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Ole Andersen - One of the best experts on this subject based on the ideXlab platform.
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effects of the polychaetes arenicola marina and nereis diversicolor on microbial Pyrene mineralization
Aquatic Microbial Ecology, 2008Co-Authors: Karen Timmermann, Gary Thomas Banta, Anders R Johnsen, Ole AndersenAbstract:The effects of 2 polychaetes, Nereis diversicolor and Arenicola marina, on the microbial mineralization of the organic contaminant Pyrene, a polycyclic aromatic hydrocarbon (PAH), were followed over 44 d. We also examined whether the effect of the polychaetes was caused by enhanced oxygen supply, altered Pyrene bioavailability and/or a changed abundance or activity of Pyrenedegrading bacteria. The presence of polychaetes enhanced microbial Pyrene mineralization by 180 to 200% compared with defaunated sediment. Collectively, the replicates of the different treatments showed that mineralization rates were positively correlated with the amount of oxidized sediment, which comprised mainly the 3 mm surface layer and zones around burrows (burrow sediment). The biogenic sediment structures had similar mineralization potential and abundance of Pyrene-degrading bacteria as surface sediments. Pyrene mineralization potential in bulk (reduced and presumably anoxic) sediment was significantly lower than for surface and burrow sediments. However, when the bulk sediments were oxidized, mineralization rates increased rapidly. Collectively, these data indicate that oxygen availability controlled Pyrene mineralization in these experiments. On the other hand, the presence of the polychaetes significantly reduced the bioavailability of Pyrene to the microbial degraders. Pyrene bioavailability in burrow sediment was always lower than the bioavailability in both surface and bulk sediments. In addition, N. diversicolor and especially A. marina decreased the bioavailability of Pyrene in surface sediments compared with that of surface sediments in the non-bioturbated control. In conclusion, these polychaetes enhanced microbial Pyrene mineralization significantly and this enhancement seemed to be caused by the increased oxygen supply due to burrow construction and irrigation. In contrast, these worms decreased Pyrene bioavailability and, hence, counteracted to some extent the stimulating effect of irrigation.
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bioavailability of Pyrene to the deposit feeding polychaete arenicola marina importance of sediment versus water uptake routes
Marine Ecology Progress Series, 2003Co-Authors: Karen Timmermann, Ole AndersenAbstract:The bioavailability of the PAH (polycyclic aromatic hydrocarbon) model compound Pyrene to the deposit-feeding polychaete Arenicola marina was studied at Pyrene concentrations ranging from 0 to 10 ppm. By manipulating the sediment organic content, different distributions of Pyrene between particle-associated Pyrene, Pyrene bound to dissolved organic matter (DOM) and freely dissolved Pyrene were obtained at the same Pyrene concentration in bulk sediment. The results showed that organic matter influenced the partitioning of Pyrene in the sediment matrix. The concentration of dissolved Pyrene in porewater and overlying water was higher in sediment with a high organic content, probably due to an increased DOM concentration. In contrast, the concentra- tion of freely dissolved Pyrene was, as expected, higher in sediment with low organic content. Bio- accumulation of Pyrene correlated very well with the amount of Pyrene passing through the gut, indi- cating that particle-associated Pyrene is bioavailable and that ingestion is an important uptake route. Body burden was correlated neither with total dissolved Pyrene nor with freely dissolved Pyrene, leading one to reject the hypothesis that Pyrene uptake is due to simple diffusion processes from water to sediment. Furthermore, no relation between bioaccumulation and dissolved Pyrene passing through the gills via irrigation was observed. Bioconcentration factors relative to sediment and water declined with increasing external Pyrene concentrations, enhancing the likelihood of sediment toxi- city being underestimated when using these factors in risk assessment.
Karen Timmermann - One of the best experts on this subject based on the ideXlab platform.
