Euglena gracilis, A Test Organism for Study of Zinc

Price, Colin; Vallée, Bert L.

doi:10.1104/pp.37.3.428

Cited by 80 publications

(28 citation statements)

References 15 publications

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“…The assay method used most frequently in this paper has been described (10) (29) and were rested in Stem, pH 5.5, resting medium (37). The cells were then exposed to light at 0 time, and aliquots were taken for measurements at the times indicated.…”

Section: Nuclearmentioning

confidence: 99%

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: 99%

Studies on Chloroplast Development and Replication in Euglena

Egan

Carell

1972

Plant Physiol.

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“…A second requirement for the recovery process was found to be protein synthesis. When 1 mg of zinc was added to 1 liter of zinc-deficient cultures on day 6 along with 20 ,ug of cycloheximide, a potent inhibitor of protein synthesis by the 80S class of ribosomes (26), there was neither any increase in cell mass nor was there any reappearance of ribosomes in these cells. However, when 1 mg of zinc was added to cultures containing 2 g per liter of chloramphenicol, recovery of growth and ribosomal reappearance occurred, but usually to the extent of less than 70% of the control value without inhibitor.…”

Section: A260/amentioning

confidence: 99%

A Role for Zinc in the Structural Integrity of the Cytoplasmic Ribosomes of Euglena gacilis

Prask

Plocke

1971

Plant Physiol.

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Zinc deficiency in dark-grown Euglena gracilis Klebs, Z strain Pringshein, results in the disappearance of cytoplasmic ribosomes. In contrast, ribosomes in zinc-sufficient Euglena are conserved, do not undergo turnover, and can be demonstrated at any stage of growth. The zinc content of ribosomes from zincdeficient Euglena just prior to ribosomal disappearance is 300 to 380 micrograms of zinc per gram rRNA as compared to 650 to 1280 micrograms of zinc per gram rRNA in ribosomes from zinc-sufficient cells. Ribosomal disappearance is believed to involve a generalized disintegration process related to the lower content of zinc in the ribosomes. Reappearance of ribosomes requires the addition of zinc. It is proposed that adequate zinc may be essential for nornal tertiary and quaternary structure of the cytoplasmic ribosomes of Euglena.

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“…Zinc and cadmium metabolism in Euglena gracilis have been studied extensively as a model for human and mammalian cells (1)(2)(3)(4). These cells show characteristic zinc and cadmium antagonism which is common to most species.…”

Section: Introductionmentioning

confidence: 99%