Stems cells, with their ability to differentiate into any sort of cell, have allowed our ancestors to evolve from single-celled organisms to animals with complex body plans.


So what makes a stem cell so special?


Alexandre Alié and coworkers in a research group led by Noriko Funayama have found an answer by analyzing the genetic basis of stem cells in our distant relatives -- the sponge.


Sponges are one of the first organisms that diverged from our common unicellular ancestor, possessing some of the same genes our common ancestors did to produce stem cells. "As such, they are pivotal to unraveling the molecular mechanisms that underpinned the acquisition of stem cells in the last common ancestor," the authors wrote.


Analysis and comparison of the stem cell gene expression sets (transcriptomes) of sponges, cnidarians, and flatworms revealed that genes which act directly on RNA predominate.


"[This implies that the] posttranscriptional regulation of gene expression has been crucial in animal stem-cell biology across hundreds of millions of years of animal evolution," the authors concluded.

Left -- Juvenile sponge hatched from a gemmule    Right -- Stem cell system of sponges