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EFFECTS OF SHORT PULSES OF BLUE LIGHT ON THE ALKALINIZATION ASSOCIATED WITH THE UPTAKE OF NO 3 − AND CL − BY THE GREEN ALGA MONORAPHIDIUM BRAUNII AND RELATED ACTION SPECTRA
Author(s) -
Witt Federico G.,
Aparicio Pedro J.
Publication year - 1995
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1995.tb09878.x
Subject(s) - chemistry , biophysics , blue light , flavin group , absorption (acoustics) , photochemistry , analytical chemistry (journal) , biochemistry , biology , chromatography , materials science , optoelectronics , composite material , enzyme
In Monoraphidium braunii , uptake of NO 3 − , NO 2 − and Cl − is associated with proton transport and triggered by blue light (BL). Only 10 s after cells able to reduce NO 3 − to NH 4 + were irradiated with continuous, low‐fluence BL in the presence of NO 3 − , an alkalinization of the medium began and only became interrupted by switching off the BL with a 60–90 s time lag. With 30 s BL pulses, the NO 3 − ‐dependent alkalinization lasted 3–5 min until it stopped. When the cells were exposed to continuous BL in the presence of Cl − , the alkalinization also started within 10 s but lasted only 3 min. After that, the pH remained constant and decreased when the BL was switched off. With 30 s BL pulses, the Cl − ‐dependent alkalinization lasted 3 min and then decreased to its initial value. The NO 3 − ‐dependent alkalinization shown by cells unable to reduce NO 3 − to NH 4 + was similar to that observed in the presence of Cl − . These alkalinization rates fit the Bunsen‐Roscoe reciprocity law. With 2 s pulses of high‐fluence BL, the delay time of the NO 3 ‐ or Cl − ‐dependent alkalinizations was only 2 s, one of the fastest BL responses reported so far. The action spectra for Cl − and NO 3 − uptakes proved to be very similar and matched the absorption spectra of flavins, including the 267 nm peak.