Journal Article

Limiting CO<sub>2</sub> levels induce a blue light‐dependent HCO<sub>3</sub><sup>−</sup> uptake system in <i>Monoraphidium braunii</i>

Nuria Giráldez, Pedro J. Aparicio and Miguel A. Quiñones

in Journal of Experimental Botany

Volume 51, issue 345, pages 807-815
Published in print April 2000 | ISSN: 0022-0957
Published online April 2000 | e-ISSN: 1460-2431 | DOI:
Limiting CO2 levels induce a blue light‐dependent 
 HCO3− uptake system in Monoraphidium braunii

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The in situ photoactivation of an [math] uptake system in the green alga Monoraphidium braunii requires the irradiation of the cell suspensions with short wavelength radiation (blue, UVA and/or UVC). Plasma membrane ATPase inhibitors block the uptake of this monovalent anion at pH 9. M. braunii cells grown in high CO2lack an [math] uptake system in their plasma membrane, but those grown in low CO2can take up this anion at high rates. Cells grown in high CO2, transferred to CO2‐limiting conditions in the light, start taking up [math] in 30 min, although they take 90 min to reach maximum rates of [math] transport. Therefore, this induction process seems to be triggered by low external CO2 concentration. In fact, increasing or decreasing the external [math] concentration does not induce the uptake system and only a decrease in CO2 concentration in the medium triggers the induction process. The appearance of the [math] transport activity is sensitive to cycloheximide, indicating that cytoplasmic protein biosynthesis is necessary for the induction of the uptake system. Photosynthetically active radiation, but not particularly blue light, is essential for induction of the uptake system to occur and the inhibition of photosynthesis by DCMU blocks it. From these results it can be inferred that when M. braunii cells detect a drop in CO2 concentration, they induce a blue light‐dependent [math] uptake system.

Keywords: Blue light; \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(HCO_{3}^{{-}}\) \end{document} transport; CO2 concentration; Monoraphidium braunii; photosynthesis; protein biosynthesis.; AZA, acetazolamide; BL, blue light; CA, carbonic anhydrse; CAP, chloramphenicol; CCM, carbon concentrating mechanism; CHI, cycloheximide, Chl, chlorophyll; Ci, inorganic carbon; DES, diethylstilbestrol; PFD, photon fluence density; RL, red light; WL, white light.

Journal Article.  7811 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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