Species: Chinese Hamster
Tissue: Ovary
Mode of Growth: attached
Method of Passage: Trypsin - EDTA
Culture Medium: DMEM / MCDB 302 with 10 % FBS (in roller bottles with HEPES)
Freeze Medium: culture medium + 10 % DMSO
ATCC: ATCC CCL-61 CHO-K1 (Ovary, Chinese hamster, Cricetulus griseus), proline reqiuring, Current medium for propagation: Ham's F-12 medium, 90%; FBS, 10%. The CHO-K1 cells were derived as a subclone from the parental CHO cell line initiated from a biopsy of an ovary of an adult Chinese hamster by T.T. Puck in 1957 (J. Exp. Med. 108: 945, 1958). The original culture medium consisted of Medium N16 with Saline F, 81%; NCTC 109, 4%; FBS, 15%. For subclones the culture medium was changed to Ham's F-12 Medium (Proc. Natl. Acad. Sci. USA 52: 288, 1965) plus FBS. The CHO-K1 cells have a requirement for proline and a modal chromosome number of 20 (Proc. Natl. Acad. Sci. USA 60: 1275, 1968). The cells apparently lack the active gene form needed for proline synthesis and the block in the biosynthetic chain lies in the step converting glutamic acid to glutamic gamma-semialdehyde. The reversion frequency to proline independence is approximately 10(-6) (Genetics 55: 513, 1967). The cells have been used for the induction and isolation of nutritionally deficient mutants (Proc. Natl. Acad. Sci. USA 60: 1275, 1968) and in studies relating to the regulation of gene expression through hybridization (Science (Washington, DC) 164: 312, 1969; Proc. Natl. Acad. Sci. USA 64: 1284, 1969). The cell line was submitted to the American Type Culture Collection in June, 1970, after undergoing over 400 serial subcultivations from the tissue of origin. DESCRIPTION OF REPOSITORY REFERENCE SEED STOCK Number of Serial Subcultures from Tissue of Origin: Approximately 400; 7 at ATCC. Freeze Medium: Culture medium, 92%; glycerol, 8%; antibiotic-free. Viability: Approximately 90% (dye exclusion). Culture Medium: F-12 Medium (Ham) 90%; FBS, 10%; antibiotic-free. Growth Characteristics of Thawed Cells: An inoculum of 10(5) viable cells/ml in the above culture medium at 37C increases 15- to 20-fold within 7 days. Plating Efficiency: Approximately 90% in the above culture medium. Morphology: Epithelial-like. Karyology: Chromosome Frequency Distribution 50 Cells: 2n = 22 Cells: 2 2 35 3 4 1 1 1 1 Chromosomes: 18 19 20 21 22-24-32-39-42 Stemline number is hypodiploid. Sterility: Tests for mycoplasma, bacteria, and fungi were negative. Species: Confirmed as Chinese hamster by cytotoxic-antibody dye-exclusion test and isoenzyme analysis. Virus Susceptibility: Susceptible to vesicular stomatitis (Indiana Strain), and Getah arboviruses. Not susceptible to poliovirus type 2, Modoc and Button Willow arboviruses. Reverse Transcriptase: Not detected. Special Characteristics: The reference cells require proline for growth. Submitted by: T.T. Puck, Eleanor Roosevelt Institute for Cancer Research, University of Colorado Medical Center, Denver, CO. Prepared and characterized by: ATCC, Rockville, MD. Price Code: J