Nitrogen assimilation following NH4+ pulses in the red alga Gracilariopsis lemaneiformis:effect on C metabolism

Abstract

Nitrogen assimilation following NH4+ pulses in the red alga Gracilariopsis lemaneiformis: effect on C metabolism Juan J. V e r g a r a l , Kimon T. ~i r d~, F. X. ~i e l l~ ABSTRACT: The short-term effect of external NH,' availability on N assimilation, as well as on C metabolism, has been studied in the red alga Gracilariopsis lemaneiformis. This agarophyte seaweed showed a high capacity to take up external NH,' and to channel it toward proteins. As in a previous study in Corallina elongata, it appears that N limitation redirected the flow of internal N toward nonpigmented proteins, whereas phycobiliprotein synthesis was preferentially stimulated with respect to other proteins in response to external NH,+ pulses. A possible mechanism by which chloroplastic protein synthesis is limited by external N availability more than cytosolic proteins could be involved. In relation to C metabolism, insoluble and soluble carbohydrates were mobilized in response to NH,+ assimilation at a non-saturating irradiance for photosynthesls of 80 pm01 m-2 S-'. The main change in C metabolism was not seen for total C. The principal effect was the flow of C among different compounds, from carbohydrates to organic N compounds (amino acids and prote~ns) during transient NH, + assimilation.

Effects of Environmental Factors and Nutrient Availability on the Biochemical Composition of Algae for Biofuels Production: A Review

“…Nitrogen is an essential constituent of all structural and functional proteins in the algal cells and accounts for 7%-20% of cell dry weight [58]. Inorganic nitrogen taken up by algae is rapidly assimilated into biochemically active compounds and recycled within cells to meet changing physiological needs [156,157]. Major effects of nitrogen deficiency in algal culture include the enhanced biosynthesis and accumulation of lipids [75,80,[158][159][160] and triglycerides [161,162] with a concomitant reduction in protein content [25,29,[163][164][165][166].…”

Short-term ecophysiological and biochemical responses of Cystoseira tamariscifolia and Ellisolandia elongata to environmental changes

“…Nitrogen limitation affects many processes in macroalgae including photosynthetic capacity (Pérez-Lloréns et al 1996), protein content (Vergara et al 1995, Martínez & Rico 2002 and photoprotection mechanisms (Korbee-Peinado et al 2004, Korbee et al 2005b, Huovinen et al 2006. Under moderate to highly desiccated conditions, some intertidal macroalgae increase their nitrogen and carbon uptake (Lobban & Harrison 1994, Flores-Moya et al 1998, Nygard & Dring 2008.…”

Environmental control of the annual erect phase of <i>Nemalion helminthoides</i> (Rhodophyta) in the field

“…As reported for several macroalgae species growing under transient nutrient pulses (McGlathery, 1992;Barr and Rees, 2003;Costanzo et al, 2000;Nielsen, 2003), the nutrient requirements for sustaining maximum growth and high reproductive effort are usually higher than the mean nutrient availability, even in areas where nutrient background levels exceed those reported in this study (McGlathery, 1992;Borum, 1996, 1997;Phil et al, 1996;Fong et al, 1998;Barr and Rees, 2003;Nielsen, 2003). This nutrient restriction implies that the nutrient uptake during pulses is directly diverted into growth and reproduction (Fong et al, 1994;Vergara et al, 1995), which might explain the lack of short-term physiological responses in N. helminthoides.…”

“…These nutrients are mainly provided in the form of transient pulses. However, the physiological response may depend greatly on the nutrient storage capability of the species at short time scales (Vergara et al, 1995;McGlathery, 1996;Pedersen and Borum, 1996;Costanzo et al, 2000;Nielsen, 2003;Bracken, 2004;Clavier et al, 2005;Lartigue and Sherman, 2005).…”