Exploring the use of fish as indicators of eicosapentaenoic and docosahexaenoic supply in lake ecosystems

An adequate supply of food sources with high levels (i.e., weight proportion of total fatty acids) and contents (i.e., absolute amount per mass) of long chain polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are important for ecosystems. Therefore, the supply of EPA and DHA from basal food sources is a useful indicator of ecosystem health. To determine whether EPA and DHA levels and contents in fish can be used as indicators of EPA and DHA supply in lakes, five dominant species of fish and basal food sources (seston and sediment) were collected monthly from June to November from 2016 to 2021 from Lake Hachiro, Japan. Seston and Hypomesus nipponensis were collected from 12 lakes (one collection per lake) with varying seston contents in EPA and DHA. The trends of EPA and DHA in all fish species were similar to those of the basal food sources. Correlation analysis showed that the EPA levels were strongly correlated between fish and seston; moreover, the correlation coefficient increased when a 1- or 2-month moving average was applied to the basal food sources, suggesting that fish represent a time-integrated supply of EPA and DHA. EPA levels of H. nipponensis had the highest correlation coefficients with seston among all fish species. EPA levels of H. nipponensis were significantly correlated with those of seston among lakes. The results of this study suggest that H. nipponensis is a useful indicator of EPA and DHA supplies in lake ecosystems.

Effects of Algal Extracellular Polysaccharides on the Formation of Filamentous Manganese Oxide Particles in the Near-Bottom Layer of Lake Biwa

Filamentous manganese (Mn) oxide particles, which occur in the suboxic zone of stratified waterbodies, are important drivers of diverse elemental cycles. These particles are considered to be bacteriogenic; despite the importance of biogeochemical implications, however, the environmental factor responsible for their formation has not been identified. The aim of this study was to demonstrate the involvement of algal extracellular polysaccharides in Mn oxide particle formation. Based on this study of laboratory cultures of a model Mn(II)-oxidizing bacterium, the supply of algal extracellular mucilage was shown to stimulate Mn(II) oxidation and thus the production of filamentous Mn oxide particles. This observation was consistent with the results obtained for naturally occurring particles collected from a near-bottom layer (depth of approximately 90 m) in the northern basin of Lake Biwa, Japan, that is, most Mn particles resembling δ-MnO₂ were associated with an extracellular mucilage-like gelatinous matrix, which contained dead algal cells and was lectin-stainable. In the lake water column, polysaccharides produced by algal photosynthesis sank to the bottom layer. The analysis of the quality of water samples, which have been collected from the study site for 18 years, reveals that the annual average total phytoplankton biovolume in the surface layer correlates with the density of filamentous Mn particles in the near-bottom layer. Among different phytoplankton species, green algae appeared to be the key species. The results of this study suggest that algal extracellular polysaccharides serve as an important inducer for the formation of filamentous Mn oxide particles in the near-bottom layer of the northern basin of Lake Biwa.

Desulfofustis limnaeus sp. nov., a freshwater sulfate-reducing bacterium isolated from marsh soil

A novel sulfate-reducing bacterium, strain PPLL^T, was isolated from marsh soil. Cells of strain PPLL^T were rod-shaped with length of 1.5 μm and width of 0.7 μm. Growth was observed at 22-37 °C (optimum 35 °C) and pH 6.8-8.4 (optimum 7.3). Lactate, succinate, fumarate, formate and malate were utilized as electron donors for sulfate reduction. Fermentative growth was not observed on tested organic acids. Besides sulfate, sulfite, thiosulfate and elemental sulfur were utilized as electron acceptors. Hydrogen is used only in the presence acetate or yeast extract. The major fatty acid was C_16:0. The complete genome of strain PPLL^T was composed of a circular chromosome with length of 4.2 Mbp and G + C content of 57.7 mol%. Sequence analysis of the 16S rRNA gene showed that strain PPLL^T was affiliated with the genus Desulfofustis in the family Desulfocapsaceae. On the basis of differences in the phylogenetic and phenotypic properties between the strain and the type strain of the genus Desulfofustis, strain PPLL^T (DSM 110475^T = JCM 39161^T) is proposed as the type strain of a new species, with name of Desulfofustis limnaeus sp. nov.

Sulfuricystis multivorans gen. nov., sp. nov. and Sulfuricystis thermophila sp. nov., facultatively autotropic sulfur-oxidizing bacteria isolated from a hot spring, and emended description of the genus Rugosibacter

Strains J5B^T and M52^T are facultatively autotrophic sulfur-oxidizing bacteria isolated from a microbial mat from a hot spring. They were isolated and partially characterized in previous studies, as facultative anaerobes which use nitrate as electron acceptor. In this study, additional characterizations were made to determine their taxonomic status. In both strains, major cellular fatty acids were C_16:1 (C_16:1ω7c and/or C_16:1ω6c) and C_16:0. Their chemolithoautotrophic growth was supported by thiosulfate and elemental sulfur. They used some organic acids as growth substrates. Their 16S rRNA gene sequences indicated the highest sequence identities to species in the family Sterolibacteriaceae, but the identities were 95% or lower. Phylogenetic analysis indicated that these strains do not belong to any existing genera. Values of average nucleotide identity and digital DNA-DNA hybridization between strains J5B^T and M52^T were 87.93% and 34.3%, respectively. On the basis of phenotypic and genomic characteristics, Sulfuricystis multivorans gen. nov. sp. nov., and Sulfuricystis thermophila sp. nov. are proposed, with type strains of J5B^T and M52^T, respectively. An emended description of the genus Rugosibacter is also proposed, for its reclassification to the family Sterolibacteriaceae.

Fungal mn oxides supporting Mn(II) oxidase activity as effective Mn(II) sequestering materials

We examined the Mn(II)-oxidizing ability of the biogenic Mn oxide (BMO) formed in cultures ofa Mn(II)-oxidizing fungus, Acremonium strictum strain KR21-2. The newly formed BMO effectively sequestered dissolved Mn(II) mainly by oxidizing Mn(II) to insoluble Mn under air-equilibrated conditions, and this ability lasted for at least 8 days. Deaerating the BMOs, poisoning them with NaN3, or heating them all readily weakened their Mn(II) oxidation ability, indicating the involvement of enzymatic Mn(II) oxidation. There was no Mn(II)-oxidizing ability observed for mycelia cultivated without Mn(II) or for residual mycelia after the BMO phase was dissolved, suggesting the need for the oxide phase. A sodium dodecyl sulphate-polyacrylamide gel electrophoresis assay demonstrated that the oxide phase embeds the Mn(II) oxidase and thereby maintains the enzymatic activity in BMOs. Freezing at -80 degrees C preserved the Mn(II)-oxidizing ability in BMOs for at least 4 weeks, while lyophilization caused a complete loss of this ability. Based on these results, we propose that fungal Mn oxides supporting Mn(II) oxidase activity are an effective Mn(II)-sequestering material capable of oxidizing Mn(II) continuously from solutions containing no additional nutrients to maintain biological activity.

