CHANGES IN DINOFLAGELLATE INTRACELLULAR AMINO-ACIDS IN RESPONSE TO DIURNAL CHANGES IN LIGHT AND N-SUPPLY

Citation
K. Flynn et al., CHANGES IN DINOFLAGELLATE INTRACELLULAR AMINO-ACIDS IN RESPONSE TO DIURNAL CHANGES IN LIGHT AND N-SUPPLY, Marine ecology. Progress series, 100(3), 1993, pp. 245-252
Citations number
22
Categorie Soggetti
Marine & Freshwater Biology",Ecology
ISSN journal
01718630
Volume
100
Issue
3
Year of publication
1993
Pages
245 - 252
Database
ISI
SICI code
0171-8630(1993)100:3<245:CIDIAI>2.0.ZU;2-C
Abstract
Seven species of dinoflagellates were examined with respect to their i ntracellular amino acid (InAA) content under different conditions of N -nutrition and light, and for release of dissolved free amino acids (D FAA). Alexandrium spp. did not contain significant amounts of a neutra l nonprotein amine present in all other phototrophic dinoflagellates t ested but, in contrast, it always maintained high levels of glutamine and of the ratio of intracellular glutamine/glutamate (Gln/Glu). Dinof lagellates responded to a decreased availability of N with a fall in G ln/Glu but, unlike other microalgae, arginine was always a significant component of InAA. Refeeding of N-limited cultures with nitrate durin g the dark phase of growth, simulating refeeding of a natural populati on following a diurnal migration to the nutricline, resulted in an inc reased Gln/Glu during the dark phase followed by a decline during the light phase. N-refeeding of N-deprived cells led a rapid rise in the r atio, except during N-refeeding of stationary phase Gymnodinium catena tum (which were of abnormal shape and motility) when Glu rather than G ln increased. The sensitivity of the analytical method would enable sa mpling from natural dinoflagellate populations in order to assess thei r physiological status; extracts from 200 to 2000 cells, depending on cell size, are sufficient. A significant quantity of an unidentified a mino acid accumulated in the growth media of Gymnodinium catenatum but otherwise DFAA in dinoflagellate culture media were similar to that f rom other microalgae.