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effects of the polychaetes arenicola marina and nereis diversicolor on microbial Pyrene mineralization
Aquatic Microbial Ecology, 2008Co-Authors: Karen Timmermann, Gary Thomas Banta, Anders R Johnsen, Ole AndersenAbstract:The effects of 2 polychaetes, Nereis diversicolor and Arenicola marina, on the microbial mineralization of the organic contaminant Pyrene, a polycyclic aromatic hydrocarbon (PAH), were followed over 44 d. We also examined whether the effect of the polychaetes was caused by enhanced oxygen supply, altered Pyrene bioavailability and/or a changed abundance or activity of Pyrenedegrading bacteria. The presence of polychaetes enhanced microbial Pyrene mineralization by 180 to 200% compared with defaunated sediment. Collectively, the replicates of the different treatments showed that mineralization rates were positively correlated with the amount of oxidized sediment, which comprised mainly the 3 mm surface layer and zones around burrows (burrow sediment). The biogenic sediment structures had similar mineralization potential and abundance of Pyrene-degrading bacteria as surface sediments. Pyrene mineralization potential in bulk (reduced and presumably anoxic) sediment was significantly lower than for surface and burrow sediments. However, when the bulk sediments were oxidized, mineralization rates increased rapidly. Collectively, these data indicate that oxygen availability controlled Pyrene mineralization in these experiments. On the other hand, the presence of the polychaetes significantly reduced the bioavailability of Pyrene to the microbial degraders. Pyrene bioavailability in burrow sediment was always lower than the bioavailability in both surface and bulk sediments. In addition, N. diversicolor and especially A. marina decreased the bioavailability of Pyrene in surface sediments compared with that of surface sediments in the non-bioturbated control. In conclusion, these polychaetes enhanced microbial Pyrene mineralization significantly and this enhancement seemed to be caused by the increased oxygen supply due to burrow construction and irrigation. In contrast, these worms decreased Pyrene bioavailability and, hence, counteracted to some extent the stimulating effect of irrigation.
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bioavailability of Pyrene to the deposit feeding polychaete arenicola marina importance of sediment versus water uptake routes
Marine Ecology Progress Series, 2003Co-Authors: Karen Timmermann, Ole AndersenAbstract:The bioavailability of the PAH (polycyclic aromatic hydrocarbon) model compound Pyrene to the deposit-feeding polychaete Arenicola marina was studied at Pyrene concentrations ranging from 0 to 10 ppm. By manipulating the sediment organic content, different distributions of Pyrene between particle-associated Pyrene, Pyrene bound to dissolved organic matter (DOM) and freely dissolved Pyrene were obtained at the same Pyrene concentration in bulk sediment. The results showed that organic matter influenced the partitioning of Pyrene in the sediment matrix. The concentration of dissolved Pyrene in porewater and overlying water was higher in sediment with a high organic content, probably due to an increased DOM concentration. In contrast, the concentra- tion of freely dissolved Pyrene was, as expected, higher in sediment with low organic content. Bio- accumulation of Pyrene correlated very well with the amount of Pyrene passing through the gut, indi- cating that particle-associated Pyrene is bioavailable and that ingestion is an important uptake route. Body burden was correlated neither with total dissolved Pyrene nor with freely dissolved Pyrene, leading one to reject the hypothesis that Pyrene uptake is due to simple diffusion processes from water to sediment. Furthermore, no relation between bioaccumulation and dissolved Pyrene passing through the gills via irrigation was observed. Bioconcentration factors relative to sediment and water declined with increasing external Pyrene concentrations, enhancing the likelihood of sediment toxi- city being underestimated when using these factors in risk assessment.
Masahiko Inouye - One of the best experts on this subject based on the ideXlab platform.
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circularly polarized luminescence from Pyrene excimers
Tetrahedron Letters, 2019Co-Authors: Yuki Ohishi, Masahiko InouyeAbstract:Abstract Recently, many reports have emerged about circularly polarized luminescence (CPL) based on excimer emission of Pyrenes. The intense CPL was observed from various Pyrene derivatives such as Pyrenes having chiral side chains, chiral oligomers bearing multiple Pyrene rings, and Pyrenes encapsulated by γ-cyclodextrins. The luminescence dissymmetry factor was found to be obviously higher than the absorption one in those Pyrenes. In addition, several Pyrenes revealed reversible “on-off” CPL switching upon the complexation/decomplexation of metal ions.
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photophysical properties of 1 3 6 8 tetrakis arylethynyl Pyrenes with donor or acceptor substituents their fluorescence solvatochromism and lightfastness
Tetrahedron, 2009Co-Authors: Kazuhisa Fujimoto, Hisao Shimizu, Masaru Furusyo, Seiji Akiyama, Mio Ishida, Utako Furukawa, Toshiaki Yokoo, Masahiko InouyeAbstract:Abstract We prepared a series of 1,3,6,8-tetrakis(arylethynyl)Pyrenes with donor or acceptor substituents and investigated their photophysical properties. Solvent polarity hardly affected on the UV/vis spectra of all of the tetrakis(arylethynyl)Pyrenes used in this study. On the other hand, electron-donating groups, NMe2 and NPh2 groups imparted fluorescence solvatochromicity to the skeleton by intramolecular charge transfer in the excited state. Furthermore, a tetrakis(arylethynyl)Pyrene showed better lightfastness upon exposure to laboratory weathering using a xenon long arc lamp than coumarin.
