Project description:The transition from maternal to zygotic gene expression during zygotic genome activation (ZGA) is tightly associated with chromatin accessibility modulated by maternal transcription factors. However, due to technical limitations, it remains elusive how the chromatin regulatory landscape is established in Xenopus tropicalis ZGA, and let alone DNA binding transcription regulators involved in this process. Here, by developing concanavalin A beads-based nucleus capture followed by Tn5-mediated accessible chromatin assay with sequencing (CANTAC-seq), we generated a first genome-wide map of accessible chromatin in X. tropicalis embryos from early blastula to neurula stage. We found that open chromatin landscape is progressively established at cis-regulatory elements during ZGA. Based on the motif analysis and perturbation experiments, we demostrated E2f1, a well-known transcriptional activator, maintains a repressive chromatin environment preceding minor ZGA. Moreover, we identified another maternal factor Otx1 counteracts the inhibitory function of E2f1. Mechanistically, E2f1 and Otx1 co-regulate a set of genes required for zygotic gene transcription and germ layer differentiation before the midblastula transition (MBT) through a seesaw model. Taken together, our data reveals the dynamic chromatin regulatory landscape that accompanies early development and elaborates on the function of a coupled transcriptional repressor-activator regulating zygotic gene transcription in a classical model organism.
Project description:Lipids play an important role in energy storage, membrane structure stabilization and signaling. Parasitoids are excellent models to study lipidomics because a majority of them do not accumulate during their free-living life-stage. Studies on parasitoids have mostly focused on the changes in the lipids and gene transcripts in hosts and little attention has been devoted to lipidomics and transcriptomics changes in parasitoids. In this study, a relative quantitative analysis of lipids and their gene transcripts in 3-days-old Lysiphlebia japonica larva (3 days after spawning) and pupae were performed using liquid chromatography, mass spectrometry and RNA-seq. Thirty-three glycerolipids and 250 glycerophospholipids were identified in this study; all triglycerides and the vast majority of phospholipids accumulated in the pupal stage. This was accompanied by differentially regulated lipid uptake and remolding. Furthermore, our data showed that gene transcription was up-regulated in key nutrient metabolic pathways involved in lipid synthesis in 3-days-old larvae. Finally, our data suggests that larva and pupa of L. japonica may lack the ability for fatty acids synthesis. A comprehensive, quantitative, and expandable resource was provided for further studies of metabolic regulation and molecular mechanisms underlying parasitic response to hosts defense.
