Glycolate metabolism in low and high CO sub 2 -grown chlorella pyrenoidosa and Pavlova lutheri as determined by sup 18 O-labeling

Journal Article · Wed Nov 01 04:00:00 EST 1989 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.91.3.1085· OSTI ID:5922423

de Veau, E J; Burris, J E ^[1]

---

1. 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), Journal Name: Plant Physiology; (USA) Vol. 91:3; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110
550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALGAE
BIOLOGICAL EFFECTS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHLORELLA
CHLOROPHYCOTA
EVEN-EVEN NUCLEI
GLYCOLIC ACID
HYDROXY ACIDS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
METABOLISM
MICROORGANISMS
MONOCARBOXYLIC ACIDS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PLANTS
STABLE ISOTOPES
TRACER TECHNIQUES
UNICELLULAR ALGAE