Growth hormone (GH) is now considered to be involved in the mechanism of seawater adaptation as well as in the growth-promoting reaction in teleosts. In an effort to elucidate the reaction mechanisms of GH in the osmoregulation and growth promotion, we have cloned and analyzed the cDNAs of yellowtail, hard tail and flounder GHs. The deduced mature yellowtail, hard tail and flounder GHs are composed of 187, 188 and 173 amino acid residues, respectively. These and other GHs are found to conserve 5 GH-specific domains, GD1 to GD5. In the teleost GHs, the GD5 is particularly highly conserved, suggesting the specific role of this domain in these GHs. Flounder GH, which has the smallest molecule ever found, lacks an extra region of these GD domains. To study the biological activities of teleost GHs, we have synthesized recombinant yellowtail and flounder GHs by E. coli expression vectors. Synthesized GHs have been purified and folded in glutathione red/ox buffer, and both recombinant GHs exhibited full growth-promoting activities on rainbow trout fries.
Potassium, magnesium, calcium and sulfate in salt crystal were determined in a case of a combined process of electrodialysis with ion-exchange membrane and multi effect pan. And fluctuation of impurity content was discussed in connection with concentration of mother liquor and particle. 1) Potassium content is 300 to 1,600 ppm. These values are in proportion to concentration of Inother liquor. 2) Sulfate content is 100 to 500 ppm. These values increase with smalier particle size. And the increase in bittern pan is remarkable. 3) Caicium salt, except calcium sulfate, is 30 to 140 ppm. These values increase with concentratiop of mother liquor. 4) Magnesium content is below 10 ppm, which will exist in liquor in crystal.