic insult. These results may have the clinical implication of expanding the definition of hypercortisolism in patient populations with compromised oxidative metabolism. Furthermore...

SODIUM AZIDE SELECTIVE MEDIUM FOR THE PRIMARY ISOLATION OF ANAEROBIC BACTERIA

Forget, A.; Fredette, V.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1962 EN
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Forget, A. (University of Montreal, Montreal, Canada) and V. Fredette. Sodium azide selective medium for the primary isolation of anaerobic bacteria. J. Bacteriol. 83:1217–1223. 1962.—A selective medium has been devised for the primary isolation of anaerobic bacteria from a mixture of both aerobes and anaerobes. The solid medium contains 0.05% NaN3, and the liquid medium has 0.2% NaN3 in an identical base, namely, Trypticase soy broth. Addition of either 5% blood or 10% normal serum does not alter the selective action of sodium azide. The only defect which the medium exhibits is that it is unable to limit the growth of the facultative streptococci.

Two cases of sodium azide poisoning by accidental ingestion of Isoton.

Richardson, S G; Giles, C; Swan, C H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1975 EN
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Accidental ingestion of sodium azide in 0-1% solution by a patient and a laboratory technician in a haematological laboratory has demonstrated that very small quantities of sodium azide can give rise to toxic symptoms and that Isoton should be handled with care.

Immunoperoxidase techniques: the deleterious effect of sodium azide on the activity of peroxidase conjugates.

Richardson, T C; Chapman, D V; Heyderman, E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1983 EN
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46.61%
The effect of including sodium azide as a bacteriostatic agent in solutions used to dilute antibodies conjugated with the enzyme horseradish peroxidase was examined. An enzyme-linked immunosorbent assay (ELISA) and an immunohistochemical method were used and both techniques demonstrated an inhibitory effect of sodium azide on the activity of the peroxidase conjugates. It is concluded that the use of sodium azide in solutions used to dilute peroxidase conjugates is to be avoided.

Exposure to the metabolic inhibitor sodium azide induces stress protein expression and thermotolerance in the nematode Caenorhabditis elegans

Massie, Michelle R.; Lapoczka, Elizabeth M.; Boggs, Kristy D.; Stine, Karen E.; White, Glenn E.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em /01/2003 EN
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46.72%
Historically, sodium azide has been used to anesthetize the nematode Caenorhabditis elegans; however, the mechanism by which it survives this exposure is not understood. In this study, we report that exposure of wild-type C elegans to 10 mM sodium azide for up to 90 minutes confers thermotolerance (defined as significantly increased survival probability [SP] at 37°C) on the animal. In addition, sodium dodecyl sulfate–polyacrylamide gel electrophoresis revealed enhanced Hsp70 expression, whereas Western blot analysis revealed the induction of Hsp16. We also tested the only known C elegans Hsp mutant daf-21 (codes for Hsp90), which constitutively enters the stress-resistant state known as the dauer larvae. Daf-21 mutants also acquire sodium azide–induced thermotolerance, whereas 3 non-Hsp, constitutive dauer-forming mutants exhibited a variable response to azide exposure. We conclude that the ability of C elegans to survive exposure to azide is associated with the induction of at least 2 stress proteins.

Sodium azide inhibition of complement-mediated functions.

Shaw, D R; Shaw, M W; Hickman, S E; Lamon, E W; Griffin, F M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1980 EN
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46.65%
Moderate concentrations of sodium azide (0.1-0.2%) significantly inhibited guinea-pig and human complement-mediated lysis of both IgM- and IgG-sensitized sheep erythrocytes. The reduction in cytolysis was not attributable to non-specific ionic effects, to inactivation of native complement components by azide, or to irreversible interactions of azide with sensitized erythrocytes. Mouse complement-dependent opsonization of sensitized erythrocytes, as judged by macrophage complement receptor-mediated attachment and phagocytosis of the erythrocytes, was comparably inhibited by sodium azide, suggesting that azide acted within the sequence of the first four components of the classical complement pathway.

