Successful in vivo Transplantation of Cultured and Enriched Testicular Germ Cells of Pre-Pubertal Bucks to Busulfan-Treated Homologous Recipients.

The objective of the present study was to establish a workable approach for the production of germ cell (GC)-depleted recipient goat model using intra-testicular busulfan treatment and transplantation of cultured and enriched caprine-male GC (cmGCs) into the homologous recipients under ultrasonography (USG) guidance. The evaluation of post-transplantation colonization of donor cmGCs and restoration of the normal architecture of seminiferous tubules (ST) was performed. For this, the cmGCs of pre-pubertal male goats were isolated and enriched by differential platting for culture until the third passage. Thereafter, cells were harvested and further enriched by magnetic-activated cell sorting using rabbit-anti-CD90 antibody. After confirmation of metabolic viability (MTT-assay) and cluster-forming ability (crystal violet staining) of CD90+ cmGCs, the cells were labeled with a lipophilic red-fluorescent dye (PKH26) before transplanted into the recipient male goats by injection directly into the mediastinum testes under USG guidance. The colonization and repopulation of transplanted CD90+ cmGCs into the recipient ST was observed up to 8 weeks post-transplantation. The PKH26-labeled donor cell-derived colonies were identified in enzymatically digested ST and cryosections of recipient testes. Moreover, histochemical analyses revealed the restoration of the normal architecture of ST of recipient testis after GC transplantation. Therefore, the results suggest that the reproductive competence of infertile animals can be restored through mGC therapy and thus the methodology presented herein could be useful to obtain donor mGCs-derived functional male gametes in the recipient animal testis.

A Y-linked anti-Müllerian hormone duplication takes over a critical role in sex determination.

Gonadal sex determination in vertebrates generally follows a sequence of genetically programmed events. In what is seemingly becoming a pattern, all confirmed or current candidate "master" sex-determining genes reported in this group, e.g., SRY in eutherian mammals, DMY/dmrt1bY in medaka, DM-W in the African clawed frog, and DMRT1 in chicken encode transcription factors. In contrast, here we show that a male-specific, duplicated copy of the anti-Müllerian hormone (amh) is implicated in testicular development of the teleost fish Patagonian pejerrey (Odontesthes hatcheri). The gene, termed amhy because it is found in a single metacentric/submetacentric chromosome of XY individuals, is expressed much earlier than the autosomal amh (6 d after fertilization vs. 12 wk after fertilization) and is localized to presumptive Sertoli cells of XY males during testicular differentiation. Moreover, amhy knockdown in XY embryos resulted in the up-regulation of foxl2 and cyp19a1a mRNAs and the development of ovaries. These results are evidence of a functional amh duplication in vertebrates and suggest that amhy may be the master sex-determining gene in this species. If confirmed, this would be a unique instance of a hormone-related gene, a member of the TGF-ß superfamily, in such a role.

Germ cell transplantation using sexually competent fish: an approach for rapid propagation of endangered and valuable germlines.

The transplantation of germ cells into adult recipient gonads is a tool with wide applications in animal breeding and conservation of valuable and/or endangered species; it also provides a means for basic studies involving germ cell (GC) proliferation and differentiation. Here we describe the establishment of a working model for xenogeneic germ cell transplantation (GCT) in sexually competent fish. Spermatogonial cells isolated from juveniles of one species, the pejerrey Odontesthes bonariensis (Atherinopsidae), were surgically transplanted into the gonads of sexually mature Patagonian pejerrey O. hatcheri, which have been partially depleted of endogenous GCs by a combination of Busulfan (40 mg/kg) and high water temperature (25 degrees C) treatments. The observation of the donor cells' behavior showed that transplanted spermatogonial cells were able to recolonize the recipients' gonads and resume spermatogenesis within 6 months from the GCT. The presence of donor-derived gametes was confirmed by PCR in 20% of the surrogate O. hatcheri fathers at 6 months and crosses with O. bonariensis mothers produced hybrids and pure O. bonariensis, with donor-derived germline transmission rates of 1.2-13.3%. These findings indicate that transplantation of spermatogonial cells into sexually competent fish can shorten considerably the production time of donor-derived gametes and offspring and could play a vital role in germline conservation and propagation of valued and/or endangered fish species.