Rhythms in respiratory metabolism of Lemna gibba G_3 under continuous illumination

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概要

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• Changes in chemical constituents and respiratory metabolism of a long-day duck-weed, Lemna gibba G_3, exposed to continuous illumination after short-day cultivation were investigated. The dry weight to fresh weight ratio was constant during the first 72 hr of continuous illumination. pH of the crude extract was constant at 6.6, but pH of the culture medium was raised with the Lemna growth. Titratable acidity decreased after about 44 hr, whereas malic acid content increased in 18 hr. There were no significant changes in total reducing sugar and pentose. Total protein content and lipid showed rhythmical changes with cycles of 48 hr. O_2-Uptake gave a damped oscillation with cycles of 24 hr. It was low in the first half day and high in the second half. ^<14>CO_2-Output from glucose-1-^<14>C showed a similar damped oscillation ^<14>CO_2-Output from glucose-2-^<14>C or glucose-6-^<14>C was almost constant. The C_6/C_1 ratio, then, showed damped oscillation in the reverse way to O_2-uptake between 0.3-0.5, and the C_6/C_2 ratio was constant at 0.9. Accordingly,the diurnal rhythm of O_2-uptake was thought to be brought about by variation in activity of the pentose-Phosphate pathway. Reproduction of glucose-6-phosphate by the pentose-phosphate pathway was presumably limited in amount. Glyceraldehyde-3-phosphate dehydrogenase activity varied diurnally. The activities of NADP-linked and NAD-linked enzymes increased and decreased, respectively, in the first half day. Variations in these enzymatic activities are discussed in correlation with rhythmical changes in 02-uptake and in the C_6/C_1 ratio. Acid phosphatase activity also followed a diurnal variation. No activities of alcohol and formic dehydrogenases were found. The activities of NADP glucose-6-phosphate dehydrogenase, 6-Phosphogluconate dehydrogenase, pyruvic kinase and NADP isocitric dehydrogenase were high, but showed no rhythmical variation.

• 日本植物生理学会の論文

著者

• Miyata Hisao

  Biological Institute L'aculty Of Science Nagoya University

• Miyata Hisao

  Biological Institute Faculty Of Science Nagoya University

• Miyata Hisao

  Biological Institute Faculty Of Science Nagoya Univesity

• YAMAMOTO YUKIO

  Biological Institute, Faculty of Science, Nagoya Univesity

• Yamamoto Yukio

  Biological Institute Faculiy Of Science Nagoya Univesrity

• Yamamoto Yukio

  Biological Institute Faculty Of Science Nagoya Univesity

関連論文

• Endogenous light-on rhythm in respiration of a long-day duckweed, Lemna gibba G_3
• Rhythms in respiratory metabolism of Lemna gibba G_3 under continuous illumination
• Endogenous light-on rhythm in respiration of a long-day duckweed, Lemna gibba G3 III. Relationship to frond production
• Endogenous light-on rhythm in respiration of a long-day duckweed, Lemna gibba G3 II. On basic and rhythmic components of the rhythm
• A METABOLIC PATHWAY OF ISOCITRIC ACID IN COTYLEDONS OF A BEAN, VIGNA SESQUIPEDALIS

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