Blood cells are found in vertebrates, whether involved in immunity (lymphocytes and granulocytes), oxygen transportation (erythrocytes) or clotting (the main function of platelets produced by megakaryocytes in mammals, and thrombocytes in non-mammalian vertebrates). However, in mammals, some key evolutionary developments have occurred. Specifically, within the erythrocyte cell lineage, erythrocyte progenitor cells undergo progressive chromatin condensation and eventually expel their nucleus, resulting in enucleated mature red blood cells whereas in nonmammals, mature red blood cells still contain their nucleus.
Using an assay for transposase-accessible chromatin (ATAC-seq), I have generated in-house datasets and collected publicly available datasets from several key species within the vertebrate subphylum (human, mouse, chicken, and lamprey). We have also collected transcriptional data from these species.
These datasets will allow me to characterize which genes are key for erythrocyte function throughout vertebrates and which are specific to mammals. We can then identify the different regions of accessible chromatin across mammalian erythrocyte progenitors that are associated with these genes and compare them to nonmammalian red blood cells.
Ultimately, this analysis will lead to the identification of evolutionarily conserved and species-specific regulatory sequences involved in the maturation of erythrocytes, which may be associated with the species-specific features.