Sox2 plays an essential role in maintaining the pluripotency of embryonic and neural stem cells as well as in the neurogenesis. While it has been well studied in mammals, information from lower invertebrate especially marine fish is still limited. In this study, we cloned and sequenced the full-length cDNA and partial 5'-flanking region of the Japanese flounder Sox2. Phylogenetic, gene structure, and protein comparison analyses revealed that Paralichthys olivaceus Sox2 (Po-Sox2) was homologous to mammalian Sox2. Quantitative real-time RT-PCR results showed that Po-Sox2 was not maternal inherited, and the transcripts were present from high blastula-stage onwards, with the highest level at the mid-gastrula stage. Tissue distribution analysis revealed that Po-Sox2 was present not only in neural tissues, but also in gonadal and gill tissues. In addition, we analyzed the Po-Sox2 promoter region for several species-conserved motifs as well as various transcription factor binding sites. The overall hypomethylation status of the identified CpG sites in the 5'-regulatory region revealed that it was not involved in the transcriptional modulation of Po-Sox2. All these results suggest that Po-Sox2 may have a conserved function in neurogenesis and early embryonic development.
The vasa gene encodes an ATP-dependent RNA helicase of the DEAD box protein family that functions in a broad range of molecular events involving duplex RNA. In most species, the germline specific expression of vasa becomes a molecular marker widely used in the visualization and labeling of primordial germ cells (PGCs) and a tool in surrogate broodstock production through PGC transplantation. The vasa gene from tongue sole (Cynoglossus semilaevis) was characterized to promote the development of genetic breeding techniques in this species. Three C. semilaevis vasa transcripts were isolated, namely vas-l, vas-m, and vas-s. Quantitative real-time PCR results showed that C. semilaevis vasa transcripts were prevalently expressed in gonads, with very weak expression of vas-s in other tissues. Embryonic development expression profiles revealed the onset of zygotic transcription of vasa mRNAs and the maternal deposit of the three transcripts. The genetic ZW female juvenile fish was discriminated from genetic ZZ males by a pair of female specific primers. Only the expression of vas-s can be observed in both sexes during early gonadal differentiation. Before PGCs started mitosis, there was sexually dimorphic expression of vas-s with the ovary showing higher levels and downward trend. The results demonstrated the benefits of vasa as a germline specific marker for PGCs during embryonic development and gonadal differentiation. This study lays the groundwork for further application of C. semilaevis PGCs in fish breeding.
The superradiant Rayleigh scattering using a pump laser incident along the short axis of a Bose-Einstein condensate with a density distortion is studied, where the distortion is formed by shocking the condensate utilizing the residual magnetic force after the switching-off of the trapping potential. We find that very small variation of the atomic density distribution would induce remarkable asymmetrically populated scattering modes by the matter-wave superradiance with long time pulse. The optical field in the diluter region of the atomic cloud is more greatly amplified, which is not an ordinary mode amplification with the previous cognition. Our numerical simulations with the density envelop distortion are consistent with the experimental results. This supplies a useful method to reflect the geometric symmetries of the atomic density profile by the superradiance scattering.
Vasa is a DEAD box helicase and has shown essential functions during gametogenesis and embryogenesis. In most species, research revealed a specific expression of vasa gene in the germ cells. Thus, vasa has become the candidate gene in identifying germ cells. In this study, the vasa gene was isolated from gonads of Japanese flounder (Paralichthys olivaceus). In the 11.4kb genomic sequence, 23 exons were identified besides 5 and 3 flanking regions. The promoter region contained several putative TF binding sites which may have the function of regulating vasa expression. Quantitative real-time PCR analysis showed that vasa gene expression was restricted to adult gonads, with a higher level in the ovary. Development expression profiling revealed a maternal deposit and constant embryonic expression at early stages, but the relative mRNA amount decreased after gastrula. Nine other PoVasa transcripts were detected and their expression in gonads and during early development was not all the same, implying potential different functions during gametogenesis or early embryonic development. These results together confirmed the feasibility of using vasa as a marker of germ cells and that vasa gene had an important role in spermatogenesis and oogenesis. Furthermore, our study laid the groundwork for identifying fish primordial germ cells (PGCs) and investigating germ cell biology.
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