The Effects of Hypergravity on Planarian Regeneration, Morphology, and Behavior   X. Zhang1, T. He1, C. Lin1, N. Tseng1, A. Dupati1, R. Johns1, N. Rayl2, and J. Smith3   1Troy High School, Troy MI, 2Life Sciences Division Education and Outreach and 3Gravitational Biology Research Branch, NASA Ames Research Center, Moffett Field, CA

   Planaria (d. japonica) belong to the phylum Platyhelminthes.  Inhabiting freshwater lakes and streams they are free-living, flat bodied, organisms that exhibit the ability to regenerate injured or lost body parts.  Their anatomy consists of a simple nervous system that includes a “brain”, muscle bundles, an internal reproductive system and a blind gut.  Planaria can be conditioned to respond to stimuli, display the ability to master a two-choice maze, and can transfer the memory of training from one to another.  Planaria were chosen as subjects of examination because of their regenerative attributes and their ability to exhibit specific behaviors such as negative phototaxis and “righting” behavior. Studying how simple organisms regenerate when exposed to hypergravity may help further the understanding of what happens to astronauts that sustain wounds in different gravitational environments.

   In this study d. japonica was used to examine the effects of hypergravity on-board the 8’ Centrifuge for five days at NASA Ames Research Center.  A treatment group of worms under went various cuts.  A “Tri-Cut” set were cut above and below the pharynx, the “Marie Antoinette” set were cut above the pharynx, and the “Centaur” set were cut below the pharynx.  The treatment group was divided into those spun on the centrifuge and those in the stationary enclosures.  Another group of un-cut worms served as the on and off-board controls.  The onboard group spun for four days at 3-G’s.  The worms were kept on a twelve-hour day/night cycle and at constant temperature. Qualitative observations and digital images were taken.  Behavioral analysis was conducted at days two-five.  Righting behavior, tactile stimulation and phototaxis were tested.

   The results of this experiment indicate that there is an observed change in regeneration and behavior due to exposure to hypergravity on a centrifuge.

   Support: NASA, Hyper-G Competition