The potential for archiving and reconstituting valuable strains of turkey (Meleagris gallopavo) using primordial germ cells.

Diseases such as avian influenza can de-stroy turkey flocks, potentially resulting in the loss of valuable or rare genetic material. Consequently, there is an urgent need to develop a means to archive such germplasm. Germline chimeras produced by intravas-cular transfer of primordial germ cells (PGC) have been reported in other avian species but not turkeys. This study examined the feasibility of both establishing an archive of frozen PGC, and producing germline chime-ras by injecting the thawed PGC into host embryos. To meet these aims, the following experiments were per-formed: (1) PGC identification within turkey embryos; (2) development of an efficient method for isolation of turkey PGC; (3) demonstration that PGC can be cryopreserved, recovered, and retain viability; (4) re-injection into embryos and detection of injected PGC. Primordial germ cells were identified using periodic ac-id-Schiff reagent and the immunological marker OLP-1. Bloodstream PGC were isolated using Ficoll density gradient centrifugation with PGC recovery peaking at stages 13, 14, and 15 with 32 ± 4.9, 33 ± 6.4, and 26 ± 5.4 PGC recovered, respectively. Primordial germ cells were frozen using Dulbecco's modified Eagle medium, 20% fetal calf serum, and 10% dimethylsulfoxide and demonstrated 90 ± 1.7% viability after 3 mo frozen in liquid nitrogen. Freshly isolated and frozen thawed Dil- and Q-Tracker-labeled PGC repopulated stage 30 gonads after vascular transfer into ex ovo cultured embryos. The Dil-labeled cells repopulated gonads less frequently, with 36 ± 13.2% of gonads containing the Dil-labeled PGC, and 7 ± 3.8% of reinjected PGC reaching the gonads of positive embryos. The Q-track-er-labeled cells were detected more frequently in embry-os, with 67 ± 21.1% having positive signals, and 44 ± 4.9% of reinjected Q-tracker-labeled PGC colonized the gonads of positive embryos. This study demonstrated the feasibility of using turkey PGC to archive turkey germplasm from different strains because frozen PGC reintroduced into host embryos can colonize the host gonads, suggesting the possibility of producing turkey germline chimeras. [ABSTRACT FROM AUTHOR]