Wiedererscheinen von Tetrahydrobiopterin in der Regenerationsknospe von Triturus-Arten

Abstract

Tetrahydrobiopterin which is present in larval skin of Triturus completely disappears after metamorphosis. In T. cristatus it is mainly riboflavin which remains in the dorsal skin, while in T. alpestris it is mainly isoxanthopterin as well as smaller amounts of pterincarbonic-acid (6), 2-amino-4-hydroxypteridin and (in T. alpestris) biopterin which are found. In T. vulgaris all 4 compounds are found in about equal amounts. The regeneration buds of the tail in T. cristatus and T. alpestris are dark and show melanophores in the epidermis. Moreover, the tetrahydrobiopterin has reappeared whereas riboflavin and isoxanthopterin are diminished respectively. As differentation progresses, the ratios tetrahydrobiopterin/riboflavin and tetrahydrobiopterin/isoxanthopterin gradually regain their “adult” values. The slightly greyish regeneration bud in T. vulgaris, however, does not show any melanophores in the epidermis, nor does tetrahydropterin of the larval stage reappear. The relations between repigmentation of the regeneration bud and the biosynthesis of tetrahydrobiopterin from its purin-precursor are discussed.