Frank Seela - One of the best experts on this subject based on the ideXlab platform.
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nucleoside and oligonucleotide Pyrene conjugates with 1 2 3 triazolyl or ethynyl linkers synthesis duplex stability and fluorescence changes generated by the dna dye connector
Tetrahedron, 2014Co-Authors: Sachin A Ingale, Frank SeelaAbstract:Abstract Fluorescent nucleosides and oligonucleotides functionalized with Pyrene were synthesized using ‘click’ chemistry or the Sonogashira cross-coupling reaction. The dye was connected to position-7 of 7-deaza-2′-deoxyguanosine or to the 2′-deoxyribofuranose moiety. Four different DNA-dye connectors with 1,2,3-triazolyl residues or triple bonds were constructed. Phosphoramidites of the Pyrene conjugates (9, 14, 25) were prepared and used in solid-phase synthesis. Short linkers (2, 4) destabilize DNA, while long linkers (1) increased duplex stability. Nucleosides and oligonucleotides with single dye incorporations show linker dependent fluorescence. Linker dependent excimer emission with Pyrenes in proximal positions was also observed. A ‘superchromophore’ formed by the 7-deaza-2′-deoxyguanosine ethynylPyrene conjugate shows strong red shifted fluorescence emission at 495 nm.
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7 deazapurine and 8 aza 7 deazapurine nucleoside and oligonucleotide Pyrene click conjugates synthesis nucleobase controlled fluorescence quenching and duplex stability
Journal of Organic Chemistry, 2012Co-Authors: Sachin A Ingale, Suresh S Pujari, Venkata Ramana Sirivolu, Ping Ding, Hai Xiong, Hui Mei, Frank SeelaAbstract:7-Deazapurine and 8-aza-7-deazapurine nucleosides related to dA and dG bearing 7-octadiynyl or 7-tripropargylamine side chains as well as corresponding oligonucleotides were synthesized. “Click” conjugation with 1-azidomethyl Pyrene (10) resulted in fluorescent derivatives. Octadiynyl conjugates show only monomer fluorescence, while the proximal alignment of Pyrene residues in the tripropargylamine derivatives causes excimer emission. 8-Aza-7-deazapurine Pyrene “click” conjugates exhibit fluorescence emission much higher than that of 7-deazapurine derivatives. They are quenched by intramolecular charge transfer between the nucleobase and the dye. Oligonucleotide single strands decorated with two “double clicked” Pyrenes show weak or no excimer fluorescence. However, when duplexes carry proximal Pyrenes in complementary strands, strong excimer fluorescence is observed. A single replacement of a canonical nucleoside by a Pyrene conjugate stabilizes the duplex substantially, most likely by stacking interacti...
Mallavarapu Megharaj - One of the best experts on this subject based on the ideXlab platform.
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Pyrene degradation by chlorella sp mm3 in liquid medium and soil slurry possible role of dihydrolipoamide acetyltransferase in Pyrene biodegradation
Algal Research-Biomass Biofuels and Bioproducts, 2017Co-Authors: Suresh R Subashchandrabose, Panneerselvan Logeshwaran, Kadiyala Venkateswarlu, Ravi Naidu, Mallavarapu MegharajAbstract:Abstract Microalgae inhabiting the real contaminated sites are capable of degrading organic pollutants. In the present study, the potential of a microalga, Chlorella ssp. MM3, a soil isolate from a former cattle dip site, was assessed in degrading Pyrene both in aqueous medium and soil slurry. Strain MM3 can grow on Pyrene in culture medium at concentrations as high as 250 μM. When grown in presence of 50 μM Pyrene, the cell density increased from 1.1 × 105 cells mL− 1 to 16.45 × 105 cells mL− 1 within 7 days. With an initial cell density of 3 × 107 cells mL− 1, nearly 70% of 50 μM Pyrene was degraded after 7 days of incubation. When compared with Triton X-100, Tween 80 was a better non-ionic surfactant for Pyrene biodegradation. Nearly 20% increase in degradation of Pyrene was observed with the use of 0.005% Tween 80. Differential protein expression in Pyrene-grown cells of the microalga resulted in distinct accumulation of dihydrolipoamide acetyltransferase (or dihydrolipoyl transacetylase), one of the three components of pyruvate dehydrogenase complex, indicating a possible role of this enzyme in microalgal degradation of Pyrene. The microalgal cells immobilized in calcium alginate completely degraded 50 μM of Pyrene within 10 days in nonsterile soil slurry treated with 0.005% Tween 80. Our results clearly indicate that the strain MM3 has a great potential for its use in remediating soils contaminated with Pyrene.