RNA-seq analysis comparing WT, Rad21 MO and CTCF MO zebrafish embryos at stages (2.5, 3.3, 4.5, 5.3, 10 hpf) pre and post ZGA (zygotic genome activation)

Methods: Triplicate RNA samples from morphologically stage-matched embryos were sequenced to compare expression profiles over time. Strand-specific libraries were prepared using the TruSeq stranded total RNA-ribozero kit (Illumina) and 100-bp paired-end sequencing was performed to depth of 10 million reads per library on an Illumina HiSeq 2000. Methods: On average, 19 million 100 bp paired-end reads per library were generated. These were then adapter and quality trimmed using cutadapt and SolexaQA. Each sequencing data set was independently mapped to the zebrafish genome with a bowtie2 index generated from Danio_rerio.Zv9.70 (Ensembl) downloaded from Illumina's iGenomes collection. Zebrafish genome danRer7was used to provide known transcript annotations from Ensembl using TopHat2 (version 2.0.9) with the following options: “tophat2 --GTF genes.gtf --library-type fr-firststrand -p 24 --mate-inner-dist -8 --mate-std-dev 6 zv9” (on average, 75.38% reads mapped uniquely to the genome). Transcriptomes were assembled with Cufflinks (version 2.2.0) using options: 'cufflinks -p 32 --GTF genes.gtf' and differential expression analysis between control and knockdown embryos was performed using Cuffdiff. A FDR corrected p-value of 0.05 was applied as the cut off to identify differentially regulated transcripts Results: We could show that MO assisted depletion of Rad21 and CTCF affected the transcriptional profiles of embryos in different ways. Overall design: mRNA profiles of (2.5, 3.3, 4.5, 5.3, 10 hpf) wild type (WT) and morpholino depleted Rad21 MO (Rad21) and CTCF MO (CTCF) embryos were generated by deep sequencing, in triplicate, using Illumina HiSeq 2000.

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Meier M, Grant J, Dowdle A, Thomas A, Gerton J, Collas P, O'Sullivan JM, Horsfield JA