EcR depletion affects ovarian follicle differentiation and oocyte growth in the cockroach Blattella germanica

Abstract

Ecdysteroid hormones in insects regulate a diverse amount of physiological processes during developmental and adult stages. The molecular basis of ecdysteroid signalling has been deeply studied in holometabolous insects with meroistic ovaries, such as Drosophila melanogaster, while in hemimetabolous insects the ecdysone role is still poorly understood. Taking Blattella germanica as an hemimetabolous model with panoistic ovaries, in the present work we have studied the ecdysone role on ovaries during oogenesis by depleting the Ecdysone Receptor (EcR) and characterizing phenotypic differences in 6-day-old last instar nymphs through microscope images. Depletion of EcR mediated by dsRNA-treatment allow us to describe the roles of ecdysone in panoistic ovary. Overall results indicate that ecdysone signalling acts in two different levels: in the germarium controlling ovarian follicle differentiation and in the vitellarium where it regulates oocyte growth. Thus, ecdysone presents a crucial role in the regulation of oogenesis of B. germanica confirming that it is not an exclusive function of meroistic ovaries.