The gut is formed in the most proximal region of the normally developing bud.
When a retinoic acid-containing bead is implanted into the distal region,
an additional gut is formed near the bead, resulting in the complete duplication
of the entire body axis.


The activity of aldehyde dehydrogenase (ALDH, potential retinoic acid synthase)
is detected in the proximal region of the normally developing bud.
The amount of retinal is greatly reduced in the developing bud.
These observations suggest that retinoic acid is an endogenous determinant
directing transdifferentiation of the atrial epithelium


Fujiwara,S. & Kawamura,K. (1992) Ascidian budding as a
     transdifferentiation-like system: multipotent epithelium is not
     undifferentiated. Dev. Growth Differ. 34: 463-472.
Hara,K., Fujiwara,S. & Kawamura,K. (1992) Retinoic acid can induce a
     secondary axis in developing buds of a colonial ascidian, Polyandrocarpa
    misakiensis. Dev. Growth Differ. 34: 437-445.
Kawamura,K., Hara,K. & Fujiwara,S. (1993) Developmental role of
     endogenous retinoids in the determination of morphallactic field in
     budding tunicates. Development 117: 835-845.
Kawamura,K. & Fujiwara,S. (1994) Transdifferentiation of pigmented
     multipotent epithelium during morphallactic development of budding
     tunicates.  Int. J. Dev. Biol. 38: 369-377.

To reveal mechanism of transdifferentiation in the developing bud,
we are investigating expression and function of ALDHs and retinoid receptors.
We are also interested in genes that are activated by retinoic acid.

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