14 DAY TRIAL // Researchers at the University of Oxford, found the reason for which the earliest evidence of complex multicellular animal life appears some 550 million years ago, at the same time as the increase of the planet's oxygen levels from 3% to the current 21%.
Professor Chris Schofield's team discovered that humans have the same method of sensing oxygen as the world's simplest known living animal – Trichoplax adhaerens.
This discovery suggests that this method is 550 million years old, and it allowed multicellular animals to evolve.
Professor Schofield explains that “it’s absolutely necessary for any multicellular organism to have a sufficient supply of oxygen to almost every cell and so the atmospheric rise in oxygen made it possible for multicellular organisms to exist.
“But there was still a very different physiological challenge for these organisms than for the more evolutionarily ancient single-celled organisms such as bacteria.
“Being multicellular means oxygen has to get to cells not on the surface of the organism.
“We think this is what drove the ancestors of Trichoplax adhaerens to develop a system to sense a lack of oxygen in any cell and then do something about it.”
This primitive living being, is a very small seawater organism that doesn't have any organs and only has five types of cells – which makes it look like an amoeba.
Oxford researcher Dr Christoph Loenarz analyzed the way that Trichoplax reacts to a lack of oxygen, and found that humans have the same mechanism – the researchers actually put the key enzyme from Trichoplax in a human cell, and it worked just as well as a human enzyme would.
This systems responds to hypoxia in humans, like that caused by very high altitudes of physical exertion, and this is very important in preventing stroke and heart attacks, and even some types of cancer.
The scientists also analyzed the genomes of several other species and concluded that this defense mechanism only appears in multicellular animals, meaning that it must have evolved at the same time as the earliest multicellular animals.
There are people who suffer from polycythemia, which is an increase red blood cells caused by a flaw in the most important human oxygen sensing enzyme.
This new work could also lead the way to new approaches and therapies for this kind of disorder.
The research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC), and Professor Douglas Kell, Chief Executive at BBSRC said that “understanding how animals – and ultimately humans – evolved is essential to our ability to pick apart the workings of our cells.
“Knowledge of normal biological processes underpins new developments that can improve quality of life for everyone.
“The more skilful we become in studying the evolution of some of our most essential cell biology, the better our chances of ensuring long term health and well being to match the increase in average lifespan in the UK and beyond.”
This discovery was published today (17 December) in the January 2011 edition of EMBO Reports.