Project description:The development of massively parallel sequencing technologies has revolutionized transcriptome analysis. Sequencing of total cDNA (RNA-Seq) can determine the expression levels of known and novel transcripts with high sensitivity from various developmental stages or conditions. Here we report a robust method for RNA-Seq in Xenopus laevis and apply it to understanding how modulation of retinoic acid signaling alters the transcriptome in early Xenopus laevis development. Three biological conditions were tested: early blastula stage embryos were treated with 1. a retinoic acid receptor (RAR) agonist NRX204647 (4647) at a concentration that stimulated all 3 RAR subtypes (alpha, beta, and gamma); 2. The same agonist at an RAR[gamma] selective dose, and 3. vehicle control. Five single-clutch replicates were obtained for each chemical treatment group, and harvested at neurula stage. We found that single-clutch replicates reflect the stochastic variation of the general outbred population and contribute more statistical power to RNA-Seq experiments due to their feasibility of replication. Our RNA-Seq dataset identified 1590 up-regulated and 685 down-regulated unique genes differentially regulated by all RAR subtypes, and 160 up-regulated and 60 down-regulated genes likely to be regulated specifically by RAR[gamma]. Differential expression detected by RNA-Seq was validated for selected genes by QPCR, which demonstrated nearly 100% quantitative agreement with the deep sequencing data. We further validated RAR-responsive genes by comparison with two previous, published microarray datasets and found substantial agreement. Gene ontology analysis identified RAR targets which may underlie such developmental processes as axial elongation, neurogenesis/synaptogenesis, dorsoventral regulation of the retina, homeotic fate specification, and central nervous system development. We investigated RAR[gamma]-selective targets identified by RNA-Seq and inferred that transcriptional repression by unliganded RARs is of substantial importance to embryonic patterning events. Overall, this paper demonstrates the utility of RNA-Seq in Xenopus laevis, obviating the perceived requirement to use X. tropicalis for genomic analyses.
Project description:Analysis of whole body of unfertilized eggs and two-cell stage, 16-cell stage, stage 8, stage 9, stage 10.5, stage 12, stage 15, stage 20, stage 25, stage 30, stage 35 and stage 40 embryos. Results provide insight into the global molecular changes in Xenopus embryogenesis.