Utilisation of 32P-labelled nucleotide- and non-nucleotide dissolved organic phosphorus by freshwater plankton

Nedoma, J. and Padisák, Judit and Koschel, R. (2003) Utilisation of 32P-labelled nucleotide- and non-nucleotide dissolved organic phosphorus by freshwater plankton. ARCHIV FÜR HYDROBIOLOGIE BEIHEFT ADVANCES IN LIMNOLOGY, 58. pp. 87-99. ISSN 0071-1128

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Abstract

The portion of (32)P acquired by phytoplankton cells (>3µm) in a eutrophic lake and in an acid bog-lake was about three times higher if added as glucose-6-phosphate ([(32)P]G6P) then if added as [(32)P]orthophosphate. Such prefential use of [(32)P]G6P was not evident in an oligotrophic lake, and preferential use of [ɣ-(32)P]ATP was not observed in neither of the three lakes studied. Preferential use of [(32)P]G6P by > 3µm cells coincided with the dominance of this size fraction in particulate phosphatase activity, measured with 4-methylumbelliferyl phosphate (MFUP). Turnover rates of [(32)P]G6P and MUFP were similar but 2-22 times lower than turnover rates of [ɣ-(32)P]ATP. Nucleotide- and the non-nucleotide dissolved organic phosphorus may thus differ in turnover, and significance for phosphorus competition, between bacteria and phytoplankton.

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