A Large Scale Systemic RNAi Screen in the Red Flour Beetle Tribolium castaneum Identifies Novel Genes Involved in Insect Muscle Development

Although muscle development has been widely studied in Drosophila melanogaster there are still many gaps in our knowledge, and it is not known to which extent this knowledge can be transferred to other arthropods. To help closing these gaps we participated in a large-scale RNAi screen that used the red flour beetle, Tribolium castaneum , as a screening platform. The effects of systemic RNAi were screened upon double-stranded RNA injections into appropriate muscle-GFP tester strains. Injections into larvae were followed by the analysis of the adult thoracic muscle patterns, and injections into pupae by the analysis of the late embryonic/larval muscle patterns. Herein we focus on the results of our pupal injection screen for late embryonic/larval muscle phenotypes, which covered 8.500 of a total of ~16.500 genes of the Tribolium genome. Apart from many genes known from Drosophila as regulators of muscle development, a collection of genes previously unconnected to muscle development yielded larval body wall and leg muscle phenotypes. We present the main candidates that remained after being processed through a series of verification and selection steps. Further, we discuss why distinct though overlapping sets of genes are revealed by the Drosophila and Tribolium screening approaches.