Project description:Methyl tert-butyl ether (MTBE) has been shown to target developing vasculature in piscine and mammalian model systems. In the zebrafish, MTBE induces vascular lesions throughout development. These lesions result from exposure to MTBE at an early stage in development (6-somites to Prim-5 stages). During this time period, transcript levels of vegfa, vegfc, and vegfr1 were significantly decreased in embryos exposed to 5 mM MTBE. We performed global gene analysis as an unbiased approach to discover possible modes of action of MTBE vascular toxicity. Embryos were exposed at 3 hours post fertilization (hpf) in triplicate to one of three concentrations of MTBE: 5mM (induces vascular lesions and significantly decreases vegfa), 0.625mM (NOAEL; no observed adverse effect level), and 0.00625mM (100-fold below NOAEL), or to embryo media (control). Samples were collected at 6-somites (~15hpf), 21-somites (~24 hpf), and Prim-5 (~30 hpf) stages of development. Embryos were meticulously staged at exposure and at the time of collection to maintain a homogeneous population. Our experimental design sought to explore the effect of three concentrations MTBE on three different stages of zebrafish embryonic development during the critical period established for the chemical. This time period also corresponds to an important time in the cardiovascular system develop of our model vertebrate.
Project description:The exon junction complex (EJC) is composed of three core proteins Rbm8a, Magoh and Eif4a3 and is thought to play a role in several post-transcriptional processes. In this study we focus on understanding the role of EJC in zebrafish development. We identified transcriptome-wide binding sites of EJC in zebrafish via RNA:protein immunoprecipitation followed by deep sequencing (RIP-Seq). We find that, as in human cells, zebrafish EJC is deposited about 24 nts upstream of exon-exon junctions. We also identify transcripts regulated by Rbm8a and Magoh in zebrafish embryos using whole embryo RNA-seq from rbm8a mutant, magoh mutant and wild-type sibling embryos. This study shows that nonsense mediated mRNA decay is dysregulated in zebrafish EJC mutants.