Abstract P6-15-18: PELP1-KDM1 Axis: A Novel Therapeutic Target for Blocking Local Estrogen Synthesis

Background: Local estrogen production via deregulated expression of aromatase (Cyp19), the key enzyme in the biosynthesis of estrogen, contributes to tumor progression in post-menopausal women. Aromatase inhibitors (AI) are effective in enhancing patient survival although long term use is limited by systemic side effects and therapy resistance. Therefore, identifying novel pathways that contributes to in situ E2 in breast tumors and therapeutic agents to block these pathways are urgently needed. Recent studies from our lab demonstrated PELP1 proto-oncogene cooperates with HER2/neu and modulates epigenetic changes at aromatase promoter by interacting with lysine specific demethylase (KDM1) leading to local E2 synthesis. In this study, we examined the therapeutic efficacy of targeting the PELP-KDM1 axis in blocking local E2 production.

Methods: Three breast cancer model cells which exhibit local E2 were used: (a) MCF7 cells overexpressing HER2/neu onogene (MCF7-HER2), (b) MCF7 cells overexpressing proto-oncogene PELP1 (MCF7-PELP1), (c) MCF7 cells with acquired Letrozole resistance (MCF7-Ca-LTLT); parental MCF7 cells were used as controls. Therapeutic potential of KDM1 targeting drugs, (1) Pargyline, a monoamine oxidase inhibitor, (2) NCL-1, a KDM1-selective inhibitor to block PELP1-KDM1 axis were tested using proliferation, aromatase reporter, ChIP and RTqPCR assays. Efficacy of the KDM1 targeting drugs alone or in combination with Letrozole, and Dasatinib was also measured. Pre-clinical, post-memopausal nude mice based models were used to validate the drug effect in vivo.

Results: Depletion of PELP1 or KDM1 using siRNA substantially reduced proliferation of all three model cells and affected epigenetic modifications at the aromatase promoter. Reporter gene and ChIP assays showed growth factors and HER2/neu enhance PELP1 and KDM1 recruitment to the aromatase promoter. KDM1 inhibitors {pargyline (3mM) and NCL1 (10uM)} substantially inhibited growth of all three model cells. In postmenopausal xenograft based model, treatment with pargyline significantly inhibited the growth of local E2 producing tumor cells. IHC and ChIP analysis revealed alterations in histone methyl modifications in treated ER positive tumors. Combinatorial therapy of AI (Letrozole), Src kinaseinhibitor (Dasatinib) with Pargyline or NCL1 showed most promising therapeutic effect compared to single agent therapy to inhibit growth of therapy resistant cells.

Conclusions: Drugs targeting the PELP1-KDM1 are effective in reversing the methyl modifications at aromatase promoter that are affected by proto-oncogenes PELP1, HER2 and blocking growth of local E2 producing cells. Our results suggest targeting of PELP1-KDM1 axis in combination with current endocrine therapies will have a better therapeutic effect and may inhibit or delay development of AI resistance. This study is funded by Komen grant KG090447 and NIH grant CA095681.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-15-18.

Enzymatic formation of manganese oxides by an Acremonium-like hyphomycete fungus, strain KR21-2

A Mn-depositing fungus, Acremonium-like hyphomycete strain KR21-2, was isolated from a Mn deposit occurring on the wall of a storage bottle containing Mn(III, IV) oxide-coated streambed pebbles and stream water. 18S rRNA gene sequence analysis revealed that strain KR21-2 was phylogenetically related to members of the order Hypocreales within the class Ascomycetes. The spent culture medium at the stationary phase of fungal growth contained a 54-kDa protein capable of depositing Mn oxides. The enzymatic activity was inhibited by azide and o-phenanthroline. The Mn(II)-oxidizing protein possessed a laccase activity, as indicated by direct oxidation of p-phenylenediamine and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid). These results are consistent with the role assumed for laccase-like multicopper oxidase, which is proposed to be involved in the Mn(II)-oxidizing factors from some bacteria. Unlike laccases of basidiomycete fungi, however, the protein of strain KR21-2 did not produce soluble Mn(III) species in the presence of either of the Mn chelators pyrophosphate and malonate. This is the first report on the possible involvement of laccase and/or multicopper oxidase in Mn oxide deposition by ascomycetes (including their anamorphs) ubiquitous in natural environments.

Decreased secretion of gonadotropins in a patient with Graves' disease

A 56-year-old female with Graves' disease who presented with decreased secretion of gonadotropins is described. She was admitted to hospital because of her being in a state of confusion. One month before admission she had been diagnosed as having Graves' disease and was treated with methimazole since then. Plasma LH and FSH levels were undetectable, and their responses to LH-RH were extremely decreased in spite of undetectable levels of plasma estradiol and estriol. One year after treatment, both basal and stimulated values of LH and FSH reverted to normal as did those of TSH. Reversible suppression of gonadotropins as described herein has never been reported in cases of Graves' disease.

Microbial manganese oxide formation and interaction with toxic metal ions

Diverse bacteria and fungi oxidize Mn(II) enzymatically and produce insoluble Mn(III, IV) oxides, and these organisms are considered to be the primal agents for the occurrence of natural Mn oxide phases in most environments. Biogenic Mn oxides have a high sorption capacity for metal cations and an ability to oxidize numerous inorganic and organic compounds, owing to their structural and redox features. Thus, the microbial process is of significance in both biogeochemical and biotechnological contexts. In this article we summarize the enzymatic Mn(II) oxidation and interactions of biogenic Mn oxides with toxic metal and metalloid ions. Although Mn oxide formation by fungi has not been fully characterized yet, recent researches with ascomycetes emphasize the similarity between the bacterial and fungal Mn(II) oxidation with respect to the involved catalyst (i.e., multicopper oxidase-type enzymes) and the reaction product [i.e., layer-type Mn(IV) oxides]. Laboratory cultures of bacterial and fungal Mn oxidizers are expected to provide fundamental knowledge in their potential use for remediation of environments and effluents contaminated with toxic metal(loid) ions.

