Intensive cellular movements occur during gastrulation. These cellular movements rely heavily on dynamic actin assembly. Rho with its associated proteins, including the Rho-activated formin, Diaphanous, are key regulators of actin assembly in cellular protrusion and migration. However, the function of Diaphanous in gastrulation cell movements remains unclear. To study the role of Diaphanous in gastrulation, we isolated a partial zebrafish diaphanous-related formin 2 (zdia2) clone with its N-terminal regulatory domains. The GTPase binding domain of zDia2 is highly conserved compared to its mammalian homologues. Using a yeast two-hybrid assay, we showed that zDia2 interacts with constitutively-active RhoA and Cdc42. The zdia2 mRNAs were ubiquitously expressed during early embryonic development in zebrafish as determined by RT-PCR and whole-mount in situ hybridization analyses. Knockdown of zdia2 by antisense morpholino oligonucleotides (MOs) blocked epiboly formation and convergent extension in a dose-dependent manner, whereas ectopic expression of a human mdia gene partially rescued these defects. Time-lapse recording further showed that bleb-like cellular processes of blastoderm marginal deep marginal cells and pseudopod-/filopod-like processes of prechordal plate cells and lateral cells were abolished in the zdia2 morphants. Furthermore, zDia2 acts cell-autonomously since transplanted zdia2-knockdown cells exhibited low protrusive activity with aberrant migration in wild type host embryos. Lastly, co-injection of antisense MOs of zdia2 and zebrafish profilin I (zpfn 1), but not zebrafish profilin II, resulted in a synergistic inhibition of gastrulation cell movements. These results suggest that zDia2 in conjunction with zPfn 1 are required for gastrulation cell movements in zebrafish.

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In this study we investigate the intra-ovarian pathways underlying early follicle development in Japanese eels, Anguilla japonica. We conducted high-throughput transcriptome analyses in the initial development of the ovary via the next-generation sequencing (NGS). Japanese eels were treated with three weekly salmon pituitary homogenate (SPH) injections. Using RNA-seq, we obtained 29,117,237 and 41,867,557 reads from the control and the SPH-injected groups, respectively. Combining these RNA-seq datasets, we acquired a total of 101,711 unigenes (N50=1,517bp) after performing de novo assembly. After differentially expressed gene (DEG) analysis, 4,211 and 7,059 annotated genes showed upregulation and downregulation respectively in SPH-injected ovarian tissues. Furthermore, functions of annotated genes were classified by GO and KEGG analyses. The PTEN/PI3K-Akt pathway, Tsc/mTOR signaling, oocyte meiosis and reproduction functions were found in data of differentially expressed genes.