The Tyrosinase Gene from Medakafish : Transgenic expression Rescues Albino Mutation

测定了水稻酪氨酸酶基因及其5‘上游区的9.8kb基因组核苷酸序列，结果表明，该基因编码区由5个外显子和4个内含子组成，全长4.7kb。虽然外显子的数量和大小与哺乳动物酪氨酸酶基因相似，但编码区(4.7kb)的总长度(4.7kb)不到小鼠(约70kb)和人类(约70kb)基因的十分之一。将两种胞质克隆显微注射到白化突变株受精卵中进行转基因实验，其中一种含有基因组酪氨酸酶基因，上游10kb，另一种含有酪氨酸酶基因，上游3kb。结果表明，在114枚和118枚转基因卵中，分别有53枚和45枚在孵化后发育正常，15枚和10枚呈现马赛克着色。因此，从白化-I^1突变中拯救出的转基因表达，以及青竹基因组的I基因座，可以推断为编码酪氨酸酶基因。

We have determined the 9.8 kb genomic nucleotide sequence of the tyrosinase gene and its 5' upstream region from a telost, medakafish (Oryzias latipes), and shown thata the coding region is composed of five exons and four introns, spanning 4.7 kb. While the number and sizes of the exons were found to be similar to those of mammalian tyrosinase gens, however, the total size of the coding region (4.7kb) was demonstrated to be less thatn one tenth those of mouse (ca.70 kb) and human (>70 kb) genes. transgenic experiments were carried out by microinjecting two kinds of plasmic clones into fertilized eggs of the albino i^1 mutant ; one consisting of the genomic tyrosinase gene with the 10 kb 5' upstream region, and the other the tyrosinase cDNA with the 3 kb 5' upstream region. The results showed that 53 and 45 of 114 and 118 transgenic eggs, respectively, developed normally beyound hatching and 15 and 10 exhibited a mosaic pattern of pigmentation. Thus, transgenic expression rescued from the albino-i^1 mutation, and the i locus of the medaka genome can be concluded to encode the tyrosinase gene.