| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 92 === Tyrosinase is an important key enzyme in the pathway of melanin metabolism. Tyrosinase catalyzed tyrosine to melanin. The lacks of tyrosinase activity would cause albinism. A partial tyrosinase cDNA 1371 nucleotid encoded for 451 amino acid was isolated from goldfish by RT-PCR method. Comparing with higher vertebrates such as Homo sapiens, Denio rerio, Rana nigromaculata, Mus musculus, Oncorhynchus mykiss, Gallus gallus, Halocynthia roretzi, Pelodiscus sinensis and Coturnix japonica, the identities of nucleic acid sequence of tyrosinase gene ranging from 49% to 82%, respectively. The similarities of amino acid sequence ranging from 47% to 88%, respectively. In goldfish, the high level expression of tyrosinase gene was detected in the eye and liver. In zebrafish, the higher level expression of tyrosinase gene was founded in the eye and skin. The result of tyrosinase gene expression profile on pigmentation of goldfish and zebrafish during early embryonic stage indicated that tyrosinase mRNA was detected start from 0 pfh and highest expression was detected at 44 pfh in goldfish and 22pfh in zebrafish. The tyrosinase mRNA was detected in eyes and neural crest at 44 pfh in goldfish embryo by whole mount in situ hybridization analysis. Pigmentation process was delayed at least 12 hours in zebrafish embryo development by employ MO （morpholino antisense tyrosinase gene RNA）manipulation. However, injection of the bi-cistronic U6-anti-tyr-EGFP construct has less effect on inhibiting zebrafish embryo pigmentation process, however, the GFP activity can be detected in some fish through adult fish.
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