Meioc-Piwil1 complexes regulate rRNA transcription for differentiation of spermatogonial stem cells.

Ribosome biogenesis is vital for sustaining stem cell properties, yet its regulatory mechanisms are obscure. Herein, we show unique properties of zebrafish mutants in which spermatogonial stem cells (SSCs) do not differentiate or upregulate rRNAs. Meioc colocalized with Piwil1 in perinuclear germ granules, but Meioc depletion resulted in Piwil1 accumulation in nucleoli.

Establishment of a zebrafish inbred strain, M-AB, capable of regular breeding and genetic manipulation.

Inbred strains of organisms are genetically highly uniform and thus useful for life science research. We have previously reported the ongoing generation of the zebrafish IM strain from the India (IND) strain through full sib-pair mating for 16 generations. However, the IM fish laid a small number of offspring and had a short lifespan, implying the need for discreet care in breeding.

Storage of Functional Sperm at Room Temperature in Zebrafish and Medaka.

The longevity of sperm in teleost such as zebrafish and medaka is short when isolated even in saline-balanced solution at a physiological temperature. In contrast, some internal fertilizers exhibit the long-term storage of sperm, >10 months, in the female reproductive tract. This evidence implies that sperm in teleost possesses the ability to survive for a long time under suitable conditions; however, these conditions are not well understood.

Germ cell-specific expression of Venus by Tol2-mediated transgenesis in endangered endemic cyprinid Honmoroko (Gnathopogon caerulescens).

Fishes expressing a fluorescent protein in germ cells are useful to perform germ cell transfer experiments for conservation study. Nonetheless, no such fish has been generated in endangered endemic fishes. In this study, we tried to produce a fish expressing Venus fluorescent protein in germ cells using Honmoroko (Gnathopogon caerulescens), which is one of the threatened small cyprinid endemic to the ancient Lake Biwa in Japan.

Sycp1 Is Not Required for Subtelomeric DNA Double-Strand Breaks but Is Required for Homologous Alignment in Zebrafish Spermatocytes.

In meiotic prophase I, homologous chromosomes are bound together by the synaptonemal complex, in which two axial elements are connected by transverse filaments and central element proteins. In human and zebrafish spermatocytes, homologous recombination and assembly of the synaptonemal complex initiate predominantly near telomeres. In mice, synapsis is not required for meiotic double-strand breaks (DSBs) and homolog alignment but is required for DSB repair; however, the interplay of these meiotic events in the context of peritelomeric bias remains unclear.

Sycp2 is essential for synaptonemal complex assembly, early meiotic recombination and homologous pairing in zebrafish spermatocytes.

Meiotic recombination is essential for faithful segregation of homologous chromosomes during gametogenesis. The progression of recombination is associated with dynamic changes in meiotic chromatin structures. However, whether Sycp2, a key structural component of meiotic chromatin, is required for the initiation of meiotic recombination is still unclear in vertebrates.

Correction: Effectiveness of plasma lyso-Gb3 as a biomarker for selecting high-risk patients with Fabry disease from multispecialty clinics for genetic analysis.

The HTML version of this Article contained errors in Supplementary Figure S2 "Flowchart of the lyso-Gb3 screening and gene analysis in female patients", which have been detailed in the associated Correction.

Correction: Effectiveness of plasma lyso-Gb3 as a biomarker for selecting high-risk patients with Fabry disease from multispecialty clinics for genetic analysis.

The PDF and HTML versions of the article have been updated to include the Creative Commons Attribution 4.0 International License information.

Robust and local positional information within a fin ray directs fin length during zebrafish regeneration.

It has been proposed that cells are regulated to form specific morphologies and sizes according to positional information. However, the entity and nature of positional information have not been fully understood yet. The zebrafish caudal fin has a characteristic V-shape; dorsal and ventral fin rays are longer than the central ones.

Germ cells in the teleost fish medaka have an inherent feminizing effect.

Germ cells are the only cells that can transfer genetic materials to the next generation via the sperm or egg. However, recent analyses in teleosts revealed another essential role of germ cells: feminizing the gonads. In our study, medaka mutants in which gametogenesis was blocked at specific stages provides the novel view that the feminizing effect of germ cells occurs in parallel with other reproductive elements, such as meiosis, the sexual fate decision of germ cells, and gametogenesis.

Effectiveness of plasma lyso-Gb3 as a biomarker for selecting high-risk patients with Fabry disease from multispecialty clinics for genetic analysis.

Purpose: Plasma globotriaosylsphingosine (lyso-Gb3) is a promising secondary screening biomarker for Fabry disease. Here, we examined its applicability as a primary screening biomarker for classic and late-onset Fabry disease in males and females.