Proteome analyses of the growth inhibitory effects of NCH-51, a novel histone deacetylase inhibitor, on lymphoid malignant cells

Recent reports showing successful inhibition of cancer and leukemia cell growth using histone deacetylase inhibitor (HDACi) compounds have highlighted the potential use of HDACi as anti-cancer agents. However, high incidence of toxicity and low stability in vivo were observed with hydroxamic acid-based HDACi such as suberoylanilide hydroxamic acid (SAHA), thus limiting its clinical applicability. In this study, we found that a novel non-hydroxamate HDACi NCH-51 could inhibit the cell growth of a variety of lymphoid malignant cells through apoptosis induction, more effectively than SAHA. Activation of caspase-3, -8 and -9, but not -7 was detected after the treatment with NCH-51. Gene expression profiles showed that NCH-51 and SAHA similarly upregulated p21 and downregulated anti-apoptotic molecules including survivin, bcl-w and c-FLIP. Proteome analysis using two-dimensional electrophoresis revealed that NCH-51 upregulated anti-oxidant molecules including peroxiredoxin 1 and 2 and glutathione S-transferase at the protein level. Interestingly, NCH-51 induced reactive oxygen species (ROS) after 8 h whereas SAHA continuously declined ROS. Pretreatment with an antioxidant, N-acetyl-L-cysteine, abolished the cytotoxicity of NCH-51. These findings suggest that NCH-51 exhibits cytotoxicity by sustaining ROS at the higher level greater than SAHA. This study indicates the therapeutic efficacy of NCH-51 and novel insights for anti-HDAC therapy.

Production of biogenic manganese oxides by repeated-batch cultures of laboratory microcosms

We investigated the production of manganese (Mn) oxides using repeated-batch bioreactors maintained over long periods under laboratory conditions. Freshwater epilithic biofilms were used as the initial inocula. The bioreactors yielded suspended solids that could remove 0.1 mM dissolved Mn(II) within a few days. Chemical titration, X-ray absorption near-edge structure spectroscopy, and X-ray diffraction analysis revealed that the Mn(II) had been converted to poorly crystallized layer-type Mn(IV) oxides, which were similar to known biogenic Mn oxides from pure bacterial cultures. Spherical or rod-shaped Mn microconcretions occurred in the suspended solids; transmission electron microscopy showed that these structures likely resulted from the microbial activity but not represent living cells. Instead, the presence of encapsulated, sheathed, and hyphal budding cells in the suspended solids indicated that a range of Mn-depositing bacteria contributed to the Mn oxide formation. To our knowledge, our data represent the first observation of production of such Mn oxides in a laboratory microcosm wherein a range of Mn-depositing bacteria coexist. The fact that sorption of trace Zn(II) and Ni(II) ions onto the suspended solids co-occurred with the removal of dissolved Mn(II) emphasizes the important role of Mn-oxidizing microorganisms in the fates of trace or contaminant metals in the aquatic environment.

Manganese(IV) oxide production by Acremonium sp. strain KR21-2 and extracellular Mn(II) oxidase activity

Ascomycetes that can deposit Mn(III, IV) oxides are widespread in aquatic and soil environments, yet the mechanism(s) involved in Mn oxide deposition remains unclear. A Mn(II)-oxidizing ascomycete, Acremonium sp. strain KR21-2, produced a Mn oxide phase with filamentous nanostructures. X-ray absorption near-edge structure (XANES) spectroscopy showed that the Mn phase was primarily Mn(IV). We purified to homogeneity a laccase-like enzyme with Mn(II) oxidase activity from cultures of strain KR21-2. The purified enzyme oxidized Mn(II) to yield suspended Mn particles; XANES spectra indicated that Mn(II) had been converted to Mn(IV). The pH optimum for Mn(II) oxidation was 7.0, and the apparent half-saturation constant was 0.20 mM. The enzyme oxidized ABTS [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] (pH optimum, 5.5; Km, 1.2 mM) and contained two copper atoms per molecule. Moreover, the N-terminal amino acid sequence (residues 3 to 25) was 61% identical with the corresponding sequence of an Acremonium polyphenol oxidase and 57% identical with that of a Myrothecium bilirubin oxidase. These results provide the first evidence that a fungal multicopper oxidase can convert Mn(II) to Mn(IV) oxide. The present study reinforces the notion of the contribution of multicopper oxidase to microbially mediated precipitation of Mn oxides and suggests that Acremonium sp. strain KR21-2 is a good model for understanding the oxidation of Mn in diverse ascomycetes.

Reversal of delayed vasospasm by TS-011 in the dual hemorrhage dog model of subarachnoid hemorrhage

PURPOSE

Arachidonic acid is avidly metabolized to a potent vasoconstrictor, 20-hydroxyeicosatetraenoic acid (20-HETE), in the cerebral circulation. 20-HETE has been reported to contribute to the acute fall in cerebral blood flow following subarachnoid hemorrhage (SAH), but its role in the development of delayed vasospasm is unknown. The present study examined whether delayed vasospasm is associated with elevations in 20-HETE in CSF in the dual hemorrhage model of SAH in dogs and if blockade of the synthesis of 20-HETE with N-(3-chloro-4-morpholin-4-yl)phenyl-N'-hydroxyimido formamide (TS-011) can reverse delayed vasospasm in this model.

MATERIALS AND METHODS

Delayed vasospasm was induced in 22 adult beagle dogs by dual injection of blood (0.5 mL/kg) into the cisterna magna on days 1 and 4. Sequential samples of CSF were collected before intracisternal injections of blood on days 1 and 4 and after the development of delayed vasospasm on day 7. Sequential angiograms were obtained before and after intracisternal injection of blood on days 1 and 4 and before and 1 hour after administration of TS-011 (1 mg/kg IV) on day 7.

RESULTS

The dogs consistently developed delayed vasospasm, and the diameter of the basilar artery fell to 68 +/- 3% (n = 15), 3 days after the second intracisternal injection of blood. The levels of 20-HETE in CSF increased from 4 +/- 2 to 39 +/- 16 pg/mL. In 9 dogs with delayed vasospasm, acute blockade of the synthesis of 20-HETE with TS011 (1 mg/kg IV) significantly increased the diameter of the basilar artery by 39%. Chronic administration of TS-011 (1 mg/kg per day) attenuated the development of delayed vasospasm, and the diameter of the basilar artery fell by 17 +/- 1% versus the 33 +/- 3% decrease in diameter seen in control animals 3 days following the second injection of blood into the cisterna magna.

