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1.
Diploid gametes generated with tetraploid animals are a stepping stone to improving chromosome manipulation techniques. However, artificially induced tetraploid individuals generally die soon after hatching. Diploid gametes could be induced by in vivo cultures of tetraploid primordial germ cells (PGCs) through germ-line chimera. In the present study, characteristics of PGCs were studied in inviable tetraploid masu salmon, Oncorhynchus masou. Histological observation of tetraploid embryos revealed that the same or smaller numbers of PGCs were observed and they migrate into the genital ridges as did diploid PGCs during gonadogenesis. By whole-mount in situ hybridization using vasa messenger RNA (mRNA), 4–35 vasa-positive signals were detected in a pair of genital ridges of tetraploids. By cytological observation of genital ridge cell suspensions, several large round cells were observed, some of which extended pseudopodia. They also contained large nuclei and round granules in their cytoplasm, characteristics of PGCs. As the results suggest that inviable artificial tetraploids have PGCs, we expect to achieve diploid gamete production through surrogate propagation and tetraploid fish production.  相似文献   

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生殖细胞移植是指将供体的生殖细胞移植到同种或异种受体体内,供体生殖细胞嵌合到受体性腺,经过增殖、分化并最终发育为功能性配子的过程。作为辅助生殖技术,它不仅为珍稀濒危动物的繁育和保护提供了新途径,同时也为生殖干细胞的功能研究提供了有效手段。鱼类生殖细胞移植研究首先在模式鱼类斑马鱼中开展,经过十多年的发展,取得了一系列突破性的进展:主要包括先后建立了以胚胎、仔鱼和成鱼为受体的生殖细胞移植体系,精原和卵原干细胞的发现拓宽了供体生殖细胞的选择,受体的选择与制备方法的完善。该技术在缩短鱼类性成熟周期、性控育种、珍稀濒危鱼类保护等方面具有巨大的应用前景,已成功在多种淡水和海水鱼类中开展了研究和应用。本文结合作者的研究实践和经验,系统地梳理和总结了鱼类生殖细胞移植的研究进展,指出了该技术实践应用的关键问题,并探讨了其应用前景。  相似文献   

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We reported previously that two isoforms of vasa mRNA and protein are present in tilapia (Kobayashi et al. 2002). One (vas-s) lacks a part of the N-terminal region found in the other isoform (vas). Both isoforms are expressed in oocytes through the embryonic stages when PGCs localize in the lateral plate mesoderm. After PGCs localized in the gonadal anlagen, vas-s expression increased and vas expression became undetectable. Expression of both isoforms was observed again after morphological gonadal sex differentiation, irrespective of genotypic sexes. These changes are in accordance with sex differences in number of gonial germ cells during this period, suggesting that molecular sexual dimorphism occurs in germ cells between both sexes during this period.  相似文献   

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Recently, we developed an intraspecies spermatogonial transplantation technique in a pelagic egg spawning marine teleost, nibe croaker Nibea mitsukurii. Nibe croaker is an ideal candidate recipient for spermatogonial transplantation since it has a short generation time and small body size. In the present study, yellowtail Seriola quinqueradiata spermatogonia were transplanted into nibe croaker larvae, and the behavior of transplanted spermatogonia in recipient gonads was observed. Three weeks post-transplantation, yellowtail spermatogonia were incorporated into the gonads of 72 out of 88 recipients. An antiproliferating cell nuclear antigen was detected in incorporated yellowtail spermatogonia, suggesting that the xenogenic germ cells were proliferating in recipient gonads. Yellowtail vasa-positive spermatogonia survived for 11 months after transplantation in the gonads of recipient fish. Thus, we showed that the microenvironment in nibe croaker gonads can support the colonization, proliferation, and survival of germ cells derived from a different taxonomic family.  相似文献   

