Ultraviolet Inactivation of Chloroplast Formation in Synchronously Dividing Euglena Gracilis.
نویسنده
چکیده
Ultraviolet inactivation of chloroplast formation was studied in synchronously dividing cultures of Euglena gracilis. Sensitivity to sublethal doses given at intervals throughout the cell cycle was greater just before cell division than during division. There was approximately a twofold difference in the doseresponse relationships for the periods of high and low sensitivity.
منابع مشابه
Specific Inhibition of Chloroplast Replication in Euglena Gracilis by Nalidixic Acid
In Euglena gracilis the synthesis of the chloroplast from its precursor, the proplastid, is separated in time from the division or replication of the organelle which occurs just prior to cell division (10, 12). The proplastids are only found in darkgrown cells and rapidly form chloroplasts when such cells are exposed to light. The proplastids divide during dark growth. Ultraviolet irradiation i...
متن کاملAction of Nalidixic Acid on Chloroplast Replication in Euglena gracilis.
The role of light in nalidixic acid bleaching of Euglena gracilis var. bacillaris was investigated. The kinetics of loss of the chloroplast-associated DNA and the sensitivity of chloroplast replication to ultraviolet light was followed during treatment with nalidixic acid. By using the mutant P(4)ZUL, and 3-(3,4-dichlorophenyl)-, 1-dimethylurea, it was demonstrated that the requirement for ligh...
متن کاملIsolation of mutants of Euglena gracilis with impaired photosynthesis.
Four mutant strains of Euglena gracilis have been isolated after treatment of wild type cells with ultraviolet light or the chemical mutagen nitrosoguanidine. None of the mutants is capable of autotrophic growth or photosynthetic carbon dioxide fixation. The mutant strains contain normal amounts of the enzymes of the reductive pentose phosphate cycle and are qualitatively similar to the wild ty...
متن کاملCircadian changes in cyclic AMP levels in synchronously dividing and stationary - phase cultures of the achlorophyllous ZC mutant of Euglena gracilis
Oscillations in adenosine 3',5'-cyclic monophosphate (cyclic AMP) level have been proposed to be part of the biochemical feed-back loop(s), or clock(8)', believed to underlie circadian rhythmicity. This possibility has been examined for a cellular circadian oscillator in synchronously dividing (or nondividing) cultures of the photosynthesis-deficient ZC mutant of the alga Euglena gracilis Klebs...
متن کاملThe Synthesis of Cytoplasmic Dna in Synchronized Euglena
Chloroplastic DNA in Euglena gracilis is self-replicating (7), and presumably contains information directing reproduction and differentiation of the chloroplast. Mechanisms governing control of chloroplastic DNA replication in Euglena and the role of the nucleus in these events are unknown. Knowledge of the time course of DNA synthesis in the chloroplasts of Euglena, when compared with that of ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Science
دوره 145 3630 شماره
صفحات -
تاریخ انتشار 1964