CONCLUSIONS

These results indicate that the development of delayed vasospasm in dogs is associated with an increase in 20-HETE levels in CSF, and acute blockade of the synthesis of 20-HETE with TS-011 reverses delayed vasospasm in this model.

Formation of stable foam by the cells and culture supernatant of Gordonia (Nocardia) amarae

Gordonia amarae is the cause of foaming activated sludge. In this study, the mechanism of foam formation by G. amarae SC1 was investigated. A liquid culture of SC1 cells generated a stable foam when shaken reciprocally. This foam formation was dependent on the presence of both bacterial cells and culture supernatant. A high-molecular-weight fraction (Mw>10000) of the supernatant was capable of emulsifying n-hexadecane in addition to exhibiting foaming activity, indicating that it contains a surface-active substance(s). The bacterial cells showed a high affinity to hexadecane. This hydrophobic cell surface property might be involved in the attachment of cells to air bubbles to generate a stable foam. The results demonstrated the participation of cells and the extracellular biosurfactant in the formation and stabilization of foam in G. amarae SC1 culture.

Anaerobic degradation of cis-1,2-dichloroethylene and vinyl chloride by Clostridium sp. strain DC1 isolated from landfill leachate sediment

The bacterial community structure of anaerobic enrichment cultures that are capable of degrading both cis-1,2-dichloroethylene (cis-DCE) and vinyl chloride (VC) and isolation of the organism responsible for the degradation were investigated. Denaturing gradient gel electrophoresis (DGGE) of a PCR-amplified 16S rRNA gene from the cultures showed the possible predominance of Clostridium species. One isolate, designated strain DC1, was closely related to members of Clostridiaceae, based on 16S rRNA gene analysis, and the highest sequence similarity (98.9%) was obtained for Clostridium saccarobutylicum. In culture experiments, strain DC1 was shown to degrade cis-DCE and VC during the stationary phase of growth without accumulation of VC and/or ethene. The bacterial growth was not linked to the degradation of cis-DCE and VC. Stoichiometric analysis revealed that two moles of chloride ions as released from one mole of cis-DCE during the incubation period, indicating that cis-DCE was fully dechlorinated. The results appear consistent with the presence of a mechanism of oxidative dechlorination rather than respiratory reductive dechlorination; the latter is accompanied by transient formation of dechlorinated ethenes from cis-DCE and VC.

Production of anti-Gordonia amarae mycolic acid polyclonal antibody for detection of mycolic acid-containing bacteria in activated sludge foam

Mycolic acid-containing actinomycetes (mycolata) are considered the causative agents of foaming of activated sludge and scum formation in activated sludge treatment plants. In this study, the production of anti-Gordonia amarae mycolic acid polyclonal antibodies was investigated. Rabbits were immunized with a conjugate of keyhole limpet hemocyanin and mycolic acids of G. amarae, which contained 48 to 56 carbon atoms (average, 52.0). Enzyme-linked immunosorbent assay (ELISA) demonstrated that the polyclonal antibodies could recognize cells of G. amarae ranging from 0.1 to 10 microg. The antibodies also reacted with other tested mycolata strains belonging to the genera Nocardia, Rhodococcus, Dietzia, Mycobacterium and Tsukamurella. However, reactivities against other gram-positive and gram-negative bacteria not containing mycolic acid were negligible or much lower. The results indicate that the anti-G. amarae mycolic acid antibodies show a reactivity selective for a group of mycolata involved in the foaming of activated sludge.

Interaction of inorganic arsenic with biogenic manganese oxide produced by a Mn-oxidizing fungus, strain KR21-2

In batch culture experiments we examined oxidation of As(III) and adsorption of As(III/V) by biogenic manganese oxide formed by a manganese oxide-depositing fungus, strain KR21-2. We expected to gain insight into the applicability of Mn-depositing microorganisms for biological treatment of As-contaminated waters. In cultures containing Mn2+ and As(V), the solid Mn phase was rich in bound Mn2+ (molar ratio, approximately 30%) and showed a transiently high accumulation of As(V) during the early stage of manganese oxide formation. As manganese oxide formation progressed, a large proportion of adsorbed As(V) was subsequently released. The high proportion of bound Mn2+ may suppress a charge repulsion between As(V) and the manganese oxide surface, which has structural negative charges, promoting complex formation. In cultures containing Mn2+ and As(III), As(III) started to be oxidized to As(V) after manganese oxide formation was mostly completed. In suspensions of the biogenic manganese oxides with dissolved Mn2+, As(III) oxidation rates decreased with increasing dissolved Mn2+. These results indicate that biogenic manganese oxide with a high proportion of bound Mn2+ oxidizes As(III) less effectively than with a low proportion of bound Mn2+. Coexisting Zn2+, Ni2+, and Co2+ also showed similar effects to different extents. The present study demonstrates characteristic features of oxidation and adsorption of As by biogenic manganese oxides and suggests possibilities of developing a microbial treatment system for water contaminated with As that is suited to the actual situation of contamination.

Mechanical behavior of bioactive composite cements consisting of resin and glass-ceramic powder in a simulated body fluid: effect of silane coupling agent

Time-dependent strength behavior was investigated for bisphenol-a-glycidyl methacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) resin cements combined with glass-ceramic A-W filler treated with various kinds of silane coupling agents. The fracture strength of the composite resin cements was measured by three-point bending as a function of stressing rate in a simulated body fluid (SBF), and thereby the stress-corrosion susceptibility constant was evaluated. The fracture strength was found to depend on the kind of coupling agent used. For the present Bis-GMA/TEGDMA resin, the silane coupling agents without hydrophilic amine groups can be used to obtain good adhesion between resin and A-W filler owing to their nature of co-polymerizing with the resin. On the other hand, all the composite resin cements showed nearly the same degree of stress-corrosion susceptibility whether the A-W fillers were treated or untreated with silane coupling agents. This means that the stress-corrosion susceptibility of the present composite cements is predominantly affected by that of the matrix resin. Thus, the microcrack formation and growth at the resin matrix near particle - resin interface were thought to determine overall time-dependent strength behavior of the composite cements.

