As we prepare for cold weather, we stock up on firewood and ready our warm jackets. It turns out that seasonal changes are felt not only by humans and animals, but also by bacteria whose lifespan is only a few hours. They can sense the approach of winter and prepare for it.
When microbiologist Luísa Jabbur from the John Innes Centre in Norwich, England proposed studying seasonal responses in bacteria, her colleagues were skeptical. How could an organism with a five-hour lifespan respond to processes that take months? However, experiments showed an unusual result. Cyanobacteria that were grown in conditions approximating winter daylight periods before the cold test survived three times more than those grown in summer daylight conditions. Based on day length, they had prepared for low temperatures as well.
This discovery is not just an interesting fact - it makes us reconsider how cyanobacteria use their biological clock, which registers changes in day length. When days become shorter, certain genes are activated that alter the composition of cell membranes and make them more resistant to low temperatures. When researchers disabled these genes, the bacteria completely lost their ability to prepare for winter. This proves that this is not a random reaction, but rather a precise mechanism that has evolved over time.
The chronobiologist Luísa Jabbur, standing in front of a pond at the John Innes Center
Even more surprising is the discovery of how this mechanism might have originated. Scientists have previously assumed that organisms first developed the ability to sense day and night, and only later - the ability to measure day length to predict seasons. But this study suggests it could have been the other way around. Perhaps the ability to sense that days are getting shorter and therefore winter is approaching emerged first, because it was critically important for life. And only later did the simple circadian rhythm develop from this basic mechanism. If this is the case, then seasonal sensing would be older than the biological clock, which seems so fundamental to us.
Cyanobacteria are among the oldest known organisms. They once changed the planet's atmosphere by producing oxygen. The fact that even these simple organisms can sense seasons indicates that life has been following nature's rhythms from the very beginning.
Source: Quantamagazine