Methods: Between 1 July 2014 and 31 December 2015, we screened 2,359 patients (1,324 males) referred from 168 Japanese specialty clinics (cardiology, nephrology, neurology, and pediatrics), based on clinical symptoms suggestive of Fabry disease.

Development and growth of organs in living whole embryo and larval grafts in zebrafish.

Age-related systemic environments influence neurogenesis and organ regeneration of heterochronic parabiotic partners; however, the difficulty of manipulating small embryos prevents the effects of aged systemic environments on primitive organs at the developmental stage from being analysed. Here, we describe a novel transplantation system to support whole living embryos/larvae as grafts in immunodeficient zebrafish by the intrusion of host blood vessels into the grafts, allowing bodies similar to those of heterochronic parabiosis to be generated by subcutaneous grafting. Although grafted embryos/larvae formed most organs, not all organogenesis was supported equally; although the brain, eyes and the intestine usually developed, the liver, testes and heart developed insufficiently or even occasionally disappeared.

In vitro differentiation of fertile sperm from cryopreserved spermatogonia of the endangered endemic cyprinid honmoroko (Gnathopogon caerulescens).

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 endemic fish hinders the optimization and practical use of this material.

Differentiation of zebrafish spermatogonial stem cells to functional sperm in culture.

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, we describe the production of functional sperm from self-renewing spermatogonial stem cells (SSCs) in cell culture conditions, using zebrafish testicular hyperplasia cells that accumulate early stage spermatogonia. By serially transplanting hyperplasias into immunodeficient rag1 mutant zebrafish, we succeeded in long-term maintenance and efficient production of starting material for SSC culture.

Asymmetrical allocation of JAK1 mRNA during spermatogonial stem cell division in Xenopus laevis.

During Xenopus spermatogenesis, each primary spermatogonium (PG), the largest single cell in the testis, undergoes mitotic divisions with a concomitant decrease in size to produce smaller differentiating spermatogonia. The spermatogonial stem cells (SSCs) occur in this PG population. Taking advantage of identifiable and isolatable properties of Xenopus SSCs, we examined JAK1 gene expression during the spermatogenesis because there have been reports on the important role of JAK/STAT pathway in regulating the status of SSCs in Drosophila and mouse.

Properties of gene knockdown system by vector-based siRNA in zebrafish.

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, including embryonic manipulations, forward and reverse genetics, and molecular biology.

Production of zebrafish offspring from cultured spermatogonial stem cells.

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 SSCs after their differentiation into sperm in transplanted testicular cell aggregates. Dissociated testicular cells were cultured in specific medium with some modified supplements, including several mammalian growth factors.

Evaluation of Sycp3, Plzf and Cyclin B3 expression and suitability as spermatogonia and spermatocyte markers in zebrafish.

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 were raised against Sycp3, Plzf and Cyclin B3 in zebrafish and then used to determine the localization of these proteins in the testis.

Circadian variation in coronary flow velocity reserve and its relation to α1-sympathetic activity in humans.

Background: The circadian change in coronary microvascular function has not been directly assessed in human beings. Recent advances in transthoracic Doppler echocardiography (TTDE) provide noninvasive, physiological assessment of coronary flow velocity reserve (CFVR).

Methods: This study consisted of 20 young healthy subjects (24 ± 2 years, 20 men) who underwent CFVR examinations at 3 different times; early morning (6AM), late morning (11AM) and late evening (10PM).

Aromatherapy alleviates endothelial dysfunction of medical staff after night-shift work: preliminary observations.

Night-shift work causes mental stress and lifestyle changes, and is recognized as a risk of cardiovascular diseases associated with impaired endothelial function. Aromatherapy is becoming popular as a complementary therapy that is beneficial for mental relaxation. The purpose of this study was to investigate the effect of aromatherapy on the endothelial function of medical staff after night-shift work.

Regeneration of spermatogenesis and production of functional sperm by grafting of testicular cell aggregates in Zebrafish (Danio rerio).

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 in zebrafish (Danio rerio) in which allogeneic SSCs can undergo self-renewal and differentiation.

"Passive exercise" using whole body periodic acceleration: effects on coronary microcirculation.

Background: The whole body periodic acceleration (WBPA) system has recently been developed as a "passive exercise" device by providing increased pulsatile shear stress for improvement of endothelial function. This study aimed to investigate the short-term effect of WBPA on coronary flow reserve (CFR) through transthoracic Doppler echocardiography (TTDE) in healthy subjects and patients with coronary artery disease (CAD).

Methods: This study consisted of 15 healthy subjects and 20 patients with CAD who underwent CFR examination before and immediately after WBPA.