Long-term effect of NaCl on the activity of uridine and uracil salvage for nucleotide synthesis in cultured mangrove (Bruguiera sexangula) cells

The long-term effect of 100 mM NaCl on the salvage activity of uridine and uracil was investigated using salt-resistant cultured cells of the mangrove species, Bruguiera sexangula. In situ metabolic fate studies indicated that [2-14C]uridine and [2-14C]uracil were efficiently converted to uridine nucleotides, UDP-sugars and RNA. Conversion was greater in the NaCl-treated cells than in control cells after culturing for 14 and 21 days. The activity of uridine kinase (EC 2.7.1.48) and uracil phosphoribosyltransferase (EC 2.4.2.9), and the expression of one of the UK/UPRT homologs of the Arabidopsis gene encoding dual functional uridine kinase–uracil phosphoribosyltransferase, were all greater in the NaCl-treated cells. In contrast, catabolism of [2-14C]uridine and [2-14C]uracil and uridine nucleosidase activity was lower in the NaCl-treated cells. The role of pyrimidine salvage in mangrove cells is discussed.