Abstract: In accordance with the present invention, there are provided humanized fish insulin genes. Humanized insulin the present invention encode human insulin alpha and/or beta chains while using fish-preferred codons and regulatory sequences. These humanized genes are thus expressible in fish islet cells. Also provided are transgenic fish having islet cells containing and capable of expressing humanized insulin genes. These islet cells (Brockmann Bodies) can be xenotransplanted into subjects having diabetes. In this manner normoglycemia can be achieved in the recipient of the islets.

Abstract: This invention relates to transgenic fish containing a humanized insulin gene which has been altered to secrete human insulin and its use in the treatment of diabetes. In the transgenic fish of the present invention, the fish insulin gene has been modified to code for human insulin gene while leaving the regulatory sequences of fish insulin gene intact. Islet transplantation may provide the meticulous glycemia control required in the treatment of diabetes. The islet tissue of the present invention offers an inexpensive and a nearly unlimited supply of human insulin-producing tissue and therefore, may be useful in the treatment of diabetes. In this regard, an improved method of mass isolation of islet tissue is provided by the present invention. The present invention also provides the use of the humanized insulin gene to promote growth in fish.