Mechanical properties of glass-ceramic A–W-polyethylene composites: effect of filler content and particle size

Composites which comprise a bioactive filler and ductile polymer matrix are desirable as implant materials since both their biological and mechanical properties can be tailored for a given application. In the present study three-point bending was used to characterise biomedical materials composed of glass-ceramic apatite-wollastonite (A-W) particulate reinforced polyethylene (PE) (denoted as AWPEX). The effects of filler volume fraction, varied from 10 to 50 vol%, and average particle size, 4.4 and 6.7 microm, on the bending strength, yield strength, mode of fracture, Young's modulus and strain to failure were investigated. HAPEX, a commercially used composite of hydroxyapatite and polyethylene, with a 40 vol% filler content, was used for comparison. Increasing the filler content caused an increase in Young's modulus, yield strength and bending strength, and a decreased strain to failure. When filler particle size was increased, the Young's modulus, yield and bending strengths were found to be slightly reduced. A transition in fracture behaviour from ductile to brittle behaviour was observed in samples containing between 30 and 40 vol% filler.

Growth of Aspergillus oryzae during treatment of cassava starch processing wastewater with high content of suspended solids

Aspergillus oryzae IFO 30113 was used for the treatment of the cassava starch processing (CSP) wastewater. The observations on the fungal morphology showed that, in the shake flasks containing the CSP wastewater with the high concentration of suspended solids, the formation of pellets originated from the adherence of germinated spores to solid particles in medium. The attached solid particles were also digested during the fungal fermentation and resulted in the formation of the smooth and hollow pellets. The changes of the culture conditions such as inoculum size, initial pH of wastewater, inoculum type and nutrient elements affected on the fungal morphology, biomass accumulation and treatment efficiencies of A. oryzae IFO 30113. In the typical pH range (pH 4-5) of the CSP wastewater, the formation of smooth pellets was predominant and A. oryzae IFO 30113 was satisfiable for the production of fungal biomass and treatment efficiencies. The supplementation of nitrogen sources has shown an improvement in the fungal biomass accumulation and the treatment efficiency of A. oryzae IFO 30113 growing in the CSP wastewater. Especially, high biomass yields (up to 0.8 g/g-COD) were achieved in flasks supplied with peptone. With ammonium sulfate as nitrogen source, 87% total organic carbon (TOC), 91% COD and 94% starch were removed after 96-h incubation. The possibility of the pellet formation despite the presence of the high content of suspended solids would be of great advantage to perform the treatment process and the fungal biomass production on the airlift-type bioreactors by lowering medium viscosity and better mass exchange of oxygen and nutrients.

Sorption of Co(II), Ni(II), and Zn(II) on biogenic manganese oxides produced by a Mn-oxidizing fungus, strain KR21-2

The characteristics of Co(II), Ni(II), and Zn(II) sorption on freshly produced biogenic Mn oxides by a Mn-oxidizing fungus, strain KR21-2, were investigated. The biogenic Mn oxides showed about 10-fold higher efficiencies for sorbing the metal ions than a synthetic Mn oxide (gamma-MnO2) on the basis of unit weight and unit surface area. The order of sorption efficiency on the biogenic Mn oxides was Co(II) > Zn(II) > Ni(II), while that on the synthetic Mn oxide was Zn(II) > Co(II) > Ni(II). These sorption selectivities were confirmed by both sorption isotherms and competitive sorption experiments. Two-step extraction, using 10mM CuSO4 solution for exchangeable sorbed ions and 10-20mM hydroxylamine hydrochloride for ions bound to reducible Mn oxide phase, showed higher irreversibility of Co(II) and Ni(II) sorption on the biogenic Mn oxides while Zn(II) sorption was mostly reversible (Cu(II)-exchangeable). Sorptions of Co(II), Ni(II), and Zn(II) on the synthetic Mn oxide were, however, found to be mostly reversible. Higher irreversibility of Co(II) and Ni(II) sorption on the biogenic Mn oxides may partly explain higher accumulation of these metal ions in Mn oxide phases in natural environments. The results obtained in this study raise the possibility to applying the biogenic Mn oxide formation to treatment of water contaminated with toxic metal ions.

Saturable, energy-dependent uptake of phenanthrene in aqueous phase by Mycobacterium sp. strain RJGII-135

The mechanism of uptake of phenanthrene by Mycobacterium sp. strain RJGII-135, a polycyclic hydrocarbon-degrading bacterium, was examined with cultures grown on phenanthrene (induced for phenanthrene metabolism) and acetate (uninduced). Washed cells were suspended in aqueous solutions of [9-(14)C]phenanthrene, and then the cells were collected by filtration. Low-level steady-state (14)C concentrations in uninduced cells were achieved within the first 15 s of incubation. This immediate uptake did not show saturation kinetics and was not susceptible to inhibitors of active transport, cyanide and carbonyl cyanide m-chlorophenylhydrazone. These results indicated that phenanthrene enters rapidly into the cells by passive diffusion. However, induced cells showed cumulative uptake over several minutes. The initial uptake rates followed saturation kinetics, with an apparent affinity constant (K(t)) of 26 +/- 3 nM (mean +/- standard deviation). Uptake of phenanthrene by induced cells was strongly inhibited by the inhibitors. Analysis of cell-associated (14)C-labeled compounds revealed that the concurrent metabolism during uptake was rapid and was not saturated at the substrate concentrations tested, suggesting that the saturable uptake observed reflects membrane transport rather than intracellular metabolism. These results were consistent with the presence of a saturable, energy-dependent mechanism for transport of phenanthrene in induced cells. Moreover, the kinetic data for the cumulative uptake suggested that phenanthrene is specifically bound by induced cells, based on its saturation with an apparent dissociation constant (K(d)) of 41 +/- 21 nM (mean +/- standard deviation). Given the low values of K(t) and K(d), Mycobacterium sp. strain RJGII-135 may use a high-affinity transport system(s) to take up phenanthrene from the aqueous phase.

Apatite formation on CaO-free polydimethylsiloxane (PDMS)-TiO2 hybrids

Polydimethylsiloxane (PDMS)-TiO(2) hybrids with PDMS (M=550)/tetraethylorthotitanate molar ratios at 0.27, 0.68 and 1.35, i.e. Si/Ti atomic ratios at 2, 5 and 10 (hybrids PD2, PD5 and PD10, respectively) were prepared by a sol-gel method. Hybrid PD2 formed many cracks. Hybrids PD5 and PD10 were subjected to hot-water treatment 80 degrees C for 7 d. Hybrid PD5 produced cracks, whereas hybrid PD10 was crack-free after the hot-water treatment. Hybrid PD10 took a homogeneous amorphous structure before the hot-water treatment, and precipitated anatase particles 10-20 nm in size after the hot-water treatment. Hybrid PD10 did not form apatite on its surface in a simulated body fluid before the hot-water treatment, but formed it after the hot-water treatment. The obtained hybrid showed elastic deformation as large as 200% after the hot-water treatment. This kind of hybrid could be useful as a new type of bone-repairing material.

