List of chromosomes » Chromosome 8
Would you like an orange?
About sailors…
Fruit juice for breakfast became a tradition after an enlightened doctor noticed, in 1747, that sailors suffering from scurvy got better when they were given citrus fruit to eat. Today, we know that scurvy is caused by a lack of vitamin C. The daily recommended dose is equivalent to that found in two oranges. Vitamin C is necessary for our body’s health. It slows ageing and is involved in the synthesis of collagen which, among other things, supports the structure of our tissues.
A protein that let us down
Topping up our diet with food that is rich in vitamin C seems quite natural to us. Yet the large majority of mammals make their own vitamin C – like mice and dogs for instance. So how did we lose the faculty to make ours? We no longer produce the protein which synthesises vitamin C: Gulo. This is because Gulo underwent a mutation in our ancestors about 40 million years ago. The protein is also inactive in other species, such as the chimpanzee, the guinea pig and certain bats which, like us, have to find a substitute in their diet.
Mice already have the gene which produces vitamin C |
A tricky path
The set of processes that lead to the synthesis of vitamin C is complex. Bioinformatics tools – such as metabolic maps – give a complete and global overview of the different stages of its production. Comparisons between species have become possible and shed light on differences such as those which exist between mice and humans for example.
External links
Prolune – snapshot : L-gulonolactone oxidase
Bioinformatics expert: Metabolic pathways of reference (KEGG)
Internal links
What is a protein?
What is a mutation?
Chromosome 16: Fossil genes, Nature’s flotsam
