Fig. 2: apcE2 is a marker of chlorophyll f. apcE2 primers are specific for chlorophyll f-forming cyanobacteria, and the amplicons they form can be seen as ~1.2 kb bands on agarose gels.

They can be used to efficiently distinguish between (a) strains that have the far-red acclimation cluster and (b) strains that lack it. Primers of moderate degeneracy were used unless otherwise mentioned. Even at higher degeneracy, no false positives appeared in the negative controls. c Newly-sequenced strains from the Japanese NIES culture collection tested positive for apcE2. The gene was originally found via BLAST searches. d Particularly significant, the method is useful for discovering new strains. The apcE2 gene is present in enriched samples from Heron Island beach rock (“beach rock 2,4,5”) and thrombolites from Lake Clifton (Halomicronema, Clifton). It was also recovered directly from a beach rock environmental sample (rightmost, separate PCR). The environmental sample band is the result of three consecutive PCR runs; however, a faint band was visible after the first run. This strongly suggests that chlorophyll f cyanobacteria are present in these environments. Molecular weight marker: 2-Log Ladder.