Mikio Satake

A stable line of transgenic medaka (Oryzias latipes) carrying the CAT gene

Abstract A stable homozygous line of transgenic medaka (Oryzias latipes) was produced by injecting plasmid DNA containing rainbow trout metallothionein A promoter region followed by bacterial acetyltransferase gene (rtMT-A-CAT), into the cytoplasm of 111 fertilized eggs. The line transmitted active CAT gene to all of the offsprings until sixth generation in mendelian fashion. The Southern blot analysis and the crossing experiments indicated that the DNA was integrated into the chromosome. These results reveal that the medaka is a good model for basic studies of the production of transgenic fish.

Metal-inducible activities of metallothionein promoters in fish cells and fry

Activities of trout metallothionein-A promoter and mouse metallothionein-I promoter in fish cells and fry were examined using the chloramphenicol acetyltransferase (CAT) gene as a reporter. Transfection and transient CAT assays on a trout liver cell line indicated that both promoters were inducible by metals, including zinc. In vivo activities of both promoters were examined using microinjection system into medaka eggs. Some of the hatched fry were exposed to zinc and their CAT activities were assayed. Both promoters revealed considerable activities after exposure to zinc while only weak activities were detected in unexposed fry.