Details

Autor(en) / Beteiligte

• Figge, Frank H. J.

Titel

Squid Melanin: A Naturally Occurring Reversibly Oxidizable Pigment

Ist Teil von

• Proceedings of the Society for Experimental Biology and Medicine, 1940-05, Vol.44 (1), p.293-294

Ort / Verlag

London, England: SAGE Publications

Erscheinungsjahr

1940

Beschreibungen/Notizen

• It was reported previously that synthetic melanin resulting from either the enzymatic oxidation of tyrosine or auto-oxidation of dihy-droxyphenylalanine was reversibly oxidizable. 1 It was also found that natural melanin was reversibly oxidizable but that the reaction was far more sluggish and barely perceptible. This was thought to be due to the necessarily low concentrations obtainable and the contaminations present in the solutions of natural melanin. 1 The change in percentage light absorption on reduction of synthetic melanin was very marked. It was thought that these could be duplicated if a source of relatively pure and concentrated natural melanin could be found. Such a source was found in the so-called ink of the ink-sac of the squid (Loligo pealii). The ink is a highly concentrated, relatively pure colloidal solution of melanin. The particles were so small that they were invisible under the ordinary microscope, but visible with dark field illumination. The ink was collected by removing the squid from the water with a net as carefully as possible to prevent discharge of the ink. The mantle was slit immediately with a pair of long scissors. The ink-sac was then dissected out without much danger of being discharged. Many attempts to anesthetize or immobilize the animal by cooling almost always caused the discharge of most of the ink. The ink was withdrawn with a syringe or expressed into a vial after the sphincter had been removed. The ink collected in this manner was extremely concentrated. After diluting with 300 volumes of water, an ink solution, approximately 1 cc in thickness, would transmit an amount of light that was barely registered by a sensitive photoelectric colorimeter. For purposes of comparison, a solution of dopa melanin was prepared by auto-oxidation in air.