Dual actions of the metabolic inhibitor, sodium azide on KATP channel currents in the rat CRI-G1 insulinoma cell line

Harvey, J; Hardy, S C; Ashford, M L J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1999 EN
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46.79%
The effects of various inhibitors of the mitochondrial electron transport chain on the activity of ATP-sensitive K+ channels were examined in the Cambridge rat insulinoma G1 (CRI-G1) cell line using a combination of whole cell and single channel recording techniques.Whole cell current clamp recordings, with 5 mM ATP in the pipette, demonstrate that the mitochondrial uncoupler sodium azide (3 mM) rapidly hyperpolarizes CRI-G1 cells with a concomitant increase in K+ conductance. This is due to activation of KATP channels as the sulphonylurea tolbutamide (100 μM) completely reversed the actions of azide. Other inhibitors of the mitochondrial electron transport chain, rotenone (10 μM) or oligomycin (2 μM) did not hyperpolarize CRI-G1 cells or increase K+ conductance.In cell-attached recordings, bath application of 3 mM sodium azide (in the absence of glucose) resulted in a rapid increase in KATP channel activity, an action readily reversible by tolbutamide (100 μM). Application of sodium azide (3 mM), in the presence of Mg-ATP, to the intracellular surface of excised inside-out patches also increased KATP channel activity, in a reversible manner.In contrast, rotenone (10 μM) or oligomycin (2 μM) did not increase KATP channel activity in either cell-attached...

Sensitivity of Kir6.2-SUR1 currents, in the absence and presence of sodium azide, to the KATP channel inhibitors, ciclazindol and englitazone

McKay, N G; Kinsella, J M; Campbell, C M; Ashford, M L J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/2000 EN
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Two electrode voltage clamp and single channel recordings were used to investigate the actions of various ATP-sensitive K+ (KATP) channel inhibitors on cloned KATP channels, expressed in Xenopus oocytes and HEK 293 cells.Oocytes expressing Kir6.2 and SUR1 gave rise to inwardly rectifying K+ currents following bath application of 3 mM sodium azide. Inside-out recordings from non-azide treated oocytes demonstrated the presence of KATP channels which were activated by direct application of 3 mM azide and 0.1 mM Mg-ATP.Tolbutamide inhibited azide-induced macroscopic Kir6.2-SUR1 currents, recorded from Xenopus oocytes, with an IC50 value similar to native KATP channels. Ciclazindol and englitazone also inhibited these currents in a concentration-dependent manner, but with relative potencies substantially less than for native KATP channels.Single channel currents recorded from inside-out patches excised from oocytes expressing Kir6.2-SUR1 currents were inhibited by tolbutamide, Mg-ATP, englitazone and ciclazindol, in the absence of azide, with potencies similar to native KATP channels. In the presence of azide, Kir6.2-SUR1 currents were inhibited by englitazone and tolbutamide but not ciclazindol.Single channel currents derived from Kir6.2Δ26...

Atriopeptin, sodium azide and cyclic GMP reduce secretion of aqueous humour and inhibit intracellular calcium release in bovine cultured ciliary epithelium

Shahidullah, Mohammad; Wilson, William S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1999 EN
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This study examined the involvement of cyclic GMP, protein kinase G and intracellular Ca2+ movements in the modulation of aqueous humour formation.Using the bovine arterially-perfused eye preparation, drug effects on intraocular pressure and aqueous humour formation rate were measured by manometry and fluorescein dilution, respectively. Drug effects on intracellular [Ca2+] were determined by fura-2 fluorescence ratio technique in non-transformed, cultured ciliary epithelium.Intra-arterial injection of atriopeptin (50 pmol) or sodium azide (10 nmol) produced significant reduction in aqueous humour formation (>38%). This was blocked by selective inhibition (KT-5823) of protein kinase G, but not by selective inhibition (KT-5720) of protein kinase A. Reductions of intraocular pressure produced by atriopeptin or azide were almost completely blocked by KT-5823.ATP (100 μM) caused rapid, transient increase in intracellular Ca2+ followed by a slow decline and prolonged plateau. This response showed concentration-dependent inhibition by atriopeptin, azide or 8-bromo cyclic GMP, and this inhibition of the rapid (peak) Ca2+ increase was enhanced by zaprinast (100 μM; phosphodiesterase inhibitor). KT-5823 blocked the suppression of the peak Ca2+ response but not suppression of the plateau.Arterial perfusion of ATP (0.1–100 μM) produced a concentration-dependent decrease in aqueous humour formation.Aqueous humour formation in the bovine eye can be manipulated through cyclic GMP...

The inhibitory effect of 3-amino-1,2,4-triazole on relaxation induced by hydroxylamine and sodium azide but not hydrogen peroxide or glyceryl trinitrate in rat aorta.

