On Thursday (19.02) we will host Dr. Ludwik Gąsiorowski (Comparative Invertebrate Zoology,Institute of Evolutionary Biology,University of Warsaw). His lecture will be entitled: "Unusual pluripotent stem cell system in a microscopic flatworm Stenostomum brevipharyngium". The lecture will take place at 3 p.m. in the CN lecture hall and it will be followed by a get together.

Abstract:

The remarkable regenerative abilities of flatworms are closely linked to neoblasts – adult pluripotent stem cells that are the only division-competent cell type outside of the reproductive system. In all flatworms studied thus far, the neoblast cells rely on the expression of the germline multipotency program, a battery of ancient metazoan genes that maintain their pluripotent state. For this reason, the functioning germline multipotency program has been considered necessary for flatworm regeneration. To gain insight into the evolution of the stem cell system and its role in the regenerative process, we studied stem cells in a microscopic flatworm, Stenostomum brevipharyngium, a member of the earliest-branching flatworm lineage. Using a combination of single-nuclei transcriptomics and in situ gene expression analysis, we find that in Stenostomum, the components of the germline multipotency program are not expressed in the dividing stem cells, but are instead restricted to the germline progenitors. We also experimentally show that they are neither required for cell proliferation nor regeneration. Moreover, the neoblast-like cells of Stenostomum express a unique set of genes, including newly identified ones without clear homologs in other animals, that potentially are involved in maintaining their multipotency. Overall, our results highlight previously underappreciated evolutionary plasticity of the molecular control of the pluripotent stem cell systems, which remains flexible without impairing regenerative abilities.