Circadian oscillation in nitrogen metabolism pathway. Expression profiles of microarray probesets are overlapped with the Kyoto Encyclopedia of Genes and Genomes (KEGG) map of the nitrogen metabolism in Arabidopsis thaliana. Some genes are represented by more than one set of alternative probes. Expression of the NIA2 (Nitrate Reductase 2, EC:18.104.22.168) at the start of the cascade shows the evidence of alternative probes (and thus most likely alternative transcripts) oscillating in counter-phase. Green color marks the elements of the pathway for which KEGG has additional information accessible by a clickable link and for which Affymetrix probesets are traced in the Davis data set.