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In the budding ascidian Polyandrocarpa misakiensis, chimeric zooids are induced by the fusion of two different adultbody fragments. If each body fragments was derived from a different visceral pattern zooid (cf, normal body pattern zooidand situs inversus or reversed zooid), some types of chimeric zooids were known to be produced. Using two different colorphenotypes, white-spot strain and spotless one, it is confirmed that chimeric zooids are surely produced. In this study, wemade chimeric zooids between body fragments with reversed white-spot and ones with normal spotless, and analyzedoffspring of the chimeric zooids. The chimeric zooids produced blastozooids with new combination of color pattern andvisceral pattern, that is, blastozooids with normal white-spot or ones with reversed spotless. In blastogenic generation,palleal budding, a bud consists of two envelopes of cell layers: the epidermal and the peribranchial epithelium. Previously,we found that the epidermal epithelium is the carrier of the color pattern. Therefore, our results strongly suggest thatthe information of determining of visceral pattern (L-R axial polarity) exists in the peribranchial epithelium in asexualreproduction ie., palleal budding.

There are two different color strains in the budding ascidian, Polyandrocarpa misakiensis. One is spotless strain and the other is white-spot strain. A zooid of spotless strain has a white-band between branchial and atrial siphons. However, a zooid of white-spot strain has a clear white-spot between branchial and atrial siphons. Ishii et al. (1993) revealed that the differences between the color patterns of the two strains were mainly based on the distribution of red pigments in the epidermal cells. The area that lacks red pigments forms a fine white-band in the spotless strain or a circular white spot in the white-spot strain on the dorsal side. In this area, white pigment cells, which are distributed in the mesenchymal space, can be seen through the epidermal layer. In this report, red-orange pigments and white blood cells were examined with TEM. Also, by solubility test, the natures of pigments were studied. By TEM observation, red or orange pigments were thought to be the granules in the epidermal cells and white blood cells were the nephrocytes (one of blood cells). Solubility test revealed that the red-orange pigments are carotenoids and pteridines.

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資料番号: AA0046920035

資料番号: AA0045981041

In the phylogeny of immune response, at present, the origin of the adaptive immune response in vertebrates is one of major questions. Since it is generally believed that the vertebrates evolved directly from the phylum ..., 1981