Circadian and Light Perturbed Circadian Gene Expression in Prochlorococcus marinus MED4

A circadian gene expression study in model marine cyanobacteria Prochlorococcus marinus MED4 was performed in order to evaluate circadian gene expression and identify genes which were regulated dependent on circadian photoperiod or light intensity. Overall design: Prochlorococcus marinus MED4 was cultured in adapted Pro99 media prepared using Salish Seawater (Sequim, Washington) and 2X standard concentrations of Pro99 N/P sources, while maintaining 1× concentration of Pro99 trace metals. Cultures were acclimated to a circadian photoperiod of 12:12 h light:dark at an incident white-light intensity of 45 µmol photons m?² s?¹ and a temperature of 22 °C for XX days / generations prior to sampling. Accimaltion was performed in a single XL batch flask before splitting samples into individual 50mL tubes. Circadian perturbed samples were exposed to extended periods of light during circadian night (ZT = 14, 16h) or dark during circadian day (ZT = 2, 4h). Destructive sampling was performed for three biological replicates every two-hours across a full circadian cycle. At each time point, biological replicates were harvested via rapid filtration and flash-frozen in liquid nitrogen.