Biodegradation of cis-1,2-dichloroethylene and vinyl chloride in anaerobic cultures enriched from landfill leachate sediment under Fe(III)-reducing conditions

An anaerobic, Fe(III)-reducing enrichment culture, which originated from a sediment sample collected at a landfill in Nanji-do, Seoul, Korea, was capable of degrading cis-1,2-dichloroethylene (cis-DCE) and vinyl chloride (VC). Although it exhibited the ability under Fe(III)-reducing conditions, the chlorinated ethenes degradation was not linked to the Fe(III) reduction. During cis-DCE degradation, no VC, ethene, or ethane was detected through the experimental period. Also, this culture did not accumulate ethene and ethane during the VC degradation. It was unlikely that cis-DCE was reductively dechlorinated to VC and then the VC formed was dechlorinated fast enough. Because the kinetic data showed that the rate of cis-DCE degradation was 3.5 times higher than that of VC. Whereas glucose supported the culture growth and the degradation, formate, acetate, butyrate, propionate, lactate, pyruvate, and yeast extract did not. The results appeared consistent with the involvement of oxidative degradation mechanism rather than reductive dechlorination mechanism. The traits of the culture described here are unusual in the anaerobic degradation of chlorinated ethenes and may be useful for searching an effective organism and mechanism regarding anaerobic cis-DCE and VC degradation.

Application of Euglena gracilis cells to comet assay: evaluation of DNA damage and repair

Alkaline single-cell gel electrophoresis (comet assay) enables sensitive detection of DNA damage in eukaryotic cells induced by genotoxic agents. We performed a comet assay of unicellular green alga Euglena gracilis that was exposed to genotoxic chemicals, 1-methyl-3-nitro-1-nitrosoguanidine (MNNG), benzo[a]pyrene (BAP), mitomycin C (MMC) and actinomycin D (AMD). Tail length and tail moment in migrated DNA were measured as indications of DNA damage. MNNG and BAP were found to cause concentration-dependent increases in DNA damage. The responses were more sensitive than those of human lymphocytes under the same treatment conditions. MMC and AMD showed no positive response, as reported elsewhere. The comet assays performed at specified times after treatment revealed that the DNA damaged by MNNG and gamma-ray irradiation was repaired during the initial 1h. The results clearly show that the comet assay is useful for evaluating chemically-induced DNA damage and repair in E. gracilis. Given the ease of culturing and handling E. gracilis as well as its sensitivity, the comet assay of this alga would undoubtedly prove to be a useful tool for testing the genotoxicity of chemicals and monitoring of environmental pollution.

Apatite-forming ability of glass-ceramic apatite-wollastonite - polyethylene composites: effect of filler content

The bioactivity of a range of glass-ceramic apatite-wollastonite (A-W) - polyethylene composites (AWPEXs) with glass-ceramic A-W volume percentages ranging from 10 to 50, has been investigated in an acellular simulated body fluid (SBF) with ion concentrations similar to those of human blood plasma. The formation of a biologically active apatite layer on the composite surface after immersion in SBF was demonstrated by thin-film X-ray diffraction (TF-XRD) and field-emission scanning electron microscopy (FE-SEM). An apatite layer was formed on all the composites, with the rate of formation increasing with an increase in glass-ceramic A-W percentage. For composites with glass-ceramic A-W filler contents >or=30 vol %, the apatite layer was formed within 12 h of immersion, which is a comparable time for apatite formation on monolithic glass-ceramic A-W. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) demonstrated that the apatite formation on AWPEX samples with 50 vol % filler content occurred in a manner similar to that seen on pure glass-ceramic A-W, in that the calcium, silicon, and magnesium ion concentrations increased and, conversely, a decrease was observed in the phosphate ion concentration. These results indicate that a suitable in vitro response was achieved on a composite incorporating particulate glass-ceramic A-W with a particularly favorable response being observed on the AWPEX sample with 50 vol % filler content.

Bonding strength of the apatite layer formed on glass-ceramic apatite-wollastonite-polyethylene composites

Bioactive glass-ceramic apatite-wollastonite (A-W) has been incorporated into polyethylene in particulate form to create new bioactive composites for potential maxillofacial applications. The effects of varying the volume fraction of glass-ceramic A-W filler and the glass-ceramic A-W particle size were investigated by measuring the bonding strength of the bonelike apatite layer formed on the surface of glass-ceramic A-W-polyethylene composites. The bonding strength was evaluated via a modified ASTM C-333 standard in which a tensile stress was applied to the substrate and the strength of the bioactive layer was compared with that formed on commercially available hydroxyapatite-polyethylene composite samples, HAPEX. The composites demonstrated greater bonding strength with increased filler content and reduced filler particle size (maximum 6.9 +/- 0.5 MPa) and a marginally greater bonding strength as compared with HAPEX (2.8 +/- 0.5 MPa), when glass-ceramic A-W-polyethylene composite samples with the same filler content were tested. The higher bonding strength of the apatite layer formed on the A-W-polyethylene composite samples suggests that, in addition to maxillofacial applications, these composites might also be utilized in applications involving higher levels of load bearing.

Bioactivity and mechanical properties of polydimethylsiloxane (PDMS)-CaO-SiO2 hybrids with different calcium contents

Polydimethylsiloxane (PDMS)-CaO-SiO(2) hybrids with starting compositions containing PDMS/(Si(OC(2)H(5))(4)+PDMS) weight ratio=0.30, H(2)O/Si(OC(2)H(5))(4) molar ratio=2, and Ca(NO(3))(2)/Si(OC(2)H(5))(4) molar ratios=0-0.2, were prepared by the sol-gel method. The apatite-forming ability of the hybrids increased with increasing calcium content in the Ca(NO(3))(2)/Si(OC(2)H(5))(4) molar ratio range 0-0.1. The hybrids with a Ca(NO(3))(2)/Si(OC(2)H(5))(4) molar ratio range 0.1-0.2 formed apatite on their surfaces in a simulated body fluid (SBF) within 12 h. The hybrid with a Ca(NO(3))(2)/Si(OC(2)H(5))(4) molar ratio of 0.10 showed an excellent apatite-forming ability in SBF with a low release of silicon into SBF. It also showed mechanical properties analogous to those of human cancellous bones. This hybrid is expected to be useful as a new type of bioactive material.