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Interspecific transplantation of germ cells from the brown trout Salmo trutta m. fario and the European grayling Thymallus thymallus into rainbow trout Oncorhynchus mykiss recipients was carried out in order to improve current practices in conservation of genetic resources of endangered salmonid species in the Balkan Peninsula. Current conservation methods mainly include in situ efforts such as the maintenance of purebred individuals in isolated streams and restocking with purebred fingerlings; however, additional ex situ strategies such as surrogate production are needed. Steps required for transplantation such as isolation of high number of viable germ cells and fluorescent labeling of germ cells which are to be transplanted have been optimized. Isolated and labeled brown trout and grayling germ cells were intraperitoneally transplanted into 3 to 5 days post hatch rainbow trout larvae. Survival of the injected larvae was comparable to the controls. Sixty days after transplantation, fluorescently labeled donor cells were detected within the recipient gonads indicating successful incorporation of germ cells (brown trout spermatogonia and oogonia—27%; grayling spermatogonia—28%; grayling oogonia—23%). PCR amplification of donor mtDNA CR fragments within the recipient gonads additionally corroborated the success of incorporation. Overall, the transplantation method demonstrated in this study presents the first step and a possible onset of the application of the germ cell transplantation technology in conservation and revitalization of genetic resources of endangered and endemic species or populations of salmonid fish and thus give rise to new or improved management strategies for such species.  相似文献   

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Domestication is a long-term process during which wild fish are acclimated to farming conditions and hopefully are reproduced over several generations, possibly using selective breeding. Preservation of the genetic diversity of the original population, together with that of the ongoing selection steps, is important for ecological and economical purposes. Cryobanking of reproductive cells is one answer to meet this need. In fish, however, only sperm can be cryopreserved as neither oocytes nor embryos are capable of handling the freeze-thawing stress. In this review, we explore to what extent diploid cells obtained from fin pieces can be used for the preservation of both parental genomes. The main parameters, which should be under control to ensure proper production of fin cells in culture and to enable cryopreservation of the material are described. After cryobanking of such non-reproductive cells, fish can be reconstructed using the nuclear transfer technology whose potentials and difficulties are discussed. The gametes produced by the fish reconstructed after somatic cells nuclear transfer are different to some extent from the gametes obtained after the direct transplantation of primordial germ cell or spermatogonial germ cells into host embryos or larvae. However, in some cases, only somatic cells can be obtained in quantities which would be compatible with strain restoration purposes. From the knowledge available today, it is reasonable to expect that nuclear transfer becomes available for fish reconstruction, even if restricted to high-tech biotechnology facilities. Therefore, cryobanking of fin somatic cells can be farsightedly considered for high-throughput diploid genome conservation.  相似文献   

10.
在鱼类的早期胚胎发育中生殖细胞便与体细胞分离,形成所谓的原始生殖细胞(Primordial germ cells,PGCs)。母源性基因Dead end(dnd)在胚胎发育中特异地表达于原始生殖细胞,编码一种进化上保守的RNA结合蛋白,对生殖细胞发育具有重要作用。本研究通过PCR获得大黄鱼(Larimichthys crocea)dnd基因(Lcdnd)的部分cDNA序列,结合实时定量PCR、整胚原位杂交等技术,研究Lcdnd在各组织和胚胎发育中的表达。实时定量PCR结果显示:dnd在性腺中特异表达,且其在卵巢中的表达量高于精巢;检测的各期胚胎中都有dnd的表达,随着胚胎的发育其表达量呈下降的趋势。整胚原位杂交结果显示:Lcdnd在早期卵裂阶段主要分布于分裂沟,到囊胚期至原肠早期则开始定位于细胞内,原肠早期时定位在胚环中的中内胚层,且阳性信号增多,暗示此时原始生殖细胞的形成。接着原始生殖细胞沿胚环向胚体形成处(胚盾)迁移;随着胚胎的发育,发现胚体两侧的阳性信号增多;到体节发生期,阳性信号细胞分布于胚体两侧的侧板中胚层,随着体节的发生这些细胞沿背腹轴向腹部运动;发育到孵出期时,到达了发育中的原始生殖嵴。本研究首次使用dnd作为一种较为可靠的大黄鱼生殖细胞标记,揭示了大黄鱼原始细胞的起源与迁移,为大黄鱼生殖细胞发生发育及养殖大黄鱼的育性控制的研究奠定了一定的基础。  相似文献   

