Effect of carbon and nitrogen assimilation on chlorophyll fluorescence emission by the cyanobacterium Anacystis nidulans

Abstract

O2 evolution and chlorophyll a fluorescence emission have been monitored in intact cells of the cyanobacterium Anacystic nidulans 1402–1 to stdy the influence of carbon and nitrogen assimilation on the operation of the photosynthetic apparatus. The pattern of fluorescence induction in dark‐adapted cyanobacterial cells was different from that of higher plants. Cyanobacteria undergo large, rapid state transitions upon illumination, which lead to marked changes in the fluorescence yield, complicating the estimation of quenching coefficients. The Kautsky effect was not evident, although it could be masked by a state II–state I transition, upon illumination with actinic light. The use of inhibitors of carbon assimilation such as D,L‐glyceraldehyde or iodoacetamide allowed us to relate changes in variable fluorescence to active CO2 fixation. Ammonium, but not nitrate, induced non‐photochemical fluorescence quenching, in agreement with a previous report on green algae, indicative of an ammonium‐induced state I transition.

Acclimation of photosystem II in a cyanobacterium and a eukaryotic green alga to high and fluctuating photosynthetic photon flux densities, simulating light regimes induced by mixing in lakes

“…F^,, was related to PPFD in a manner similar to that seen in Scenedesmus, but F,'^ decreased upon termination of the hght period, and displayed a sudden increase immediately upon the start of the light period. Romero, Lara & Sivak (1992) made similar observations for the cyanobacterium Anacystis nidulmis. Figure 8.…”

“…In Microcystis decreased values of 0,, in the dark probably indicated that the redox state of the PQ-cytbf complexes changed. This could induce a state 1-2 transition, resuhing in a redistribution of excitation energy between PS I and PS II, inducing a low fluorescent state, since less excitation enei'gy reaches PS II (Allen et al, 1985;Romero et al, 1992). During deep mixing phytoplankton spends alternating periods in the light and the dark, as in our Z,,, = 2 Z^.,, light regime.…”

“…Fluorescence rises from a minimal level F^ to an intermediate maximum Fj, followed by a plateau or dip, F,;, and finally to its peak level F,, (Q^ fully reduced, all PS II reaction centres closed). Romero et al (1992) reported that the cyanobacterium Anacystis did not show the Kautsky effect, F^ of dark acclimated cells was minimal, and state transitions interfered with the Kautsky effect upon actinic illumination. Microcystis did show a typical Kautsky effect; although caution is needed to interpret the data.…”

Two forms of the Photosystem II D1 protein alter energy dissipation and state transitions in the cyanobacterium Synechococcus sp. PCC 7942

“…fluorescence are achieved at about the growth light intensity, when the cells are in State I. qN again develops (Krause et al 1982) as the light surpasses the growth level. State transitions may help balance the excitation distribution between PS II and PSI under low and variable light (Vincent 1979(Vincent , 1990 or during metabolic changes (Dominy and Williams 1987;Miller et al 1991;Mullineaux and Allen 1986;Romero et al 1992;Turpin and Bruce 1990).…”