Glycolate metabolism in low and high CO sub 2 -grown chlorella pyrenoidosa and Pavlova lutheri as determined by sup 18 O-labeling
- Pennsylvania State Univ., University Park (USA)
Photorespiration in Chlorella pyrenoidosa Chick. was assayed by measuring {sup 18}O-labeled intermediates of the glycolate pathway. Glycolate, glycine, serine, and excreted glycolate were isolated and analyzed on a gas chromatograph/mass spectrometer to determine isotopic enrichment. Rates of glycolate synthesis were determined from {sup 18}O-labeling kinetics of the intermediates, pool sizes, derived rate equations, and nonlinear regression techniques. Glycolate synthesis was higher in high CO{sub 2}-grown cells than in air-grown cells when both were assayed under the same O{sub 2} and CO{sub 2} concentrations. Synthesis of glycolate, for both types of cells, was stimulated by high O{sub 2} levels and inhibited by high CO{sub 2} levels. Glycolate synthesis in 1.5% CO{sub 2}-grown Chlorella, when exposed to a 0.035% CO{sub 2} atmosphere, increased from about 41 to 86 nanomoles per milligram chlorophyll per minute when the O{sub 2} concentration was increased from 21 to 40%. Glycolate synthesis in air-grown cells increased from 2 to 6 nanomoles per milligram chlorophyll per minute under the same gas levels. Synthesis was undetectable when either the O{sub 2} concentration was lowered to 2% or the CO{sub 2}-concentration was raised to 1.5%. Glycolate excretion was also sensitive to O{sub 2} and CO{sub 2} concentrations in 1.5% CO{sub 2}-grown cells and the glycolate that was excreted was {sup 18}O-labeled. Air-grown cells did not excrete glycolate under any experimental condition. Indirect evidence indicated that glycolate may be excreted as a lactone in Chlorella. Photorespiratory {sup 18}O-labeling kinetics were determined for Pavlova lutheri, which unlike Chlorella and higher plants did not directly synthesize glycine and serine from glycolate. This alga did excrete a significant proportion of newly synthesized glycolate into the media.
- OSTI ID:
- 5922423
- Journal Information:
- Plant Physiology; (USA), Vol. 91:3; ISSN 0032-0889
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of light and elevated atmospheric CO/sub 2/ on the ribulose bisphosphate carboxylase activity and ribulose bisphosphate level of soybean leaves
Effects of glycine hydroxamate, carbon dioxide, and oxygen on photorespiratory carbon and nitrogen metabolism in spinach mesophyll cells
Related Subjects
54 ENVIRONMENTAL SCIENCES
CARBON DIOXIDE
BIOLOGICAL EFFECTS
CHLORELLA
GLYCOLIC ACID
METABOLISM
OXYGEN 18
OXYGEN COMPOUNDS
TRACER TECHNIQUES
ALGAE
CARBON COMPOUNDS
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHLOROPHYCOTA
EVEN-EVEN NUCLEI
HYDROXY ACIDS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
MONOCARBOXYLIC ACIDS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN ISOTOPES
PLANTS
STABLE ISOTOPES
UNICELLULAR ALGAE
550201* - Biochemistry- Tracer Techniques
540110