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Although the use of germ cell transplantation has been relatively well established in mammals, the technique has only been adapted for use in fish after entering the 2000s. During the last decade, several different approaches have been developed for germ cell transplantation in fish using recipients of various ages and life stages, such as blastula-stage embryos, newly hatched larvae and sexually mature specimens. As germ cells can develop into live organisms through maturation and fertilization processes, germ cell transplantation in fish has opened up new avenues of research in reproductive biotechnology and aquaculture. For instance, the use of xenotransplantation in fish has lead to advances in the conservation of endangered species and the production of commercially valuable fish using surrogated recipients. Further, this could also facilitate the engineering of transgenic fish. However, as is the case with mammals, knowledge regarding the basic biology and physiology of germline stem cells in fish remains incomplete, imposing a considerable limitation on the application of germ cell transplantation in fish. Furthering our understanding of germline stem cells would contribute significantly to advances regarding germ cell transplantation in fish.  相似文献   

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鱼类生殖细胞移植技术是通过诱导不同物种之间生殖系嵌合体来实现。原始生殖细胞和精原细胞(或卵原细胞)是诱导生殖细胞系嵌合体的关键材料。在过去的十多年中,通过采用不同的供体生殖细胞和不同发育阶段(囊胚期胚胎、初孵仔鱼和成鱼)的鱼为受体,开发出多种鱼类生殖细胞移植技术。这些成果的取得,为生殖细胞移植技术应用于诸多水产养殖新兴领域打下了坚实基础。该技术可以应用于:(1)生殖细胞生物学和转基因鱼等基础研究;(2)遗传资源和濒危鱼种的保护;(3)鱼类性别选择育种;(4)有效提高放流鱼苗的遗传多样性。  相似文献   

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Cre/loxP-mediated cell targeting is considered to be a powerful tool for biotechnology in farmed fish. As a first step toward establishing cell targeting in salmonids, we analyzed the functionality of the Cre/loxP system in rainbow trout. We first established stable transgenic strains carrying the DsRed gene, which was flanked by loxP sites and further spliced with the EGFP gene. By microinjecting Cre complementary RNA (cRNA) into fertilized eggs of the transgenic trout, the functionality of the Cre/loxP system was evaluated. The results showed that all of the embryos exhibited green fluorescence in at least some of their cells. While 19 out of 20 embryos comprised cells showing both green and red fluorescence, the remaining embryo showed only green fluorescence. Polymerase chain reaction (PCR) using primers designed to recognize sequences outside of the two loxP sites revealed that, in addition to long intact fragments, the 19 individuals carried short fragments that were equivalent in length to the loxP-excised fragments. The remaining green embryo carried only this short fragment. DNA sequencing of the short fragment revealed that it lacked the DNA fragments flanking the loxP sites and the spliced fragments did not contain any sequence rearrangements. These results suggest that the Cre/loxP system is functional in rainbow trout.  相似文献   

