Vitellogenesis, including vitellogenin (Vg) production in the fat body and Vg uptake by maturing oocytes, is of great importance for the successful reproduction of adult females. The endocrinal and nutritional regulation of vitellogenesis differs distinctly in insects. Here, the complex crosstalk between juvenile hormone (JH) and the two nutrient sensors insulin/IGF signaling (IIS) and target of rapamycin complex1 (TORC1), was investigated to elucidate the molecular mechanisms of vitellogenesis regulation in the American cockroach, Periplaneta americana. Our data showed that a block of JH biosynthesis or JH action arrested vitellogenesis, in part by inhibiting the expression of doublesex (Dsx), a key transcription factor gene involved in the sex determination cascade. Depletion of IIS or TORC1 blocked both JH biosynthesis and vitellogenesis. Importantly, the JH analog methoprene, but not bovine insulin (to restore IIS) and amino acids (to restore TORC1 activity), restored vitellogenesis in the neck-ligated (IIS-, TORC1- and JH-deficient) and rapamycin-treated (TORC1- and JH-deficient) cockroaches. Combining classic physiology with modern molecular techniques, we have demonstrated that IIS and TORC1 promote vitellogenesis, mainly via inducing JH biosynthesis in the American cockroach.

As a model hemimetabolous insect species and an invasive urban pest that is globally distributed, the American cockroach, Periplaneta americana, is of great interest in both basic and applied research. Previous studies on P. americana neuropeptide identification have been based on biochemical isolation and molecular cloning. In the present study, an integrated approach of genomics- and peptidomics-based discovery was performed for neuropeptide identification in this insect species. First, 67 conserved neuropeptide or neurohormone precursor genes were predicted via an in silico analysis of the P. americana genome and transcriptome. Using a large-scale peptidomic analysis of peptide extracts from four different tissues (the central nervous system, corpora cardiac and corpora allata complex, midgut, and male accessory gland), 35 conserved (predicted) neuropeptides and a potential (novel) neuropeptide were then identified. Subsequent experiments revealed the tissue distribution, sex difference, and developmental patterns of two conserved neuropeptides (allatostatin B and short neuropeptide F) and a novel neuropeptide (PaOGS36577). Our study shows a comprehensive neuropeptidome and detailed spatiotemporal distribution patterns, providing a solid basis for future functional studies of neuropeptides in the American cockroach (data are available via ProteomeXchange with identifier PXD021660).

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28Vitellogenesis, including vitellogenin (Vg) production in the fat body and Vg uptake 29 by maturing oocytes, is of great importance for the successful reproduction of adult 30 females. The endocrinal and nutritional regulation of vitellogenesis differs distinctly in 31 insects. Here, the complex crosstalk between juvenile hormone (JH) and the two 32 nutrient sensors, insulin/IGF signaling (IIS) and target of rapamycin (TOR), was 33 investigated to elucidate the molecular mechanisms regulating vitellogenesis in the 34 American cockroach, Periplaneta americana. Our data showed that a block of JH 35 biosynthesis or JH action arrested vitellogenesis, partially by inhibiting the expression 36 of doublesex (Dsx), a key transcription factor gene involved in the sex determination 37 cascade. Depletion of IIS and TOR blocked both JH biosynthesis and vitellogenesis. 38 Importantly, the JH analog methoprene, but not bovine insulin (to restore IIS) and 39 amino acids (to restore TOR activity), restored vitellogenesis in the neck-ligated (both 40 nutrient-and JH-deficient) cockroaches. Combining classic physiology with modern 41 molecular techniques, we have demonstrated that JH signaling alone is able to induce 42 vitellogenesis and thus ovarian maturation. By contrast, IIS and TOR do not induce 43 vitellogenesis independent of JH, the nutrient sensors promote vitellogenesis in an 44 indirect manner via activating JH biosynthesis. 45 46 KEYWORDS: IIS, TOR, Juvenile hormone, Dsx, vitellogenesis 47 48 Vitellogenesis, an imperative event of insect reproduction, involves vitellogenin (Vg) 49 production in the fat body, the release of Vg into the hemolymph, and Vg uptake by and 50 its modification in maturing oocytes. During the process of Vg uptake, extensive 51 intercellular spaces are formed among follicle cells (follicular patency), allowing the 52 internalization of hemolymph Vg into maturing oocytes by receptor-mediated 53 endocytosis (Raikhel, 2005; Roy et al., 2018). However, the connection between Vg 54 production and the formation of follicular patency has not been determined yet.55