| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Due to the tissue dynamics of hydra, every neuron is constantly changing its location within the animal. At the same time a specific subset of neurons defined by morphological or immunological criteria maintain a particular spatial distribution suggesting that neurons switch their phenotype as they change their location. A position-dependent switch in neuropeptide expression has been demonstrated (Koizumi and Bode, 1986). The possibility that ganglion cells of the body column are converted into epidermal sensory cells of the head was examined using a monoclonal antibody, TS33, whose binding is retricted to a subset of epidermal sensory cells of the hypostome. Animals devoid of interstitial cells were decapitated, allowed to regenerate, and shown to form TS33+ epidermal sensory cells. AS this cell type is not found in the body column, and the interstitial cell-free contained only ganglion cells as nerve components in the ectoderm that formed the head, the TS33+ epidermal sensory cells most likely arose from the TS33- ganglion cells. The observation of epidermal sensory cells labelled with both TS33 and TS26, a monoclonal antibody that binds to ganglion cells, in regenerating and normal head provides further support. The doulble-labelled cells are probably in transition form a ganglion cell to an epidermal sensory cell. These results provide a second example of position-dependent changes in neuron phenotype, and suggest that the differentiated state of a neuron is only metastable with regard to type in hydra.
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