Patent ID: 8395018

Claim:
A transgenic brackish medaka fish comprising: at least one expression cassette, wherein said at least one expression cassette comprises: (i) a reporter nucleotide sequence encoding a reporter protein; (ii) an estrogen-responsive 5′-regulatory nucleotide sequence selected from the group consisting of SEQ ID NO:2, SEQ ID NO:3, and SEQ ID NO:4, wherein the regulatory nucleotide sequence is operably linked 5′ to the reporter nucleotide sequence to induce expression of the reporter protein in the presence of estrogen or an estrogen-like compound; and (iii) a 3′-regulatory region operably linked 3′ to the reporter nucleotide sequence, wherein the transgenic brackish medaka fish exhibits an observable mark when exposed to a liquid medium containing an estrogen or an estrogen-like compound, and wherein the observable mark comprises the reporter protein expressed by the at least one expression cassette.