INVESTIGATION OF THE HORMONES CONTROLLING THE DISTAL RETINAL PIGMENT OF THE PRAWN PALAEMONETES

Abstract

Physicochemical properties of the hormones activating the distal retinal pigment of the Palaemonetes vulgaris and Palaemonetes pugio were determined. The light-adapting and dark-adapting hormones were heat-stable, inactivated by trypsin and migrated in an electric field. These findings suggest the hormones are polypeptides. The amount of light-adapting hormone increased four-fold in the supraesophageal ganglia of specimens kept in darkness 14 days. The quantity of this hormone in the supraesophageal ganglia of specimens illuminated for 14 days did not change detectably. These results demonstrated that the light-adapting hormone from the supraesophageal ganglia was used by the prawns in regulating the distal retinal pigment. The longer prawns were kept in darkness, the faster was the rate of migration of the distal pigment toward the light-adapted position when prawns were illuminated. The light-adapting hormone was separated from the dark-adapting one by filter paper electro-phoresis at pH 9.0. This pH is close to the isoelectric point of the dark-adapting hormone whereas at this pH the light-adapting hormone was electropositive.