Approach to Studying Nitrogen Assimilation

NH4 assimilation occurs by the action of GS and GOGAT (Wheeler, 1983 Falkowski, 1983). The source of NH4 may be externally suppfied or internally as a product of NO3 reduction or photorespiration. Consequently GS activity gives a measure of both regenerated (based on NH4) and total productivity (based on NO3 and NH4) and is commonly measured in studies of algal physiology (e.g., Slawyk et al, 1997 Slawyk and Rodier, 1986 Rees et al, 1995). Two different isoforms of eukaryotic algal GS proteins have been described based upon their size GS II that is found in eukaryotes (Chen and SMow, 1996 in Chlamydomonas reinhardtii Pesole et al, 1991) and GS III which has been identified in diatoms and some other 

and Song, B. K. (2005). Characterization of diatom (BaciUariophyceae) nitrate reductase genes and their detection in marine phytoplankton communities. J. Phycol. 41, 95-104. 

Alvarez-Slgado, X. A., Doval, M. D., and Perez, P. P. (1999). Dissolved organic matter in shelf waters off the Ria deVigo (NW Iberian upweUing system). J. Mar. Syst. 18, 383-394. 

Anderson, R. A. (1999). Glutamine synthetase holds promising insights for phycology. J. Phycol. 35, 631-633. 

Mcallister, C. D., Parsons, T. R., Stephens, K., and Strickland, J. D. H. (1963). Further measurements of primary production using a large-volume plastic sphere. Limnol. Oceanogr. 8, 166-183. 

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