Regulation by light of ammonium transport systems in Chlamydomonas reinhardtii.
The unicellular green alga Chlamydomonas reinhardtii is able to take up methylammonium/ammonium from the medium at different stages of its sexual life cycle. Vegetative cells and pre-gametes mostly used a low-affinity system (LATS) component, but gametes obtained after light treatment of N-deprived pre-gametes expressed both LATS and high-affinity system (HATS) components for the uptake of methylammonium/ammonium. The activity of the LATS component was stimulated by light in only 5 min in a process independent of protein synthesis. By using the lrg6 mutant that produces sexually competent gametes in the dark, light effects on ammonium transport and gamete differentiation have been separately analysed. We have found light regulation of four Amt1 genes: Amt1; 1, Amt1; 2, Amt1; 4 and Amt1; 5. Whereas light-dependent expression of Amt1; 1, Amt1; 2 and Amt1; 4 was independent of gametogenesis, and that of Amt1; 5 was activated in the lrg6 mutant, suggesting a connection between this transporter and the subsequent events taking place during gametogenesis.
Laboratory of Adaptation in Microorganisms, Biological Research Institute of St. Petersburg University, Oranienbaumskoe schosse 2, Stary Peterhof, St. Petersburg 198504, Russia. ermilova@ee6439.spb.edu
Elena V
EV
Ermilova
Zhanneta M
ZM
Zalutskaya
Maxim M
MM
Nikitin
Tatyana V
TV
Lapina
Emilio
E
Fernández
D001692:Biological Transport / Q000528:radiation effects; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*; D056130:Gametogenesis, Plant / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D055993:Germ Cells, Plant / Q000378:metabolism / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D008744:Methylamines / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D008744:Methylamines; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; C027451:methylamine