Anticipating Seasons
Noteworthy
Plants and animals can measure differences in the length of days and nights – what is known as photoperiodic time measurement – that allows them to adjust their physiology to seasonal changes, a response known as photoperiodism. But bacteria, with their short life spans, would not be expected to have such adaptive responses to seasonal changes.
Synechococcus elongatus Source
A recent study carried out at Vanderbilt University shows that cyanobacteria, with generation times as short as 5 to 6 hours, are capable of such photoperiodic timekeeping. When exposed to short, winter-like days (8 hours of light followed by 16 hours of darkness), cyanobacteria developed enhanced resistance to cold. This response also required a functional circadian clock, which is an internal 24-hour cycle synchronized clock that responds to changes in the environment. These short periods of light exposure (photoperiods) characteristic of winter stimulated adjustments in membrane lipids and gene expression, including pathways involved in stress responses.
This unanticipated capacity of cyanobacteria to carry out photoperiodic timekeeping and respond to seasonal changes suggests an ancient evolutionary origin. Before the evolution of multicellularity and eukaryotes, the ability to respond to seasonal changes evolved in prokaryotes from preexisting stress pathways.
("Noteworthy" is the new format for STC's Thursday posts. Please read our Jan 20, 2025 post outlining this and other changes in our blog.)
