Almost all animal species, including humans, have blood cells, but in different species, our blood tells different stories. The lineage and composition of blood cells vary widely, and this diversity is evidence of how animals have evolved to protect themselves from infectious diseases.
Thanks to advances in hematology and immunology, we now have detailed knowledge of the composition and function of both human and mouse blood cells. However, little is known about its evolutionary history. Inspired by this, a research team from Kyoto University investigated when and how blood cells arose and how they diversified.
The team began by developing new analytical methods to compare gene expression profiles across different cell lineages and animal species. This allowed them to construct phylogenetic trees of cell lineages and estimate the evolutionary history of these lineages in animals. They also included unicellular organisms in their comparison to trace the origin of blood cells back to their unicellular ancestors.
Among the various lineages of human blood cells observed by the research team: macrophage shows the most striking similarity to unicellular organisms, suggesting that early blood cells were macrophage-like. Then they traced the gene Foss It is commonly expressed in blood cells across animal species and can be traced back to unicellular ancestors that lived 700 million years ago, suggesting that the first blood cells appeared around the same time as multicellular animals.
This discovery suggests that early animals generated the first blood cells by recycling genetic material inherited from their unicellular ancestors. The researchers’ analysis also revealed that mast cells diverged from macrophages, and later prototype T cells and red blood cells diverged from mast cells. Additionally, prototype B cells diverged from macrophages after mast cell isolation.
In the end, scientists succeeded in reconstructing the 700 million-year-old family tree of blood cells, revealing the evolutionary history that has been imprinted on our bodies by the differentiation pathways of these cells. This study shows that the blood and immune cells circulating in our bodies can be considered a successful extension of the legacy left to us by our single-celled ancestors.
We are deeply moved by these discoveries, which represent the culmination of our research and show that the differentiation pathways of vertebrate blood cells reflect the 700 million-year evolutionary history of these cells. ”
Hiroshi Kawamoto Team Leader
“Realizing that this heritage from time immemorial is circulating in my body as blood cells makes me feel closer to our distant ancestors,” added lead author Yosuke Nagahata from the Spanish Institute of Evolutionary Biology.
The researchers hope that the methods developed in this study will help elucidate the evolutionary origins of diseases such as cancer, potentially leading to a deeper understanding of mechanisms and the development of new treatments.
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Reference magazines:
Animals have extended the evolutionary legacy of their unicellular ancestors in blood cells. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.2528110123
