The reversible developmental unipotency of germ cells in chicken

Abstract

We recently developed bimodal germline chimera production approaches by transfer of primordial germ cells (PGCs) or embryonic germ cells (EGCs) into embryos and by transplantation of spermatogonial stem cells (SSCs) or germline stem cells (GSCs) into adult testes. This study was undertaken to investigate the reversible developmental unipotency of chicken germ cells using our established germline chimera production systems. First, we transferred freshly isolated SSCs from adult testis or in vitro cultured GSCs into stage X and stage 14-16 embryos, and we found that these transferred SSCs/GSCs could migrate to the recipient embryonic gonads. Of the 527 embryos that received SSCs or GSCs, 135 yielded hatchlings. Of 17 sexually mature males (35.3%), six were confirmed as germline chimeras through testcross analysis resulting in an average germline transmission efficiency of 1.3%. Second, PGCs/EGCs, germ cells isolated from embryonic gonads were transplanted into adult testes. The EGC transplantation induced germline transmission, whereas the PGC transplantation did not. The germline transmission efficiency was 12.5 fold higher (16.3 vs 1.3%) in EGC transplantation into testis (EGCs to adult testis) than that in SSC/GSC transfer into embryos (testicular germ cells to embryo stage). In conclusion, chicken germ cells from different developmental stages can (de)differentiate into gametes even after the germ cell developmental clock is set back or ahead. Use of germ cell reversible unipotency might improve the efficiency of germ cell-mediated germline transmission.

Spermatogonial Stem Cells

“…Gonadal germ cells isolated from 6.5 -20.5 day incubated embryos and newly hatched chicks and adult chickens entered the germline when they were transferred to the bloodstream of recipient embryos (Chang et al, 1997;Tajima et al, 1998;Han et al, 2002;Minematsu et al, 2004;Naito et al, 2007;Shiue et al, 2009). Furthermore, when spermatogonial stem cells or germline stem cells derived from chicken testes were transferred to the stage X blastoderm or bloodstream of recipient embryos, they contributed to the germline and part of them gave rise to functional gametes (Jung et al, 2010). Thus, germline cells can re-enter the germline when transferred to the stage X blastoderm or bloodstream of recipient embryos.…”

Xenogeneic Transfer of Adult Quail (Coturnix coturnix) Spermatogonial Stem Cells to Embryonic Chicken (Gallus gallus) Hosts: A Model for Avian Conservation1

“…These findings match previous reports; Li et al [35] established that chicken PGCs could be directionally differentiated into adipose, neuronlike cells and osteoblasts. Jung et al [16] reported successful transfer of both chicken adult GSCs and embryonic GGCs to embryo and adult chicken hosts, whereas Trefil et al [21,36] restored spermatogenesis in sterilized roosters by transplantation of dispersed testicular cells from chicken adult donors. Pereira et al [23] used dispersed adult quail testis cells to recolonize and reinitiate spermatogenesis in irradiated adult roosters.…”

“…Instead, routine collection of GSCs at the time of necropsy of genetically valuable individuals would be a more feasible method of preserving germplasm, because self-renewing spermatogonial stem cells (spermatogonia A d ; see Lin and Jones [19]) are found throughout the reproductive lifespan of a bird. Previous studies by Minematsu et al [20] and Jung et al [16] have demonstrated that adult chicken gonads contain cells, presumably spermatogonia A d , that are capable of migrating and colonizing the gonadal ridge following transfer to host chicken embryos stages 14-17. Likewise, Trefil et al [21] and Lee et al [22] reported that dispersed testicular cells from both prepubertal and adult donors transferred directly into sterilized adult host testes recolonized the seminiferous tubules of the conspecific host, partially resumed spermatogenesis, and produced donor-derived offspring.…”

“…For example, both chicken [9] and quail (Coturnix coturnix) [10] PGCs injected into the vitelline blood vessels of stages 14-17 chicken host embryos, as well as chicken PGCs transferred into quail embryos [11], will migrate to the host's gonadal ridge. In fact, donor-derived offspring have been produced following intraspecies [5,[12][13][14][15][16] and interspecies [17,18] transfer of PGCs or GGCs.…”

“…Gonadal germ cells and GSCs, unlike PGCs, are relatively easy to maintain in both short-and long-term culture prior to successful transfer and colonization of the host gonad [16,24,25]. The current study investigates the migration of presumed spermatogonia A and colonization of host gonads following xenotransfer of adult quail testicular cells to host chicken embryos.…”