[Effect of temperature on homoeotic mutation expression in Drosophila. I. Homoeotic transformation in Proboscipedia mutants].

It is generally adopted that the homoeotic gene proboscipedia causes the transformation of the distal parts of proboscis into corresponding tarsal or antennal (aristal) segments. It is shown that actually the homoeotic effect of the mutation proboscipedia consists in the transformation of the oral lobes of proboscis into a whole prothoracic leg. Sometimes the distal parts of the homoeotic leg (segments of tarsus, claws) can coexist with or be substituted for by the aristal filaments. The transformation of oral lobes of proboscic into the leg is most conspicuous at 29 degrees C, while at 16 degrees C the substitution of tarsal structures by aristal ones is observed more frequently. The homology between the corresponding elements of the proboscis, legs and antenna (as revealed by the pattern of homoeosis) is discussed.