Mansi Srivastava, Harvard University

HOFSTENIA – AN ACOELOMORPH MODEL FOR STUDIES OF REGENERATION AND DEVELOPMENT

Hofstenia miamia, a.k.a. the three-banded panther worm, is a new model system for mechanistic investigations of development and whole-body regeneration. As an acoel worm, it represents the sister-group to all other animals with bilateral symmetry and enables the study of the evolution of regenerative and developmental process.

The Question(s)

Hofstenia re-establish entire body axes upon amputation and can regenerate any cell type that is lost to injury. Underlying this capacity to regenerate extensively is a large population of effectively pluripotent stem cells called neoblasts. Thus, studies of regeneration in Hofstenia can reveal mechanisms for initiating the wound response, for regulating stem cell self-renewal and differentiation, and for correctly patterning the identity of new tissue. Further, the phylogenetic placement of acoels as the sister-lineage to all other bilaterians makes Hofstenia a great system for studying the evolution of mechanisms for 1) regeneration and, 2) development of major bilaterian tissues such as mesoderm and the central nervous system.

The Model

Hofstenia are easily maintained in the laboratory in artificially synthesized sea water at room temperature. The worms are happy in still water, circulating tanks are not needed. They are voracious predators, and can be maintained on a diet of brine shrimp. Juvenile and adult worms regenerate most known structures within two weeks, and gene function can be assayed via robust and systemic RNAi. The worms reproduce sexually, with a generation time of about six weeks. The abundant embryos are accessible and amenable to microinjection of dyes, mRNA, and Cas9 enzyme and guide RNAs.