Studies on the light- and dark-adaptation of the colour of the crayfish, Astacus leptodactylus Eschscholz (Decapoda) controlled by the secretory activity of the central nervous system

Konok, István (1961) Studies on the light- and dark-adaptation of the colour of the crayfish, Astacus leptodactylus Eschscholz (Decapoda) controlled by the secretory activity of the central nervous system. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 28. pp. 29-47. ISSN 0365-3005

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Abstract

1. According to the variations of light-conditions, definite colouradaptation can be observed in the crayfish Astacus leptodactylus. 2. The role of pigments, the importance of light-adaptation probably consists in constituting a suitable light filter layer, especially in relation to moulting. 3. It can be proved that not only the quantity but also the quality of light plays a role in colour-adaptation. 4. In connection with the quantitative and qualitative conditions of light, phenomena of pigment- and chromatophore reduction can be observed in various degrees on the population of Astacus leptodactylus living in Lake Balaton. 5. The distribution of the three types of pigments is such as to give to Astacus leptodactylus a blue basic colour in the case of dark-adaptation. The red and white pigments contract, the blue ones diffuse. 6. Due to the action of light, red and white pigments diffuse, blue ones contract. After 24 hours of constant exposure to light, white pigments gradually contract again. The basic colour of the light-adapted animal will be red. 7. In the case of Astacus astacus, the function of the chromatophores is approximately antagonistic, red chromatophores diffusing in the darkadapted state and contracting on the action of light. The same holds true of blue pigments. 8. Light is not acting directly on the chromatophores resp. on the movement of pigments. 9. In the case of Astacus leptodactylus certain elements of the eye-stalk and of the nervous system show only an activity of dark-adapting character. 10. No antagonistic chromatophorotrop effect could be demonstrated in the postesophageal ganglion, the factor of dark-adapting character was to be found here too. 11. The sources of the dark-adapting factors are eye-stalks and the ganglia of the central nervous system, where they are produced continually 12. The chromatophorotrop activity of certain organs is growing in dark-adapted state. Most of the hormones can be found in the eye-stalk and in the infraesopageal ganglion. 13. The dark-adapting chromatophorotrop hormone is not only excreted through the sinus gland, but also directly from every ganglion into the haemolymph. 14. By the means of electrophoretic separation, an electro-positive (pH 9) RC factor could be isolated from certain elements of nerves and from the eye-stalk, effecting strong contraction of the red, and a weaker one of the white pigments. This factor is probably identical with the A’ substance shown by K nowles in the post-commissure organ of Squilla and Leander. 15. The RC factor is a heat-resisting substance well soluble in water and buthanol, presumably a polypeptid of a rather high molecular weight. 16. By electrophoresis another electro-negative (pH 9) RC’ factor could be isolated from the eye-stalk and from elements of the nervous system, having a weakly contracting effect on both red and white pigments. 17. An electronegative BD factor (pH 9) could be isolated from the supra- and infraesophageal ganglia, diffusing strongly the blue pigments. 18. In connection with the investigations, a useful process for in vitro chromatophore-testing has been elaborated.

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