Mian, K. B.; Martin, W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1995 EN
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46.77%
1. In this study we investigated the role of catalase in relaxation induced by hydroxylamine, sodium azide, glyceryl trinitrate and hydrogen peroxide in isolated rings of rat aorta. 2. Hydrogen peroxide (1 microM-1 mM)-induced concentration-dependent relaxation of phenylephrine (PE)-induced tone in endothelium-containing rings. In endothelium-denuded rings, however, higher concentrations (30 microM-1 mM) of hydrogen peroxide were required to produce relaxation. The endothelium-dependent component of hydrogen peroxide-induced relaxation was abolished following pretreatment with N(O)-nitro-L-arginine methyl ester (L-NAME, 30 microM). L-NAME (30 microM) had no effect, however, on hydrogen peroxide-induced relaxation in endothelium-denuded rings. 3. Pretreatment of endothelium-denuded rings with catalase (1000 u ml-1) blocked relaxation induced by hydrogen peroxide (10 microM-1 mM). The ability of catalase to inhibit hydrogen peroxide-induced relaxation was partially blocked following incubation with 3-amino-1,2, 4-triazole (AT, 50 mM) for 30 min and completely blocked at 90 min. 4. Pretreatment of endothelium-denuded rings with methylene blue (MeB, 30 microM) inhibited relaxation induced by hydrogen peroxide (10 microM-1 mM), sodium azide (1-300 nM)...

Chronological comparison of root dentin moisture in extracted human teeth stored in formalin, sodium azide, and distilled water

Komabayashi, Takashi; Ahn, Chul; Zhang, Song; Zhu, Qiang
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/2009 EN
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This study quantified in vitro the root dentin moisture when 10% formalin (Group A), 3% sodium azide (Group B), and distilled water (Group C) were used as teeth storage media. The root dentin moisture of 66 extracted human mandibular single-rooted teeth was measured at baseline (day 0) and at 1, 3, 7, and 14 days using a digital grain moisture meter. The baseline dentin moisture value was used as a covariate in the generalized estimating equation (GEE) analysis. The mean dentin moisture values (%) ± standard deviation on days 0, 1, 3, 7, and 14 were 10.6±0.64, 14.3±0.71, 14.6±0.84, 14.4±0.64, and 14.7±0.75 (Group A); 11.4±0.94, 14.6±0.95, 14.6±0.76, 14.6±0.93, and 14.8±0.81 (Group B); and 10.2±0.95, 12.8±0.90, 13.3±0.95, 13.0±0.91, and 13.2±0.89 (Group C), respectively. The dentin moisture increased in all three groups; however, there was no overall significant difference in moisture between the formalin and sodium azide groups.

Improved Synthesis of 5-Substituted 1H-Tetrazoles via the [3+2] Cycloaddition of Nitriles and Sodium Azide Catalyzed by Silica Sulfuric Acid

Du, Zhenting; Si, Changmei; Li, Youqiang; Wang, Yin; Lu, Jing
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 12/04/2012 EN
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A silica supported sulfuric acid catalyzed [3+2] cycloaddition of nitriles and sodium azide to form 5-substituted 1H-tetrazoles is described. The protocol can provide a series of 5-substituted 1H-tetrazoles using silica sulfuric acid from nitriles and sodium azide in DMF in 72%–95% yield.

Effects of Sodium Azide on the Abundance of Prokaryotes and Viruses in Marine Samples

Winter, Christian; Kerros, Marie-Emmanuelle; Weinbauer, Markus G.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 18/05/2012 EN
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Flow cytometry is set to become the standard method for enumerating prokaryotes and viruses in marine samples. However, the samples need to be flash-frozen in liquid nitrogen directly after aldehyde fixation. Because liquid nitrogen may not always be available, we tested the potential of sodium azide as a preservative for prokaryotes and viruses in marine samples as a possible alternative. For that we conducted incubation experiments with untreated and sodium azide treated marine water samples at 4°C and room temperature. The data indicate that sodium azide cannot be used to maintain marine samples used for the enumeration of prokaryotes and viruses.

