Establishment of cell lines derived from skin biopsies of crested ibis (Nipponia nippon) and their biological characteristics

The crested ibis is among the rarest and most endangered species worldwide. To preserve its genetic resources and conveniently provide materials for biological research, we successfully established two cell lines from biopsies of a male and female adult crested ibis. The cultured cells from both specimens had typical fibroblast morphology. Immunofluorescence staining revealed that the cultured cells strongly expressed the marker of smooth muscle specific α-actin, clearly indicating the cells were from the smooth muscle tissue. Growth property analysis showed that the cells grew well past the first 10 passages and continued growing with reduced proliferation after 15 passages, but ceased by passage 25 as the cells could not grow to form a confluent monolayer. From these two cell lines, we harvested mitotic metaphase chromosomes and conducted different staining, banding, and fluorescent in situ hybridization. Throughout the process, cells maintained normal diploidy, with the karyotypes of these two cell lines being 2n=68, ZZ in the male and 2n=68, ZW in the female. Patterns of Ag staining, C- and G-bands of the crested ibis chromosomes were also studied. Banding analyses and fluorescent in situ hybridization also allowed identification of the sex chromosomes. We suggest that the external implants method for establishing primary cell lines used in this study may also be applicable to other birds, especially similarly endangered avian species.