981 resultados para CATECHOL 1,2-DIOXYGENASE


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Polychlorinated naphthalenes are environmentally relevant compounds that are measured in biota at concentrations in the μg/kg lipid range. Despite their widespread occurrence, literature data on the accumulation and effects of these compounds in aquatic ecosystems are sparsely available. The goal of this study was to gain insights into the biomagnification and effects of 1,2,3,5,7-pentachloronaphthalene (PeCN52) in an experimental food chain consisting of benthic worms and juvenile rainbow trout. Worms were contaminated with PeCN52 by passive dosing from polydimethylsiloxane silicone. The contaminated worms were then used to feed the juvenile rainbow trout at 0.12, 0.25 or 0.50 μg/g fish wet weight/day, and the resulting internal whole-body concentrations of the individual fish were linked to biological responses. A possible involvement of the cellular detoxification system was explored by measuring PeCN52-induced expression of the phase I biotransformation enzyme gene cyp1a1 and the ABC transporter gene abcb1a. At the end of the 28-day study, biomagnification factors were similar for all dietary intake levels with values between 0.5 and 0.7 kg lipid(fish)/kg lipid(worm). The average uptake efficiency of 60% indicated that a high amount of PeCN52 was transferred from the worms to the fish. Internal concentrations of up to 175 mg/kg fish lipid in the highest treatment level did not result in effects on survival, behavior, or growth of the juvenile trout, but were associated with the induction of phase I metabolism which was evident from the significant up-regulation of cyp1a1 expression in the liver. In contrast, no changes were seen in abcb1a transcript levels.

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The study of colon cancer has taken advantage of the development of a model in animals in which tumors in the colon are easily induced by chemical treatment. When 1,2-dimethylhydrazine (DMH) is injected into rats tumor growth is observed in colon in preference to other tissues. This observation led us to investigate the Cytochrome P450 system in colon and its participation in the particular “colon sensitivity” to DMH. It has been established that the Cytochrome P450 system participates in the metabolism of DMH and the methyl carbonium product of Cytochrome P450 activation of DMH is responsible for DNA damage which is considered an initial step to carcinogenesis. The Cytochrome P450 system is a reasonable place to search for an explanation of this organotropic effect of DMH and we feel that the knowledge obtained from this study can take us closer to understanding the development of colonic malignancy. In our study we used a human colon cell line (LS174T) treated with DMH. The Cytochrome P450 system in the cells was manipulated with inducers of different isoforms of Cytochrome P450. The effect of DMH on colon cells was measured by determination of O-6-methylguanine which is a DNA adduct derived from the metabolism of this chemical and is associated with development of tumors. Our results support the hypothesis that Cytochrome P450 plays an important role in the damage to cellular DNA by DMH. This damage is increased after induction of Cytochromes P450 1A1 and 2E1. The effect of inhibition of the methyltransferase and glutathione systems on protection against DMH damage in colon demonstrated the importance of the protective role of the former and the lack of effective protection of the latter system. ^

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The sigma (σ) subunit of eubacterial RNA polymerase is required for recognition of and transcription initiation from promoter DNA sequences. One family of sigma factors includes those related to the primary sigma factor from E. coli, σ70. Members of the σ70 family have four highly conserved domains, of which regions 2 through 4 are present in all members. Region 1 can be subdivided into regions 1.1 and 1.2. Region 1.1 affects DNA binding by σ 70 alone, as well as transcription initiation by holoenzyme. Region 1.2, present and highly conserved in most sigma factors, has not yet been assigned a putative function, although previous work demonstrated that it is not required for either association with the core subunits of RNA polymerase or promoter specific binding by holoenzyme. This study primarily investigates the functional role of region 1.2 during transcription initiation. In vivo and in vitro characterization of thirty-two single amino acid substitutions targeted to region 1.2 of E. coli σ70 as well as a deletion of region 1.2, revealed that mutations in region 1.2 can affect promoter binding, open complex formation, initiated complex formation, and the transition from abortive transcription to elongation. The relative degree of solvent exposure of several positions in region 1.2 has been determined, with positions 116 and 122 likely to be located near the surface of σ70. ^ During the course of this study, the existence of two “wild type” variants of E. coli σ70 was discovered. The identity of amino acid 149 has been reported variably as either arginine or aspartic acid in published articles and in online databases. In vivo and in vitro characterization of the two reported variations of E. coli σ70 (N149 and D149) has determined that the two variants are functionally equivalent. However, in vivo and in vitro characterization of single amino acid substitutions and a region 1.2 deletion in the context of each variant background revealed that the behavior of some mutations are greatly affected by the identity of amino acid 149. ^

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Zemach Schabad

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Zemach Schabad

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Beide Bände in einem Digitalisat

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Bei der Foliierung wurden Blätter übergangen, jetzt foliiert als Bl. 55a, 121a und 137a.

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Rubriziert

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"Problem der neueren Philosophie", Vorlesung Wintersemester 1950/51 und Sommersemester 1951, 1) Heft, 78 Blatt und 20 zusätzliche Blätter, eigenhändige Notizen (GS 14, S. 145, 151-152), 2) Friedrich Pollock: Notizen zur Volesung Max Horkheimers, Wintersemester 1950/51), eigenhändige Notizen, 9 Blatt; "Philosophie im 17. Jahrhundert (insbes. Spinoza)", Vorlesung Winteremester 1951/52, 1) Heft 1, 17 Blatt und 2 zusätzliche Blätter, eigenhändige Notizen, 2) Heft 2, 46 Blatt, davon 3 leer, und 15 zusätzliche Blätter, eigenhändige Notizen; "Philosophie im 18. Jahrhundert", Vorlesung Sommersemester 1952, 1 Heft mit eigenhändigen Notizen, 64 Blatt, davon 30 leer, und 44 zusätzliche Blätter;

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"Einführung in die Philosophie", Vorlesung, Wintersemester 1956/57, 1 Heft mit eigenhändigen Notizen, 16 Blatt, davon 4 leer, mit 1 zusätzlichem Blatt; "Geschichte des Materialismus (ausgewählte Kapitel)" (GS 13, S. 397-451), Vorlesung, Sommersemester 1957, 1. Max Horkheimer, eigene Notizen, 1 Heft ohne Einband, 16 Blatt und 3 zusätzliche Blätter, 2. Hilmar Tillack: Ausgearbeitete Nachschrift der Vorlesung Max Horkheimers, Typoskript, 46 Blatt; "Society and Value", Vorlesung Chicago 1957, Heft 1: eigene Notizen, 60 Blatt, davon 13 leer, und zusätzliche 6 Blätter; Heft 2: eigene Notizen, 45 Blatt, davon 30 leer, und zusätzlich 8 Blatt; darin auch enthält: Begriff der Seele seit Leibniz", Vorlesung, Sommersemester 1958;

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"Society and Value", Vorlesung Chicago 1957, Heft 1: eigene Notizen, 60 Blatt, davon 13 leer, und zusätzlich 6 Blatt; Heft 2: eigene Notizen, 45 Blatt, davon 30 leer, und zusätzlich 8 Blätter. (Enthält auch: "Begriff der Seele seit Leibniz", Vorlesung Sommersemester 1958); "Die Idee der Freiheit" (GS 13, S. 452-514), Vorlesung Wintersemester 1957/58, eigene Notizen, 1 Heft, 45 Blatt, davon 23 leer, und zusätzlich 25 Blätter; Hilmar Tillack: Ausgearbeitete Nachschrift der Vorlesung Max Horkheimers, Typoskript, 58 Blatt;