Enzyme Levels in Relation to Obligate Phototrophy in <i>Chlamydobotrys</i>

Merrett, M. J.

doi:10.1104/pp.58.2.179

Cited by 9 publications

(9 citation statements)

References 19 publications

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“…Thus, the pool of photosynthetically produced substrates for the synthesis of RuBPCase is reduced. The latter strong inhibition of the accumulation of RuBPCase in Euglena by an organic carbon source may represent a common nutritional regulatory mechanism among algae because a similar result has been reported for Chlamydobotrys (15) and for Chlorogonium and Cyanidium (2).…”

Section: Resultssupporting

confidence: 73%

Kinetics of Accumulation of Ribulose-1,5-bisphosphate Carboxylase during Greening in Euglena gracilis

Freyssinet

Freyssinet²,

Buetow³

1984

Plant Physiol.

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The accumulation of ribulose-1,5-bisphosphate carboxylase (RuBPCase) MATERIALS AND METHODS Euglena gracilis strain Z Pringsheim was grown in the dark to a density of 106 cells ml1' on Hutner's pH 3.5 medium and then greened on pH 6.8 'resting' medium as before (9).In experiments with DCMU, dark-grown resting or greening cell cultures were divided into four equal portions. The first received DCMU (from a stock solution of 10 mm DCMU in absolute ethanol) and ethanol at final concentrations of 10 jAM and 17 mm respectively. The second received an equivalent amount of ethanol. The third received DCMU at a final concentration of 10 Mm. In this case, DCMU was suspended by magnetic stirring at a concentration of 1 mm in sterile distilled H20 and an appropriate aliquot was added immediately to the third flask. The fourth received an equivalent amount of sterile distilled H20. Then all four cultures were placed in the light and incubated for the desired time. When necessary, DCMU was removed by centrifuging an aliquot of culture for 2 min at 300g at room temperature under sterile conditions. Pelleted cells were resuspended in fresh sterile resting medium and put back in the light. Control cultures lacking DCMU were treated the same way.Cell density, Chl, RuBPCase activity, and photosynthetic CO2 fixation were measured as described (9). RuBPCase content per cell was determined with an antibody to the holoenzyme also as described (9). Paramylum concentration was measured according to Freyssinet et al. (10).

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Section: Resultssupporting

confidence: 73%

Kinetics of Accumulation of Ribulose-1,5-bisphosphate Carboxylase during Greening in Euglena gracilis

Freyssinet

Freyssinet²,

Buetow³

1984

Plant Physiol.

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“…3). RuDP Case activity in the cotyledon was barely detectable on day 3 being less than 1 nmol/min/mg protein but by day 15 this had increased to 170 nmol/min/mg protein. This substantial increase in catalytic activity during cotyledon development was accompanied by a parallel increase in RuDP Case protein (Fig.…”

Section: Resultsmentioning

confidence: 89%

Development of Ribulose-1,5-Diphosphate Carboxylase in Castor Bean Cotyledons

Dockerty¹,

Lord²,

Merrett³

1977

Plant Physiol.

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Light was not essential for the development of ribulose-1,5-diphosphate carboxylase protein or catalytic activity in the photosynthetic cotyledons of germinating castor beans (Ricinus communis). Cotyledons developing in the dark showed higher activity than those in the Light. Returning cotyledons developing in the light to darkness resulted in a significant increase in ribulose-1,5-diphosphate carboxyhse activity compared to cotyledons in continuous light.

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“…In contrast acetate-grown cells of Chlamydobotrys stellata contain high levels of glyoxylate cycle enzymes (Goulding and Merrett, 1967) but acetate will not support heterotrophic growth. The probable reason for obligate phototrophy in C. stellata is the absence of a-ketoglutarate dehydrogenase and succinate thiokinase so that the yield of adenosine triphosphate from acetate oxidation may be insufficient to support heterotrophic growth (Merrett, 1976). Obligate phototrophy in Neospongiococcum ovatum results from impermeability to exogenous substrates so although tricarboxylic acid cycle enzymes are present their catalytic activity is restricted to endogenous substrates.…”

Section: Discussionmentioning

confidence: 99%

“…Aconitase (EC. Merrett (1976). Phosphoenolpyruvate carboxylase (EC-4.1.1.31) was assayed as described by Lord and Merrett (1970).…”

Section: Enzyme Assaysmentioning

confidence: 99%

THE PHYSIOLOGY OF NEOSPONGIOCOCCUM OVATUM DEASON

Khadke

Merrett

1976

New Phytologist

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Summary By enrichment culture and conventional microbiological techniques the dominant alga of sewage trickle filters was obtained in axenic culture and identified as Neospongiococcutn ovatum Deason. A wide range of carbon compounds failed to support heterotrophic growth or alter the mean generation time or final cell yield in the light. The rate of photosynthetic carbon dioxide fixation was also unaffected by the growth conditions. The enzymes of the tricarboxylic acid cycle were present at comparable specific activity in cell extracts, but significant uptake of [14C]‐acetate or [14C]‐glycollate was not detected. It is suggested that impermeability to exogenous compounds may be an advantage in a toxic environment.

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Enzyme Levels in Relation to Obligate Phototrophy in Chlamydobotrys

Cited by 9 publications

References 19 publications

Kinetics of Accumulation of Ribulose-1,5-bisphosphate Carboxylase during Greening in Euglena gracilis

Kinetics of Accumulation of Ribulose-1,5-bisphosphate Carboxylase during Greening in Euglena gracilis

Development of Ribulose-1,5-Diphosphate Carboxylase in Castor Bean Cotyledons

THE PHYSIOLOGY OF NEOSPONGIOCOCCUM OVATUM DEASON

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