| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
The freshwater planarian Dugesia japonica has powerful regeneration ability, that is, a small piece of the body can reform a complete organism. These planarians have same pattern in the body organization, which has been thought to be independent upon their body size. It remains to know how the body pattern is established. In this study, firstly, I analyzed by RNA interference the function of DjBMP (Dugesia japonica Bone morphogenetic protein), which was cloned previously as a candidate molecule for dorso-ventral patterning. Knock down of DjBMP resulted in 'double ventral' phenotype, which is characterized by the body color, the expression of a marker gene for the dorso-ventral boundary, and location of nerve cords. This finding indicates that DjBMP is required for dorso-ventral patterning. Second, I examined the antero-posterior patterning in posterior regenerates using pharynx position as a landmark. The position of pharynx was constant, but a little depended upon size of regenerates. Based on this finding, I designated an experiment, termed 'time-differential amputation', in which the posterior regenerates were cut again into the anterior and posterior fragments at various periods after the initial amputation. Then I examined if the second amputation effected on the pharynx position in the anterior regenerates. The pharynx position was dependent upon the second amputation if it was done within 6 hours after the initial amputation. However, the pharynx position was independent upon the second amputation if it was done 12 hours after the initial amputation. This finding suggests that the antero-posterior patterning occurs within 12 hours after amputation. These results provide fundamentals to understand mechanisms of pattern formation in planarian regeneration.
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