Wirkstoffe des Insektenreiches

Biological Sunglasses in a Deep-Sea Squid: Pigment Migration in the Retina of Gonatus onyx

The outward migration of ommin pigment granules from the bases to the tips of the photoreceptors in response to light has been reported in the retina of several (mostly coastal) squid species. Following exposure to light and then dark conditions, we collected and processed retinal tissue from juvenile specimens of a deep-sea oegopsid squid, Gonatus onyx. We aimed to determine whether the ommin pigment returns to baseline, and to investigate the presence of glutamate neurotransmitter signaling under both dark and light conditions. We confirmed the presence of ommin granules but observed variability in the return of pigment to the basal layer in dark conditions, as well as changes in glutamate distribution. These findings provide support for the migration of retinal ommin pigment granules as a mechanism for regulating incoming light.

The melanins and lipofuscin

An overview of the melanins and lipofuscin is presented, taking an integrating account of their morphological relationships and chemical characteristics wherever possible. This has required inclusion of the ommochromes, the schlerotizing process, and consideration of related neurotransmitters. A number of questions are raised and commented upon.

Kynurenine hydroxylase in Musca domestica L

1. Kynurenine hydroxylase activity was assayed in extracts of Musca domestica L. 2. During the life cycle of the fly, there is a peak of enzyme activity shortly after pupation. 3. Eye-color mutants, rb2, rb1; rb2 and cm, show reduced activity during pupal stages. 4. An ocra mutant lacks this activity. 5. The rb1 and rb2 mutations were separated from the rb1; rb2 strain. From measurements of the xanthommatin content, the rb1 mutation was suggested to enhance the expression of the rb2 gene.