|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1995 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1994 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1993 : ¥800,000 (Direct Cost : ¥800,000)
During the last 3 year project, I used a strain of Xenopus laevis (JJ) and the close relative species Xenopus borealis (BB) and their F1 hybrid (JB). JJ animal has a small number of large spots, BB has many large spots, and JB has intermediate number of spots in their dorsal skin. BB and JB have a genetic cellular marker useful in experimentaion. The spots appear during late metamorphic stages when adult typeskin is formed. While animals metamorphosed in normal period (about 2 months) had typical skin color pattern with a small number of large spots, animals metamorphosed in longer periods (ca.4 months) had a large number of small spots. On the contrary, animals metamorphosed earlier (ca.45 days) had a smaller number of larger spots on their back. The spots are visualized by the expansion of dermal melanophores, the number of which are not so different between spotted areas and inter-spot areas. However, importants are the roles of thexanthophores and iridophores, the number of which are larger in inter-spot areas. The spots are considered to be made up with the three-dimensional distribution in the dermis as well as the degree of expansion of these chromatophores. It means that the skin color pattern is determined by distribution, differentiation fate, and physiological situation of the chromatophores. It is suggested by the skin transplantation experiments that the patternformation is controlled by the prepattern of the controlling factor(s)of the chromatophores, formed around metamorphic climaxstage 56. It is also shown that the melanophores are moved from the surface of muscle layrs into the skin during these stages. The nature of factor(s)in the prepattern have not yet been determined at all. Fractal images made bycomputer simulation is far from perfection for describing the pattern formation, but it has currently suggested that the Ising-spin model may be useful for it. Researches are currently undercontinuation.