Immunomagnetic separation of scum-forming bacteria using polyclonal antibody that recognizes mycolic acids

Mycolic acid-containing bacteria (mycolata) are thought to be involved in scum formation in aeration basins of activated sludge plants due to their ability to produce biosurfactants and their cell surface hydrophobicity. To isolate these bacteria, immunomagnetic separation (IMS) using an anti-mycolic acid polyclonal antibody was investigated. IMS that targeted Gordonia amarae SC1 exhibited a 100% recovery at 5x10(3) CFU ml(-1). At cell concentration of 7.8x10(6) CFU ml(-1), the recovery was lowered, but 80% of cells were still captured. Effect of bead concentrations on the recovery of SC1 at 10(6) CFU ml(-1) was examined. The results showed that addition of more than 6-7x10(6) beads for 1x10(6) CFU reached a maximum recovery (83%). Furthermore, the IMS procedure optimized with SC1 cells was tested with another mycolata. The results suggested that variation of the recovery for each mycolata is dependent on the specificity of the polyclonal antibody and that mycolata which are recognized by the antibody can be recovered by this procedure.

[Nitric oxide (NO) donor]

Nitric oxide (NO), which is synthesized from L-arginine by nitric oxide synthase (NOS) in mammals, acts as a signal molecule for vasorelaxation, cytotoxicity and neurotransmission. The difficulty in handling of a gaseous and labile NO causes problems with the effective and precise studies using NO. The increasing interest in the biological roles of NO requires the use of NO donors which releases NO under the various desirable conditions. We systematized the most commonly used NO donors in this article to support the biological investigation. NO donors were classified according to the functional groups based on NO-donating characteristics. The preparation, chemical properties and NO-donating ability of these NO donors are summarized. It is particularly described in some detail on the stability both as a solid and in solution and the handling of the compounds.

Efficient and versatile synthesis of novel 2alpha-substituted 1alpha,25-dihydroxyvitamin D(3) analogues and their docking to vitamin D receptors

Novel 2alpha-substituted 1alpha,25-dihydroxyvitamin D(3) analogues with 2alpha-alkyl and 2alpha-hydroxyalkyl groups were systematically synthesized from D-xylose. Their conformation on binding to the ligand binding domain (LBD) of the vitamin D receptor was analyzed. It has been found that the 2alpha-hydroxypropyl group best fits the cavity of the LBD, and the binding activity is three times higher than that for the natural hormone.

Discovery of a N'-hydroxyphenylformamidine derivative HET0016 as a potent and selective 20-HETE synthase inhibitor

N-(4-Butyl-2-methylphenyl)-N'-hydroxyformamidine (HET0016) was evaluated as the first potent and selective inhibitor of 20-hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE) synthase. The IC(50) value of HET0016 for the production of 20-HETE from arachidonic acid (AA) by human renal microsomes was 8.9+/-2.7 nM, with over 200 times the selectivity of xenobiotic-metabolizing cytochrome P450 enzymes. An examination of the structure-activity relationship revealed that the unsubstituted hydroxyformamidine moiety and the substituent at the para-position of the N-hydroxyformamidine moiety are necessary for the potent activity of HET0016.

Synthesis and biological evaluation of all A-ring stereoisomers of 5,6-trans-2-methyl-1,25-dihydroxyvitamin D(3) and their 20-epimers: possible binding modes of potent A-ring analogues to vitamin D receptor

BACKGROUND

The secosteroid 1 alpha,25-dihydroxyvitamin D(3) (1) has a wide variety of biological activities, which makes it a promising therapeutic agent for the treatment of cancer, psoriasis and osteoporosis. Insight into the structure-activity relationships of the A-ring of 1 is still needed to assist the development of more potent and selective analogues as candidate chemotherapeutic agents, as well as to define the molecular mode of action.

RESULTS

All possible A-ring stereoisomers of 5,6-trans-2-methyl-1,25-dihydroxyvitamin D(3) (6a-h) and their 20-epimers (7a-h) were designed and efficiently synthesized. The dependence of the affinities for vitamin D receptor (VDR) and vitamin D binding protein (DBP), as well as the HL-60 cell differentiation-inducing activity, upon the stereochemistry of the A-ring and at C20 in the side chain was evaluated.

CONCLUSIONS

The binding affinities and potency of the 5,6-trans and 5,6-cis analogues were enhanced by a 2-methyl substituent in a certain orientation. Molecular docking studies based upon the X-ray crystal structure of VDR suggested that the axial 2-methyl group would be accommodated in a pocket surrounded by hydrophobic amino acid residues in the ligand binding domain, resulting in enhanced interaction.

Syntheses, structures, stability, and insulin-like activities of peroxovanadium(V) complexes with a heteroligand

Several peroxovanadium(V) complexes were prepared with a tripodal or a quasi-tripodal tetradentate ligand. The structures of K(2)[VO(O(2))(nta)].2H(2)O and K[VO(O(2))(DL-cmhist)].H(2)O have been determined by X-ray crystallography (nta, nitrilotriacetate; cmhist, N-carboxymethylhistidinate). The structure of Cs[VO(O(2))(pda)].2H(2)O (pda, N-pyridylmethyliminodiacetate) has been estimated to be similar to that of K[VO(O(2))(DL-cmhist)].H(2)O. Each complex anion in these compounds adopts a distorted pentagonal bipyramidal structure, which is typical for heptacoordinate oxoperoxovanadium(V) complexes. The peroxide ion binds in a side-on fashion to the vanadium(V) center in the pentagonal plane. The peroxide anion in the cmhist complex dissociates rather easily in an acidic solution (pH approximately 3), while that in the other complexes stays intact under similar conditions. The in vitro insulin mimetic effect of the peroxovanadium(V) complexes has been evaluated by the inhibitory effect on free fatty acid (FFA) release in isolated rat adipocytes treated with epinephrine. The cmhist complex is effective, while the others are almost totally ineffective.

Photochemical generation of nitric oxide from 6-nitrobenzo[a]pyrene

Photolabile 6-nitrobenzo[a]pyrene (6-nitroBaP) released nitric oxide (NO) under visible-light irradiation. The generation of NO and the concomitant formation of the 6-oxyBaP radical were confirmed by ESR. BaP quinones were also detected as further oxidized products of the 6-oxyBaP radical. No such photodegradation was observed with other nitrated BaPs, such as 1-nitroBaP and 3-nitroBaP. DNA-strand breakage, caused by photoexcited 6-nitroBaP, was closely related to its NO-releasing activity. MO calculations of nitrated BaP suggest that the perpendicular conformation of the nitro substituent to the aromatic ring is important for the release of NO with light. These findings may be useful for the development of a new type of NO donor.

