Damian M. Bailey, University of South Wales, UK
Oxygen (O2) is the molecule that made our world, our brains and us. It has been around for the best part of 2.4 billion years since the dawn of photosynthesising cyanobacteria.
The work of this year’s Nobel laureates in Physiology and Medicine gives fundamental insight into the molecular machinery to explain how cells sense and respond to changing oxygen levels, including the ingenious survival strategies they exploit during low levels of oxygen, known as hypoxia.
The implications of this work is far reaching, giving us a more complete picture of ourselves and many other organisms, paving the way for new treatments for numerous diseases affecting the brain, heart, lungs and immune systems.
The beginning of oxygen production on earth was arguably the single most important event in the evolution of life of Earth. Each “pulse” of oxygen, (a time period when the amount of oxygen on Earth greatly increased) has been linked to major evolutionary innovations, including the emergence of vertebrates and development of the brain. Many organisms have a nervous system, without having a brain; this just means that their nervous system is evenly distributed throughout the body, like the left-most image in the illustration below.
Despite oxygen’s long history, we had to wait until 1774 before it was discovered, when Joseph Priestley marvelled at its magical properties of reigniting an ember of wood and increased the survival times of mice in a closed container.
While oxygen may be the “elixir of life,” it also exists in air as a toxic free radical gas, deadly to our central nervous system when in excess, yet paradoxically capable of sustaining life in physiologically controlled amounts.
Indeed, our ability to “sense” O2 and maintain it at just the right levels in our body is one of the most important roles of the central nervous system and is probably one of the main reasons we evolved a brain in the first place. Keeping the molecule that made the world under tight control is after all, what got us here, and keeps us alive!