Regeneration, the process of producing tissues that resemble missing parts of an organism, is a mechanism that is beneficial to some organisms. However, when it comes to deeming an organism as being the “ideal regenerative organism”, planaria live up to this name. As observed in Figure 2 and in Figure 3, planaria are non-parasitic flatworms that reside in freshwater environments. Planarians possess the capability to compensate for missing tissues that have either been cut or decapitated, which makes them ideal models for experiments conducted by scientists (Rink et al., 2012). Regeneration in planaria typically begins once the planaria has been cut or decapitated (Pearson et al., 2009). The rationale behind the planarians’ regenerative mechanism are Neoblasts and morphogens. Neoblasts, or stem cells, are cells within planaria that are capable of becoming specialized for a certain function, because of a substance known as a morphogen. Morphogens are ...view middle of the document...
, 2009). If planarians are cut, depending upon the Anterior/Posterior polarity, Sonic hedgehog (Shh) signals the formation of neural tissue or tail tissue based upon which Wnt genes are expressed in these areas (Yazawa et al., 2009). In the beta catenin pathway, the now differentiated stem (neoblast) cells aid in the posterior fate specification of the pluripotent stem cells that are undifferentiated so that that can become specified for a function within the planaria (Yazawa et al., 2009) (Gurley et al., 2008). This is also similar to how nuclear beta catenin plays a role in establishing the fate of vegetal stem cells in sea urchins. In other words, sea urchin stem cells undergo the same specification as neoblast in planaria in order for special cells for specialized functions to be formed (Logan, 1999). Although most experiments focus on planaria regenerating primarily in freshwater surroundings, we decided to conduct an experiment in which cut planarians were incubated in an environment involving the chemical compound, lithium chloride (LiCl). Planarians are often used to test various drugs and compounds in order to determine the drugs’ effects. Lithium chloride (LiCl) is a compound that consists of the alkali metal lithium and the halogen chlorine. Based upon previous studies involving squid embryos, scientists found that the lithium chloride enhanced the growth and formation of the mesoderm and endoderm tissues while inhibiting the development of ectoderm tissue during the gastrulation (Crawford, 2003). The experiment by Crawford used concentrations of 20, 40, and 60 mM LiCL in order to determine whether or not the effects of lithium chloride were dependent upon the concentration level. In our experiment, we’ll use similar concentrations as a starting point to see if lithium chloride affects the regeneration of planaria. We believe that LiCl will affect the regeneration of the planaria in order to show that planaria cannot regenerate outside of their natural environment of freshwater.
Materials and Methods
The materials that we used in our experiment include four dissecting scopes, four scalpel blades, for droppers, two-four small and large petri dishes, 20 mM and 60 mM LiCl concentrations, 60-70 planaria.