Project description:Juvenile hormone (JH) serves vital roles in insect reproduction, development, and many aspects of physiology. JH primarily acts at the gene-regulatory level through an intracellular receptor. The JH receptor (JHR) is a ligand-activated complex of transcription factors of the bHLH-PAS family, consisting of the JH-binding protein Methoprene-tolerant (MET) and its partner Taiman (TAI). Initial studies have indicated significance of post-transcriptional modification (phosphorylation), subunit assembly, and nucleocytoplasmic transport of JHR in JH signaling. However, our knowledge of JHR regulation at the protein level remains rudimentary, partly due to the difficulty of obtaining functional JHR proteins in a purified form. Here we present successful fermentation-level purification of JHR complexes of MET and TAI proteins from two insect species, the beetle Tribolium castaneum and the mosquito Aedes aegypti. The recombinant JHR subunits from each species were co-expressed using a baculovirus system in an insect cell line and purified through affinity steps, yielding soluble proteins, capable of binding both the hormonal ligand (JH III) and DNA bearing cognate JH-response elements. The present quantitative phosphoproteomcis analysis uncovered multiple phosphorylation sites in the TcMET protein, some of which were induced by methoprene. A functional bipartite nuclear localization signal, straddled by phosphorylated residues, was found within the disordered C-terminal region of TcMET. Our present characterization of the recombinant JHR is a primary step towards understanding JHR regulation.
Project description:We report Illumina-generated RNASeq data of several populations of Tribolium castaneum larvae selected for higher or lower immune priming specificity as well as unselected control populations. From each of these populations, we injected groups of 20 larvae with either one of three bacteria species or left them untreated as controls. Whole body samples were taken 6h after injection and used for RNASeq Analysis.
Project description:Drosophila larvae and adults possess a potent innate immune response, but the response of their eggs is particularly poor. Here we show that eggs of the beetle Tribolium castaneum, in contrast, possess a full range of immune defence mechanisms, based on complete transcriptome comparisons of naïve, sterilely injured, and bacterially challenged eggs. Upon infection, we find massive upregulation of AMPs and differential regulation of 375 other genes including both IMD and Toll signalling components. Importantly, we show that this extensive response depends on the serosa, an extraembryonic epithelium enveloping yolk and embryo. When we delete the serosa using Tc-zen1 RNAi, none of the AMPs and merely 57 other genes are differentially regulated upon infection. Furthermore, unchallenged eggs reveal serosa-biased expression of several bacterial recognition genes. Thus, the serosa is an immune competent frontier epithelium, and its loss in higher flies might account for the poor immune response of Drosophila eggs. Three different types of eggs were analysed. Wildtype eggs, eggs of which the mother was injected with a control dsRNA, and eggs without a serosa of which the mothers were injected with Tc-zen1 dsRNA. These three egg-types were subjected to three treatments, untreated (naïve), pricked with a sterile needle (sterile injury) and pricked with a mix of E.coli and M.luteus. This resulted in 9 samples which were all collected three times resulting in a total of 27 samples.