Extensive Differences in Antifungal Immune Response in TwoDrosophilaSpecies Revealed by Comparative Transcriptome Analysis

摘要

The innate immune system ofDrosophilais activated by ingestion of microorganisms.D. melanogasterbreeds on fruits fermented bySaccharomyces cerevisiae, whereasD. virilisbreeds on slime flux and decaying bark of tree housing a variety of bacteria, yeasts, and molds. In this study, it is shown thatD. virilishas a higher resistance to oral infection of a species of filamentous fungi belonging to the genusPenicilliumcompared toD. melanogaster. In response to the fungal infection, a transcriptome profile of immune-related genes was considerably different betweenD. melanogasterandD. virilis: the genes encoding antifungal peptides, Drosomycin and Metchnikowin, were highly expressed inD. melanogasterwhereas, the genes encoding Diptericin and Defensin were highly expressed inD. virilis. On the other hand, the immune-induced molecule (IM) genes showed contrary expression patterns between the two species: they were induced by the fungal infection inD. melanogasterbut tended to be suppressed inD. virilis. Our transcriptome analysis also showed newly predicted immune-related genes inD. virilis. These results suggest that the innate immune system has been extensively differentiated during the evolution of theseDrosophilaspecies.