Budding, life-span, regeneration, and colonial regulation in the ascidian,Symplegma reptans
✍ Scribed by Sugino, Yasuo M. ;Nakauchi, Mitsuaki
- Publisher
- John Wiley and Sons
- Year
- 1987
- Tongue
- English
- Weight
- 673 KB
- Volume
- 244
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
In the colonial ascidian, Symplegma reptans, the oozooid from which a particular colony has developed always degenerates about 30 days after metamorphosis, while all other zooids of the same colony are vigorous. Furthermore, an irregular type of regeneration, "blastogenic regeneration" (regeneration with the aid of budding), occurs if the zooids or their fragments are isolated under artificial conditions. Employing this species, we examined how budding and the life-span of a zooid are affected by the other zooids of the same colony and studied the relationship between the nature of fragments of zooids and the mode of regeneration. To survey the effects of the other buds and zooids of the same colony, all buds from the oozooid were removed. The zooids from which buds were removed made about twice as many buds as the controls, and they lived a little longer than the controls. This result suggests that budding of a zooid is inhibited by the ambient zooids in the same colony. When the fragments of zooids were cultured alone, they regenerated either by epimorphosis or by blastogenic regeneration according to the extent of surgical removal of tissue. In cases in which two or more buds were formed during blastogenic regeneration, only the first bud grew. These results indicate that budding and regeneration are regulated both at the zooidal level and at the colonial level.
In most species of colonial ascidians the colony is formed as follows. 1) A tadpole larva develops into an oozooid after metamorphosis. 2) The oozooid produces a series of buds