Vesterlund Liselotte, Jiao Hong, Unneberg Per, Hovatta Outi, Kere Juha
Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden.
BMC Dev Biol. 2011 May 24;11:30. doi: 10.1186/1471-213X-11-30.
The transition from fertilized egg to embryo is accompanied by a multitude of changes in gene expression, and the transcriptional events that underlie these processes have not yet been fully characterized. In this study RNA-Seq is used to compare the transcription profiles of four early developmental stages in zebrafish (Danio rerio) on a global scale.
An average of 79 M total reads were detected from the different stages. Out of the total number of reads 65% - 73% reads were successfully mapped and 36% - 44% out of those were uniquely mapped. The total number of detected unique gene transcripts was 11187, of which 10096 were present at 1-cell stage. The largest number of common transcripts was observed between 1-cell stage and 16-cell stage. An enrichment of gene transcripts with molecular functions of DNA binding, protein folding and processing as well as metal ion binding was observed with progression of development. The sequence data (accession number ERP000635) is available at the European Nucleotide Archive.
Clustering of expression profiles shows that a majority of the detected gene transcripts are present at steady levels, and thus a minority of the gene transcripts clusters as increasing or decreasing in expression over the four investigated developmental stages. The three earliest developmental stages were similar when comparing highly expressed genes, whereas the 50% epiboly stage differed from the other three stages in the identity of highly expressed genes, number of uniquely expressed genes and enrichment of GO molecular functions. Taken together, these observations indicate a major transition in gene regulation and transcriptional activity taking place between the 512-cell and 50% epiboly stages, in accordance with previous studies.
从受精卵到胚胎的转变伴随着基因表达的众多变化，而这些过程背后的转录事件尚未得到充分表征。在本研究中，RNA测序用于在全球范围内比较斑马鱼（Danio rerio）四个早期发育阶段的转录谱。
从不同阶段平均检测到7900万个总读数。在总读数中，65% - 73%的读数成功映射，其中36% - 44%是唯一映射的。检测到的独特基因转录本总数为11187个，其中10096个存在于单细胞阶段。在单细胞阶段和16细胞阶段之间观察到的共同转录本数量最多。随着发育的进行，观察到具有DNA结合、蛋白质折叠和加工以及金属离子结合分子功能的基因转录本富集。序列数据（登录号ERP000635）可在欧洲核苷酸档案馆获得。
表达谱聚类表明，大多数检测到的基因转录本处于稳定水平，因此在四个研究的发育阶段中，少数基因转录本聚类为表达增加或减少。在比较高表达基因时，最早的三个发育阶段相似，而50%外包期在高表达基因的身份、独特表达基因的数量和GO分子功能的富集方面与其他三个阶段不同。综上所述，这些观察结果表明，根据先前的研究，在512细胞和50%外包期之间发生了基因调控和转录活性的重大转变。
