Toshihiro Kawasaki

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Recent studies in mammals have revealed the heterogeneity of spermatogonial populations which contain differentiated and undifferentiated cells that further divide into actual stem cells and potential stem cells. In fish however, there are no functional definitions, and very few molecular markers, for germ cells. In our present study, specific antibodies(More)
Germ-line stem cells have the potential to be a very powerful tool for modifying the genetic information of individual animals. As a first step to use spermatogonial stem cells (SSCs) to enable genetic modification, we here describe effective long-term culture conditions for propagating zebrafish SSCs and for the production of offspring from these cultured(More)
The self-renewal and differentiation of spermatogonial stem cells (SSCs) is essential for the continuous production of sperm throughout life in male vertebrates. The development of a functional assay to analyze these properties in isolated SSCs remains necessary. In our current study, we have developed a transplantation method for testicular cell aggregates(More)
Viral vectors represent a tractable system that can efficiently introduce an exogenous gene into different target cells and are thus a potentially powerful genetic manipulation tool. In our current study, we investigated the infection efficiency of mammalian virus vectors, adenoviruses (Ads), adeno-associated viruses, and lentiviruses to the Sertoli cell(More)
RNA interference (RNAi) has emerged as a powerful tool to silence specific genes. Vector-based RNAi systems have been developed to downregulate targeted genes in a spatially and temporally regulated fashion both in vitro and in vivo. The zebrafish (Danio rerio) is a model animal that has been examined based on a wide variety of biological techniques,(More)
In vertebrates that have been examined to date, the sexual identity of germ cells is determined by the sex of gonadal somatic cells. In the teleost fish medaka, a sex-determination gene on the Y chromosome, DMY/dmrt1bY, is expressed in gonadal somatic cells and regulates the sexual identity of germ cells. Here, we report a novel mechanism by which sex(More)
Molecular dissection and chemical screening on a complex process such as spermatogenesis could be facilitated by cell culture approaches that allow easy access for experimental manipulation and live imaging of specific molecules; however, technical limitations have thus far prevented the complete reconstruction of spermatogenic events in cell culture. Here,(More)
Dense 3D reconstruction of extremely fast moving objects could contribute to various applications such as body structure analysis and accident avoidance and so on. In this paper, we propose such a technique based on a one-shot scanning method that reconstructs 3D shape from a single image. To realize dense 3D reconstruction from a single image, there are(More)
An active 3D scanning device which can capture a sequential motion in realtime is strongly demanded for 3D display and other VR systems. Since most previous and commercial products basically recover the shape with a point or a line for each scan, fast motion can not be captured in principle. One solution for the purpose is to use a single pattern (one shot(More)
Many endemic fish species are threatened with extinction. Conservation strategies and the restoration of endemic fish after extinction must therefore be investigated. Although sperm cryopreservation is indispensable for the conservation of endangered fishes, the limited number of mature fish and limited availability (volume and period) of sperm from small(More)