Primordial germ cells (PGCs) are the only cells in developing embryos with the potential to transmit genetic information to the next generation. PGCs therefore have the potential to be of value for gene banking and cryopreservation, particularly via the production of donor gametes with germ-line chimeras. Currently, it is not clear how many PGCs are required for germ-line differentiation and formation of gonadal structures. In the present study, we achieved complete germ-line replacement between two related teleost species, the pearl danio (Danio albolineatus) and the zebrafish (Danio rerio), with transplantation of a single PGC into each host embryo. We isolated and transplanted a single PGC into each blastula-stage, zebrafish embryo. Development of host germ-line cells was prevented by an antisense dead end morpholino oligonucleotide. In many host embryos, the transplanted donor PGC successfully migrated toward the gonadal anlage without undergoing cell division. At the gonadal anlage, the PGC differentiated to form one normally sized gonad rather than the pair of gonads usually present. Offspring were obtained from natural spawning of these chimeras. Analyses of morphology and DNA showed that the offspring were of donor origin. We extended our study to confirm that transplanted single PGCs of goldfish (Carassius auratus) and loach (Misgurnus anguillicaudatus) can similarly differentiate into sperm in zebrafish host embryos. Our results show that xenogenesis is realistic and practical across species, genus, and family barriers and can be achieved by the transplantation of a single PGC from a donor species.
Germ cell-deficient fish usually develop as phenotypic males. Thus, the presence of germ cells is generally considered to be essential for female gonadal differentiation or the maintenance of ovarian structure. However, little is known of the role of germ cells in the determination of the sexual fate of gonadal somatic cells. We have established an inducible germ cell deficiency system in the loach (Misgurnus anguillicaudatus, Cypriniformes: Cobitidae), a small freshwater fish, using knockdown of the dead end gene with a morpholino antisense oligonucleotide. Interestingly, loach lacking germ cells could develop as either phenotypic males or females, as characterized morphologically by the presence or absence of bony plates in the pectoral fins, respectively. The phenotypic males and females had testicular and ovarian structures, respectively, but lacked germ cells. Gene expression patterns in these male and female germ cell-deficient gonads were essentially the same as those in gonads of normal fish. Our observations indicate that sexually dimorphic gonads can develop in germ cell-deficient loach. In contrast to the situation in other model fish species, the gonadal somatic cells in phenotypic females autonomously differentiated into ovarian tissues and also played a role in the maintenance of gonadal structure. On the basis of our observations, we propose two possible models to explain the role of germ cells in sex determination in fish.dead end | gonadal development | sex differentiation
Primordial germ cells (PGCs) are the only cells in developing embryos that can transmit genetic information to the next generation. PGCs therefore have considerable potential value for gene banking and cryopreservation, particularly via production of donor gametes using germ-line chimeras. In some animal species, including teleost fish, the feasibility of using PGC transplantation to obtain donor-derived offspring, within and between species, has been demonstrated. Successful use of PGC transplantation to produce germ-line chimeras is absolutely dependent on the migration of the transplanted cells from the site of transplantation to the host gonadal region. Here, we induced germ-line chimeras between teleost species using two different protocols: blastomere transplantation and single PGC transplantation. We evaluated the methods using the rate of successful migration of transplanted PGCs to the gonadal region of the host embryo. First, we transplanted blastomeres from zebrafish, pearl danio, goldfish, or loach into blastula-stage zebrafish embryos. Some somatic cells, derived from donor blastomeres, were cotransplanted with the PGCs and formed aggregates in the host embryos; a low efficiency of PGC transfer was achieved. Second, a single PGC from the donor species was transplanted into a zebrafish embryo. In all inter-species combinations, the donor PGC migrated toward the gonadal region of the host embryo at a comparatively high rate, regardless of the phylogenetic relationship of the donor and host species. These transplantation experiments showed that the mechanism of PGC migration is highly conserved beyond the family barrier in fish and that transplantation of a single PGC is an efficient method for producing inter-species germ-line chimeras.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.