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The present study aimed to investigate whether the Gfra1/Gdnf and/or Kit/Kitlg regulatory pathways could be involved in the regulation of spermatogonial cell proliferation and/or differentiation in fish. Homologs of the mammalian gfra1, gdnf, kitr, and kitlg genes were identified in gnathostomes and reliable orthologous relationships were established using phylogenetic reconstructions and analyses of syntenic chromosomal fragments. Gene duplications and losses occurred specifically in teleost fish and members of the Salmoninae family including rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). Some duplicated genes exhibited distinct spatiotemporal expression profiles and were differently regulated by hormones in rainbow trout. Undifferentiated type A spermatogonia expressed higher levels of kitrb and kitra2 making them possible target cells for the gonadal kitlgb and somatic kitlga before the onset of spermatogenesis. Interestingly, gdnfa and gdnfb ohnologous genes were poorly expressed before the onset of spermatogenesis. The expression level of gdnfb was correlated with that of the vasa gene suggesting that the late increased abundance of gdnfb during spermatogenesis onset was due to the increased number of spermatogonial cells. gfra1a2 was expressed in undifferentiated type A spermatogonia whereas gfra1a1 was mainly detected in somatic cells. These observations indicate that the germinal gdnfb ligand could exert autocrine and paracrine functions on spermatogonia and on testicular somatic cells, respectively. Fsh and androgens inhibited gfra1a2 and gdnfb whereas gfra1a1 was stimulated by Fsh, androgens, and 17α, 20β progesterone. Finally, our data provide evidences that the molecular identity of the male germ stem cells changes during ontogenesis prior to spermatogenesis onset.  相似文献   

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The timing of primordial germ‐cell (PGC) migration with regard to the gonadal anlagen, gonad formation and sex differentiation was examined histologically in the chub mackerel (Scomber japonicus) at 5–190 days post hatching (dph). At 5 dph, PGCs appeared on the peritoneal epithelium surface or in the mesentery, on the dorsal side of the abdominal cavity. By 10 dph, stromal cells around the PGCs proliferated. The gonadal primordium was formed by 15 dph. The gonadosomatic index was 0.01% at 30 dph and increased thereafter (0.32% in females and 0.04% in males at 160 dph). Ovarian differentiation occurred at 30–40 dph, indicated by ovarian cavity formation (elongation and fusion of the upper and lower ovarian edges). Meiosis was subsequently initiated. A few meiotic oocytes surrounded the cavity at 50 dph; most were in the perinucleolus stage at 60 dph and attained a diameter of 60–70 μm at 190 dph. Testicular differentiation occurred at 30 dph, indicated by the formation of the sperm duct primordium. Spermatogonia gradually proliferated, developing into spermatocytes at the chromatin–nucleolus stage (after 90 dph) and subsequently into spermatids and spermatozoa (160 dph). These data could aid the development of seeding and cell‐engineering technologies for scombrid fish.  相似文献   

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Cryopreservation of trout primordial germ cells   总被引:2,自引:0,他引:2  
A method for cryopreserving trout primordial germ cells (PGCs) was established. Trout PGCs were successfully cryopreserved with high survival by freezing with medium containing 1.8 M ethylene glycol. Transplantation experiment revealed that frozen/thawed PGCs colonized and proliferated in the recipients' gonads.  相似文献   

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石鲽仔、幼鱼性腺发育的组织学观察   总被引:1,自引:1,他引:0       下载免费PDF全文
利用组织学方法对人工培育的石鲽(Kareius bicoloratusBasiewsky)仔、幼鱼性腺发育进行研究。结果表明,性腺的发育与体长密切相关。刚孵化石鲽的原生殖细胞数目为2个,孵化3 d数目增至8个,之后经过迁移,至孵化9 d到达生殖嵴。在全长为7.2~8.5 mm(孵化9~11 d)的仔鱼中,性腺原基中的体细胞迅速增殖并包围原生殖细胞,后者在全长10~15 mm(孵化后10~35 d)的仔幼鱼中增殖成为生殖干细胞。原始性腺在全长15~30 mm(孵化40~60 d)的幼鱼中逐渐发育完善,呈细线状,位于腹腔后部中肾管下方紧贴体壁。雌性性腺最早在全长32.5 mm(孵化66 d)的个体中出现分化特征,至全长89~102 mm时雌性性腺特征完全分化。雄性性腺的分化较雌性性腺晚,最早在全长为91 mm的幼鱼中开始,至全长为114~118 mm时雄性性腺分化特征已经十分明显。  相似文献   

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