Paradoxical potentiation of methylene blue-mediated antimicrobial photodynamic inactivation by sodium azide: Role of ambient oxygen and azide radicals

Huang, Liyi; St. Denis, Tyler G; Xuan, Yi; Huang, Ying-Ying; Tanaka, Masamitsu; Zadlo, Andrzej; Sarna, Tadeusz; Hamblin, Michael R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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Sodium azide (NaN3) is widely employed to quench singlet oxygen during photodynamic therapy (PDT), especially when PDT is used to kill bacteria in suspension. We observed that addition of NaN3 (100 μM or 10 mM) to gram-positive Staphylococcus aureus and gram-negative Escherichia coli incubated with methylene blue (MB) and illuminated with red light gave significantly increased bacterial killing (1–3 logs), rather than the expected protection from killing. A different antibacterial photosensitizer, the conjugate between polyethylenimine and chlorin(e6) (PEI-ce6), showed reduced PDT killing (1–2 logs) after addition of 10 mM NaN3. Azide (0.5 mM) potentiated bacterial killing by Fenton reagent (hydrogen peroxide and ferrous sulfate) by up to 3 logs, but protected against killing mediated by sodium hypochlorite and hydrogen peroxide (considered to be a chemical source of singlet oxygen). The intermediacy of N3• was confirmed by spin-trapping and electron spin resonance studies in both MB-photosensitized reactions and Fenton reagent with addition of NaN3. We found that N3• was formed and bacteria were killed even in the absence of oxygen, suggesting the direct one-electron oxidation of azide anion by photoexcited MB. This observation suggests a possible mechanism to carry out oxygen-independent PDT.

Controlled Functionalization of Graphene Oxide with Sodium Azide

Eigler, Siegfried; Hu, Yichen; Ishii, Yoshitaka; Hirsch, Andreas
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 21/12/2013 EN
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We present the first example of azide functionalization on the surface of graphene oxide (GO), which preserves thermally instable groups in GO through the mild reaction with sodium azide in solids. Experimental evidence, by 15N solid-state NMR and other spectroscopic methods, indicates the substitution of organosulfate with azide anions as the reaction mechanism.

Effects of Sodium Azide on Sodium Fluxes in Frog Striated Muscle

Horowicz, Paul; Gerber, Carl J.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/01/1965 EN
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46.75%
Unidirectional Na fluxes from frog's striated muscle were measured in the presence of 0 to 5 mM sodium azide. With azide concentrations of 2 and 5 mM the Na efflux was markedly stimulated; the Na efflux with 5 mM azide was about 300 per cent greater than normal. A similar increase was present when all but the 5.0 mM sodium added with azide was replaced by choline. 10-5 M strophanthidin abolished the azide effect on Na24 efflux. Concentrations of azide of 1.0 mM or less had no effect on Na efflux. The Na influx, on the other hand, was only increased by 41 per cent in the presence of 5 mM NaN3. From these findings it is concluded that the active transport of Na is stimulated by the higher concentrations of azide. The hypothesis is advanced that the active transport of Na is controlled by the transmembrane potential and that the stimulation of Na efflux is produced as a consequence of the membrane depolarization caused by the azide.

Sodium azide mutagenesis: preferential generation of A.T-->G.C transitions in the barley Ant18 gene.

Olsen, O; Wang, X; von Wettstein, D
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/09/1993 EN
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The molecular basis for the absence of anthocyanins and proanthocyanidins in four independent sodium azide-induced ant18 mutants of barley was examined by sequencing the gene encoding dihydroflavonol 4-reductase in these mutants. Sodium azide generated 21 base substitutions, which corresponds to 0.17% of the 12,704 nucleotides sequenced. Of the substitutions, 86% were nucleotide transitions, and 14% were transversions. A.T-->G.C base pair transitions were about 3 times more frequent than G.C-->A.T transitions. No deletions or mutation hot spots were found. The absence of dihydroflavonol 4-reductase activity in ant18-159, ant18-162, and ant18-164 plants is caused by missense mutations in the respective genes. By using microprojectile bombardment, a plasmid harboring the wild-type Ant18 gene was introduced into ant18-161 mutant cells and resulted in the development of anthocyanin pigmentation, which demonstrates that the mutation is corrected by expression of the introduced gene. On the other hand, a plasmid derivative with the two ant18-161-specific base transitions at the 5' splice site of intron 3 prevented complementation. It is concluded that the absence of detectable mRNA for dihydroflavonol 4-reductase in ant18-161 cells is due to the mutations in the pre-mRNA splice donor site.