Expression of nitrate assimilation related genes in Chlamydomonas reinhardtii

Plant Mol Biol. 1994 Jan;24(1):185-94. doi: 10.1007/BF00040584.


The mRNA accumulation pattern of the Chlamydomonas reinhardtii nitrate assimilation-related gene cluster has been elucidated. In ammonium-grown wild-type cells, nit-1 (nitrate reductase, NR), nar-1, nar-2 and nar-3 (nitrate transporter) genes showed very similar kinetics of expression when transferred to nitrate medium. Transcripts of all these genes accumulated transiently in ammonium-grown wild-type cells after a one-hour incubation in nitrogen-free medium, and practically disappeared at about 2 hours. Mutant strains lacking functional nitrate reductase showed similar accumulation kinetics of these transcripts during both nitrate induction and derepression in nitrogen-free media. In contrast to the other nar transcripts, that nar-4, a gene sharing similar sequences with nar-3, accumulated in small amounts in wild-type cells, and only increased after a long nitrate induction period. Nitrate and light showed a strong positive effect on the accumulation of nit-1 gene transcripts. Acetate as a carbon source allowed accumulation of nit-1 mRNA in the dark, indicating the existence of interactions between light and carbon metabolism in nit-1 gene expression. Our data strongly suggest that NR negatively autoregulates its own expression and that of nar genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Chlamydomonas reinhardtii / genetics*
  • Chlamydomonas reinhardtii / growth & development
  • Chlamydomonas reinhardtii / metabolism
  • Cloning, Molecular
  • Gene Expression Regulation*
  • Kinetics
  • Nitrate Reductase
  • Nitrate Reductases / genetics*
  • Nitrate Reductases / metabolism
  • Nitrates / metabolism*
  • Restriction Mapping
  • Transcription, Genetic


  • Carrier Proteins
  • Nitrates
  • Nitrate Reductases
  • Nitrate Reductase