IMMUNOLOGICAL COMPARISON OF THE α- AND β-ESTERASES IN <i>DROSOPHILA</i> SPECIES

Abstract

Immunological phylogenetic relationships of the α- and β-esterases of Drosophila have been studied for 31 species from 13 different species groups of four subgenera. The results of immunodiffusion tests against anti-α and anti-β serum, which were prepared against α- and β-esterase of D. virilis respectively, revealed remarkable differentiation in both these esterases among Drosophila species. Eight species belonging to the subgenera other than the subgenus Drosophila to which virilis belonged, reacted with neither anti-α nor anti-β serum. The same situation was found for the species in the quinaria section of the subgenus Drosophila, with the exception only of multispina (funebris group) in which faint precipitin lines were found against only anti-α serum. Fly extracts from 12 species of the virilis section in the subgenus Drosophila cross-reacted with both anti-α and anti-β sera without exception. However, differentiation of esterases between species groups in the virilis section as well as differentiation between three species of the virilis group was proven to be based on (a) different esterase activity of the precipitin lines, (b) the formation of the spur and (c) on inhibition of esterase activity by antisera. The amount of cross-reacting materials in reference to β-esterase estimated in comparison with virilis is as follows: about one half in ezoana (virilis group), one eighth in hydei (repleta group, vivilis section) and zero in funebris (funebris group, quinaria section). In general β-esterase seem to differentiate more than α-esterases. Differentiation of Drosophila esterases disclosed here by immunological methods coincides well with Throckmorton's scheme of phylogenetic relationships based upon morphological and biochemical characters.