The transgene construct contains a 5.3 kb fragment of genomic DNA encoding the entire mouse Gpx1 gene with about 2 kb of 5' flanking sequence. The construct was microinjected into fertilized B6C3F1 x B6C3F1 oocytes. Two lines with additional copies of the Gpx1 gene were generated and line 41 was chosen for the original study. Increased Gpx1 mRNA expression was detected in RNA blots in eye, brain, lung, muscle, spleen, tongue, and most dramatically in heart of transgenic animals. Gpx1 activity in heart was found to be increased by 500% relative to wild-type controls. Activity was increased in other tissues also.