Ommidine - ein neuer Typus von Ommochromen aus Orthopteren

Abstract

In the compound eyes of the migratory locust, xanthommatin and two other brownish-red screening pigments can be distinguished. The major component has been isolated and named ommidin. This pigment shows both similarities to and marked differences from known ommochromes. By incorporation of labelled precursors it is demonstrated, that it is derived both from tryptophan - and thus that it is an ommochrome - and from methionine. In insects, ommidin seems to be restricted to orthoptera, but it has been identified by paper chromatography in Limulus polyphemus. The red pigment extracted from locust hypodermis has been separated into two components. Although these are extremely labile, it is concluded on the basis of their general behaviour, of their colour in oxidized and reduced states, and of incorporation experiments, that they also belong to the ommochromes. The significance of these findings is discussed