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  • 1
    ISSN: 1432-2048
    Schlagwort(e): Carotenoids ; Chlorophylls ; Herbicides ; Phytochrome ; Plastid development ; Ribulosebisphosphate carboxylase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Treatment of the mustard (Sinapis alba L.) seedling with the herbicide SAN 9789 inhibits synthesis of colored carotenoids and interferes with the formation of plastid membrane lipids without affecting growth and morphogenesis significantly. In farred light, which is hardly absorbed by chlorophyll, development of plastid ultrastructure, synthesis of ribulosebisphosphate carboxylase and synthesis of chlorophyll are not affected by SAN 9789. It is concluded that normal phytochrome actions on plastid structural development, protein and chlorophyll syntheses are not affected by the absence of carotenoids provided that there is no significant light absorption in chlorophyll. The findings show that the inhibition of synthesis of one set of plastid membrane components (the carotenoids) does not stop synthesis of other components such as chlorophyll and does not halt membrane assembly. Supplementary experiments with the closely related compound SAN 9785, which affects the amount and composition of plastid lipids but not carotenoid and chlorophyll syntheses, suggest that the effect of the herbicide SAN 9789 is due exclusively to its inhibition of synthesis of colored carotenoids. In the presence of SAN 9789 white or red light at high fluence rate causes photodestruction of chlorophyll and ribulosebisphosphate carboxylase and photodecomposition of thylakoids. These effects are interpreted as resulting exclusively from the self-photooxidation and photosensitizing action of chlorophyll once the protection by carotenoids of chlorophyll against self- and sensitized photooxidation is lost.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Planta 133 (1976), S. 53-56 
    ISSN: 1432-2048
    Schlagwort(e): Plastogenesis ; Carboxylase ; Photomorphogenesis ; Sinapis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have studied the problem whether the phytochrome-mediated accumulation of ribulosebisphosphate carboxylase (“carboxylase”; EC 4.1.1.39) in the cotyledons of sinapis alba L. is related to size, ultrastructure, or organization of the plastid compartment. We have shown that under different light conditions (e.g. continuous far-red light, continuous white light) which lead to conspicuously different plastids the time course of the enzyme levels remains precisely the same. It is concluded that the onset and the rate of carboxylase accumulation is not related to the organizational state of the plastid compartment as discernible under the electron microscope.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Planta 148 (1980), S. 279-286 
    ISSN: 1432-2048
    Schlagwort(e): Carotenoids ; Chlorophylls ; Light control ; Phytochrome ; Plastid development ; Sinapis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Carotenoid accumulation in the cotyledons of the mustard seedling (Sinapis alba L.) is controlled by light. Besides the stimulatory function of phytochrome in carotenogenesis the experiments reveal the significance of chlorophyll accumulation for the accumulation of larger amounts of acrotenoids. A specific blue light effect was not found. The data suggest that light exerts its control over carotenoid biogenesis through two separate mechanisms: A phytochrome regulation of enzyme levels before a postulated pool of free carotenoids, and a regulation by chlorophyll draining the pool by complex-formation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 272 (1982), S. 269-278 
    ISSN: 1432-069X
    Schlagwort(e): Light sensitivity ; Cutaneous irritability ; Chamber testing ; DMSO test ; Alkali resistance ; Skin type ; Duhring chambers ; Lichtempfindlichkeit ; Hautirritabilität ; Kammer-Test ; DMSO-Test ; Alkali-Resistenz ; Haut-Typ ; Duhring-Kammern
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das Ziel dieser Studie war die Untersuchung des Zusammenhanges zwischen der Sonnenempfindlichkeit menschlicher Haut und deren Reaktion auf chemische Irritantien. 44 weiße Probanden mit normaler Rückenhaut wurden getestet. Die minimale Erythemdosis (MED) wurde mit dem Sonnenbrandspektrum einer Quecksilberhochdrucklampe bestimmt. Die Hautirritabilität wurde quantifiziert durch eine Serie von sieben gut bekannten chemischen Irritantien von unterschiedlicher chemischer Struktur, Löslichkeit und Konzentration. Die Reaktion wurde entweder als Schwellenwert der Expositionszeit ausgedrückt (Ammoniaklösung, Natronlauge) oder nach einer Standardexposition bewertet hinsichtlich der Intensität der urticariellen Reaktion (Dimethylsulfoxid) bzw. des Erythems (Natriumlaurylsulfat, Quaternium 1, Krotonöl, Kerosin). Es wurde eine signifikante Korrelation zwischen der MED und allen sieben chemischen Irritantien festgestellt. Die Beziehung war enger für wasserlösliche Irritantien als für lipidlösliche. Trotz starker individueller Abweichungen wird die Bestimmung der MED empfohlen für die Erkennung von empfindlicher Haut. Die Hauttypisierung aufgrund äußerer Kriterien und der Sonnenbrandvorgeschichte erwies sich als weniger zuverlässig.
    Notizen: Summary This investigation examines the relationship between the sun sensitivity of human skin and its response to chemical irritants. Forty-four Caucasoid subjects with normal back skin were studied. The minimal erythema dose (MED) was determined with the sunburning spectrum of a high-pressure mercury lamp. Cutaneous irritability was quantified using a series of seven irritants of different chemical structure, solubility, and concentrations. The response was either expressed as a threshold value of exposure time (ammonium hydroxide, sodium hydroxide) or was graded after a standard exposure in intensity of whealing (dimethyl sulphoxide) or erythema (sodium lauryl sulphate, quaternium 1, croton oil, kerosene). A significant correlation between the MED and the response to all seven primary irritants was found. The relationship was better for water-soluble irritants than for lipid-soluble ones. Despite marked individual variations the determination of the MED is suggested as a valuable tool in identifying hyperirritable skin. Skin typing based on complexion and sunburn history proved to be less reliable.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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