Nitrogen starvation in marine Synechococcus strains: clonal differences in phycobiliprotein breakdown and energy coupling

Abstract

The effect of nitrogen starvation on photosynthetic pigments and energy coupling was compared in Synechococcus sp. (Cyanophyta) strains originating from oceanic (oligotrophic) or coastal (eutrophic) marine environments. A survey indicated that those of oceanic or subtropical origin retained a greater fraction (55 to 98 %) of their major phycobiliprotein during a 24 h nitrogen starvation period compared to coastal strains (30 to 44 % ) For 3 strains studied in detail, nitrogen starvation caused a significant (> 85 ':L) loss of phycoerythrin from Synechococcussp. WH8018 after 24 h, but only a minor loss (< 25 %) from Synechococcus sp. WH7803 or WH8103 after 3 d starvation. All 3 strains exhibited reduced gross oxygen evolution dunng the first 24 h of starvation, however, indicating a reduction in energy transfer from phycoerythrin to the electron transport chain. Changes during starvation in the in vivo fluorescence excitation and emission spectra indicated a small degree of uncoupling of phycoerythrin from allophycocyanin in Synechococcus sp. WH7803 and MrH8103 but not Synechococcus sp. WH8018. In neither case could it account for the measured loss in photosynthetic efficiency, however. The unusual nature of phycobiliprotein regulation in oceanic strains may reflect an adaptation to episodic (few days time scale) inputs of limiting nutnents to oligotrophic surface waters, thus providing a mechanism for more rapid rejuvenation.

Assessing the role of dust deposition on phytoplankton ecophysiology and succession in a low-nutrient low-chlorophyll ecosystem: a mesocosm experiment in the Mediterranean Sea

“…In the autotrophic picoplankton community, Cyanophyceae and, to a lesser extent Haptophyceae, are the major players responding to nutrient pulses, in agreement with studies reporting the impact of macronutrient deprivation on Cyanophyceae (e.g., Kana et al, 1992;Collier et al, 1994) and Haptophyceae cultures growth (e.g., Riegman et al, 2000). This feature highlights the opportunistic behaviour of these groups under low-nutrient, low-chlorophyll and high light conditions, driven by allochthonous energy inputs.…”

“…Indeed, nitrogen starvation has been reported to differently affect phycobiliprotein regulation and energy transfer from phycoerythrin to the electron transport chain, in Synechococcus sp. strains originating from oceanic or coastal marine ecosystems (Kana et al, 1992), as well as nutrient deprivation is known to impact Synechococcus sp. PSII activity (Collier et al, 1994).…”

Regulation of photosynthetic pigments in micro‐algae by multiple environmental factors: a dynamic balance hypothesis

“…Modulation of light-harvesting is in response to environmental changes that influence incident light or metabolic rates and electron sinks (e.g. Turpin et al, 1988;Kana et al, 1992). These modulation mechanisms work in the direction of balancing energy flow through the light reactions and limiting overreduction of Q^, albeit imperfectly (Weis & Berry, 1987).…”

“…Laws & photosynthetic pigments in response to environ-Bannister, 1980;Rhee & Gotham, 1981;Verity, mental conditions. Light intensity, in particular, has 1982;Fabregas et al, 1986;Osborne & Geider, a strong negative effect on pigments and it is not 1986; Geider, 1987;Kana & Glibert, 1987 a, 6; unusual to observe a fivefold range in the amount of Kana, Feiwel & Flynn, 1992). For instance, pigpigment per cell depending on the growth irradiance.…”

Nitrogen limitation of North Atlantic phytoplankton: analysis of physiological condition in nutrient enrichment experiments

“…Table 2 Stn In~tial Treatment estimated that between 5 and 25% of fluorescence over 650 nm may be attrih~jted to PF, with stationary phase DC2 having the lowest relative chlorophyll fluorescence. Kana et al (1992) noted that fluorescence emission spectra of 3 strains of Synechococcus sp. in log phase showed distinct PE and chlorophyll peaks of about equal magnitude.…”