Abstract: How animals establish the anterior-posterior (AP) polarity of body is one of the most fundamental problems in biology. The positional distribution of Hox genes along the AP polarity of body may be important for primary axis patterning during animal development. Observations have revealed that Wnt/β-catenin signaling controls the AP axis patterning in most animals and is indispensable for posterior formation. Planarians possess AP polarity of body, the anterior part of the body is head and the posterior part of the body is tail. Interference of β-catenin-1 expression can reverse the AP polarity, which induce two-head planarian phenotype. However, it is an unsolved question that how the disturbance of β-catenin-1 affects the Hox genes arrangements in planarians. To answer this question, it is essential to establish a model of two-head planarian. In this work, double-stranded RNA (dsRNA) of β-catenin-1 was transcribed in vitro and was fed to planarians by mixing with liver paste, resulting in two-head phenotype. The ratio of two-head planarian phenotype could reach 100% under our experimental condition. Compared with ingestion of bacterially expression dsRNA and injection of dsRNA, the major advantage of feeding in vitro synthesized dsRNA is that it provides a simple, quantity-controllable, easily-practical method for RNA interference (RNAi) in planarians.

Key words: planarian, RNA interference, β-catenin-1