The same gene has made it possible to "invent" hemoglobin several times
Hemoglobin is a circulating protein made up of several subunits called globins. Hemoglobin has evolved independently several times in animals, such as vertebrates, segmented worms, or snails. However, a team from the IJM, working in parallel on the red-blooded marine worm Platynereis and on genomic data from all animals, has demonstrated that the different forms of animal hemoglobins all derive from the same ancestral gene, cytoglobin.
By studying the phylogenetic tree of animal globins, the team demonstrated that Urbilateria, the ancestor of most animals, devoid of red blood, already possessed at least five globin genes. On the other hand, all the animal globins that form hemoglobins are related to cytoglobin, a non-circulating protein, present in all cells, and which play multiple roles in cell metabolism. This study unveils a new 'tinkering' in evolution, which has repeatedly scavenged a protein capable of binding oxygen to make it a major component of blood.
To know more: Globins in the marine annelid Platynereis dumerilii shed new light on hemoglobin evolution in bilaterians. Song S, Starunov V, Bailly X, Ruta C, Kerner P, Cornelissen AJM and Balavoine G. BMC Evol. Biol. 2020 Dec 29;20(1):165. doi: 10.1186/s12862-020-01714-4.
Radio interview of Solène Song (in French): https://pages.rts.ch/la-1ere/programmes/cqfd/05-01-2021