Photoinduced Carotenogenesis in Chlorotic <i>Euglena gracilis</i>

Dolphin, Warren D.

doi:10.1104/pp.46.5.685

Cited by 29 publications

(9 citation statements)

References 20 publications

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“…This points to an effect of the bleaching agent on a cytoplasmic photoreceptor system. Such a photoreceptor has been indicated from other work, not only with bleached substrains (11,38), but also with bacillaris (20). It has been suggested that this photoreceptor system might be a blue-far red-absorbing pigment, which, in the wild type cells, functions to assist in the mobilization of the cytoplasm during the early hours of chloroplast differentiation (32,35).…”

Section: Nuclearmentioning

confidence: 95%

Studies on Chloroplast Development and Replication in Euglena

Egan

Carell

1972

Plant Physiol.

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During chloroplast development in Euglena, the activity of a specific DNase, Euglena alkaline DNase, increases in a manner similar to that of chlorophyll synthesis, but without the lag customarily associated with the early hours of chlorophyll synthesis. The increase in Euglena alkaline DNase activity is not inhibited by chloramphenicol or by streptomycin, but is inhibited by cycloheximide. Euglena alkaline DNase activity is present in a group of aplastidic substrains which contain carotenoids. These results are interpreted to mean that this chloroplast-related DNase is synthesized in the cytoplasm, and that the genetic information for this enzyme is probably nuclear.It is also shown that different bleached substrains exhibit substantial variation, both in total carotenoids and in Euglena and WicBSmL, used in these experiments are described elsewhere (12,30). Agar slants of the bacillaris strain and its three substrains were kindly provided by Dr. Jerome A. Schiff, Brandeis University, Waltham, Massachusetts.E. gracilis, Klebs, Strain Z Pringsheim, from our stock culture was also employed (30). The bleached substrains Y7ZHL and W,,ZHL were obtained by carrying light-grown strain Z through five rounds of culture on Hutner's modified medium (29) at 32 C. The bleached substrains Y,ZSmL and W,5ZSmLwere produced by carrying light-grown cells through five rounds of culture on the same medium, containing 1 mg/ml of streptomycin at 25 C. In both treatments, the fifth culture was plated on agar. Yellow and white colonies appeared on the agar plates, and one colony of each color was isolated and designated as described elsewhere (33). The substrain YZSL was obtained by plating light-grown cells of the Z strain and isolating a rare yellow colony from the plates. None of the Z strain mutants had detctable levels of chlorophyll, and no plastid remnants could be observed by fluorescence microscopy. No reversion to the wild type has been observed over a 2-year period; in addition, the white substrains did not revert to the yellow form during this time period.Growth and Resting Conditions. After growing dark-adapted Euglena to a density of 5 X 10' to 1 X 10' cells/ml, the cells were aseptically transferred to Stern resting medium (37). The cells were kept in the dark for 72 hr and were then exposed to 150 ft-c of white fluorescent light for the specified times. At each time period, cells were harvested, rinsed, sampled for chlorophyll (9), and frozen. Further details of growth and resting conditions are presented in the figure legends.Preparation of Cells for Assays. Frozen cells were thawed and sonicated at the maximum setting on the Branson Biosonik sonicator. The sonication time was 30 sec in the experiment of Figure 3 and 2 min in all other experiments. While 30 sec of sonication was sufficient to release all enzyme activity, sonication periods of 2 min or longer did not appear to affect the specific activities (14). The sonicated suspension was then centrifuged at 30,000g for 30 min, and the supernatant was used as...

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Section: Nuclearmentioning

confidence: 95%

Studies on Chloroplast Development and Replication in Euglena

Egan

Carell

1972

Plant Physiol.

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“…In this alga, illumination triggers a large increase in carotenoids (106,188,323,356) and is related to chloroplast develop ment as in higher plants. In wild-type strains, only Euglena gracilis is reported to show photoregulation.…”

Section: H I G H E R Plants and Algaementioning

confidence: 99%

Regulation of Carotenoid Biosynthesis

Bramley

Mackenzie

1988

Current Topics in Cellular Regulation

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“…In Euglena, a nonchloroplast, blue-absorbing photoreceptor controls cytoplasmic ribosomal RNA synthesis (5,36), carotenoid synthesis (8), the synthesis of a number of proteins (27), and the events required for the elimination of the lag period in Chl synthesis (12,17). Cell division (7,20), and protein synthesis and turnover (15,28) are also regulated by a nonchloroplast photoreceptor.…”

Section: Discussionmentioning

confidence: 99%