Regeneration of a whole new adult in only 8 days: Botrylloides leachi.

Sea squirts or Ascidians are a members of the chordate phylum and are often referred to as our "distant cousins". They make a excellent comparative model for studying how developmental processes unique to vertebrates may have evolved.
We also study them as a model for regeneration.  Regenerative ability (replace damaged tissue/organs) declines with animal complexity.  Regeneration in mammals is limited to only a few tissues such as the skin and liver.  In most cases, wounding results in healing and scarring.
We study the colonial sea squirt, Botrylloides leachi.  Colonial sea squirts form a colony, with many adult (zooids) embedded in a tunicate (clear cellulose-type matrix). The colony communicates through a vascular system (blood vessels) embedded in the tunicate.
If we remove everything but just leave a small piece of the vascular tissue -  it will regenerate an entire new adult in under 8 days! 
However they will only regenerate if all of the adults are lost from the colony.  In the case of damage, but retention of adults, the colonies heal and then reproduce asexually. 
It is unknown what triggers regeneration versus healing.
We are using a combination of histology, RNA-seq, genome sequencing, epigenetic inhibitors and cell tracking to study the whole body regeneration process.
In collaboration with Assoc. Prof. Miles Lamare and the Portobello Marine Centre, we have established a B. leachi colony at the Marine Centre.  We can also obtain B. leachi from the Otago Marina, where it grows naturally.
B. leachii Anatomy 

  Husbandry setup for B. leachi stock coloniesB. leachi colony growing in Otago HarbourFeeding Setup for our B. leachi colonies
 Collection samples and regeneration in the lab



For more about the research - see Whole Body Regeneration model: Botrylloides leachi