Ten of twelve planarians shared a common gene expression profile after barium-induced injury
Ten of twelve planarians shared a common gene expression profile after barium-induced injury
In the flatworm Dugesia japonica, barium chloride blocks potassium channels and destroys the head. After regenerating in the presence of barium, ten of twelve animals showed similar gene activity profiles, while the other two showed a different profile.
On 29 July, the team of Stefania Kapsetaki, Tomer Landsberger, and Michael Levin posted a preprint about planarians. Barium chloride blocks potassium channels and disrupts the flow of potassium across cell membranes. In most worms, the head disintegrates and then regrows in the solution, after which it becomes resistant to further barium exposure.
In the new experiment, the authors measured RNA in each animal to determine which gene expression programs accompany this stable regeneration.
Levin's group first reported this result in 2019. In that study, RNA was extracted from pooled head samples, so the average signal concealed differences among animals. The authors have now sequenced RNA from each worm separately and added a standard regeneration group: six animals regrew their heads from tail fragments without barium.
After their anatomy had been restored, this control group showed altered activity of 1 853 genes relative to intact planarians. This indicates that regeneration itself leaves a molecular trace in the tissue. Among worms that regenerated in barium, 69 genes were activated and 63 were suppressed relative to intact animals. The associated pathways included ion transport, metabolism, and innate defense.
Ten animals formed one large cluster. The other two activated a different set of genes, which the authors associate with immune regulation and developmental programs. The authors describe one predominant pathway and a possible second pathway. The new study refines the 2019 result by showing responses in individual organisms instead of an average signal from pooled tissue.
The next testable step is to perturb the changes in ion transport one at a time and determine which of them initiate stable regeneration.