Presence and Function of a Circadian Clock in Marine Cyanobacteria Prochlorococcus and Synechococcus

Abstract

This study attempts to explore cyanobacterial circadian clock-related gene expression and analysis of related environmental conditions in marine environments. A circadian clock refers to a biomechanical component that controls gene expression on a 24-hour cycle. This study aims to determine if the circadian clock is represented in the cyanobacteria Prochlorococcus and Synechococcus in natural environments in a similar manner to what has been observed in laboratory studies. Although the focus will be on the relationship between the circadian clock and light intensity, there is potential to discover new environmental connections to the cyanobacterial circadian clock by using data from cruises with greater variability in conditions. Genetic data from the Berube cycog database along with genomic data from the Gradients2 cruise was utilized to create phylogenetic trees for each component of the circadian clock. It was found that Prochlorococcus clades associated with high light adapted groups saw higher circadian clock expression values than those associated with low light adapted groups, and Synechococcus expression was generally high across all clades represented. In addition, only Synechococcus displayed a fully functioning circadian clock, and Synechococcus data illustrated increased genetic and geographical diversity when compared to Prochlorococcus.