Resveratrol, a naturally occurring polyphenol, induces sister chromatid exchanges in a Chinese hamster lung (CHL) cell line

We tested the genotoxicity of 3,5,4'-trihydroxystilbene (resveratrol), a polyphenolic phytoalexin found in grapes, in a bacterial reverse mutation assay, in vitro chromosome aberration (CA) test, in vitro micronucleus (MN) test, and sister chromatid exchange (SCE) test. Resveratrol was negative in the strains we used in the bacterial reverse mutation assay (S. typhimurium TA98 and TA100 and E. coli WP2uvrA) in the absence and presence of a microsomal metabolizing system. It induced structural CAs at 2.5-20 microg/ml and showed weak aneuploidy induction in a Chinese hamster lung (CHL) cell line. It induced MN cells and polynuclear and karyorrhectic cells after 48h treatments in the in vitro MN test. In the SCE test, resveratrol caused a clear cell-cycle delay; at 10 microg/ml, the cell cycle took twice as long as it did in the control. Resveratrol induced SCEs dose-dependently at up to 10 microg/ml, at which it increased SCE six-fold, and the number was almost as large as mitomycin C, a strong SCE inducer. No second mitoses were observed at 20 microg/ml even after 54h. Cell cycle analysis by FACScan indicated that resveratrol caused S phase arrest, and 48h treatment induced apoptosis. Our results suggest that resveratrol may preferentially induce SCE but not CA, that is, it may cause S phase arrest only when SCEs are induced.

Optical anisotropy of oxidized Si(001) surfaces and its oscillation in the layer-by-layer oxidation process

Reflectance-difference (RD) measurements for the oxidation of single-domain (2x1)-reconstructed Si(001) surfaces show that the polarity of the interface-induced optical anisotropy is reversed repeatedly with increasing oxide thickness. The oscillation of the RD amplitude, which we show is due to layer-by-layer progression of the oxidation, has allowed us to count the number of oxidized Si layers in situ during oxidation. The origins of the observed spectral line shape are discussed.

Effect of heat treatment on bioactivity and mechanical properties of PDMS-modified CaO-SiO2-TiO2 hybrids via sol-gel process

Crack- and pore-free transparent monolithic disks of polydimethylsiloxane (PDMS)- modified CaO-SiO2-TiO2 hybrids were obtained by hydrolysis and polycondensation of PDMS, tetraethoxysilane, tetraisopropyltitanate and calcium nitrate. The product as-dried at 60 degrees C formed an apatite on its surface in a simulated body fluid (SBF) within only one day, indicating its high bioactivity. The apatite-forming ability decreased slightly by a heat treatment below 250 degrees C. The bending strength of the product was about 11 MPa, independent of the heat treatment. This average strength value is comparable to that of the human cancellous bone. Young's modulus of the products increased from 100 to 500 MPa with increasing heat treatment temperature from 60 to 250 degrees C, but its values were within the range of those of the human cancellous bone. The strain at failure of the products decreased with increasing heat treatment temperature. Failure strains went down to the magnitudes exhibited by the human cancellous bone, when the products were heat treated in the temperature range from 150 to 250 degrees C. Thus, highly bioactive hybrids with mechanical properties analogous to those of the human cancellous bone were obtained. This new kind of bioactive hybrid may be useful as a bone-repairing material.

HET0016, a potent and selective inhibitor of 20-HETE synthesizing enzyme

The present study examined the inhibitory effects of N-hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (HET0016) on the renal metabolism of arachidonic acid by cytochrome P450 (CYP) enzymes. HET0016 exhibited a high degree of selectivity in inhibiting the formation of 20-hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE) in rat renal microsomes. The IC(50) value averaged 35+/-4 nM, whereas the IC(50) value for inhibition of the formation of epoxyeicosatrienoic acids by HET0016 averaged 2800+/-300 nM. In human renal microsomes, HET0016 potently inhibited the formation of 20-HETE with an IC(50) value of 8.9+/-2.7 nM. Higher concentrations of HET0016 also inhibited the CYP2C9, CYP2D6 and CYP3A4-catalysed substrates oxidation with IC(50) values of 3300, 83,900 and 71,000 nM. The IC(50) value for HET0016 on cyclo-oxygenase activity was 2300 nM. These results indicate that HET0016 is a potent and selective inhibitor of CYP enzymes responsible for the formation of 20-HETE in man and rat.

Micronucleus induction and chromosomal aberration of 1- and 3-nitroazabenzo[a]pyrene and their N-oxides

Nitro-azabenzo[a]pyrenes, 1- or 3-nitro-azabenzo[a]pyrene and their N-oxides are nitrated derivatives of azabenzo[a] pyrene (ABP) containing nitrogen in the 6-position of benzo[a]pyrene (B[a]P). The nitro-ABP-N-oxides (ABPOs) were formed by reaction of ABP with excess HNO(3). These derivatives were noteworthy as potent mutagens for Salmonella strains, and were present in fine particles of diesel particulates. In this study, micronucleus induction in mice and chromosomal aberrations due to means of Chinese hamster lung fibroblast (CHL) cells were investigated to determine genotoxicity in order to define the relationship with the mutagenic potency of these derivatives. The induction of micronucleus polychromatic erythrocytes (MNPCEs) was dependent on the dose response of 10-40 mg for 3-N-6-ABP, and of 10-40 mg for 1-N-6-ABP, and in addition, 1- and 3-N-6-ABPOs markedly induced MNPCEs in a dose range of 10-400 mg and from 1 to 80 mg, respectively, when the compound was intraperitoneally administrated in two mice at each dose. The results show that of the four compounds, 3-N-6-ABPO demonstrated a marked increase in MNPCES: On the other hand, chromosomal aberrations of the four compounds were investigated by the duplicate tests using CHLS: The results after a 48 h treatment induced aberrations of the chromatid type, chromatid breaks and exchanges for 1- and 3-N-6-ABP, and mainly chromatid exchanges for 1- and 3-N-6-ABPO. The frequency of chromosomal aberrations associated with nitro substitution on the ABPO structure. Chromosomal aberrations of nitro derivatives of ABPO substituted at the 3-position on the structure were more potent than those at the 1-postion. N-oxide derivatives have been found to be reduced to anion radicals much more easily than azaB[a]P and its nitro derivatives. This suggests that the electrochemical reduction of the chemicals plays an important role in the metabolic activation of nitrated B[a]P derivatives.