Blood. It is deep red, liquid and essential to life, and courses through us from the very early stages of our development to our final gasp. It cannot have taken long for our ancestors to make the link between blood and life. They will have seen the rich red fluid seep from wounds alongside the lifeless bodies of animals they had just hunted down, and understood that the same fluid flows through their own bodies. Blood is indeed a tissue (albeit liquid) of vital importance, composed of myriads of crucial cells and nutrients, which is why - when lost - it is transfused. There is a snag however: no two bloods are identical. But all human bloods can be sorted into well-defined groups of which the most representative are the A, B, AB and O blood groups. The O blood group can be transfused to everyone, while the other blood groups cannot. This is why scientists have been searching for ways, literally, to shift A, B and AB blood types to the 'universal' O blood type - which could resolve the problem of insufficient stocks in blood banks. There have been several attempts, none of which conclusive. One more promising attempt involves bacteria from our gut microbiome, and two enzymes: a D-galactosamine deacetylase and a D-galactosamine galactosaminidase. Read more
